1.01 Approaching the Breathless Patient

First decision: acuity and physiology. Sudden dyspnoea suggests pulmonary embolism (PE), pneumothorax, pulmonary oedema, aspiration or anaphylaxis; subacute symptoms suggest infection, pleural effusion or an exacerbation of airways disease; gradual symptoms suggest COPD, ILD, pulmonary hypertension, anaemia or cardiac disease.

• Immediate assessment: ABCDE, respiratory rate, work of breathing, ability to speak, mental status, BP, pulse, temperature and SpO₂. Look for cyanosis, stridor, unilateral absent breath sounds, raised JVP and signs of shock.
• Bedside tests: ECG, chest X-ray when stable, blood glucose, blood gas if ventilatory failure is possible; targeted bloods including FBC, U&E, CRP, troponin/BNP if indicated. Use lung ultrasound when available.
• Reasoning: Wheeze is not synonymous with asthma; it may occur in pulmonary oedema or a central airway lesion. Clear lungs with severe hypoxaemia suggest PE, early pneumonia or a shunt.
• Red flags: Exhaustion, falling consciousness, silent chest, hypotension, new stridor or rapidly rising oxygen requirements require senior/critical-care assistance.

MLA pearl: A normal oxygen saturation does not exclude impending ventilatory failure; a rising PaCO₂ and deteriorating clinical effort are more concerning than a single pulse oximeter reading.

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1.02 Acute and Chronic Cough

Classify by duration and context. Acute cough is commonly viral; persistent cough requires review of smoking, ACE inhibitors, asthma, upper-airway cough syndrome, gastro-oesophageal reflux, bronchiectasis, COPD, ILD and malignancy.

• Ask about: sputum quantity, blood, fever, weight loss, nocturnal symptoms, aspiration, occupational exposures, travel, TB contact and immunosuppression.
• Examine: ENT and chest, clubbing, lymph nodes and cardiovascular status. Persistent or unexplained cough merits chest imaging and spirometry as appropriate.
• Management: Treat the identified cause; avoid indiscriminate antibiotics or prolonged empirical steroid courses. Refer urgently for unexplained haemoptysis or features of suspected cancer under NICE pathways.

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1.03 Haemoptysis: From Streaks to Major Bleeding

Distinguish haemoptysis from haematemesis and upper-airway bleeding. Causes include infection/bronchiectasis, lung cancer, TB, PE, vasculitis and pulmonary–renal syndromes.

• Initial priorities: Assess haemodynamic stability, blood loss, airway protection, oxygenation and anticoagulant exposure; obtain FBC, clotting, group and save, renal function and imaging according to stability.
• Life-threatening haemoptysis: Call anaesthetics, respiratory and interventional radiology immediately. Place the bleeding lung down if the side is known, to protect the opposite lung; arrange targeted airway management, CT angiography and often bronchial artery embolisation.
• Smaller-volume bleeding: Chest X-ray and risk-adapted CT/bronchoscopy; assess persistent bleeding or cancer risk urgently.

Clinical pearl: Death in major haemoptysis is more often due to asphyxia than exsanguination.

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1.04 Wheeze, Stridor and Noisy Breathing

• Polyphonic expiratory wheeze: generalized intrathoracic airway narrowing, typically asthma or COPD.
• Monophonic wheeze: localized obstruction, e.g. endobronchial tumour, mucus plug or foreign body.
• Inspiratory stridor: obstruction at the larynx or proximal trachea; assess for anaphylaxis, epiglottitis, croup, foreign body, tumour or post-extubation swelling.
• Inspiratory crackles: fibrosis, pulmonary oedema or consolidation, depending on character and distribution.

Urgency: New stridor, drooling, inability to speak or agitation with deteriorating breathing demands immediate airway-specialist assessment. Do not force throat examination in a child with suspected epiglottitis.

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1.05 Pleuritic Chest Pain

Mechanism: Inflamed parietal pleura causes sharp pain worsened by breathing or coughing; lung parenchyma itself has few pain fibres.

• Must exclude: PE, pneumothorax, pneumonia, pericarditis and occasionally aortic disease/ACS.
• Questions: Sudden onset? Unilateral? Hypoxaemia? Haemoptysis? Leg swelling? Fever? Immobilisation, surgery, oestrogen exposure, pregnancy or cancer?
• Tests: ECG and chest X-ray, Wells-based PE testing where appropriate; troponin if cardiac cause suspected. A normal chest X-ray does not exclude PE.

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1.06 Clinical Respiratory Examination and Signs

Perform a consistent examination: inspection (rate, effort, oxygen delivery, cachexia), hands (clubbing, cyanosis, tremor/asterixis), face/neck (nodes, trachea, JVP), and chest expansion, percussion, auscultation and vocal resonance.

• Consolidation: reduced expansion, dull percussion, bronchial breathing, crackles, increased vocal resonance.
• Pleural effusion: stony dull, reduced breath sounds and vocal resonance.
• Pneumothorax: hyperresonance and reduced/absent sounds; tension is a clinical diagnosis with physiological compromise.
• Fibrosis: fine late-inspiratory bibasal crackles, reduced expansion ± clubbing.
• COPD: prolonged expiration, wheeze, hyperinflation; severe disease may have quiet breath sounds.

Exam trap: Clubbing is not explained by uncomplicated asthma or COPD; consider malignancy, bronchiectasis, fibrosis or another cause.

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1.07 Respiratory Physiology: V/Q and the A–a Gradient

Gas exchange depends on ventilation (V), perfusion (Q) and diffusion. Low V/Q regions (pneumonia, COPD) receive blood but insufficient ventilation; high V/Q regions (PE) are ventilated but poorly perfused. A true right-to-left shunt responds less well to added oxygen.

• Type 1 failure: low PaO₂ without primary hypercapnia; consider V/Q mismatch, shunt or diffusion limitation.
• Type 2 failure: elevated PaCO₂ due to insufficient alveolar ventilation from airway, chest-wall, neuromuscular or central causes.
• Alveolar gas equation: PAO₂ ≈ FiO₂ × (atmospheric pressure − water-vapour pressure) − PaCO₂/R; the A–a oxygen gradient helps differentiate hypoventilation from impaired gas exchange, using the inspired oxygen concentration and patient age.

MRCP pearl: Pure hypoventilation can lower PaO₂ with a near-normal A–a gradient; parenchymal disease generally widens it.

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1.08 Smoking, Vaping and Exposure History

• Smoking: calculate pack-years; assess current smoking, passive exposure and readiness to stop. Offer behavioural support and evidence-based pharmacotherapy through UK stop-smoking services.
• Vaping: ask about use, source and symptoms; it may reduce exposure for adults switching completely from smoking, but is not harmless and should not be recommended to non-smokers.
• Work/exposures: asbestos (pleural plaques, asbestosis, mesothelioma), silica (silicosis and TB risk), cotton dust, isocyanates, flour/wood dust, birds, mould and metal fumes.
• Travel and immunity: TB, fungal exposure, HIV, transplant and immunosuppressant use change the differential markedly.

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1.09 When to Refer: Same Day, Urgent and Routine

• Emergency: airway compromise/stridor, major haemoptysis, tension pneumothorax, severe hypoxaemia, suspected high-risk PE, severe asthma or acute hypercapnic acidosis.
• Urgent suspected-cancer pathway: follow NICE NG12 indications, including radiological suspicion and unexplained haemoptysis in an adult aged 40 or over.
• Specialist respiratory: suspected ILD, persistent unexplained breathlessness, severe or uncontrolled asthma, recurrent pneumothorax, unexplained pleural effusion, persistent lobar opacity, PH and OSA with driving risk.
• Safety-netting: explain when to seek review for worsening breathlessness, chest pain, new haemoptysis, syncope or deteriorating oxygenation.

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1.10 Respiratory Care in Frailty and Older Adults

Presentation can be atypical: pneumonia may present with delirium, falls, anorexia or functional decline without prominent fever. Respiratory rate is often the earliest abnormal observation.

• Aspiration: assess swallowing and cough effectiveness, oral hygiene, positioning and medication burden; dysphagia does not automatically mean every aspiration event is bacterial pneumonia.
• Delirium and hypercapnia: avoid attributing reduced consciousness to dementia or infection without checking ventilation and metabolic causes.
• Individualise: NIV tolerance, frailty, escalation plans, rehabilitation, home oxygen, anticoagulation and patient goals. Document ceilings of treatment separately from routine antibiotic or oxygen decisions.

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2.01 Respiratory Symptoms and Signs

Key symptoms:

• Breathlessness: Grade it with the MRC dyspnoea scale:
  • 1 — only on strenuous exercise.
  • 2 — when hurrying or walking up a slight hill.
  • 3 — walks slower than people of the same age, or stops for breath on the flat.
  • 4 — stops after about 100 m.
  • 5 — too breathless to leave the house.
  Ask about speed of onset, orthopnoea, wheeze and triggers.
• Cough: Acute (under 3 weeks) is usually infection. Chronic (over 8 weeks) causes:
  • Asthma.
  • Reflux.
  • Upper airway (rhinosinusitis).
  • ACE inhibitors.
  • COPD; bronchiectasis.
  • Lung cancer; ILD.
• Sputum: Large daily volumes suggest bronchiectasis.
• Haemoptysis: Always needs a chest X-ray. Smokers over 40 need urgent cancer assessment.
• Chest pain: Pleuritic (sharp, worse on breathing) suggests pleurisy, PE or pneumothorax.
• Systemic and other: Weight loss, night sweats (TB, cancer, lymphoma), snoring and daytime sleepiness (sleep apnoea).
• Exposures: Smoking (pack-years = packs a day × years), occupation (asbestos, dusts, birds, moulds), travel, pets, drugs.

Key signs:

• Clubbing:
  • Lung cancer, ILD (especially IPF), bronchiectasis and CF, empyema and lung abscess, mesothelioma.
  • Also cyanotic heart disease, endocarditis, IBD, cirrhosis.
  • Not caused by COPD or asthma — clubbing in COPD should prompt a search for cancer.
• Crackles:
  • Fine, late inspiratory ("Velcro") crackles — pulmonary fibrosis.
  • Coarse crackles — bronchiectasis, pulmonary oedema, pneumonia.
• Wheeze: Widespread (asthma, COPD) or fixed monophonic (a single narrowed airway — tumour, foreign body).
• Stridor: Upper airway narrowing.
• Dullness to percussion:
  • "Stony" dullness with absent breath sounds — effusion.
  • Dull with bronchial breathing — consolidation.
• Hyper-resonance with reduced breath sounds — pneumothorax, emphysema.
• Tracheal deviation:
  • Away from a large effusion or tension pneumothorax.
  • Towards collapse or fibrosis.
• Signs of right heart failure (cor pulmonale) — raised JVP, oedema, loud P2.

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2.02 Spirometry

What it measures: The patient breathes in fully, then blows out as hard and as long as possible.

• FEV1: Volume blown out in the first second.
• FVC: Total volume blown out (forced vital capacity).
• FEV1/FVC ratio: The key to telling obstruction from restriction.

Reading the result:

• Obstructive pattern — air cannot get out quickly:
  • FEV1/FVC ratio low — below the lower limit of normal (LLN), or below 0.7 in traditional COPD criteria.
  • FEV1 reduced; FVC normal or mildly reduced.
  • Causes: Asthma, COPD, bronchiectasis, CF, obliterative bronchiolitis.
• Restrictive pattern — the lungs cannot fill:
  • FEV1 and FVC both reduced, with a normal or high ratio.
  • Confirm restriction with lung volumes (low TLC) — a low FVC alone can be caused by air trapping or poor effort.
  • Causes:
    • Lung: ILD and fibrosis.
    • Outside the lung: obesity, chest wall deformity (kyphoscoliosis), neuromuscular weakness, pleural thickening, large effusion.
• Mixed: Both a low ratio and low lung volumes.

Severity of obstruction (by FEV1 % predicted, as used for COPD):

• Mild: 80% or more.
• Moderate: 50–79%.
• Severe: 30–49%.
• Very severe: below 30%.

Bronchodilator reversibility: Repeat spirometry 15–20 minutes after salbutamol. An FEV1 rise of 12% or more and 200 mL or more supports asthma. Large reversibility is unusual in COPD.

Reference values: UK guidance (ARTP/BTS) now recommends Global Lung Function Initiative equations and using the lower limit of normal and z-scores, rather than fixed cut-offs, to reduce over-diagnosis in older people.

💡 Clinical Pearl: Spirometry needs good technique — a hard, fast start and at least 6 seconds of blowing. Poor effort lowers both FEV1 and FVC and can look "restrictive". Always look at the trace, not just the numbers.

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2.03 Flow–Volume Loops

A flow–volume loop plots airflow (vertical axis) against lung volume (horizontal axis) through a full forced breath out and in. Its shape gives extra diagnostic clues:

• Normal: A sharp expiratory peak followed by a straight-ish decline, and a rounded inspiratory curve below.
• Obstructive (asthma, COPD): The expiratory limb is "scooped out" (concave) as small airways collapse. In emphysema there is a sharp fall after the peak.
• Restrictive: A normal shape but narrow (small volume), sometimes a tall "witch's hat" shape.
• Upper airway obstruction:
  • Fixed (tracheal stenosis, goitre, tumour): Both limbs flattened — a "box" shape.
  • Variable extrathoracic (vocal cord palsy, laryngeal problems): The inspiratory limb is flattened.
  • Variable intrathoracic (tracheomalacia, tumour in the lower trachea): The expiratory limb is flattened.

💡 Clinical Pearl: A "box-shaped" loop or an unexpectedly low peak flow compared with FEV1 suggests upper airway narrowing. Think tracheal stenosis after intubation, or a retrosternal goitre, in "asthma" that doesn't respond to treatment.

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2.04 Lung Volumes and Gas Transfer

Lung volumes (body plethysmography or gas dilution):

• Total lung capacity (TLC):
  • Low — true restriction (ILD, chest wall or neuromuscular disease).
  • High — hyperinflation (emphysema, severe asthma).
• Residual volume (RV): High in air trapping (COPD, asthma).

Gas transfer (TLCO, also called DLCO): The patient breathes in a tiny amount of carbon monoxide and holds the breath. TLCO measures how well gas crosses from the alveoli into the blood. KCO is the transfer per unit of lung volume.

💡 Clinical Pearl: Breathless with normal spirometry? Check the TLCO. A low TLCO with normal lung volumes and clear lungs suggests pulmonary vascular disease (PE, pulmonary hypertension) or early emphysema or ILD.

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2.05 Peak Flow Monitoring

• Peak expiratory flow (PEF): The fastest flow of air in a short, sharp blow. Simple and cheap — patients can measure it at home.
• Uses:
  • Assessing acute asthma severity (PEF as % of best or predicted).
  • Diagnosing asthma: Record PEF twice daily for 2 weeks. Variability (amplitude % mean) of 20% or more supports the diagnosis.
  • Occupational asthma: Serial PEF at least 4 times a day, at work and away from work — analysed with OASYS.
  • Asthma self-management plans.
• Limitations: Effort-dependent; less sensitive than spirometry; not useful in COPD diagnosis.

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2.06 FeNO and Bronchial Challenge Tests

• Fractional exhaled nitric oxide (FeNO):
  • What it shows: Nitric oxide in breath, which rises with eosinophilic (type 2) airway inflammation.
  • Diagnosis: In adults, a FeNO of 50 ppb or more confirms asthma when the history is typical (BTS/NICE/SIGN 2024).
  • Monitoring: A high FeNO in treated asthma suggests poor adherence to inhaled steroid, or ongoing inflammation. It helps choose patients for biologics.
  • Lowered by smoking and inhaled steroids. Raised by atopy and rhinitis.
• Bronchial challenge testing (specialist):
  • Inhaled methacholine, histamine or mannitol in increasing doses.
  • A fall in FEV1 at low doses shows bronchial hyperresponsiveness.
  • Useful when the diagnosis of asthma is still uncertain after other tests. A negative test makes current asthma unlikely.
• Blood eosinophils: A count above the laboratory range supports asthma (BTS/NICE/SIGN). In COPD, eosinophils of 300 cells/µL or more predict benefit from inhaled steroids.

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2.07 Respiratory Muscle Tests

• Who needs them: Neuromuscular disease (MND, myasthenia, GBS, muscular dystrophy), unexplained breathlessness on lying flat, or a raised hemidiaphragm.
• Lying and standing FVC: A fall of more than 20% on lying down suggests diaphragm weakness. In bilateral diaphragm paralysis there is marked orthopnoea and paradoxical abdominal movement.
• Sniff nasal inspiratory pressure (SNIP) and maximal inspiratory and expiratory pressures (MIP, MEP): Measure breathing muscle strength directly. Used to monitor MND and to decide when to start NIV.
• Peak cough flow: Below about 270 L/min means a weak cough, and a risk of chest infections and secretion retention.
• Overnight oximetry or CO2 monitoring: Detects nocturnal hypoventilation, which comes before daytime respiratory failure.

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2.08 Arterial Blood Gases

Normal values:

• pH 7.35–7.45.
• PaO2 above 10 kPa on air.
• PaCO2 4.7–6.0 kPa.
• Bicarbonate 22–26 mmol/L.
• Base excess −2 to +2.

Step-by-step:

• 1. Oxygenation: Is PaO2 low for the inspired oxygen? A quick rule: PaO2 (kPa) should be about 10 less than the inspired oxygen %.
• 2. pH: Acidaemia or alkalaemia?
• 3. Primary disturbance:
  • Respiratory: PaCO2 moves in the opposite direction to pH.
  • Metabolic: Bicarbonate moves in the same direction as pH.
• 4. Compensation: The kidneys compensate for respiratory problems (slowly, over days); the lungs compensate for metabolic problems (quickly).

Common patterns:

• Type 1 respiratory failure: Low PaO2, normal or low PaCO2 — pneumonia, PE, pulmonary oedema, ILD.
• Type 2 respiratory failure: Low PaO2 and high PaCO2.
  • Acute: Low pH.
  • Chronic: Normal pH, high bicarbonate.
  • Acute-on-chronic: Low pH despite a high bicarbonate.
• Respiratory alkalosis: Low PaCO2, high pH — hyperventilation (anxiety, early asthma, PE, pain, salicylates early).

Alveolar–arterial (A–a) gradient: Shows whether low oxygen is due to lung disease or just under-breathing.

• Calculation: Alveolar PO2 (PAO2) ≈ (FiO2 × 94.8) − (PaCO2 ÷ 0.8) in kPa. A–a gradient = PAO2 − PaO2.
• Normal: Below about 2–4 kPa in young adults on air (rises with age).
• Raised: Lung disease (V/Q mismatch, shunt, diffusion problem).
• Normal gradient with low oxygen: Pure hypoventilation (opioids, neuromuscular disease) or high altitude.

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2.09 Pulse Oximetry

• What it measures: The percentage of haemoglobin carrying oxygen (SpO2), by shining light through the finger.
• Limitations:
  • Overestimates saturation in people with darker skin — "occult hypoxaemia" (MHRA and NHS Race and Health Observatory warnings).
  • Falsely normal in carbon monoxide poisoning and methaemoglobinaemia (which reads about 85%).
  • Inaccurate with poor circulation, cold hands, nail varnish, movement, or severe anaemia.
  • Says nothing about CO2 — a patient can have a normal SpO2 on oxygen with a dangerously high CO2.
• Oxygen–haemoglobin curve: Saturations hold up well until PaO2 falls to about 8 kPa (about 90%), then drop steeply. Small falls below 90% mean large falls in oxygen content.
• Overnight oximetry: A screening test for sleep apnoea (repeated dips — oxygen desaturation index) and nocturnal hypoventilation.

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2.10 Chest X-ray

A systematic approach:

• Check patient details, projection (PA or AP), rotation and inspiration.
• Airway (trachea central).
• Breathing (lungs, pleura).
• Cardiac (size, borders).
• Diaphragm (free air underneath).
• Everything else (bones, soft tissues, lines and tubes).
• Review areas: Apices, behind the heart, hila, below the diaphragm.

Common patterns:

• Consolidation: White area with air bronchograms. A lost heart or diaphragm border localises it (silhouette sign):
  • Right heart border — right middle lobe.
  • Left heart border — lingula.
  • Diaphragm — lower lobe.
• Collapse: Volume loss — the trachea, fissures and hila are pulled towards it. Left lower lobe collapse gives a "sail sign" behind the heart. In an adult smoker, think obstructing tumour.
• Pleural effusion: Blunted costophrenic angle with a meniscus. A large effusion pushes the mediastinum away.
• Pneumothorax: A visible lung edge with no lung markings beyond it.
• Nodule or mass: Compare with old films; CT if new.
• Cavitation:
  • Squamous cell carcinoma.
  • TB.
  • Staphylococcus aureus or Klebsiella pneumonia; lung abscess.
  • GPA (vasculitis).
  • Septic emboli.
• Bilateral hilar lymphadenopathy: Sarcoidosis, lymphoma, TB, metastases.
• Reticular (interstitial) shadowing:
  • Lower zone: IPF, asbestosis, connective tissue disease, drugs.
  • Upper zone: Sarcoidosis, hypersensitivity pneumonitis, silicosis, TB, ankylosing spondylitis.
• Pulmonary oedema: Upper lobe diversion, bat's wing shadowing, Kerley B lines, effusions.

⚠️ Safety Pearl: A normal chest X-ray does not exclude lung cancer — about 1 in 5 lung cancers is missed on plain film. Persisting unexplained symptoms (haemoptysis, weight loss) in a smoker need a CT.

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2.11 CT and PET-CT

• Contrast-enhanced CT chest (and abdomen): Lung cancer diagnosis and staging, masses, mediastinum, pleura.
• CT pulmonary angiography (CTPA): Pulmonary embolism.
• High-resolution CT (HRCT): Thin slices without contrast for ILD and bronchiectasis.
  • Usual interstitial pneumonia (UIP) pattern — subpleural, basal reticulation with honeycombing and traction bronchiectasis — typical of IPF.
  • Ground-glass opacity — hazy grey lung (inflammation, infection, oedema, haemorrhage).
  • Mosaic attenuation with air trapping on expiratory images — small airways disease, hypersensitivity pneumonitis.
  • Tree-in-bud — small airway infection (TB, non-tuberculous mycobacteria, aspiration).
  • Bronchiectasis — an airway wider than the accompanying artery ("signet ring").
  • Crazy paving — ground glass with septal thickening (pulmonary alveolar proteinosis, PCP, oedema).
• Low-dose CT: Used in the NHS Lung Cancer Screening Programme and nodule follow-up.
• PET-CT (FDG — a radiolabelled glucose taken up by active cells):
  • Assesses nodules and staging (nodes, metastases) in lung cancer.
  • False positives: infection, inflammation, sarcoidosis.
  • False negatives: small (under 8 mm) nodules, slow-growing tumours (adenocarcinoma in situ, carcinoid).

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2.12 Thoracic Ultrasound

• Bedside, no radiation, increasingly done by respiratory doctors.
• Uses:
  • Detects and characterises pleural effusions — septations suggest infection; pleural nodules suggest malignancy.
  • Guides pleural aspiration and drains — standard of care (BTS), reducing complications.
  • Detects pneumothorax (absent lung sliding).
  • B-lines (pulmonary oedema or ILD).
  • Consolidation.
  • Diaphragm movement.

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2.13 Bronchoscopy and EBUS

• Flexible bronchoscopy: A camera passed through the nose or mouth into the airways, under sedation and local anaesthetic.
  • Diagnostic uses:
    • Central tumours — biopsy and brushings.
    • Bronchoalveolar lavage (BAL) for infection (TB, PCP, fungi) and ILD (cell counts — e.g. lymphocytes in sarcoidosis and hypersensitivity pneumonitis).
    • Haemoptysis; persistent collapse.
  • Therapeutic uses: Removing secretions or foreign bodies; stents; valves for emphysema.
• Endobronchial ultrasound (EBUS): An ultrasound probe on the bronchoscope lets the operator see and needle-sample lymph nodes next to the airways (EBUS-TBNA).
  • Used to diagnose and stage lung cancer (mediastinal nodes).
  • Also diagnoses sarcoidosis, lymphoma and TB.
• Other sampling:
  • CT-guided percutaneous lung biopsy for peripheral lesions — risk of pneumothorax (about 1 in 5) and bleeding.
  • Navigational or robotic bronchoscopy for small peripheral nodules.
  • Cryobiopsy or surgical (VATS) lung biopsy for ILD when the diagnosis is uncertain.
• Before procedures: Check FBC and clotting; stop anticoagulants and some antiplatelets per protocol; check fitness for sedation.

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2.14 Pleural Procedures

• Diagnostic pleural aspiration (ultrasound-guided) — send for:
  • Appearance.
  • Protein and LDH (with serum values, for Light's criteria).
  • pH; glucose.
  • Cytology.
  • Microbiology (Gram stain, culture, AFB).
  • Amylase, triglycerides or haematocrit if relevant.
• Light's criteria — the fluid is an exudate if any of:
  • Pleural protein ÷ serum protein above 0.5.
  • Pleural LDH ÷ serum LDH above 0.6.
  • Pleural LDH above two-thirds of the upper limit of normal serum LDH.
  Use Light's criteria when pleural protein is borderline (25–35 g/L). Above 35 g/L is likely exudate; below 25 g/L likely transudate.
• Therapeutic aspiration: Relieves breathlessness. Usually remove no more than about 1.5 L at a time.
• Chest drain: For pneumothorax, pleural infection or large effusions — inserted in the "triangle of safety" with ultrasound guidance.
• Local anaesthetic thoracoscopy: A camera into the pleural space to biopsy the pleura (cancer, mesothelioma, TB) and perform talc pleurodesis.
• Indwelling pleural catheter (IPC): A tunnelled drain for recurrent malignant effusions, drained at home.

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2.15 Exercise and Fitness-to-Fly Tests

• Six-minute walk test: Distance walked and oxygen saturations. Tracks ILD, COPD and pulmonary hypertension, and checks for exertional desaturation (ambulatory oxygen assessment).
• Incremental shuttle walk test: Walking between cones at increasing speed — used in pulmonary rehabilitation and before surgery.
• Cardiopulmonary exercise testing (CPET):
  • Measures oxygen use and CO2 output during cycling.
  • Separates cardiac, respiratory and deconditioning causes of breathlessness.
  • Assesses fitness for major surgery (including lung resection).
• Hypoxic challenge test ("fitness to fly"):
  • Breathing 15% oxygen mimics an aircraft cabin.
  • If PaO2 falls below about 6.6 kPa (or SpO2 below about 85%), in-flight oxygen is recommended (BTS air travel guidance).

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2.16 Sleep Studies

• Screening questionnaires: Epworth Sleepiness Scale (daytime sleepiness, out of 24 — above 10 is excessive); STOP-Bang (OSA risk).
• Overnight oximetry: Counts oxygen dips (oxygen desaturation index). Simple, but misses non-desaturating events.
• Respiratory polygraphy (home study — the usual first test in NICE NG202): Airflow, breathing effort, oximetry and position. It gives the apnoea–hypopnoea index (AHI), events per hour:
  • Mild: 5–14.
  • Moderate: 15–29.
  • Severe: 30 or more.
• Polysomnography (in a sleep lab): Adds EEG, eye movements and muscle activity — for complex cases and non-respiratory sleep disorders (narcolepsy, parasomnias).
• Transcutaneous CO2 monitoring: For suspected nocturnal hypoventilation (obesity hypoventilation, neuromuscular disease).

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2.17 Sputum and Blood Tests

• Sputum:
  • Culture (bacteria including Pseudomonas in bronchiectasis).
  • AFB smear, TB culture and PCR — three samples.
  • Fungi; cytology (rarely used now).
• Bloods:
  • FBC — eosinophils (asthma, ABPA, EGPA, eosinophilic pneumonia).
  • CRP.
  • Total IgE, aspergillus-specific IgE and IgG (ABPA, chronic pulmonary aspergillosis).
  • Alpha-1 antitrypsin level — young or non-smoking emphysema, basal emphysema, family history.
  • Immunoglobulins (bronchiectasis).
  • Autoimmune screen — ANA, rheumatoid factor, anti-CCP, myositis antibodies, ANCA (ILD, vasculitis).
  • Serum precipitins (specific IgG) to birds and moulds — hypersensitivity pneumonitis.
  • Serum ACE and calcium (sarcoidosis — supportive only).
  • Interferon-gamma release assay (latent TB); HIV test.
  • NT-proBNP (heart failure); D-dimer.
• Sweat test and CFTR genetics: Cystic fibrosis.
• Nasal cilia studies (nasal nitric oxide, ciliary beat analysis): Primary ciliary dyskinesia.

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2.18 Patterns at a Glance

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2.19 Spot the Diagnosis

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2.20 Exam-style Scenarios

1. A 58-year-old ex-smoker has progressive breathlessness. FEV1 1.4 L (52%), FVC 3.2 L (95%), ratio 0.44; post-bronchodilator FEV1 rises by 90 mL. TLCO is 45%.
Answer: Obstructive pattern without significant reversibility, with low gas transfer — COPD with emphysema (moderate airflow obstruction).

• Check alpha-1 antitrypsin if young or with basal emphysema.
• CT chest if cancer is suspected, or for emphysema assessment.

2. A 65-year-old woman with rheumatoid arthritis has a dry cough. FEV1 2.0 L (80%), FVC 2.2 L (70%), ratio 0.91; TLC 68%, TLCO 50%.
Answer: Restrictive pattern with low gas transfer — interstitial lung disease (possibly RA-ILD, or drug-induced, e.g. methotrexate).

• HRCT and specialist ILD review.

3. A 30-year-old man with "asthma" has worsening noisy breathing despite inhalers, 6 months after an ICU admission with intubation.
Answer: Suspect post-intubation tracheal stenosis.

• Flow–volume loop (box shape), CT of the neck and chest, and bronchoscopy.

4. A patient with COPD has ABG on air: pH 7.38, PaO2 7.1 kPa, PaCO2 7.4 kPa, bicarbonate 33 mmol/L.
Answer: Chronic (compensated) type 2 respiratory failure.

• Assess for long-term oxygen therapy — repeat when stable.
• Consider home NIV if hypercapnia persists after an admission.

5. A 42-year-old woman has breathlessness on exertion. Spirometry and lung volumes are normal; TLCO is 55%; chest X-ray is normal.
Answer: Isolated low gas transfer.

• Look for pulmonary vascular disease: echo for pulmonary hypertension, CTPA or V/Q for chronic thromboembolic disease.
• Also consider anaemia, and early ILD or emphysema on HRCT.

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2.21 Key Points

• A low FEV1/FVC ratio means obstruction. Low FEV1 and FVC with a normal ratio suggests restriction — confirm it with lung volumes.
• Bronchodilator reversibility of 12% or more and 200 mL or more supports asthma.
• FeNO of 50 ppb or more, or raised blood eosinophils, confirms asthma when the history is typical (BTS/NICE/SIGN 2024).
• TLCO is low in emphysema, ILD and pulmonary vascular disease; KCO is preserved in extrapulmonary restriction; TLCO is high in alveolar haemorrhage.
• An FVC fall of more than 20% on lying suggests diaphragm weakness.
• A box-shaped flow–volume loop means fixed upper airway obstruction.
• Oximetry misses hypercapnia and overestimates saturation in darker skin.
• A normal chest X-ray does not exclude lung cancer.
• HRCT patterns guide ILD diagnosis — UIP (honeycombing) suggests IPF.
• EBUS samples mediastinal nodes for cancer staging and sarcoidosis.
• Light's criteria separate exudates from transudates.

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2.22 Guidelines and Further Reading

• ARTP/BTS: Spirometry and lung function interpretation statements (Global Lung Function Initiative reference equations)
• BTS/NICE/SIGN Asthma guideline (2024): diagnostic algorithm
• BTS Guideline for pleural disease (2023)
• BTS Guideline for diagnostic flexible bronchoscopy in adults
• BTS Clinical statement on air travel
• NICE NG202: Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s
• BTS Guideline for oxygen use in healthcare and emergency settings

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3.01 Asthma: What It Is

Mechanism: Chronic inflammation of the airways makes them hyper-responsive. Triggers cause:

• Smooth muscle contraction (bronchospasm).
• Swelling of the airway wall.
• Mucus production.

The narrowing is variable and at least partly reversible. Most asthma is "type 2" (eosinophilic, allergic) — driven by IL-4, IL-5 and IL-13 — which responds well to steroids.

Risk factors:

• Atopy — eczema, hay fever, food allergy.
• Family history.
• Early viral infections.
• Smoking (including passive) and air pollution.
• Obesity.
• Occupational exposures.

Triggers:

• Viral infections.
• Allergens — house dust mite, pollen, pets, moulds.
• Exercise; cold air.
• Smoke; pollution.
• Drugs — beta-blockers (including eye drops), NSAIDs and aspirin in some people.
• Stress; hormones (premenstrual).

Clinical pattern:

• Wheeze, breathlessness, chest tightness, cough.
• Variable over time, often worse at night and early morning.
• Triggered by the factors above.
• Between attacks, the examination may be normal.

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3.02 Diagnosing Asthma

Asthma is over-diagnosed and under-diagnosed, so the BTS/NICE/SIGN guideline (2024) requires an objective test as well as a typical history.

Adults — test in this order:

• 1. Blood eosinophils or FeNO: A raised eosinophil count (above the lab reference range) or FeNO of 50 ppb or more confirms asthma when the history is typical.
• 2. Spirometry with bronchodilator reversibility: An FEV1 rise of 12% or more and 200 mL or more (or 10% or more of predicted) confirms asthma.
• 3. Peak flow variability (if spirometry is delayed or unavailable): Twice-daily readings for 2 weeks; variability of 20% or more confirms asthma.
• 4. Bronchial challenge test (specialist): Hyperresponsiveness confirms asthma. A normal test suggests another diagnosis.

Points to remember:

• Test before starting inhaled steroids if possible — they reduce FeNO, eosinophils and variability.
• If the patient is very unwell, treat first and test later.
• Normal spirometry between attacks does not exclude asthma.
• Record the evidence for the diagnosis in the notes.

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3.03 Treating Asthma: AIR and MART

The big change (BTS/NICE/SIGN 2024): People aged 12 and over should not use a salbutamol (SABA) inhaler alone. Relying on SABA without inhaled steroid is linked to severe attacks and asthma deaths. Treatment is now built around a combined inhaled steroid plus formoterol inhaler (e.g. budesonide/formoterol). Formoterol works within minutes, so the same inhaler can be both the reliever and the preventer.

Adult pathway:

• Step 1 — Newly diagnosed: AIR (anti-inflammatory reliever). A low-dose ICS/formoterol inhaler used as needed for symptoms.
• Step 2 — Not controlled, or very symptomatic or recent severe attack at diagnosis: low-dose MART (maintenance and reliever therapy). The same ICS/formoterol inhaler is taken regularly (e.g. 1 puff twice daily) and as needed.
• Step 3 — Moderate-dose MART (e.g. 2 puffs twice daily plus as needed).
• Step 4 — Still not controlled on moderate-dose MART despite good adherence and technique:
  • Check FeNO and blood eosinophils.
  • If either is raised, refer to a specialist (possible severe asthma).
  • If neither is raised, try adding a leukotriene receptor antagonist (montelukast) or a LAMA for 8–12 weeks, then refer if still uncontrolled.
• Step down to the lowest effective treatment once well controlled for at least 3 months.

People already on SABA plus a separate inhaled steroid: Consider switching to ICS/formoterol AIR or MART at review.

Montelukast: MHRA warning about neuropsychiatric reactions (sleep disturbance, depression, suicidal thoughts) — warn patients and carers.

💡 Clinical Pearl: Before stepping up, check four things: inhaler technique, adherence, triggers (smoking, allergens, occupation) and the diagnosis itself. Most "uncontrolled asthma" is one of these.

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3.04 Asthma Review and Risk

Review at least once a year, and after every attack:

• Symptom control: Asthma Control Questionnaire or Asthma Control Test; night waking; reliever use; activity limitation.
• Attacks: Courses of oral steroids, emergency visits, admissions.
• Inhaler technique — watch the patient use it; choose the right device.
• Adherence — check prescription records.
• Triggers and comorbidities: Smoking, rhinitis, reflux, obesity, anxiety, dysfunctional breathing.
• Written personalised asthma action plan — what to do when symptoms worsen.
• Vaccinations: Influenza; COVID-19 (and pneumococcal if eligible).
• Consider the inhaler's environmental impact — dry powder inhalers have a lower carbon footprint than metered-dose inhalers, where suitable.

Warning signs of high risk of a fatal attack (National Review of Asthma Deaths):

• Previous near-fatal attack or ICU admission.
• Hospital admissions or emergency visits in the past year.
• Heavy reliever use — frequent SABA prescriptions.
• Low use of inhaled steroids; poor adherence.
• Psychological or social problems.
• Recent discharge after an attack.

These patients need urgent review and close follow-up.

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3.05 Severe Asthma and Biologics

Definition: Asthma that stays uncontrolled despite high-dose treatment with good adherence and technique, after comorbidities and triggers have been addressed. It affects about 5% of people with asthma, but causes a large share of attacks and costs.

Assessment in a specialist severe asthma centre:

• Confirm the diagnosis.
• Check adherence (including FeNO suppression testing).
• Look for comorbidities — rhinosinusitis and nasal polyps, reflux, obesity, inducible laryngeal obstruction, dysfunctional breathing, anxiety.
• Phenotype the asthma: Blood eosinophils, FeNO, IgE, allergen sensitisation.
• Look for ABPA and EGPA.

Biologic treatments (injected monoclonal antibodies; NICE technology appraisals — specialist use):

• Omalizumab (anti-IgE): Severe allergic asthma with raised IgE.
• Mepolizumab, reslizumab (anti-IL-5) and benralizumab (anti-IL-5 receptor): Severe eosinophilic asthma.
• Dupilumab (anti-IL-4 receptor alpha — blocks IL-4 and IL-13): Type 2 asthma with raised eosinophils and FeNO. Also treats nasal polyps and eczema.
• Tezepelumab (anti-TSLP): Acts "upstream" and works in both eosinophilic and non-eosinophilic severe asthma.
• Typical NICE criteria: Frequent attacks needing oral steroids (often 3–4 or more a year), or long-term maintenance oral steroids, with the biomarker thresholds specific to each drug.

Why it matters: Biologics reduce attacks by about half, and allow many patients to stop maintenance oral steroids — which otherwise cause osteoporosis, diabetes, cataracts, weight gain and adrenal suppression.

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3.06 Occupational Asthma

• What it is: Asthma caused by something at work. It accounts for about 1 in 6 cases of adult-onset asthma.
• Common causes:
  • Isocyanates (spray painting — the commonest).
  • Flour and grain (bakers).
  • Wood dust.
  • Latex (healthcare).
  • Laboratory animals.
  • Glutaraldehyde, cleaning products.
  • Solder flux (colophony).
  • Hairdressing chemicals (persulfates).
• Clues: Adult-onset asthma, or asthma that worsens, which improves on days off and holidays. Rhinitis often comes first.
• Diagnosis:
  • Serial peak flow at least 4 times a day for 3–4 weeks, at work and away from work.
  • Specific IgE or skin prick tests.
  • Specialist challenge tests.
• Management:
  • Early removal from exposure gives the best chance of recovery.
  • Involve occupational health.
  • The patient may be entitled to Industrial Injuries Disablement Benefit.
  • Work-exacerbated asthma (pre-existing asthma made worse by work) is different — improve control and reduce exposure.

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3.07 Asthma in Special Situations

• Pregnancy:
  • Asthma may improve, stay the same or worsen.
  • Continue all usual asthma medicines, including inhaled and oral steroids — uncontrolled asthma is far more dangerous to the baby than the drugs.
  • Treat acute attacks as in non-pregnant patients.
  • Use regional rather than general anaesthesia where possible in labour.
• Aspirin-exacerbated respiratory disease (Samter's triad):
  • Asthma, nasal polyps, and reactions to aspirin and NSAIDs.
  • Avoid NSAIDs (paracetamol is usually tolerated).
  • Leukotriene antagonists may help; specialist desensitisation; dupilumab for polyps.
• Exercise-induced symptoms: Usually means poorly controlled asthma — improve maintenance treatment. ICS/formoterol can be taken before exercise.
• Eosinophilic granulomatosis with polyangiitis (EGPA):
  • Late-onset severe asthma with very high eosinophils.
  • Sinusitis.
  • Neuropathy (mononeuritis multiplex).
  • Rash; cardiac and kidney involvement.
  • About 40% are ANCA-positive.
  • Specialist immunosuppression; mepolizumab.
• Older adults: Asthma and COPD often overlap. Check inhaler technique — arthritis and cognitive problems affect device use.

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3.08 Asthma Mimics

• Inducible laryngeal obstruction (vocal cord dysfunction):
  • The vocal cords close inappropriately on breathing in, causing sudden throat tightness and noisy breathing.
  • Often in young women and people with anxiety or reflux.
  • Normal oxygen during attacks; poor response to asthma treatment.
  • Diagnosis: Laryngoscopy during symptoms.
  • Treatment: Speech and language therapy.
• Dysfunctional breathing (breathing pattern disorder): Sighing, air hunger, tingling, chest tightness, often with anxiety. Physiotherapy breathing retraining.
• COPD — smokers, fixed obstruction.
• Heart failure ("cardiac asthma").
• Central airway obstruction — tumour, tracheal stenosis, goitre, foreign body. Monophonic wheeze; abnormal flow–volume loop.
• Bronchiectasis; ABPA; obliterative bronchiolitis.
• Chronic cough from reflux, rhinitis or ACE inhibitors.

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3.09 COPD: What It Is

Mechanism: Chronic obstructive pulmonary disease is long-term, largely irreversible airflow obstruction caused by inhaled damage — mainly smoking. Two processes combine:

• Chronic bronchitis and small airways disease: Inflamed, narrowed small airways and excess mucus.
• Emphysema: Destruction of the alveolar walls, so the lungs lose their elastic recoil and air is trapped (hyperinflation). Gas exchange surface is lost.

Causes:

• Tobacco smoking — about 90% in the UK.
• Occupational dusts and fumes (coal, silica, cadmium).
• Biomass fuel smoke (worldwide).
• Alpha-1 antitrypsin deficiency.
• Poor lung growth in childhood (prematurity, early infections).
• Cannabis smoking.

Clinical pattern:

• Over 35, a smoker or ex-smoker.
• Exertional breathlessness; chronic cough; regular sputum.
• Frequent winter "bronchitis"; wheeze.
• Signs in advanced disease:
  • Hyperinflated chest, pursed-lip breathing.
  • Reduced breath sounds.
  • Cor pulmonale (raised JVP, ankle oedema).
  • Weight loss and muscle wasting.
• Clubbing is not a feature of COPD — look for cancer or bronchiectasis.

Comorbidities: Cardiovascular disease, lung cancer, osteoporosis, depression and anxiety, diabetes and frailty are all common and affect survival.

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3.10 Diagnosing and Assessing COPD

• Diagnosis (NICE NG115):
  • Symptoms plus risk factors.
  • Post-bronchodilator spirometry with an FEV1/FVC ratio below 0.7 (or below the lower limit of normal).
  • COPD is not diagnosed without spirometry.
• Severity of airflow obstruction (FEV1 % predicted): Mild 80% or more; moderate 50–79%; severe 30–49%; very severe below 30%.
• Initial tests:
  • Chest X-ray (exclude other causes, look for cancer).
  • FBC (anaemia, polycythaemia, eosinophils).
  • BMI.
  • Alpha-1 antitrypsin level if early onset (under 45), minimal smoking or family history.
  • Oxygen saturation (assess for long-term oxygen if 92% or less).
  • ECG and echo if heart disease or cor pulmonale is suspected.
  • CT if symptoms don't fit, or for surgical and valve assessment.
• Assess the impact: MRC dyspnoea scale, the COPD Assessment Test (CAT), exacerbation frequency, and comorbidities.
• Asthmatic or steroid-responsive features (NICE) — these change treatment:
  • Previous diagnosis of asthma or atopy.
  • Raised blood eosinophils.
  • Substantial variation in FEV1 over time (400 mL or more).
  • Substantial diurnal variation in peak flow (20% or more).

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3.11 Treating Stable COPD

Foundations — these do the most good:

• Stop smoking — the only measure (with oxygen in selected people) proven to slow decline and improve survival. Offer behavioural support plus drugs (NRT, varenicline where available, bupropion). E-cigarettes are a less harmful alternative to smoking.
• Vaccinations: Annual influenza, pneumococcal, COVID-19 and RSV (for eligible older adults).
• Pulmonary rehabilitation — for MRC grade 3 or more, and after an admission. A 6–8 week exercise and education programme that improves breathlessness, exercise capacity and quality of life, and reduces readmissions.
• Self-management plan and a "rescue pack" (prednisolone and antibiotics) for those who can use it safely.
• Treat comorbidities; nutrition; inhaler technique at every review.

Inhaled treatment (NICE NG115):

• Step 1: A short-acting bronchodilator (SABA or SAMA) as needed.
• Step 2 — still breathless or having exacerbations:
  • No asthmatic features: LABA plus LAMA (combination inhaler).
  • Asthmatic or steroid-responsive features: LABA plus ICS.
• Step 3 — triple therapy (LABA plus LAMA plus ICS):
  • For people still having exacerbations (or severe symptoms) on dual therapy — especially with blood eosinophils of 300 cells/µL or more.
  • ICS increases pneumonia risk. Review the benefit, particularly with low eosinophils.

Further options for frequent exacerbations (specialist):

• Azithromycin long-term prophylaxis:
  • For non-smokers with frequent exacerbations despite optimal treatment.
  • Check ECG (QT), LFTs and sputum for non-tuberculous mycobacteria first.
  • Warn about hearing loss.
• Roflumilast (PDE4 inhibitor): Severe COPD with chronic bronchitis and frequent exacerbations despite triple therapy (NICE TA461).
• Mucolytics (carbocisteine) for chronic productive cough.
• Dupilumab (biologic): NICE (TA1142) recommends it as an add-on for uncontrolled COPD with raised blood eosinophils despite triple therapy (or dual therapy if ICS is unsuitable). Uncontrolled means 1 or more severe, or 2 or more moderate, exacerbations in the past year.
• Oral theophylline: Rarely used — narrow therapeutic range, many interactions.

💡 Clinical Pearl: In COPD, the treatments that make the biggest difference are not inhalers: stopping smoking, pulmonary rehabilitation, vaccination, and oxygen for the right patients.

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3.12 Oxygen and Home NIV

Long-term oxygen therapy (LTOT) improves survival when used for at least 15 hours a day in chronic hypoxaemia.

• Assess when stable (at least 8 weeks after an exacerbation), with two arterial or capillary gases at least 3 weeks apart.
• Offer LTOT if:
  • PaO2 below 7.3 kPa, or
  • PaO2 7.3–8.0 kPa plus polycythaemia, peripheral oedema or pulmonary hypertension.
• Do not offer LTOT to people who smoke (or live with smokers) — there is a serious fire and burns risk. Assess home safety.
• Ambulatory oxygen: For people already on LTOT who are mobile. It is not routinely offered for exertional breathlessness alone.
• Palliative oxygen: Not for breathlessness without hypoxaemia — a hand-held fan and other measures work as well.

Home non-invasive ventilation:

• Consider for people with persistent hypercapnia (PaCO2 above about 7 kPa) 2–4 weeks after an admission with acute hypercapnic respiratory failure.
• It reduces readmission and death (HOT-HMV trial).
• Specialist home ventilation service.

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3.13 Advanced COPD

• Lung volume reduction (for severe emphysema with hyperinflation, after rehabilitation, in non-smokers):
  • Endobronchial valves — one-way valves that collapse a damaged lobe (needs no collateral ventilation between lobes).
  • Lung volume reduction surgery — for upper-lobe-predominant emphysema.
  • Both improve breathlessness, exercise capacity and, in selected patients, survival.
• Lung transplantation: For selected younger patients with very severe disease and no major comorbidity.
• Palliative and supportive care:
  • Breathlessness management — a hand-held fan, breathing techniques, pacing, treating anxiety.
  • Low-dose oral morphine for refractory breathlessness (specialist guidance).
  • Advance care planning, including a treatment escalation plan (NIV, intubation, CPR decisions) before the next crisis.
  • Carer support.
• Signs of poor prognosis:
  • Frequent admissions.
  • Hypercapnia; LTOT.
  • Low BMI and muscle loss.
  • MRC grade 5.
  • Cor pulmonale.
  • Needing NIV.

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3.14 Alpha-1 Antitrypsin Deficiency

• Mechanism: Alpha-1 antitrypsin is made in the liver and protects the lungs from neutrophil elastase. In deficiency (inherited — autosomal codominant, PiZZ genotype is the severe form), elastase destroys alveolar walls.
  • The abnormal protein also builds up in the liver and damages it.
• Clinical pattern:
  • Early-onset emphysema (30s–40s), especially in smokers.
  • Basal, panlobular emphysema (usual smoking emphysema is upper lobe).
  • Bronchiectasis.
  • Liver disease — neonatal jaundice, cirrhosis, hepatocellular carcinoma.
  • Rarely, panniculitis or ANCA vasculitis.
• Tests: Serum alpha-1 antitrypsin level, then phenotype or genotype.
• Management:
  • Never smoke.
  • Standard COPD care.
  • Liver monitoring.
  • Family screening.
  • Augmentation therapy (IV alpha-1 antitrypsin) slows emphysema progression, but is not routinely funded on the NHS.
  • Transplant (lung or liver) in severe cases.

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3.15 Bronchiectasis

Mechanism: Permanent widening and damage of the bronchi. Damaged airways cannot clear mucus, so bacteria grow, causing inflammation and further damage — a "vicious cycle" of infection, inflammation and airway destruction.

Causes (find one in about half):

• After infection — severe pneumonia, whooping cough, measles, TB.
• Immune deficiency — antibody deficiency (CVID), HIV.
• ABPA (central bronchiectasis in asthma).
• Cystic fibrosis and primary ciliary dyskinesia.
• Connective tissue disease — rheumatoid arthritis.
• Inflammatory bowel disease.
• Aspiration and reflux.
• Non-tuberculous mycobacteria.
• Airway obstruction (tumour, foreign body).
• Alpha-1 antitrypsin deficiency.
• Yellow nail syndrome.

Clinical pattern:

• Daily productive cough with large volumes of sputum.
• Recurrent chest infections; haemoptysis; breathlessness; fatigue.
• Signs: Coarse crackles, wheeze, sometimes clubbing.

Diagnosis: HRCT — dilated airways (bronchus wider than its artery: "signet ring"), no normal tapering, thickened walls.

Investigations for the cause (BTS 2019):

• FBC.
• Immunoglobulins (IgG, IgA, IgM).
• Total IgE and aspergillus-specific IgE and IgG (ABPA).
• Sputum culture — including mycobacteria.
• Spirometry.
• Further tests if indicated: rheumatoid factor and anti-CCP, CF testing (younger patients, upper lobe disease, infertility, malabsorption), PCD testing (lifelong symptoms, sinus and ear disease), alpha-1 antitrypsin, HIV.

Management:

• Airway clearance — daily physiotherapy techniques (active cycle of breathing, oscillating devices); exercise; pulmonary rehabilitation.
• Treat the cause — immunoglobulin replacement, ABPA treatment, reflux.
• Exacerbations:
  • Send sputum first.
  • Antibiotics for 14 days, guided by previous cultures.
• New Pseudomonas aeruginosa: Eradication treatment (e.g. oral ciprofloxacin, sometimes with nebulised colistin).
• Three or more exacerbations a year: Consider long-term macrolide (azithromycin, after excluding NTM and checking QT) or nebulised antibiotics (colistin, gentamicin) if Pseudomonas is present.
• Mucoactive treatment: Nebulised hypertonic saline or carbocisteine for thick sputum.
• Vaccinations.
• Surgery for localised disease or severe haemoptysis (bronchial artery embolisation).

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3.16 Cystic Fibrosis

Mechanism: An autosomal recessive disease caused by mutations in the CFTR gene (the commonest is F508del). CFTR is a chloride channel. When it fails, secretions in the lungs, pancreas, gut, liver and reproductive tract become thick and sticky. About 1 in 25 white Europeans carries a mutation.

Clinical pattern:

• Lungs:
  • Chronic infection — Staphylococcus aureus, H. influenzae, then Pseudomonas aeruginosa; also Burkholderia cepacia complex, NTM and aspergillus.
  • Bronchiectasis, haemoptysis, pneumothorax.
  • ABPA.
  • Respiratory failure — the main cause of death.
• Upper airways: Nasal polyps, sinusitis.
• Pancreas:
  • Pancreatic insufficiency — fatty stools, poor growth, fat-soluble vitamin deficiency.
  • CF-related diabetes — increasingly common with age.
• Gut: Meconium ileus at birth; distal intestinal obstruction syndrome in adults.
• Liver: CF-related liver disease; gallstones.
• Reproductive: Almost all men are infertile (congenital absence of the vas deferens); women have reduced fertility.
• Other: Osteoporosis; salt loss in heat.

Diagnosis:

• Newborn screening (heel-prick immunoreactive trypsinogen), then a sweat test — chloride of 60 mmol/L or more is diagnostic.
• CFTR genetic testing.
• Milder forms may present in adults with bronchiectasis, pancreatitis or male infertility.

Management (specialist CF centre):

• CFTR modulators — drugs that fix the faulty protein:
  • Elexacaftor/tezacaftor/ivacaftor (Kaftrio) for people with at least one F508del mutation (most patients; NICE TA988).
  • Large improvements in lung function, weight and exacerbations, transforming survival.
  • Monitor LFTs; many interactions (CYP3A).
• Airway clearance physiotherapy; exercise.
• Mucolytics — dornase alfa, hypertonic saline.
• Antibiotics: Eradicate early Pseudomonas; inhaled antibiotics for chronic infection; IV courses for exacerbations.
• Infection control — people with CF must not mix with each other (cross-infection with Burkholderia and Pseudomonas).
• Nutrition: High-calorie diet, pancreatic enzyme replacement with meals, vitamins A, D, E and K.
• Diabetes, bone and liver care.
• Lung transplantation for end-stage disease.

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3.17 Primary Ciliary Dyskinesia

• Mechanism: An inherited (usually autosomal recessive) defect in the structure or function of cilia — the tiny hairs that sweep mucus out of the airways.
• Clinical pattern:
  • Lifelong wet cough from birth (neonatal breathing problems).
  • Chronic rhinosinusitis and otitis media (glue ear, hearing loss).
  • Bronchiectasis (often middle and lower lobes).
  • Subfertility — immotile sperm; ectopic pregnancy in women.
• Kartagener syndrome: PCD with situs inversus (organs on the opposite side — dextrocardia) in about half of cases.
• Diagnosis (specialist centres):
  • Low nasal nitric oxide.
  • High-speed video analysis of cilia beating.
  • Electron microscopy; genetic testing.
• Management: Airway clearance, treatment of infections, ENT care — similar to bronchiectasis.

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3.18 Allergic Bronchopulmonary Aspergillosis

• Mechanism: An allergic reaction to the fungus Aspergillus fumigatus growing in the airways of people with asthma or cystic fibrosis. It is not an invasive infection. The reaction causes mucus plugging and damages the central airways.
• Clinical pattern:
  • Worsening, hard-to-control asthma.
  • Cough with brown mucus plugs.
  • Fleeting chest X-ray shadows.
  • Fever, malaise.
• Diagnosis:
  • Very high total IgE (often above 1,000 IU/mL).
  • Raised aspergillus-specific IgE (or a positive skin prick test).
  • Aspergillus-specific IgG (precipitins).
  • Blood eosinophilia.
  • CT: central (proximal) bronchiectasis, mucus plugging, "finger-in-glove" shadows.
• Management:
  • Oral prednisolone (tapering course).
  • Itraconazole (antifungal) to reduce the fungal load and steroid needs — check levels and watch for interactions (including steroid interactions causing Cushing's).
  • Biologics (omalizumab, anti-IL-5) in difficult cases.
  • Monitor with IgE levels.

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3.19 Drug Reference Table

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3.20 Spot the Diagnosis

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3.21 Exam-style Scenarios

1. A 28-year-old woman has 3 months of night cough and wheeze. She uses salbutamol most days. FeNO is 58 ppb.
Answer: Asthma confirmed (FeNO 50 ppb or more with a typical history).

• Stop SABA-only treatment.
• Start ICS/formoterol — as low-dose MART, given the daily symptoms (or AIR if symptoms were mild).
• Check technique; give a written action plan; review in 4–8 weeks.

2. A man with asthma on moderate-dose MART still has 4 attacks a year needing prednisolone. Adherence and technique are good. Eosinophils are 0.6 × 10⁹/L.
Answer: Uncontrolled asthma with raised eosinophils.

• Refer to a severe asthma service.
• He may be eligible for an anti-IL-5 biologic, after the diagnosis is confirmed and comorbidities and ABPA excluded.

3. A 67-year-old ex-smoker with COPD (FEV1 45%) is breathless despite LABA/LAMA and has had 2 exacerbations this year. Eosinophils are 0.35 × 10⁹/L.
Answer: Escalate to triple therapy (add ICS) — eosinophils of 300 cells/µL or more predict benefit.

• Check technique.
• Pulmonary rehabilitation; vaccinations; rescue pack.
• Consider dupilumab if exacerbations continue on triple therapy.

4. A woman with COPD who still smokes 10 a day has PaO2 6.9 kPa when stable.
Answer: She meets the oxygen criterion, but LTOT should not be offered while she smokes (fire risk).

• Intensive smoking cessation support.
• Reassess for LTOT once she has stopped.

5. A 45-year-old has chronic daily sputum and recurrent infections. HRCT shows bronchiectasis. Sputum grows Pseudomonas aeruginosa for the first time.
Answer: Bronchiectasis with new Pseudomonas.

• Eradication treatment (e.g. ciprofloxacin ± nebulised colistin).
• Airway clearance physiotherapy.
• Investigate the cause — immunoglobulins, ABPA screen and others.

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3.22 Key Points

• Asthma: variable, steroid-responsive airway inflammation. Confirm with FeNO or eosinophils, spirometry with reversibility, peak flow variability or challenge.
• Do not treat asthma with SABA alone (aged 12 and over). Use ICS/formoterol — AIR, then MART.
• Check technique, adherence, triggers and the diagnosis before stepping up.
• Severe asthma with raised eosinophils or FeNO: refer for biologics.
• Occupational asthma: improves away from work — serial peak flows; remove from exposure early.
• COPD: smoking-related, fixed obstruction (post-bronchodilator ratio below 0.7).
• COPD treatment: stop smoking, vaccination, pulmonary rehabilitation; then LABA/LAMA (or LABA/ICS if asthmatic features); triple if exacerbations persist.
• LTOT for at least 15 hours a day if PaO2 is below 7.3 kPa when stable — not for smokers.
• Home NIV for persistent hypercapnia after an acute hypercapnic admission.
• Bronchiectasis: airway clearance, 14-day antibiotics for exacerbations, eradicate new Pseudomonas, find the cause.
• CF: CFTR modulators (Kaftrio) have transformed outcomes.
• ABPA: asthma or CF with very high IgE, aspergillus sensitisation and central bronchiectasis — steroids plus itraconazole.

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3.23 Guidelines and Further Reading

• BTS/NICE/SIGN NG245: Asthma — diagnosis, monitoring and chronic asthma management (2024)
• National Review of Asthma Deaths (RCP, 2014)
• NICE NG115: COPD in over 16s — diagnosis and management
• NICE TA1142: Dupilumab for uncontrolled COPD with raised blood eosinophils
• GOLD: Global Strategy for the Diagnosis, Management and Prevention of COPD
• BTS Guideline for bronchiectasis in adults (2019)
• NICE NG78: Cystic fibrosis — diagnosis and management; NICE TA988: CFTR modulators
• BTS Guideline for home oxygen use in adults
• BNF — for current doses

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4.01 Pneumonia: Organisms and Clues

Most pneumonia is treated without identifying the organism, but clinical clues help choose antibiotics and spot unusual infections:

Antibiotic choice follows NICE NG250 by severity (CURB-65 plus clinical judgement):

• Low severity: Amoxicillin.
• Moderate: Amoxicillin, adding clarithromycin if atypical infection is suspected.
• High severity: Co-amoxiclav plus clarithromycin.
• Usually a 5-day course.

See the Respiratory Emergencies chapter for acute management.

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4.02 Pneumonia That Won't Resolve

Most patients improve within 3 days of antibiotics. If not, think through:

• Wrong antibiotic or resistant organism — atypical organisms, S. aureus, Gram-negatives, TB, fungi. Review cultures and antigens.
• A complication:
  • Parapneumonic effusion or empyema — ultrasound and tap.
  • Lung abscess.
  • Metastatic infection (endocarditis, septic arthritis).
• Something blocking the airway — lung cancer, foreign body (repeated pneumonia in the same lobe).
• Not infection at all:
  • Organising pneumonia.
  • Eosinophilic pneumonia.
  • Vasculitis (GPA).
  • Pulmonary infarction (PE).
  • Pulmonary oedema.
  • Drug reaction.
  • Lymphoma.
• Impaired host defences: Immunosuppression, HIV, aspiration, bronchiectasis.
• Drug fever or C. difficile.

Next steps: Repeat chest X-ray; CT chest; pleural ultrasound; sputum for AFB; HIV test; bronchoscopy with BAL.

Follow-up chest X-ray at about 6 weeks for people at higher risk of lung cancer (e.g. smokers over 50) or with persisting symptoms — to make sure the shadow has gone.

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4.03 Aspiration and Lung Abscess

• Aspiration pneumonia:
  • Who: Reduced consciousness (alcohol, seizures, sedation), swallowing problems (stroke, dementia, Parkinson's, MND), vomiting, reflux, poor oral hygiene.
  • Where: Usually the right lower lobe, or the posterior segments if aspiration happened lying down.
  • Prevention: Speech and language therapy, posture, oral care, reviewing sedatives.
• Lung abscess:
  • What it is: A localised cavity of pus — usually from aspiration of mouth anaerobes (and streptococci), or from S. aureus, Klebsiella or septic emboli.
  • Features: Weeks of fever, weight loss, foul-smelling sputum, sometimes haemoptysis.
  • Imaging: Thick-walled cavity with an air–fluid level.
  • Treatment: Prolonged antibiotics (e.g. 4–6 weeks, with anaerobic cover); postural drainage; percutaneous drainage or surgery if it fails.
  • Exclude an underlying cancer (cavitating squamous carcinoma or a blocked bronchus) and TB.

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4.04 Influenza, COVID-19 and RSV

• Influenza:
  • Sudden fever, muscle aches, headache, cough — winter epidemics.
  • Complications: Viral pneumonia, secondary bacterial pneumonia (S. pneumoniae, S. aureus), myocarditis, worsening of COPD and heart failure.
  • Antivirals — e.g. oseltamivir — when influenza is circulating:
    • For people in at-risk groups (ideally within 48 hours of symptoms).
    • For all patients admitted to hospital with suspected influenza, regardless of timing (UKHSA guidance).
  • Infection control; prophylaxis for exposed at-risk contacts in some settings.
• COVID-19:
  • Ranges from mild illness to severe viral pneumonia with ARDS; risk of VTE.
  • Hospital patients needing oxygen: Dexamethasone (6 mg daily for up to 10 days) and, in selected patients, an IL-6 inhibitor (tocilizumab). VTE prophylaxis.
  • High-risk people in the community: Antivirals (e.g. nirmatrelvir with ritonavir — check interactions) per NICE.
  • Long COVID — persistent symptoms beyond 12 weeks.
• Respiratory syncytial virus (RSV):
  • A major cause of bronchiolitis in infants, and of serious illness in older adults and people with heart or lung disease.
  • Treatment is supportive.
  • RSV vaccination is offered to older adults and in pregnancy (to protect newborns).

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4.05 Whooping Cough

• Cause: Bordetella pertussis. Immunity from vaccination fades, so adults and adolescents get it and pass it on to unvaccinated babies, who can die. Outbreaks occur every few years (a large one in 2024).
• Clinical pattern in adults:
  • A cold-like start, then paroxysms of coughing lasting weeks to months ("the 100-day cough").
  • Inspiratory "whoop".
  • Vomiting after coughing.
  • Broken ribs; subconjunctival haemorrhage.
• Diagnosis:
  • PCR of a nasopharyngeal swab (within about 3 weeks of onset).
  • Serology (anti-pertussis toxin IgG) later.
  • Oral fluid testing in children.
• Treatment: A macrolide (clarithromycin or azithromycin) if started within 3 weeks of cough onset — mainly to reduce spread rather than symptoms.
• Public health: Notifiable; prophylaxis for close contacts in priority groups; vaccination in pregnancy (from 16 weeks) protects newborns.

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4.06 Respiratory Vaccination

• Influenza (annual): Aged 65 and over, chronic heart, lung, kidney, liver or neurological disease, diabetes, immunosuppression, pregnancy, morbid obesity, carers, healthcare workers, children (nasal vaccine).
• Pneumococcal: Aged 65 and over, and at-risk groups (asplenia, chronic disease, immunosuppression, cochlear implants, CSF leaks).
• COVID-19: Seasonal boosters for older and at-risk people, per current JCVI advice.
• RSV: Older adults (as per the national programme) and pregnant women.
• Pertussis: In every pregnancy; routine childhood schedule.
• BCG (TB): Targeted — infants in high-incidence areas or with parents or grandparents from high-incidence countries, and some at-risk adults.

💡 Clinical Pearl: Every admission with a chest infection is a chance to check vaccination status and smoking — two of the most effective things you can do to prevent the next admission.

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4.07 Tuberculosis: What It Is

Mechanism: Infection with Mycobacterium tuberculosis, spread by airborne droplets from people with active lung TB.

• After infection, most people's immune systems wall the bacteria off in granulomas — latent TB infection. This causes no symptoms and is not infectious.
• About 5–10% of people with latent infection develop active TB during their lifetime, most within the first 2 years.
• The risk of active TB is much higher with weakened immunity.

UK picture: Around 5,000 cases a year in England, and rising. Most cases are in people born in high-incidence countries, with higher rates in large cities.

Risk factors for active TB:

• Birth in or travel to high-incidence countries (South Asia, sub-Saharan Africa, Eastern Europe).
• Close contact with a case.
• HIV.
• Immunosuppressive drugs — anti-TNF and other biologics, steroids, transplant drugs.
• Diabetes; CKD and dialysis.
• Silicosis.
• Malnutrition; alcohol or drug misuse.
• Homelessness; prison.
• Smoking.
• Extremes of age.

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4.08 Clinical Features of TB

Pulmonary TB (about half of cases):

• Cough for more than 3 weeks.
• Haemoptysis.
• Fever and night sweats.
• Weight loss; fatigue.
• Chest X-ray: Upper lobe shadowing and cavitation; hilar nodes; effusion; or "miliary" (millet-seed) nodules throughout.

Extrapulmonary TB — common, especially in people from South Asia and in HIV:

• Lymph node TB (the commonest): Painless swollen neck nodes that may discharge (scrofula).
• Pleural TB: Lymphocytic exudate; pleural biopsy has the highest yield.
• Spinal TB (Pott's disease): Back pain, vertebral collapse, paraspinal abscess, cord compression.
• TB meningitis:
  • Gradual headache, fever, confusion, cranial nerve palsies.
  • CSF: lymphocytes, very low glucose, very high protein.
  • High mortality — treat on suspicion.
• Miliary TB: Widespread blood-borne spread — fever, weight loss, small nodules on CXR, choroidal tubercles in the eye. Look for meningitis.
• Other sites:
  • Abdominal (ileocaecal — mimics Crohn's; ascites).
  • Genitourinary (sterile pyuria).
  • Pericardial (constrictive pericarditis).
  • Bone and joint.
  • Skin.
  • Adrenal (Addison's).

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4.09 Diagnosing TB

• Sputum — at least three samples (including an early morning sample) for:
  • AFB smear (acid-fast bacilli on microscopy) — fast, but only positive with large numbers of bacteria. A positive smear means highly infectious.
  • Culture — the gold standard; takes 2–6 weeks; gives drug sensitivities.
  • Rapid molecular test (NAAT) — e.g. GeneXpert — detects TB DNA and rifampicin resistance within hours.
  • Whole-genome sequencing of cultures (used in England) gives the full resistance profile and links cases in outbreaks.
• If unable to cough up sputum: Induced sputum (hypertonic saline) or bronchoscopy with lavage.
• Extrapulmonary: Biopsy of nodes, pleura or other tissue — caseating granulomas on histology, and samples sent fresh (not in formalin) for TB culture.
• Imaging: Chest X-ray; CT; MRI spine for spinal TB.
• Test everyone with TB for HIV, hepatitis B and C; check baseline LFTs, U&E, FBC, visual acuity and colour vision (ethambutol).
• Tuberculin skin test (Mantoux) and IGRA show TB infection — they cannot tell latent from active TB, and can be negative in active disease. Do not use them to rule out active TB.

⚠️ Safety Pearl: Never send a suspected TB biopsy in formalin only — formalin kills the bacteria, so culture and sensitivity testing become impossible. Always send a fresh sample in saline for microbiology.

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4.10 Treating Active TB

Standard treatment for drug-sensitive TB (NICE NG33) — 6 months in total:

• Initial phase — 2 months of four drugs:
  • Rifampicin.
  • Isoniazid (with pyridoxine).
  • Pyrazinamide.
  • Ethambutol.
• Continuation phase — 4 months of rifampicin and isoniazid.
• Given as combination tablets, dosed by weight, once daily.

Special cases:

• CNS TB (meningitis): 12 months of treatment, plus dexamethasone (or prednisolone) at the start.
• Pericardial TB: Steroids may be added to reduce constriction (specialist decision).
• Spinal TB: Usually 6 months (longer if CNS involvement); surgery for cord compression or instability.

Side effects — know them well:

• Rifampicin:
  • Orange-red urine, tears and sweat (stains contact lenses).
  • Hepatitis.
  • Powerful enzyme inducer — it reduces the effect of the contraceptive pill, warfarin, DOACs, steroids, HIV drugs, methadone and many others.
  • Thrombocytopenia; flu-like illness.
• Isoniazid:
  • Peripheral neuropathy — prevent it with pyridoxine (vitamin B6).
  • Hepatitis.
  • Drug-induced lupus.
• Pyrazinamide: Hepatitis (the most hepatotoxic); raised urate and gout; arthralgia; rash.
• Ethambutol: Optic neuritis — reduced visual acuity and red-green colour vision. Check vision before starting and advise patients to report changes. Reduce the dose in renal impairment.

Monitoring:

• LFTs before starting, and repeat if there are liver risk factors or symptoms. Stop drugs and seek advice if ALT is above 5 times normal (or 3 times with symptoms) or jaundice develops.
• Adherence — directly observed therapy (including video-observed) for people at risk of non-adherence.
• Monthly review by the TB nurse service.

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4.11 TB: Public Health and Infection Control

• Notification: TB is a notifiable disease — notify UKHSA on clinical suspicion (don't wait for culture).
• Infection control in hospital:
  • Patients with suspected pulmonary TB go in a single room.
  • Negative-pressure rooms and FFP3 masks for suspected drug-resistant TB, aerosol-generating procedures, or nearby immunocompromised patients.
  • Patients with drug-sensitive TB are usually considered non-infectious after about 2 weeks of effective treatment with clinical improvement.
• Contact tracing: Close contacts (household, prolonged contact) are screened — symptoms, chest X-ray, and IGRA or Mantoux for latent infection.
• Treatment support: TB nurses, translation, housing and benefits support, free treatment regardless of immigration status.
• BCG vaccine: Offered to infants at higher risk, and to some adults (e.g. unvaccinated healthcare workers under 35 at risk). Protects mostly against severe childhood TB (meningitis, miliary TB).

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4.12 Latent TB

• What it is: Infection without active disease — no symptoms, normal chest X-ray, not infectious, but a risk of future active TB.
• Testing: Interferon-gamma release assay (IGRA) blood test, or a Mantoux skin test (which BCG can make falsely positive).
• Who to test:
  • Close contacts of people with pulmonary TB.
  • New entrants from high-incidence countries (national programme for those aged 16–35).
  • Before starting anti-TNF and other biologics, or before transplant or major immunosuppression.
  • People with HIV.
  • Dialysis and other high-risk groups.
• Before treating: Exclude active TB first (symptoms, chest X-ray, sputum if needed). Treating active TB with one or two drugs breeds resistance.
• Treatment (NICE NG33):
  • 3 months of rifampicin plus isoniazid (with pyridoxine), or
  • 6 months of isoniazid (with pyridoxine) — e.g. if rifampicin interactions are a problem.
  • Rifampicin alone for 3–4 months in some cases.
• Reduces the risk of active TB by about 60–90%.

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4.13 Drug-resistant TB

• Definitions:
  • Isoniazid-resistant TB — the commonest resistance.
  • MDR-TB (multidrug-resistant) — resistant to rifampicin and isoniazid.
  • Pre-XDR and XDR-TB — MDR plus resistance to fluoroquinolones and other key drugs.
• Risk factors:
  • Previous TB treatment (especially incomplete).
  • Contact with drug-resistant TB.
  • Birth in high-MDR countries (e.g. Eastern Europe, Central Asia).
  • HIV.
  • Not responding to standard treatment.
• Diagnosis: Rapid molecular testing for rifampicin resistance, then whole-genome sequencing.
• Treatment (specialist, with the national MDR-TB clinical advice service):
  • All-oral regimens built around newer drugs — bedaquiline, pretomanid and linezolid (with or without moxifloxacin) for 6 months (the "BPaL(M)" regimen) in many cases, or longer individualised regimens.
  • Side effects: QT prolongation (bedaquiline, moxifloxacin), and myelosuppression and neuropathy (linezolid).
• Infection control: Negative-pressure isolation until sputum cultures are negative.

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4.14 TB and HIV

• The connection: HIV greatly increases the risk of active TB, and TB is a leading cause of death in people with HIV worldwide. Every patient with TB should have an HIV test.
• Presentation in advanced HIV: Atypical — lower lobe or diffuse shadows, no cavities, extrapulmonary and disseminated disease, negative sputum smears.
• Treatment:
  • Standard TB drugs.
  • Start antiretroviral therapy — usually within 2 weeks of TB treatment if the CD4 count is low (later in TB meningitis, to reduce the risk of brain inflammation).
  • Co-trimoxazole prophylaxis.
• Drug interactions: Rifampicin lowers levels of many antiretrovirals — specialist regimen choice (e.g. adjusted dolutegravir dosing).
• IRIS (immune reconstitution inflammatory syndrome): As immunity recovers on antiretrovirals, there may be a paradoxical worsening of TB — fever, enlarging nodes, new effusions. Continue both treatments; steroids if severe.

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4.15 Non-tuberculous Mycobacteria

• What they are: Environmental mycobacteria (in water, soil, showerheads) that do not spread between people (except possibly M. abscessus in CF). They cause chronic lung infection in damaged or vulnerable lungs.
• Common species:
  • Mycobacterium avium complex (MAC) — the commonest.
  • M. kansasii — behaves like TB.
  • M. abscessus — hard to treat, important in CF.
  • M. xenopi, M. malmoense.
• Who:
  • Bronchiectasis, COPD, CF.
  • Previous TB.
  • Immunosuppression.
  • Thin, older women with nodular bronchiectasis ("Lady Windermere syndrome").
• Diagnosis (BTS) — all three needed, because NTM can be harmless colonisers:
  • Symptoms.
  • Compatible imaging (nodules with bronchiectasis, or cavities).
  • At least two positive sputum cultures of the same species (or one BAL or biopsy).
• Treatment:
  • Not everyone needs it — some are monitored.
  • MAC: Rifampicin, ethambutol and azithromycin, continued for at least 12 months after cultures become negative. Amikacin (IV or nebulised) for severe or refractory disease.
  • Prolonged, specialist-led treatment.
• Before starting long-term macrolides (e.g. for bronchiectasis or COPD), exclude NTM — macrolide monotherapy causes resistance.

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4.16 Aspergillus Lung Disease

Aspergillus fumigatus is a mould whose spores are inhaled by everyone. The disease it causes depends on the person's immune response and lung structure:

• Allergic (ABPA): Asthma or CF — see the Airways Disease chapter.
• Aspergilloma ("fungal ball"):
  • Fungus growing in an existing cavity (old TB, sarcoidosis, cavitating disease).
  • Often no symptoms, but can cause haemoptysis — sometimes massive.
  • Imaging: A ball in a cavity with an air crescent, which moves when the patient changes position.
  • Treatment: Surgery or bronchial artery embolisation for bleeding.
• Chronic pulmonary aspergillosis:
  • Slowly progressive cavities and fibrosis over months, in people with previous TB, COPD, NTM or sarcoidosis.
  • Weight loss, cough, fatigue, haemoptysis.
  • Raised aspergillus IgG.
  • Long courses of oral antifungals (itraconazole or voriconazole) for at least 6 months.
• Invasive aspergillosis:
  • Severely immunocompromised — prolonged neutropenia (leukaemia, stem cell transplant), organ transplant, high-dose steroids; also severe influenza or COVID-19 in ICU.
  • Fever despite antibiotics, cough, pleuritic pain, haemoptysis.
  • CT: nodules with a surrounding "halo sign", cavitation.
  • Serum or BAL galactomannan.
  • Voriconazole or isavuconazole (monitor levels and interactions). High mortality.

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4.17 Pneumocystis Pneumonia

• Cause: Pneumocystis jirovecii, a fungus that causes pneumonia in people with weakened cell-mediated immunity.
• Who:
  • HIV with a CD4 count below 200 — often the presenting illness of undiagnosed HIV.
  • High-dose or long-term steroids.
  • Transplant recipients.
  • Chemotherapy and some biologics (e.g. rituximab).
• Clinical pattern:
  • Gradual (weeks in HIV, faster in other immunosuppression).
  • Dry cough, increasing breathlessness, fever.
  • Desaturation on exertion — often with a near-normal chest examination.
• Imaging: Chest X-ray may be normal or show bilateral perihilar haziness. CT shows ground-glass opacities and sometimes cysts. Risk of pneumothorax.
• Diagnosis: PCR or immunofluorescence on induced sputum or BAL; raised serum beta-D-glucan supports it. Test for HIV.
• Treatment:
  • High-dose co-trimoxazole for 21 days.
  • Add prednisolone if hypoxic (e.g. PaO2 below 9.3 kPa on air) — this reduces mortality in HIV.
  • Alternatives for co-trimoxazole allergy: clindamycin with primaquine (check G6PD), atovaquone, IV pentamidine.
• Prophylaxis: Co-trimoxazole for people with HIV and CD4 below 200, and those on prolonged high-dose steroids or other high-risk immunosuppression.

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4.18 Other Fungal Infections

• Cryptococcus: Lung nodules or pneumonia; in HIV, meningitis (headache, raised CSF pressure). Diagnosed by cryptococcal antigen.
• Endemic fungi — ask about travel:
  • Histoplasmosis (Americas, caves, bat and bird droppings).
  • Coccidioidomycosis (south-west USA).
  • Blastomycosis (North America).
  • These mimic TB or sarcoidosis.
• Mucormycosis: Aggressive invasion of the sinuses and lungs in poorly controlled diabetes (DKA), neutropenia and steroid use — black necrotic tissue. Emergency surgery plus amphotericin.
• Candida: Rarely causes true pneumonia — it is usually just a contaminant in sputum.

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4.19 Lung Infection in the Immunocompromised

The type of immune defect predicts the organism:

• Neutropenia (chemotherapy):
  • Bacteria (including Pseudomonas).
  • Invasive aspergillus and other moulds if prolonged.
  • Neutropenic sepsis needs antibiotics within 1 hour.
• Low T cells (HIV, transplant drugs, high-dose steroids):
  • PCP.
  • TB and NTM.
  • CMV pneumonitis (especially after transplant).
  • Cryptococcus.
  • Nocardia.
  • Viruses.
• Low antibodies or no spleen: Encapsulated bacteria — S. pneumoniae, H. influenzae.
• Biologics:
  • Anti-TNF — TB reactivation, Legionella, fungi.
  • Rituximab — PCP, viral infections, low antibodies.

Approach:

• Have a low threshold — symptoms and signs are often muted.
• Early CT chest; early bronchoscopy with BAL for PCR and cultures.
• Blood and urine antigen tests; HIV test.
• Broad empirical treatment while results are awaited.
• Involve infectious diseases, microbiology and the patient's specialist team.
• Remember non-infectious mimics — drug pneumonitis, alveolar haemorrhage, pulmonary oedema, malignancy, graft-versus-host disease.

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4.20 Drug Reference Table

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4.21 Spot the Diagnosis

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4.22 Exam-style Scenarios

1. A 34-year-old man who moved from Somalia 2 years ago has 2 months of cough, night sweats and weight loss. Chest X-ray shows right upper lobe cavitation.
Answer: Probable pulmonary TB.

• Single room; three sputum samples for smear, NAAT (rifampicin resistance) and culture.
• HIV, hepatitis B and C tests; baseline LFTs and vision.
• Start RIPE (with pyridoxine); notify UKHSA; contact tracing.

2. A woman on rifampicin-containing TB treatment uses the combined oral contraceptive pill.
Answer: Rifampicin induces liver enzymes and makes the pill unreliable.

• Advise a non-hormonal method or an injectable or intrauterine method during treatment and for 4 weeks after.
• Review all her other drugs for interactions.

3. A man with rheumatoid arthritis is due to start an anti-TNF drug. He was born in India.
Answer: Screen for latent TB first — IGRA and chest X-ray (and symptoms).

• If IGRA is positive and active TB is excluded: 3 months of rifampicin plus isoniazid (or 6 months of isoniazid) before or alongside starting the biologic, per specialist advice.

4. A 45-year-old with no known medical history has 3 weeks of dry cough and breathlessness, with SpO2 falling to 86% on walking. CT shows diffuse ground-glass. HIV test is positive; PaO2 is 8.6 kPa.
Answer: PCP in newly diagnosed HIV.

• Induced sputum or BAL for PCR.
• High-dose co-trimoxazole for 21 days, plus prednisolone (PaO2 below 9.3 kPa).
• HIV specialist care; start ART (usually within 2 weeks).

5. A 70-year-old has had "pneumonia" in the right lower lobe treated three times in 4 months.
Answer: Recurrent pneumonia in the same lobe.

• Look for an obstructing lesion (lung cancer, foreign body) — CT chest and bronchoscopy.
• Also consider aspiration (swallow assessment) and bronchiectasis.

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4.23 Key Points

• Pneumonia clues: Legionella (hyponatraemia, travel), Mycoplasma (young, haemolysis), S. aureus (after flu, cavitation), Klebsiella (alcohol), psittacosis (birds), Q fever (farm animals).
• Non-resolving pneumonia: think empyema, abscess, obstruction (cancer), TB, wrong diagnosis.
• Give influenza antivirals to all hospital admissions with suspected flu in season; dexamethasone for COVID-19 needing oxygen.
• TB: cough over 3 weeks, sweats, weight loss; three sputum samples; NAAT for rifampicin resistance; culture is the gold standard.
• Treatment: 2 months RIPE then 4 months RI (12 months plus steroids for CNS TB). Give pyridoxine with isoniazid.
• Know the side effects: rifampicin (orange secretions, enzyme induction), isoniazid (neuropathy), pyrazinamide (gout, liver), ethambutol (eyes).
• Notify TB; contact tracing; HIV test for everyone with TB.
• Screen for latent TB before biologics; treat with 3 months RH or 6 months H — after excluding active disease.
• MDR-TB is rifampicin plus isoniazid resistance — specialist all-oral regimens.
• NTM diagnosis needs symptoms, imaging and at least 2 positive cultures. Exclude NTM before long-term macrolides.
• Aspergillus causes a spectrum: ABPA, aspergilloma, chronic pulmonary aspergillosis, invasive aspergillosis.
• PCP: CD4 below 200 or high-dose steroids; desaturation on exertion; co-trimoxazole plus steroids if hypoxic.

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4.24 Guidelines and Further Reading

• NICE NG250: Pneumonia — diagnosis and management
• NICE NG33: Tuberculosis
• UKHSA: TB in England annual reports; national TB action plan
• UKHSA: Guidance on the use of antiviral agents for the treatment and prophylaxis of influenza
• BTS Guideline for the management of non-tuberculous mycobacterial pulmonary disease (2017)
• BHIVA: Guidelines for the management of tuberculosis in adults living with HIV
• UKHSA: Green Book — immunisation against infectious disease
• BNF — for current doses

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5.01 What Is Interstitial Lung Disease?

Mechanism: The interstitium is the thin tissue between the air sacs and the capillaries. In ILD it becomes inflamed or scarred (fibrosis). This makes the lungs:

• Stiff — small, restricted lung volumes.
• Poor at gas exchange — low TLCO and oxygen levels, worse on exercise.

A practical classification:

• Known cause:
  • Hypersensitivity pneumonitis.
  • Connective tissue disease.
  • Drugs and radiation.
  • Occupational dusts (asbestosis, silicosis).
  • Smoking-related.
• Idiopathic interstitial pneumonias:
  • Idiopathic pulmonary fibrosis (the commonest).
  • Non-specific interstitial pneumonia.
  • Cryptogenic organising pneumonia.
  • Others.
• Granulomatous: Sarcoidosis.
• Rare: Lymphangioleiomyomatosis, Langerhans cell histiocytosis, alveolar proteinosis, eosinophilic pneumonias.

Clinical pattern:

• Progressive exertional breathlessness.
• Dry cough.
• Fine "Velcro" crackles (especially at the bases in fibrosis).
• Clubbing (IPF, asbestosis).
• Desaturation on walking.
• Late: right heart failure (pulmonary hypertension).

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5.02 Assessing Suspected ILD

• History — exposures are key:
  • Drugs — past and present (methotrexate, amiodarone, nitrofurantoin, chemotherapy, immunotherapy).
  • Birds (pigeons, budgies, feather duvets), moulds (damp homes, hot tubs, humidifiers).
  • Occupation — asbestos, silica, coal, metals, farming.
  • Smoking.
  • Radiotherapy.
  • Family history (familial pulmonary fibrosis).
• Connective tissue disease symptoms:
  • Joint pain; Raynaud's; skin thickening.
  • Rash, mechanic's hands.
  • Muscle weakness; dry eyes and mouth; dysphagia.
• Tests:
  • HRCT — the key test.
  • Full lung function — restrictive pattern, low TLCO.
  • 6-minute walk test (desaturation).
  • Bloods: FBC, U&E, LFTs, CRP; autoimmune screen (ANA, ENA, rheumatoid factor, anti-CCP, myositis antibodies including anti-Jo-1, ANCA); serum precipitins (bird, mould) if hypersensitivity pneumonitis is possible.
  • Echo if pulmonary hypertension is suspected.
• Bronchoalveolar lavage — lymphocytosis suggests hypersensitivity pneumonitis or sarcoidosis; also excludes infection.
• Lung biopsy (transbronchial cryobiopsy or surgical) — only when the diagnosis is still uncertain and the result would change treatment.
• ILD multidisciplinary team (MDT) discussion — respiratory physicians, radiologists and pathologists agree the diagnosis. This is the gold standard.

💡 Clinical Pearl: Before labelling anyone with "idiopathic" pulmonary fibrosis, actively look for a cause — a hidden bird exposure, a drug, or an early connective tissue disease. Finding one changes treatment and prognosis.

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5.03 Idiopathic Pulmonary Fibrosis

Mechanism: Progressive scarring of the lungs with no known cause, thought to result from repeated injury to the alveolar lining with abnormal healing. It is the commonest and most serious idiopathic ILD. Median survival from diagnosis is about 3–5 years — worse than many cancers.

Who: Usually over 60; more common in men and ex-smokers; some cases are familial (e.g. telomere gene mutations).

Clinical pattern:

• Slowly progressive breathlessness; dry cough.
• Bibasal fine crackles.
• Clubbing (about half).
• Associated with reflux, lung cancer and pulmonary hypertension.

Diagnosis:

• HRCT with a usual interstitial pneumonia (UIP) pattern:
  • Basal and subpleural reticulation.
  • Honeycombing.
  • Traction bronchiectasis.
  • Little ground-glass.
• Exclusion of known causes.
• MDT agreement. Biopsy is rarely needed when the HRCT pattern is typical.

Management:

• Antifibrotic drugs slow the decline in FVC by about half — they do not reverse scarring:
  • Pirfenidone or nintedanib for people with FVC 50–80% predicted (NICE TA504, TA379).
  • Nintedanib is now also recommended when FVC is above 80% (NICE TA864).
  • Pirfenidone side effects: photosensitivity rash, nausea, weight loss. Nintedanib side effects: diarrhoea, raised LFTs.
  • Monitor LFTs.
  • NICE stopping rules apply for some indications (e.g. FVC decline of 10% or more in 12 months).
• Do not use steroids or immunosuppressants for stable IPF — they cause harm.
• Supportive care:
  • Pulmonary rehabilitation.
  • Oxygen (ambulatory and long-term) for hypoxaemia.
  • Smoking cessation; vaccinations.
  • Treat reflux if symptomatic; manage cough.
  • Screen for pulmonary hypertension and lung cancer.
• Lung transplantation for suitable patients — refer early (usually under about 65).
• Palliative care — breathlessness and cough management, advance care planning. Many patients die of respiratory failure.

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5.04 Acute Exacerbation of IPF

• What it is: A sudden worsening of breathlessness over less than a month, with new bilateral ground-glass change on CT on top of the fibrosis. Not explained by heart failure or fluid overload.
• Triggers: Infection, surgery, bronchoscopy or biopsy, often none.
• Prognosis: Very poor — about half die in hospital.
• Management:
  • Exclude other causes — infection, PE, heart failure, pneumothorax.
  • Oxygen (often high-flow); antibiotics while infection is excluded.
  • High-dose steroids are often given, though evidence is weak.
  • Continue antifibrotics.
  • Early discussion of goals of care — mechanical ventilation rarely helps unless it is a bridge to transplant.

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5.05 Progressive Pulmonary Fibrosis

• What it is: Any fibrotic ILD other than IPF that keeps getting worse despite treatment of the cause. Examples include fibrotic hypersensitivity pneumonitis, connective tissue disease ILD and fibrotic NSIP.
• Definition — two or more of these in a year:
  • Worse symptoms.
  • Falling lung function (e.g. FVC down by 5% or more, or TLCO down by 10% or more).
  • More fibrosis on CT.
• Treatment: Nintedanib slows FVC decline (NICE TA747), alongside treatment of the underlying condition.

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5.06 Non-specific Interstitial Pneumonia

• What it is: A pattern of more even, uniform inflammation and fibrosis — often in younger people and women.
• Causes: Frequently linked to connective tissue disease (especially systemic sclerosis and myositis), drugs or hypersensitivity pneumonitis. It can also be idiopathic.
• HRCT: Bilateral basal ground-glass with fine reticulation, often sparing the area just under the pleura; little or no honeycombing.
• Treatment: Treat the cause. Immunosuppression (prednisolone, mycophenolate) often helps — unlike IPF.
• Prognosis: Better than IPF, especially in the inflammatory (cellular) form.

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5.07 Hypersensitivity Pneumonitis

Mechanism: An immune reaction in the small airways and alveoli to an inhaled organic antigen in a sensitised person.

Common causes:

• Birds — bird fancier's lung (pigeons, budgies, feather duvets and pillows).
• Mouldy hay or grain — farmer's lung.
• Moulds — damp homes, humidifiers, air conditioning, hot tubs.
• Metalworking fluids; some drugs.
• No cause is found in up to half.

Types:

• Non-fibrotic (inflammatory): Episodes of cough, breathlessness, fever and flu-like symptoms 4–8 hours after exposure, or gradual onset. Often reversible.
• Fibrotic: Chronic progressive scarring — can mimic IPF, and has a worse outlook.

Diagnosis:

• Exposure history — ask specifically about birds, feathers and damp.
• HRCT: Ground-glass, centrilobular nodules, mosaic attenuation with air trapping (the "three-density" sign); upper and mid zones.
• Serum precipitins (specific IgG) — show exposure, not disease.
• BAL lymphocytosis.
• Biopsy if uncertain.

Management:

• Avoid the antigen completely — the most important step (remove birds, feather bedding; fix damp).
• Prednisolone for significant disease; mycophenolate or azathioprine to spare steroids.
• Nintedanib if progressive fibrosis.

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5.08 Connective Tissue Disease ILD

• Systemic sclerosis:
  • ILD affects up to half — the leading cause of death in this disease.
  • Usually an NSIP pattern; associated with anti-Scl-70 (topoisomerase) antibodies.
  • Also pulmonary arterial hypertension (limited disease, anticentromere) — screen yearly.
  • Treatment: Mycophenolate (or cyclophosphamide); tocilizumab or rituximab in selected cases; nintedanib for progression.
• Rheumatoid arthritis:
  • ILD (often UIP pattern, especially in male smokers).
  • Also bronchiectasis, pleural effusions (very low glucose), rheumatoid nodules.
  • Caplan's syndrome — nodules with coal or silica exposure.
  • Drug toxicity — methotrexate, and infection risk with biologics.
• Inflammatory myositis (especially antisynthetase syndrome — anti-Jo-1):
  • ILD, myositis, arthritis.
  • Mechanic's hands, Raynaud's, fever.
  • Anti-MDA5 dermatomyositis can cause rapidly progressive ILD.
  • Treatment: Steroids plus immunosuppression.
• Sjögren's syndrome: Lymphocytic interstitial pneumonia, cysts, small airways disease, lymphoma.
• SLE:
  • Pleurisy and effusions (commonest).
  • Acute lupus pneumonitis.
  • Alveolar haemorrhage.
  • "Shrinking lung syndrome" (diaphragm dysfunction).
  • PE (antiphospholipid syndrome).

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5.09 Drug- and Radiation-induced Lung Disease

Common culprits (pneumotox.com lists hundreds):

• Methotrexate — acute or subacute pneumonitis (fever, cough, breathlessness); can occur at any dose.
• Amiodarone — pneumonitis and fibrosis; dose- and duration-related. High-density lungs and liver on CT. Monitor lung function and chest X-ray.
• Nitrofurantoin — acute reaction (fever, eosinophilia) or chronic fibrosis with long-term use (e.g. UTI prophylaxis).
• Chemotherapy — bleomycin (made worse by high oxygen), busulfan, cyclophosphamide.
• Immune checkpoint inhibitors (pembrolizumab, nivolumab) — immune-related pneumonitis.
• Biologics and others — anti-TNF, rituximab, leflunomide, sulfasalazine.

Radiation pneumonitis: 1–6 months after thoracic radiotherapy, with breathlessness, cough and shadowing that matches the radiation field. It can progress to fibrosis.

Management:

• Stop the drug; exclude infection.
• Prednisolone for significant disease.
• Record as an adverse reaction (Yellow Card).
• Avoid rechallenge (immune checkpoint pneumonitis — specialist decision).

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5.10 Occupational Lung Disease

• Asbestos-related disease (shipbuilding, construction, plumbing, electricians — exposure often decades earlier):
  • Pleural plaques — calcified, benign, a marker of exposure only.
  • Diffuse pleural thickening — can restrict the lungs.
  • Benign asbestos pleural effusion.
  • Asbestosis — lower-zone fibrosis, like IPF, needing heavy exposure.
  • Mesothelioma and lung cancer (risk multiplied by smoking).
• Silicosis (quarrying, sandblasting, stonemasonry, engineered stone worktops):
  • Upper-zone nodules.
  • "Eggshell" calcification of hilar nodes.
  • Progressive massive fibrosis.
  • Increased risk of TB, lung cancer, autoimmune disease.
• Coal worker's pneumoconiosis: Upper-zone nodules; progressive massive fibrosis; Caplan's syndrome with RA.
• Berylliosis (aerospace, electronics): A granulomatous disease identical to sarcoidosis — the beryllium lymphocyte proliferation test distinguishes it.
• Management:
  • Remove from exposure; stop smoking.
  • Supportive care; screen for TB in silicosis.
  • Advise on compensation (Industrial Injuries Disablement Benefit, civil claims).
  • Some cases (e.g. mesothelioma) are reportable to the coroner on death.

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5.11 Smoking-related ILD

• Respiratory bronchiolitis ILD (RB-ILD) and desquamative interstitial pneumonia (DIP):
  • Smoke-laden macrophages fill the small airways and alveoli.
  • Ground-glass on CT.
  • Improves with stopping smoking (steroids sometimes).
• Pulmonary Langerhans cell histiocytosis:
  • Young adult smokers.
  • Upper-zone nodules and odd-shaped cysts (sparing the bases).
  • Pneumothorax.
  • Sometimes diabetes insipidus or bone lesions.
  • Stopping smoking is essential.
• Combined pulmonary fibrosis and emphysema:
  • Upper-lobe emphysema with lower-lobe fibrosis.
  • Near-normal spirometry but a very low TLCO.
  • High risk of pulmonary hypertension and lung cancer.

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5.12 Organising Pneumonia

• What it is: Plugs of granulation tissue fill the small airways and alveoli after injury.
  • Cryptogenic — no cause.
  • Or secondary — infection, connective tissue disease, drugs, radiotherapy (often breast cancer), immune checkpoint inhibitors.
• Clinical pattern: A flu-like illness with cough, breathlessness, fever and weight loss over weeks — often treated as "pneumonia that won't resolve" after several courses of antibiotics.
• Imaging: Patchy, often migratory, peripheral or peribronchial consolidation; "reversed halo" sign.
• Treatment: Usually responds dramatically to prednisolone over months. Relapses are common when steroids are tapered.

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5.13 Eosinophilic Lung Disease

• Simple pulmonary eosinophilia (Löffler's syndrome): Transient shadows with blood eosinophilia, often from parasites (e.g. Ascaris) or drugs. Usually self-limiting.
• Acute eosinophilic pneumonia:
  • Rapid severe hypoxaemic illness in a previously well person — often after starting smoking (including vaping) or a new drug.
  • BAL eosinophils are high (blood eosinophils may be normal at first).
  • Responds quickly to steroids.
• Chronic eosinophilic pneumonia:
  • Middle-aged women, often with asthma.
  • Weeks of cough, fever and weight loss.
  • Peripheral consolidation ("photographic negative of pulmonary oedema").
  • High blood eosinophils.
  • Steroid-responsive, but relapses.
• Other causes to consider:
  • ABPA.
  • EGPA (asthma, neuropathy, vasculitis).
  • Drugs (nitrofurantoin, NSAIDs, antibiotics, anticonvulsants — including DRESS).
  • Parasites (Strongyloides — check serology before steroids in at-risk patients).
  • Hypereosinophilic syndrome.

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5.14 Cystic Lung Diseases

• Lymphangioleiomyomatosis (LAM):
  • Who: Almost exclusively women of childbearing age; sporadic or with tuberous sclerosis.
  • Lungs: Many thin-walled round cysts throughout both lungs.
  • Features: Breathlessness, recurrent pneumothorax, chylous (milky) pleural effusions, renal angiomyolipomas.
  • Diagnosis: Raised serum VEGF-D supports it.
  • Treatment: Sirolimus (mTOR inhibitor) stabilises lung function. Avoid oestrogens.
• Pulmonary Langerhans cell histiocytosis: Smokers; upper-zone irregular cysts and nodules (see Smoking-related ILD).
• Birt–Hogg–Dubé syndrome:
  • Inherited (FLCN gene).
  • Basal cysts; recurrent pneumothorax.
  • Skin fibrofolliculomas.
  • Renal tumours — screen with MRI.
• Also lymphocytic interstitial pneumonia (Sjögren's) and PCP pneumatoceles.

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5.15 Pulmonary Alveolar Proteinosis

• Mechanism: The alveoli fill with surfactant because macrophages cannot clear it. Usually autoimmune — antibodies against GM-CSF. Rarely secondary to dusts or blood cancers.
• Clinical pattern: Gradual breathlessness, often milder than the imaging suggests; infection risk (e.g. Nocardia).
• Imaging: "Crazy paving" on CT — ground-glass with thickened septa.
• Diagnosis: Milky BAL fluid; anti-GM-CSF antibodies.
• Treatment: Whole-lung lavage (specialist); inhaled GM-CSF.

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5.16 Sarcoidosis: What It Is

Mechanism: A multisystem disease of unknown cause in which clumps of immune cells — non-caseating granulomas — form in organs. It is thought to be an exaggerated immune response to an environmental trigger in genetically susceptible people. The lungs and lymph nodes are involved in about 90%.

Who: Usually ages 20–40, with a second peak in women over 50. Commoner and often more severe in people of Black African and African-Caribbean descent; also common in Scandinavians.

Course: Many cases — especially Löfgren's syndrome — resolve on their own within 2 years. About a third become chronic, and a minority develop lung fibrosis or serious organ damage (heart, eyes, nervous system).

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5.17 Clinical Features of Sarcoidosis

Lungs and nodes:

• Often found on a chest X-ray done for another reason.
• Dry cough, breathlessness, chest discomfort, fatigue.
• Chest X-ray (Scadding) stages:
  • 0 — normal.
  • I — bilateral hilar lymphadenopathy (BHL) only.
  • II — BHL plus lung infiltrates.
  • III — infiltrates only.
  • IV — fibrosis (upper zone).
  Higher stages are less likely to resolve.

Löfgren's syndrome — an acute form with an excellent prognosis (usually resolves within 2 years):

• Erythema nodosum.
• Bilateral hilar lymphadenopathy.
• Ankle arthritis (periarticular).
• Fever.

Outside the lungs:

• Skin: Erythema nodosum; lupus pernio (purple plaques on the nose — chronic disease); scar infiltration.
• Eyes: Uveitis (anterior or posterior), dry eyes — can threaten sight. Everyone needs an eye examination.
• Heart (cardiac sarcoidosis):
  • Heart block, ventricular arrhythmias, sudden death, cardiomyopathy.
  • Can be the first presentation in a young adult.
  • Screen everyone with an ECG; cardiac MRI or FDG-PET if abnormal or symptomatic.
• Calcium: Granulomas make active vitamin D (calcitriol), causing hypercalcaemia and hypercalciuria (kidney stones, nephrocalcinosis).
• Nervous system (neurosarcoidosis):
  • Facial nerve palsy (sometimes bilateral).
  • Meningitis.
  • Pituitary and hypothalamic disease (diabetes insipidus).
  • Spinal cord lesions.
• Other: Liver and spleen enlargement; parotid swelling; kidneys; joints; fatigue (very common and disabling).
• Heerfordt's syndrome: Parotid enlargement, uveitis, fever and facial palsy.

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5.18 Diagnosing Sarcoidosis

Sarcoidosis is diagnosed by three things:

• A compatible clinical and radiological picture.
• Non-caseating granulomas on biopsy (usually not needed in classic Löfgren's syndrome).
• Exclusion of other causes of granulomas — TB (caseating granulomas, culture), fungal infection, lymphoma, berylliosis, drug reactions (including immune checkpoint inhibitors), hypersensitivity pneumonitis.

Tests:

• Biopsy: EBUS-guided needle aspiration of mediastinal nodes is the usual route; skin lesions are easy to biopsy too.
• Bloods: Calcium, U&E, LFTs, FBC (lymphopenia).
• Serum ACE — often raised, but neither sensitive nor specific; not diagnostic.
• Urine calcium; immunoglobulins.
• Lung function (restriction, low TLCO) and HRCT (nodules along lymphatics, upper zones; nodes).
• Screening for organ involvement in everyone:
  • ECG.
  • Eye examination.
  • Calcium.
  • Renal and liver function.
• FDG-PET to find biopsy sites, assess activity and look for cardiac disease.

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5.19 Treating Sarcoidosis

• Many patients need no treatment — monitor stage I and mild stage II disease with symptoms, lung function and imaging. Löfgren's syndrome needs only NSAIDs for joint pain and erythema nodosum.
• Treat if there is:
  • Significant or worsening lung disease (symptoms with falling lung function).
  • Organ- or life-threatening disease — cardiac, eye (posterior uveitis), neurological, hypercalcaemia, renal.
  • Disfiguring skin disease (lupus pernio).
• First line: Oral prednisolone (e.g. 20–40 mg daily for pulmonary disease), tapered to the lowest effective dose over 6–12 months or more. Give bone protection.
• Steroid-sparing: Methotrexate (most used), azathioprine, mycophenolate, leflunomide.
• Refractory disease: Anti-TNF (infliximab) — especially for cardiac, neuro and skin disease.
• Cardiac sarcoidosis: Steroids plus immunosuppression; pacing for heart block; an ICD for ventricular arrhythmias or severe LV dysfunction.
• Hypercalcaemia: Steroids; avoid vitamin D supplements and excess sun.
• Topical or local steroids for anterior uveitis and skin.
• End-stage fibrosis: Oxygen, pulmonary hypertension assessment, transplant.
• Recognise and support fatigue.

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5.20 Drug Reference Table

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5.21 Spot the Diagnosis

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5.22 Exam-style Scenarios

1. A 74-year-old ex-smoker has 18 months of breathlessness and dry cough. He has clubbing and bibasal crackles. HRCT shows subpleural basal honeycombing. FVC is 68%. No exposures or autoimmune features.
Answer: Idiopathic pulmonary fibrosis (UIP pattern).

• ILD MDT confirmation.
• Offer an antifibrotic (pirfenidone or nintedanib).
• Pulmonary rehabilitation; oxygen assessment; advance care planning.
• No steroids.

2. A 50-year-old woman has 6 months of breathlessness. She has a feather duvet and two budgies. HRCT shows ground-glass, centrilobular nodules and air trapping. Bird precipitins are positive.
Answer: Non-fibrotic hypersensitivity pneumonitis.

• Remove the birds and feather bedding completely.
• Consider prednisolone if there is significant impairment.
• Monitor lung function.

3. A 28-year-old woman has painful red lumps on her shins, ankle swelling and fever. Chest X-ray shows bilateral hilar lymphadenopathy.
Answer: Löfgren's syndrome.

• NSAIDs for symptoms; no biopsy needed if typical.
• Screen with ECG, calcium and an eye examination.
• Excellent prognosis — usually resolves.

4. A 35-year-old man with known pulmonary sarcoidosis has palpitations and a syncopal episode. ECG shows second-degree heart block.
Answer: Suspected cardiac sarcoidosis.

• Urgent cardiology review.
• Cardiac MRI and/or FDG-PET.
• Pacing or ICD as indicated; immunosuppression.

5. A woman with RA on methotrexate has 2 weeks of fever, dry cough and breathlessness. CT shows new bilateral ground-glass.
Answer: Possible methotrexate pneumonitis — but exclude infection (including PCP) first.

• Stop methotrexate.
• Investigate for infection (BAL if needed).
• Steroids once infection is excluded.

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5.23 Key Points

• ILD causes restriction, low TLCO and exertional desaturation; fine crackles and sometimes clubbing.
• Always search for a cause — drugs, birds, moulds, occupation, connective tissue disease.
• HRCT and the ILD MDT are central to diagnosis.
• IPF: UIP pattern with honeycombing; antifibrotics (pirfenidone or nintedanib) slow decline; no steroids.
• Acute exacerbation of IPF has a very high mortality — discuss goals of care early.
• Progressive non-IPF fibrosis: add nintedanib.
• Hypersensitivity pneumonitis: antigen avoidance first; steroids and mycophenolate if needed.
• Drug-induced ILD: methotrexate, amiodarone, nitrofurantoin, bleomycin, checkpoint inhibitors — stop the drug.
• Silicosis raises the risk of TB; asbestos causes plaques, asbestosis, mesothelioma and lung cancer.
• Sarcoidosis: non-caseating granulomas; often resolves; screen everyone for heart, eye and calcium involvement.
• Treat sarcoidosis only for progressive or organ-threatening disease — steroids first, then methotrexate or infliximab.

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5.24 Guidelines and Further Reading

• NICE CG163: Idiopathic pulmonary fibrosis in adults
• NICE TA504 (pirfenidone), TA379 and TA864 (nintedanib for IPF), TA747 (nintedanib for progressive fibrosing ILD)
• ATS/ERS/JRS/ALAT: Idiopathic pulmonary fibrosis and progressive pulmonary fibrosis guideline (2022)
• ATS/JRS/ALAT: Hypersensitivity pneumonitis guideline (2020)
• BTS Clinical statement on pulmonary sarcoidosis (2021); ERS sarcoidosis treatment guideline (2021)
• Pneumotox (www.pneumotox.com) — drug-induced lung disease
• BNF — for current doses

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6.01 Lung Cancer: What It Is

Risk factors:

• Smoking — about 70–85% of cases; risk rises with pack-years and falls after stopping.
• Passive smoking.
• Radon gas.
• Asbestos and other occupational carcinogens.
• Air pollution.
• Previous chest radiotherapy.
• Family history; COPD and pulmonary fibrosis.
• HIV.

About 1 in 7 cases occur in never-smokers, often women and people of East Asian descent, usually with adenocarcinoma.

Main types:

• Non-small cell lung cancer (NSCLC) — about 85%:
  • Adenocarcinoma — the commonest. Usually peripheral; the commonest type in never-smokers. Often has targetable mutations (EGFR, ALK, ROS1, KRAS).
  • Squamous cell carcinoma — usually central, smokers. May cavitate; linked to hypercalcaemia (PTHrP).
  • Large cell carcinoma — less common, poorly differentiated.
• Small cell lung cancer (SCLC) — about 15%:
  • Central, almost always in smokers.
  • Neuroendocrine; grows and spreads very fast.
  • Linked with paraneoplastic syndromes (SIADH, ectopic ACTH, Lambert–Eaton).
• Carcinoid tumours — low-grade neuroendocrine tumours, often in younger people.

Outlook: 5-year survival is over 60% for stage I but under 10% for stage IV — so early diagnosis is everything.

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6.02 Symptoms and Urgent Referral

Symptoms:

• Local: Persistent cough, change in a chronic cough, haemoptysis, breathlessness, chest pain, recurrent chest infection, hoarseness.
• General: Weight loss, loss of appetite, fatigue.
• Spread: Bone pain, confusion and headache (brain), jaundice, lymph nodes in the neck.
• Signs: Clubbing, supraclavicular nodes, signs of effusion or collapse, thrombocytosis.

NICE NG12 (suspected cancer):

• Refer urgently on the suspected cancer pathway if:
  • The chest X-ray suggests lung cancer, or
  • The patient is aged 40 or over with unexplained haemoptysis.
• Offer an urgent chest X-ray (within 2 weeks) to people aged 40 or over with two or more unexplained symptoms — or one if they have ever smoked:
  • Cough.
  • Fatigue.
  • Breathlessness.
  • Chest pain.
  • Weight loss.
  • Appetite loss.
• Consider an urgent chest X-ray for those aged 40 or over with persistent or recurrent chest infection, clubbing, supraclavicular or persistent cervical nodes, chest signs consistent with cancer, or thrombocytosis.
• A normal chest X-ray does not exclude cancer — refer or arrange CT if symptoms persist.

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6.03 Diagnosis and Staging

The aim: Get the diagnosis and stage in the fewest, safest steps — ideally one biopsy that confirms both. The National Optimal Lung Cancer Pathway aims for treatment within 49 days of referral.

• CT chest, liver and adrenals with contrast — before any biopsy.
• PET-CT — for patients being considered for curative treatment, to look for nodal and distant spread.
• Tissue sampling — choose the site that gives the highest stage:
  • EBUS-TBNA of mediastinal nodes (diagnosis and staging together).
  • Bronchoscopy for central tumours.
  • CT-guided biopsy for peripheral lesions.
  • Pleural fluid cytology or thoracoscopy for effusions.
  • Ultrasound-guided neck node or liver biopsy.
• Brain MRI — for stage II–III disease being considered for curative treatment, or with neurological symptoms.
• Molecular testing on non-squamous NSCLC (and some squamous):
  • EGFR, ALK, ROS1, BRAF, KRAS G12C, MET, RET, NTRK, HER2.
  • Plus PD-L1 expression.
  • Increasingly done as a panel (next-generation sequencing), including blood-based "liquid biopsy".

TNM staging (simplified):

• T — tumour size and invasion.
• N — lymph nodes:
  • N1 — same-side hilar.
  • N2 — same-side mediastinal.
  • N3 — opposite side or supraclavicular.
• M — metastases (pleural effusion, opposite lung, distant organs).
• Stage I–II: Localised — usually treated with curative surgery or radiotherapy.
• Stage III: Locally advanced (mediastinal nodes) — combined treatment.
• Stage IV: Metastatic — systemic treatment.

Performance status (ECOG / WHO 0–4) matters as much as stage when choosing treatment:

• 0 — fully active.
• 1 — restricted in strenuous activity.
• 2 — up and about more than half the day.
• 3 — in bed or chair more than half the day.
• 4 — bedbound.

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6.04 Treating Non-small Cell Lung Cancer

Treatment is planned by the lung cancer MDT and depends on stage, molecular profile, fitness and patient choice.

Early stage (I–II):

• Surgery — usually lobectomy (often keyhole, VATS or robotic) with lymph node sampling. Segmentectomy for small peripheral tumours.
• Fitness assessment: Lung function (predicted post-operative FEV1 and TLCO), exercise testing (shuttle walk or CPET), cardiac risk.
• Stereotactic ablative radiotherapy (SABR) — highly focused radiation for people unfit for or declining surgery, with excellent local control.
• Added systemic treatment to reduce recurrence, for larger or node-positive tumours:
  • Neoadjuvant chemo-immunotherapy (e.g. nivolumab with chemotherapy before surgery).
  • Adjuvant chemotherapy.
  • Osimertinib after surgery for EGFR-mutant disease.
  • Immunotherapy.

Locally advanced (stage III):

• Usually concurrent chemoradiotherapy, followed by durvalumab (immunotherapy) for a year if PD-L1-positive.
• Selected patients have surgery as part of combined treatment.

Advanced (stage IV):

• Targetable mutation: Oral targeted therapy:
  • EGFR: Osimertinib.
  • ALK: Alectinib or lorlatinib.
  • Others for ROS1, BRAF, KRAS G12C, MET, RET.
  Responses are often dramatic and long-lasting.
• No targetable mutation: Immunotherapy (checkpoint inhibitors such as pembrolizumab), alone if PD-L1 is high (50% or more), or with platinum chemotherapy.
• Chemotherapy for those unsuitable for immunotherapy.
• Palliative radiotherapy for symptoms (bone pain, haemoptysis, airway obstruction, brain metastases).
• Best supportive care for those too frail for anticancer treatment.

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6.05 Small Cell Lung Cancer

• Behaviour: Grows and spreads very quickly — most patients have spread at diagnosis. It is very sensitive to chemotherapy and radiotherapy at first, but usually relapses.
• Limited stage (confined to one hemithorax and treatable in one radiotherapy field):
  • Concurrent chemoradiotherapy (platinum plus etoposide).
  • Prophylactic cranial irradiation or brain MRI surveillance.
  • Rarely surgery for very small tumours.
• Extensive stage:
  • Platinum-etoposide chemotherapy plus immunotherapy (atezolizumab or durvalumab), then maintenance immunotherapy.
  • Thoracic radiotherapy in selected patients.
• Urgency: SCLC can deteriorate within days — fast-track to oncology. Treat SVCO, SIADH and other complications promptly.
• Prognosis: Median survival is about 12–18 months for extensive disease, longer for limited disease.

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6.06 Paraneoplastic Syndromes

Effects of the cancer caused by hormones or antibodies rather than by direct spread. They may appear before the cancer is found.

• SIADH (mostly SCLC):
  • Euvolaemic hyponatraemia.
  • Treat the cancer; fluid restriction; tolvaptan or urea.
• Ectopic ACTH (SCLC, carcinoid):
  • Rapid Cushing's — often without the classic appearance.
  • Hypokalaemic alkalosis, hypertension, hyperglycaemia, weakness, pigmentation.
• Hypercalcaemia (squamous cell — PTHrP):
  • Thirst, confusion, constipation.
  • Fluids and IV bisphosphonate.
• Lambert–Eaton myasthenic syndrome (SCLC):
  • Antibodies to voltage-gated calcium channels.
  • Proximal leg weakness that improves briefly with repeated effort.
  • Reduced reflexes; dry mouth and other autonomic symptoms.
• Paraneoplastic neurological syndromes (often SCLC, anti-Hu antibodies):
  • Cerebellar degeneration.
  • Limbic encephalitis.
  • Sensory neuronopathy.
• Hypertrophic pulmonary osteoarthropathy (NSCLC): Clubbing plus painful swelling of the wrists and ankles, with periosteal new bone on X-ray.
• Other:
  • Dermatomyositis.
  • Thrombosis (Trousseau's — migratory thrombophlebitis).
  • Gynaecomastia (hCG).
  • Anaemia, thrombocytosis.
  • Cachexia.

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6.07 Local Spread and Complications

• Superior vena cava obstruction (SVCO):
  • Cause: A tumour (often SCLC or lymphoma) compresses or invades the SVC.
  • Signs: Facial and arm swelling, headache worse on bending, distended neck and chest wall veins, breathlessness. Stridor or confusion means an emergency.
  • Tests: CT with contrast; tissue diagnosis if possible.
  • Treatment:
    • Sit up; dexamethasone (if lymphoma is not suspected, or after biopsy).
    • Endovascular stenting for quick relief.
    • Then chemotherapy (SCLC, lymphoma) or radiotherapy.
    • Anticoagulate if there is thrombus.
• Pancoast tumour (apical tumour invading the chest wall and nerves):
  • Shoulder and arm pain (C8–T1).
  • Wasting of the small hand muscles.
  • Horner's syndrome (sympathetic chain) — ptosis, small pupil, reduced sweating.
• Nerve involvement:
  • Recurrent laryngeal nerve (left-sided tumours or nodes) — hoarse voice, weak cough.
  • Phrenic nerve — raised hemidiaphragm.
• Airway obstruction: Collapse, post-obstructive pneumonia, stridor — airway stents, debulking or radiotherapy.
• Malignant pleural and pericardial effusions (tamponade).
• Haemoptysis — palliative radiotherapy, tranexamic acid, bronchial artery embolisation.
• Metastases:
  • Brain — headache, seizures, focal signs; dexamethasone, stereotactic radiosurgery.
  • Bone — pain, fracture, hypercalcaemia, spinal cord compression.
  • Liver and adrenal.

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6.08 Immunotherapy Side Effects

Mechanism: Checkpoint inhibitors (pembrolizumab, nivolumab, atezolizumab, durvalumab, ipilimumab) release the brakes on the immune system. As well as attacking the cancer, they can cause immune-related adverse events in almost any organ — at any time, even months after stopping.

• Common:
  • Rash, itch.
  • Colitis (diarrhoea).
  • Hepatitis.
  • Thyroiditis — often hyperthyroid then hypothyroid.
• Serious — must not be missed:
  • Pneumonitis (new cough, breathlessness, CT shadowing).
  • Hypophysitis (headache, fatigue, low cortisol — check a 9 am cortisol).
  • Adrenal insufficiency.
  • New type 1 diabetes (DKA).
  • Myocarditis (troponin, arrhythmia — high mortality).
  • Myositis, myasthenia, neuropathy, encephalitis.
  • Nephritis.
• Management:
  • Contact the acute oncology team; grade the severity.
  • Withhold the drug.
  • Steroids (oral prednisolone or IV methylprednisolone) for moderate or severe events; further immunosuppression (e.g. infliximab for colitis) if refractory.
  • Endocrine problems usually need lifelong hormone replacement.

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6.09 Supportive and Palliative Care

• Lung cancer clinical nurse specialist for every patient; early specialist palliative care improves quality of life (and in some studies survival).
• Breathlessness:
  • Treat reversible causes — effusion, anaemia, airway obstruction, infection, PE.
  • Breathing techniques, a hand-held fan.
  • Low-dose opioids; benzodiazepines for anxiety.
• Cough: Treat the cause; simple linctus, opioids (codeine or morphine).
• Pain: WHO analgesic approach; radiotherapy for bone pain.
• Smoking cessation — it still improves outcomes after diagnosis.
• VTE risk is high — have a low threshold to investigate.
• Nutrition and cachexia; fatigue; psychological support.
• Advance care planning: Preferred place of care and death; DNACPR discussions.
• Benefits: Help with financial support, including the special rules for terminal illness.

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6.10 Pulmonary Nodules

What it is: A round shadow up to 3 cm in the lung (larger is a "mass"). Nodules are very common on CT, and most are benign (old infection, scars, lymph nodes).

Management (BTS pulmonary nodule guideline):

• Very small nodules (below 5 mm, or below 80 mm³): No follow-up.
• 5–8 mm (80–300 mm³): CT surveillance to check growth — usually volumetric CT at 3 months and 1 year.
• 8 mm or more (300 mm³ or more): Estimate the risk of cancer with the Brock model, which uses:
  • Age and sex.
  • Family history; emphysema.
  • Nodule size, type, upper-lobe location, spiculation and number.
• Brock risk 10% or more: PET-CT, then recalculate the risk with the Herder model:
  • Low risk: Surveillance.
  • Intermediate risk: Biopsy, or treatment, or surveillance.
  • High risk: Treat as cancer — surgery or SABR, sometimes without a biopsy.
• Growth — volume doubling time under 400 days suggests cancer. No growth over 2 years means a solid nodule is very likely benign.
• Ground-glass (subsolid) nodules grow slowly — longer follow-up. A part-solid nodule has a higher cancer risk.

Features suggesting cancer:

• Larger size.
• Spiculated edge.
• Upper lobe.
• Growth.
• Part-solid.
• Smoker.
• Emphysema.

Benign features: "Popcorn" or central calcification (hamartoma, old granuloma), fat (hamartoma), stability.

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6.11 Lung Cancer Screening

• Evidence: Low-dose CT screening of high-risk people reduces lung cancer deaths by about 20–25% (NLST and NELSON trials).
• NHS Lung Cancer Screening Programme (England; previously the Targeted Lung Health Check):
  • Who: People aged 55–74 who have ever smoked, identified from GP records.
  • Risk assessment: A telephone assessment calculates their risk (e.g. PLCOm2012 or LLP models). Those at high risk are offered a low-dose CT.
  • Follow-up: Repeat CT every 2 years until age 74.
  • Includes smoking cessation support.
  • Being rolled out across England by the end of the decade.
• Results: Most cancers found are early stage (about three-quarters at stage I–II, compared with about a quarter in routine care).
• Downsides:
  • False positives and anxiety.
  • Incidental findings — coronary calcium (treat CVD risk), emphysema, ILD.
  • Radiation (small).
  • Over-diagnosis.

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6.12 Other Lung Tumours

• Lung metastases — commoner than primary lung cancer on CT:
  • Multiple round "cannonball" nodules.
  • From kidney, colorectal, breast, sarcoma, melanoma, testis, head and neck.
  • Lymphangitis carcinomatosa (breast, stomach, lung) — breathlessness with interstitial thickening.
• Bronchial carcinoid:
  • Low-grade neuroendocrine tumour in younger adults (often non-smokers).
  • Central — wheeze, haemoptysis, recurrent pneumonia (blocked bronchus).
  • Carcinoid syndrome is rare.
  • Surgery is usually curative.
• Hamartoma: The commonest benign lung tumour — "popcorn" calcification and fat on CT.
• Lymphoma: Mediastinal masses (anterior mediastinum), lymph nodes, effusions.
• Anterior mediastinal masses — the "4 Ts":
  • Thymoma (myasthenia).
  • Thyroid (retrosternal goitre).
  • Teratoma (germ cell).
  • "Terrible" lymphoma.

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6.13 Pleural Effusion: Approach

Mechanism: Fluid builds up in the pleural space when production outstrips drainage.

• Transudates: Pressure problems — high venous pressure or low protein.
• Exudates: Leaky, inflamed or blocked pleura.

Causes:

• Transudates:
  • Heart failure — the commonest overall, usually bilateral.
  • Cirrhosis (hepatic hydrothorax, usually right-sided).
  • Nephrotic syndrome; hypoalbuminaemia.
  • Peritoneal dialysis.
  • Hypothyroidism.
  • Meigs' syndrome (ovarian fibroma).
• Exudates:
  • Parapneumonic effusion and empyema.
  • Malignancy (lung, breast, lymphoma, mesothelioma, ovary).
  • TB.
  • PE.
  • Rheumatoid arthritis, SLE.
  • Pancreatitis (high amylase); oesophageal rupture.
  • Drugs (methotrexate, amiodarone, dasatinib).
  • Benign asbestos effusion.
  • Post-cardiac injury (Dressler's).

Approach (BTS 2023):

• Typical bilateral effusions with clear heart failure: Treat the heart failure. Aspirate only if atypical (unequal sizes, fever, chest pain) or not responding.
• Unilateral or unexplained: Ultrasound-guided diagnostic aspiration:
  • Appearance.
  • Protein and LDH (with serum, for Light's criteria).
  • pH (blood gas analyser).
  • Glucose.
  • Cytology.
  • Gram stain, culture and AFB.
  • Amylase, triglycerides or haematocrit if relevant.
• Light's criteria — exudate if any of:
  • Protein ratio above 0.5.
  • LDH ratio above 0.6.
  • Pleural LDH above two-thirds of the upper limit of normal serum LDH.
• Clues from the fluid:
  • Low pH and low glucose — infection, rheumatoid, malignancy, TB.
  • Lymphocytes — TB, malignancy, lymphoma, chronic effusions.
  • Milky — chylothorax.
  • Bloody — malignancy, PE, trauma, asbestos.
• Still undiagnosed exudate: Contrast CT chest (pleural thickening, nodules), then thoracoscopy with pleural biopsy. Cytology alone misses many cancers, especially mesothelioma.
• Consider TB — pleural biopsy culture has a much higher yield than fluid.

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6.14 Malignant Pleural Effusion

• What it means: It usually means stage IV disease. Common primaries are lung, breast, lymphoma, mesothelioma and ovary. Median survival depends on the cancer type and fitness.
• Goal: Relieve breathlessness with as few procedures and hospital days as possible.
• Options (discussed with the patient — BTS 2023):
  • Therapeutic aspiration — quick relief, but fluid usually returns. Useful when life expectancy is very short.
  • Talc pleurodesis (via a drain or thoracoscopy) — sticks the pleural layers together to stop fluid returning. Needs a hospital stay and an expandable lung.
  • Indwelling pleural catheter (IPC) — a tunnelled drain, drained at home by district nurses or family. It can be used when the lung does not re-expand ("trapped lung"), and reduces hospital time.
• Trapped (non-expandable) lung: The lung cannot re-expand because of thick visceral pleura — pleurodesis will fail; use an IPC.
• Treat the cancer — chemotherapy-sensitive cancers (lymphoma, SCLC, breast) may control the effusion.

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6.15 Mesothelioma

• What it is: A cancer of the pleura (or peritoneum) caused almost entirely by asbestos exposure. There is a long latency of 30–50 years. The UK has one of the highest rates in the world, reflecting past use in shipbuilding, construction, railway work and plumbing.
• Clinical pattern:
  • Breathlessness from a pleural effusion.
  • Dull chest wall pain.
  • Weight loss, sweats.
  • Later, encasement of the lung and chest wall invasion.
• Diagnosis:
  • CT shows pleural thickening — nodular, circumferential, involving the mediastinal pleura.
  • Biopsy — usually by thoracoscopy or CT-guided — because fluid cytology is often negative.
• Treatment (specialist MDT):
  • Immunotherapy (nivolumab plus ipilimumab, NICE TA818) or chemotherapy (platinum plus pemetrexed).
  • Effusion control — IPC or pleurodesis.
  • Palliative radiotherapy for pain.
  • Early palliative care.
• Prognosis: Median survival about 1–2 years.
• Legal and benefits:
  • Patients are entitled to compensation (civil claims, government schemes, Industrial Injuries Disablement Benefit).
  • Death from mesothelioma must be reported to the coroner (an industrial disease).

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6.16 Asbestos and the Pleura

• Pleural plaques:
  • Discrete, often calcified, thickened patches on the parietal pleura and diaphragm.
  • A marker of exposure only — no symptoms, not pre-malignant.
  • Reassure (but the patient remains at risk of other asbestos diseases from the exposure itself).
• Diffuse pleural thickening: Extensive thickening of the visceral pleura, often after a benign asbestos effusion. It can cause restrictive breathlessness, and may qualify for compensation.
• Benign asbestos pleural effusion: A blood-stained exudate, often within 20 years of exposure — mesothelioma must be excluded.
• Rounded atelectasis: A rounded area of folded, collapsed lung next to thickened pleura ("comet tail" on CT) — can mimic a tumour.
• Asbestosis (lung fibrosis), mesothelioma and lung cancer are the more serious consequences.

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6.17 Pneumothorax: Follow-up and Recurrence

Acute management is covered in the Respiratory Emergencies chapter. In the longer term:

• Recurrence: About 1 in 3 primary spontaneous pneumothoraces recur, mostly within the first year. Secondary pneumothorax recurs more often and is more dangerous.
• Smoking (tobacco and cannabis) greatly increases recurrence — stopping is the most effective prevention.
• Surgery (VATS bullectomy with pleurodesis) is offered for:
  • A second pneumothorax (same side).
  • A first contralateral pneumothorax.
  • Bilateral pneumothorax.
  • A persistent air leak.
  • High-risk occupations (pilots, divers).
• Look for an underlying cause in atypical or recurrent cases — e.g. LAM (women, catamenial), Birt–Hogg–Dubé, Langerhans cell histiocytosis, Marfan's syndrome, cystic fibrosis, PCP.
• Catamenial pneumothorax: Linked to periods (thoracic endometriosis).
• Flying and diving:
  • Do not fly until resolution is confirmed on imaging (and usually for 1–2 weeks after).
  • Diving is unsafe unless definitive surgery has been done.

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6.18 Chylothorax and Haemothorax

• Chylothorax:
  • What it is: Lymphatic fluid (chyle) in the pleural space — milky fluid with triglycerides above 1.24 mmol/L (chylomicrons present).
  • Causes: Thoracic duct damage — lymphoma, other cancers, surgery (especially oesophagectomy), trauma, LAM.
  • Treatment: Treat the cause; drain; low-fat diet with medium-chain triglycerides; octreotide; thoracic duct embolisation or ligation.
• Pseudochylothorax: A milky, cholesterol-rich effusion in long-standing effusions (e.g. rheumatoid, TB). Cholesterol is high and triglycerides are low.
• Haemothorax:
  • Definition: Pleural fluid haematocrit more than half the blood haematocrit.
  • Causes: Trauma, procedures (biopsy, drain), anticoagulation, malignancy, aortic rupture.
  • Treatment: Large-bore chest drain and surgical review if bleeding continues (e.g. more than 1.5 L initially or ongoing loss).

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6.19 Drug Reference Table

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6.20 Spot the Diagnosis

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6.21 Exam-style Scenarios

1. A 63-year-old smoker has 6 weeks of cough, weight loss and one episode of haemoptysis.
Answer: Unexplained haemoptysis over 40 — urgent suspected cancer referral (NICE NG12), with a chest X-ray.

• CT chest, liver and adrenals with contrast.
• PET-CT and EBUS or biopsy as directed by the lung MDT.
• Smoking cessation support.

2. A 52-year-old never-smoker has stage IV lung adenocarcinoma with an EGFR exon 19 deletion.
Answer: First-line osimertinib (oral EGFR inhibitor) rather than chemotherapy or immunotherapy.

• Brain imaging.
• Monitor for rash, diarrhoea and QT; check for pneumonitis if new breathlessness.

3. A man on nivolumab for lung cancer has 2 weeks of watery diarrhoea, 8 times a day.
Answer: Likely immune-related colitis (grade 3).

• Contact acute oncology; withhold immunotherapy.
• Stool tests to exclude infection.
• IV methylprednisolone; infliximab if no response.
• Check TFTs and cortisol.

4. A 70-year-old former plumber has a right pleural effusion. Fluid is a blood-stained exudate with negative cytology. CT shows nodular pleural thickening.
Answer: Suspected mesothelioma.

• Thoracoscopic or CT-guided pleural biopsy (cytology is often negative).
• Effusion control (IPC or talc).
• Specialist MDT; advise about compensation.

5. A 66-year-old has a 12 mm spiculated upper-lobe nodule on CT. Brock risk is 28%.
Answer: Brock risk of 10% or more — PET-CT and Herder assessment.

• If high risk: surgical resection (or SABR if unfit), with or without a prior biopsy.
• Lung MDT discussion.

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6.22 Key Points

• Lung cancer is mostly smoking-related, but about 1 in 7 cases occur in never-smokers (often EGFR-mutant adenocarcinoma).
• Refer urgently for unexplained haemoptysis aged 40 or over. A normal chest X-ray does not exclude cancer.
• Stage with CT, then PET-CT and EBUS. Choose the biopsy that gives both diagnosis and the highest stage.
• Early NSCLC: surgery or SABR. Stage III: chemoradiotherapy then durvalumab. Stage IV: targeted therapy for mutations, otherwise immunotherapy with or without chemotherapy.
• SCLC: fast-growing, chemosensitive, frequent paraneoplastic syndromes.
• Paraneoplastic syndromes: SIADH and ectopic ACTH (SCLC), hypercalcaemia (squamous), Lambert–Eaton (SCLC), HPOA (NSCLC).
• Know SVCO, Pancoast tumour and recurrent laryngeal nerve palsy.
• Immunotherapy toxicity can affect any organ — steroids via acute oncology; check cortisol and TFTs.
• Nodules: under 5 mm needs no follow-up; 5–8 mm CT surveillance; 8 mm or more Brock score, then PET-CT if 10% or more.
• Pleural effusion: ultrasound-guided tap, Light's criteria, pH, cytology. Thoracoscopy for undiagnosed exudates.
• Malignant effusion: IPC or talc pleurodesis; IPC for trapped lung.
• Mesothelioma: asbestos, long latency; biopsy needed; compensation; report to the coroner.

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6.23 Guidelines and Further Reading

• NICE NG122: Lung cancer — diagnosis and management
• NICE NG12: Suspected cancer — recognition and referral
• National Optimal Lung Cancer Pathway (NHS England)
• BTS Guidelines for the investigation and management of pulmonary nodules (2015)
• NHS England: Lung Cancer Screening Programme
• BTS Guideline for pleural disease (2023)
• NICE TA818: Nivolumab with ipilimumab for untreated unresectable malignant pleural mesothelioma
• ESMO / UKONS: Management of immune checkpoint inhibitor toxicities
• BNF — for current doses

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7.01 PE: Anticoagulation and Follow-up

Choice of anticoagulant (NICE NG158):

• Most patients: A DOAC — apixaban or rivaroxaban (no heparin lead-in needed), or LMWH then dabigatran or edoxaban.
• Cancer-associated VTE: A DOAC is usually offered. LMWH is used if a DOAC is unsuitable — for example GI or genitourinary cancers with bleeding risk, or drug interactions.
• Antiphospholipid syndrome (especially triple-positive): Warfarin (INR 2–3) — DOACs are less effective.
• Pregnancy: LMWH (warfarin and DOACs are contraindicated).
• Severe renal impairment or extremes of weight: LMWH, unfractionated heparin or warfarin, depending on the situation.

Duration:

• Provoked PE (major surgery, trauma, immobility, pregnancy — with the risk factor now gone): 3 months.
• Unprovoked PE: At least 3 months, then consider long-term anticoagulation. Weigh recurrence risk against bleeding risk (e.g. using an ORBIT-type assessment), and the patient's preference.
• Active cancer: Usually 3–6 months or longer, while the cancer is active.
• Recurrent VTE: Usually lifelong.

Investigations after unprovoked PE:

• History, examination, basic bloods and chest X-ray to look for cancer. Do not routinely do extensive cancer screening (e.g. CT abdomen).
• Thrombophilia testing is not routinely needed. Consider antiphospholipid antibody testing if stopping anticoagulation is being considered, or there is a suggestive history. Consider hereditary thrombophilia testing in people with a strong family history.

Follow-up at 3 months:

• Review symptoms, bleeding and the duration plan.
• Persistent breathlessness or exercise limitation after PE should prompt an echo and a V/Q scan, to look for chronic thromboembolic disease.

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7.02 Chronic Thromboembolic Pulmonary Hypertension

• What it is: Clots from a PE fail to dissolve and turn into fibrous scar tissue that blocks the pulmonary arteries. Pressure rises and the right heart fails. It follows about 2–4% of acute PEs, and some patients have no known PE.
• Suspect it: Breathlessness that persists or worsens 3–6 months or more after a PE despite anticoagulation, or unexplained pulmonary hypertension.
• Diagnosis:
  • V/Q scan — the best screening test. A normal V/Q scan effectively rules it out.
  • Echo — pulmonary hypertension.
  • CT pulmonary angiography — webs, bands, narrowing.
  • Right heart catheter — confirms PH.
  • After at least 3 months of anticoagulation.
• Treatment (UK national CTEPH service):
  • Pulmonary endarterectomy — surgery that removes the scar tissue. It can be curative.
  • Balloon pulmonary angioplasty for inoperable distal disease.
  • Riociguat (a soluble guanylate cyclase stimulator) for inoperable or residual disease.
  • Lifelong anticoagulation.

💡 Clinical Pearl: CTEPH is the one form of pulmonary hypertension that can be cured by surgery — so always screen for it with a V/Q scan when PH is found, and in anyone who stays breathless after a PE.

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7.03 Pulmonary Hypertension: Overview

Definition (ESC/ERS 2022): A mean pulmonary artery pressure above 20 mmHg at rest, measured by right heart catheterisation.

• Pre-capillary PH (the problem is in the lung arteries): Also has a pulmonary vascular resistance above 2 Wood units and a normal left-sided (wedge) pressure.
• Post-capillary PH (backlog from the left heart): A raised wedge pressure (above 15 mmHg).

The five groups:

• Group 1 — Pulmonary arterial hypertension (PAH): Disease of the small pulmonary arteries — idiopathic, heritable, drugs, connective tissue disease, HIV, portal hypertension, congenital heart disease.
• Group 2 — Left heart disease — the commonest. Heart failure (including with preserved EF) and mitral or aortic valve disease.
• Group 3 — Lung disease and hypoxia: COPD, ILD, sleep-disordered breathing, altitude.
• Group 4 — Pulmonary artery obstruction: Mainly CTEPH.
• Group 5 — Unclear or multifactorial: Sarcoidosis, haemolytic anaemias (sickle cell), myeloproliferative disease, CKD on dialysis.

Clinical pattern:

• Exertional breathlessness and fatigue — often attributed to other causes for years.
• Exertional chest pain or syncope (a warning sign of severe disease).
• Signs of right heart strain:
  • Loud P2.
  • Right ventricular heave.
  • Raised JVP (large V waves from tricuspid regurgitation).
  • Ankle oedema, ascites, hepatomegaly.
• Signs of the cause — clubbing (ILD, congenital heart disease), sclerodactyly, signs of liver disease.

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7.04 Investigating Pulmonary Hypertension

• Echocardiogram — the key screening test:
  • Estimates the probability of PH (tricuspid regurgitation velocity, RV size and function).
  • Shows left heart disease, valve disease and shunts.
• ECG: Right axis deviation, RV hypertrophy and strain, P pulmonale, RBBB.
• Chest X-ray: Enlarged pulmonary arteries, "pruning" of peripheral vessels, lung disease.
• NT-proBNP — for severity and prognosis.
• Lung function: A disproportionately low TLCO in PAH; restriction or obstruction in group 3.
• V/Q scan — to look for CTEPH (in everyone with unexplained PH).
• CT chest — lung disease, PE, pulmonary artery size.
• Bloods: Autoimmune screen (systemic sclerosis), HIV, LFTs (portal hypertension), TFTs, haemoglobinopathy screen.
• Overnight oximetry or sleep study if sleep apnoea or hypoventilation is suspected.
• Right heart catheterisation at a specialist PH centre to confirm the diagnosis, measure severity and test vasoreactivity.

💡 Clinical Pearl: Unexplained breathlessness with a normal chest X-ray and normal spirometry, but a low TLCO, should make you think of pulmonary vascular disease — order an echo and a V/Q scan.

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7.05 Pulmonary Arterial Hypertension

Mechanism: The small pulmonary arteries thicken, constrict and become blocked (vascular remodelling). Resistance rises until the right ventricle fails. Untreated, median survival is only a few years.

Causes:

• Idiopathic — often young to middle-aged women.
• Heritable — BMPR2 mutations; screen relatives.
• Drugs and toxins — appetite suppressants (fenfluramine), methamphetamine, dasatinib, interferon.
• Connective tissue disease — especially systemic sclerosis (limited, anticentromere) — screen yearly with echo, lung function and NT-proBNP.
• HIV.
• Portal hypertension (portopulmonary hypertension).
• Congenital heart disease — left-to-right shunts. Untreated, they can reverse, causing cyanosis — Eisenmenger syndrome.
• Schistosomiasis (worldwide).

Treatment (only at UK specialist PH centres):

• General:
  • Diuretics for fluid overload.
  • Oxygen for hypoxaemia.
  • Supervised exercise.
  • Vaccinations.
  • Iron replacement.
  • Avoid pregnancy — very high maternal mortality — so effective contraception is essential.
• Vasoreactivity testing during right heart catheterisation: A small number of patients (mostly idiopathic PAH) respond to high-dose calcium channel blockers.
• PAH-specific drugs (often combined from the start):
  • Endothelin receptor antagonists — ambrisentan, bosentan, macitentan. They are teratogenic, and bosentan needs LFT monitoring.
  • PDE5 inhibitors — sildenafil, tadalafil. Do not combine with nitrates (severe hypotension).
  • Soluble guanylate cyclase stimulator — riociguat (not with PDE5 inhibitors).
  • Prostacyclin pathway — oral selexipag; inhaled iloprost; continuous IV or subcutaneous epoprostenol or treprostinil for severe disease.
  • Sotatercept (an activin signalling inhibitor) — a newer add-on that targets vascular remodelling.
• Lung (or heart–lung) transplantation for those failing medical treatment.

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7.06 PH from Heart and Lung Disease

• Group 2 (left heart disease):
  • The commonest cause of PH — often older people with hypertension, AF, diabetes and obesity (heart failure with preserved EF).
  • Treat the heart — diuretics, valve repair, AF control.
  • PAH drugs are not recommended and can be harmful.
• Group 3 (lung disease and hypoxia):
  • COPD, ILD, combined fibrosis and emphysema, obesity hypoventilation, OSA.
  • Usually mild to moderate. Treat the lung disease and correct hypoxaemia (long-term oxygen).
  • Severe disproportionate PH needs specialist referral.
• Cor pulmonale: Right heart failure caused by lung disease — peripheral oedema, raised JVP and hypoxaemia. Treat with oxygen if eligible, diuretics, and the underlying cause.

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7.07 Pulmonary AVMs and Liver-related Lung Disease

• Pulmonary arteriovenous malformations (AVMs):
  • What they are: Abnormal direct connections between pulmonary arteries and veins, bypassing the lung capillaries — a right-to-left shunt.
  • Cause: Most are due to hereditary haemorrhagic telangiectasia (HHT) — recurrent nosebleeds, telangiectasia on the lips, tongue and fingers, GI bleeding and a family history.
  • Problems:
    • Hypoxaemia, cyanosis, clubbing, polycythaemia.
    • Paradoxical embolism — stroke and brain abscess (clots and bacteria bypass the lung filter).
    • Haemoptysis and haemothorax.
  • Diagnosis: Contrast (bubble) echo, then CT.
  • Treatment: Embolisation.
  • Precautions: Antibiotic prophylaxis before dental and other procedures; IV line air filters; screen family members.
• Hepatopulmonary syndrome:
  • Liver disease with dilated lung capillaries, causing hypoxaemia.
  • Platypnoea (breathlessness when sitting up) and orthodeoxia (falling oxygen when upright).
  • Contrast echo shows a delayed shunt.
  • Resolves after liver transplant.
• Portopulmonary hypertension: PAH in people with portal hypertension. Severe disease can make liver transplant unsafe — screen transplant candidates with echo.

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7.08 Obstructive Sleep Apnoea

Mechanism: During sleep, throat muscles relax and the upper airway narrows or collapses repeatedly. This causes snoring, pauses in breathing (apnoeas), drops in oxygen, and brief awakenings that fragment sleep. It is very common — several million adults in the UK, most undiagnosed.

Risk factors:

• Obesity and a large neck circumference.
• Male sex; older age; postmenopausal women.
• Retrognathia (small or set-back jaw).
• Large tonsils (especially children).
• Alcohol and sedatives.
• Nasal obstruction; smoking.
• Hypothyroidism; acromegaly.
• Down syndrome.

Clinical pattern:

• Loud snoring and witnessed apnoeas (often reported by a partner).
• Choking or gasping at night; unrefreshing sleep; nocturia.
• Excessive daytime sleepiness — dozing while reading, watching TV or driving.
• Morning headaches; poor concentration, irritability, low mood.

Consequences:

• Road traffic accidents (several-fold increased risk).
• Hypertension (often resistant).
• AF (and recurrence after ablation).
• Stroke.
• Type 2 diabetes.
• Heart failure.
• Peri-operative complications.

Diagnosis (NICE NG202):

• Screening: Epworth Sleepiness Scale (sleepiness; above 10 is abnormal) and STOP-Bang (risk) questionnaires. Do not rely on these alone.
• Home respiratory polygraphy — the first-line test (oximetry alone if polygraphy is not available).
• Apnoea–hypopnoea index (events per hour):
  • Mild: 5–14.
  • Moderate: 15–29.
  • Severe: 30 or more.
• Check: TFTs if symptomatic; BP; glucose; obesity hypoventilation (blood gas or venous bicarbonate if BMI is high).
• Refer urgently if there is a suspected sleep disorder in someone whose job involves vehicles or safety, if they are awaiting surgery, or if they have unstable heart disease or respiratory failure.

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7.09 Treating Sleep Apnoea

• Lifestyle — for everyone:
  • Weight loss — this can cure mild OSA. GLP-1 based drugs (e.g. tirzepatide) reduce OSA severity.
  • Avoid alcohol and sedatives at night.
  • Stop smoking.
  • Positional advice (avoid sleeping on the back).
  • Treat nasal congestion.
• CPAP (continuous positive airway pressure) — the main treatment:
  • Air pressure through a mask acts as a "pneumatic splint" to keep the airway open.
  • Offer for moderate or severe OSA, and for mild OSA with symptoms affecting quality of life (NICE NG202).
  • Improves sleepiness, quality of life and driving safety; lowers BP modestly.
  • Adherence is the main challenge — mask fitting, humidification and support.
• Mandibular advancement device (custom dental splint that holds the jaw forward): For mild OSA, or for people who cannot tolerate CPAP.
• Surgery:
  • Tonsillectomy for large tonsils.
  • Hypoglossal nerve stimulation in selected CPAP-intolerant patients (specialist centres).
  • Bariatric surgery for severe obesity.
• Peri-operative care: Tell anaesthetists. Patients should bring their CPAP to hospital. Use opioids and sedatives with caution.

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7.10 Sleep Apnoea and Driving

• Why it matters: Sleepy drivers cause serious accidents. Doctors must give clear advice and document it.
• DVLA rules (group 1 — car and motorcycle):
  • People with excessive sleepiness that affects driving — from suspected or confirmed OSA — must not drive until their symptoms are controlled.
  • They must tell the DVLA if they have moderate or severe OSA with excessive sleepiness, or if sleepiness is not controlled within 3 months.
  • They can usually resume driving once symptoms are controlled with treatment (and adherence is confirmed).
• Group 2 drivers (lorries, buses): Stricter rules — sleep studies and evidence of treatment adherence and control are needed.
• Advice for all patients: Never drive while feeling sleepy — whatever the diagnosis.
• Check current DVLA guidance — the rules change.

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7.11 Obesity Hypoventilation Syndrome

• Definition: BMI of 30 or more plus daytime hypercapnia (PaCO2 above 6 kPa), with no other cause. Most patients also have OSA.
• Mechanism: The weight of the chest and abdomen reduces lung volumes, increases the work of breathing and blunts the drive to breathe — especially during sleep.
• Clinical pattern:
  • Daytime sleepiness, morning headaches.
  • Breathlessness.
  • Peripheral oedema, right heart failure (cor pulmonale).
  • Polycythaemia.
  • Often first diagnosed during an acute admission with hypercapnic respiratory failure (sometimes mislabelled as COPD).
• Clue: A raised venous bicarbonate (above 27 mmol/L) in an obese patient suggests chronic hypercapnia.
• Treatment:
  • Home NIV (or CPAP in selected stable patients with severe OSA).
  • Weight loss — dietary, drugs or bariatric surgery.
  • Controlled oxygen (target 88–92%) when acutely unwell.
  • Avoid sedatives.

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7.12 Chest Wall and Neuromuscular Disease

• Causes:
  • Chest wall: Severe kyphoscoliosis, thoracoplasty (old TB surgery), post-polio syndrome.
  • Neuromuscular: Motor neurone disease, Duchenne and other muscular dystrophies, myotonic dystrophy, post-polio, spinal muscular atrophy, diaphragm paralysis.
• How it develops: Weak breathing muscles cause nocturnal hypoventilation first (especially in REM sleep), then daytime hypercapnic respiratory failure.
• Symptoms to ask about:
  • Morning headaches.
  • Disturbed sleep, nightmares.
  • Daytime sleepiness.
  • Orthopnoea (diaphragm weakness).
  • Weak cough; recurrent chest infections.
  • Poor appetite and weight loss.
• Monitoring: FVC (sitting and lying), SNIP, peak cough flow, overnight oximetry or CO2 monitoring, blood gases.
• Treatment:
  • Home NIV — improves symptoms and survival in MND (NICE NG42) and other neuromuscular disease.
  • Cough augmentation (assisted cough, mechanical insufflation–exsufflation devices).
  • Vaccinations; early antibiotics.
  • MND: Discuss NIV, gastrostomy, and advance care planning (including stopping NIV) early, while the patient can communicate.

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7.13 Other Sleep Disorders

• Central sleep apnoea and Cheyne–Stokes breathing:
  • Waxing and waning breathing with pauses but no obstruction.
  • Causes: Heart failure, stroke, opioids, high altitude.
  • Treatment: Optimise heart failure treatment. Adaptive servo-ventilation is contraindicated in heart failure with reduced EF (EF 45% or less) — it increased mortality (SERVE-HF).
• Narcolepsy:
  • Excessive daytime sleepiness with sudden sleep attacks.
  • Cataplexy — sudden muscle weakness triggered by emotion such as laughter (type 1).
  • Sleep paralysis; vivid hallucinations on falling asleep or waking.
  • Diagnosis: Polysomnography and multiple sleep latency test.
  • Treatment: Modafinil, pitolisant, sodium oxybate; scheduled naps.
• Restless legs syndrome:
  • An urge to move the legs at rest and in the evening, relieved by movement.
  • Check ferritin (replace iron if below about 75 µg/L), renal function and drugs (antidepressants, antihistamines).
  • Dopamine agonists can cause "augmentation" (symptoms getting worse with treatment) — gabapentinoids are increasingly used.
• Insomnia: CBT for insomnia is first-line; hypnotics only short-term.
• REM sleep behaviour disorder: Acting out dreams. It may come years before Parkinson's disease or Lewy body dementia.

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7.14 Home Oxygen

• Long-term oxygen therapy (LTOT):
  • For chronic hypoxaemia when stable — PaO2 below 7.3 kPa, or 7.3–8.0 kPa with polycythaemia, peripheral oedema or pulmonary hypertension.
  • Used for at least 15 hours a day, usually via a concentrator.
  • Improves survival in COPD.
• Ambulatory oxygen: Portable cylinders or concentrators, for people on LTOT who go out, or selected patients with exertional desaturation who show benefit on assessment.
• Short-burst oxygen: Not recommended — little evidence of benefit.
• Palliative oxygen: Only for hypoxaemic patients. Breathlessness without hypoxaemia responds as well to air from a fan.
• Safety:
  • Smoking (including by others in the home) and e-cigarettes near oxygen cause serious burns, fires and deaths. Assess the risk before prescribing; do not prescribe to people who smoke.
  • Keep away from flames and heat; fire service home safety checks.
• Process (England): Assessment by the specialist home oxygen assessment and review service; ordered via a Home Oxygen Order Form; regular review.
• Hypercapnic patients: Check blood gases on oxygen — too much oxygen can raise CO2.

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7.15 Air Travel and Lung Disease

Why it matters: Aircraft cabins are pressurised to the equivalent of 1,500–2,400 m altitude. The inspired oxygen is like breathing about 15% oxygen at sea level. Healthy people's saturations fall a few percent; people with lung disease can become significantly hypoxic.

BTS air travel advice:

• Who to assess: People with significant lung disease, previous breathing problems when flying, SpO2 below about 95% at rest, recent exacerbation, or hypercapnia.
• Hypoxic challenge test (breathing 15% oxygen): If PaO2 falls below about 6.6 kPa (or SpO2 below about 85%), recommend in-flight oxygen (usually 2 L/min).
• Patients on LTOT need in-flight oxygen — usually their usual rate increased by about 2 L/min.
• Pneumothorax: Do not fly with a current pneumothorax. After resolution confirmed on X-ray, wait about 1 week (longer after a traumatic pneumothorax). After definitive surgery, flying is usually fine once recovered.
• After PE or DVT: Usually fine once stable on anticoagulation.
• Infectious TB: Do not fly until non-infectious (at least 2 weeks of effective treatment for sensitive TB).
• Bullae and cysts do not usually stop air travel, but discuss with a specialist.
• Practical: Airline oxygen must be booked in advance; portable oxygen concentrators must be airline-approved; carry medicines in hand luggage.

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7.16 High Altitude Illness

At high altitude (usually above 2,500 m), lower oxygen pressure causes three related conditions. The risk is highest with fast ascent.

• Acute mountain sickness:
  • Headache, nausea, fatigue, dizziness and poor sleep, 6–12 hours after arrival.
  • Treatment: Rest, no further ascent, analgesia. Descend if not improving.
• High altitude cerebral oedema (HACE):
  • Confusion, ataxia, drowsiness — life-threatening.
  • Treatment: Descend immediately; oxygen; dexamethasone.
• High altitude pulmonary oedema (HAPE):
  • Breathlessness at rest, cough, falling exercise tolerance, crackles, cyanosis — the commonest cause of altitude death.
  • Treatment: Descend; oxygen; nifedipine (lowers pulmonary artery pressure); portable hyperbaric bag.
• Prevention:
  • Gradual ascent — above 3,000 m, sleep no more than about 500 m higher each night, with rest days.
  • Acetazolamide for people at risk or with rapid ascent planned.
  • Nifedipine for people with previous HAPE.
• Lung disease: People with COPD, ILD, pulmonary hypertension or heart disease are at higher risk and need specialist advice before travelling to altitude.

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7.17 Drug Reference Table

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7.18 Spot the Diagnosis

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7.19 Exam-style Scenarios

1. A 48-year-old man had an unprovoked PE 3 months ago and is on apixaban. He has no bleeding risk factors.
Answer: Unprovoked PE.

• Discuss long-term anticoagulation (e.g. continuing apixaban, possibly at the reduced 2.5 mg dose after 6 months).
• Assess bleeding risk and preference.
• If still breathless: echo and V/Q scan to look for CTEPH.

2. A 38-year-old woman has 2 years of worsening exertional breathlessness and a recent faint while climbing stairs. Chest X-ray and spirometry are normal; TLCO is 48%; echo shows a high probability of PH.
Answer: Suspected pulmonary arterial hypertension.

• V/Q scan (exclude CTEPH); autoimmune screen, HIV, LFTs.
• Refer to a specialist PH centre for right heart catheterisation and treatment.
• Contraception advice — pregnancy is dangerous.

3. A 52-year-old taxi driver with BMI 38 has loud snoring and falls asleep watching TV. His Epworth score is 15.
Answer: Suspected OSA with excessive sleepiness.

• He must not drive while sleepy.
• Urgent referral for a home sleep study (vocational driver).
• CPAP if moderate or severe; weight loss.
• Inform the DVLA if moderate or severe with sleepiness, or not controlled within 3 months.

4. A woman with COPD on 2 L/min LTOT asks whether she can fly to Spain.
Answer: Yes, with in-flight oxygen booked in advance — usually her baseline rate increased by about 2 L/min.

• Confirm she is stable.
• Hypoxic challenge testing if unsure.
• Arrange oxygen at the destination.

5. A 60-year-old with MND has morning headaches and broken sleep. FVC is 48% predicted; overnight oximetry shows frequent desaturation.
Answer: Nocturnal hypoventilation from respiratory muscle weakness.

• Offer home NIV (improves survival and symptoms).
• Cough assistance.
• Advance care planning, including future decisions about NIV.

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7.20 Key Points

• Most PE: DOAC for 3 months if provoked; consider long-term if unprovoked. Warfarin for antiphospholipid syndrome; LMWH in pregnancy.
• Persistent breathlessness after PE: echo and V/Q scan for CTEPH — potentially curable by pulmonary endarterectomy.
• Pulmonary hypertension: mean PAP above 20 mmHg on right heart catheter. The commonest causes are left heart and lung disease.
• Normal chest X-ray and spirometry with a low TLCO: think pulmonary vascular disease.
• PAH is treated only in specialist centres: ERAs, PDE5 inhibitors, riociguat, prostacyclin drugs. Avoid pregnancy; never combine PDE5 inhibitors with nitrates.
• HHT: pulmonary AVMs cause stroke and brain abscess — embolise; antibiotic prophylaxis.
• OSA: snoring, apnoeas, sleepiness; home polygraphy; CPAP for moderate or severe disease; weight loss.
• Sleepy drivers must not drive; inform the DVLA with moderate or severe OSA and sleepiness.
• Obesity hypoventilation: obesity plus daytime hypercapnia (raised bicarbonate) — NIV and weight loss.
• Neuromuscular disease: nocturnal hypoventilation comes first — NIV improves survival in MND.
• LTOT: PaO2 below 7.3 kPa, at least 15 hours a day — never with smoking.
• Air travel: hypoxic challenge test if at risk; in-flight oxygen if PaO2 falls below about 6.6 kPa; no flying with a pneumothorax.
• Altitude: HACE (dexamethasone) and HAPE (nifedipine) — descend.

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7.21 Guidelines and Further Reading

• NICE NG158: Venous thromboembolic diseases — diagnosis, management and thrombophilia testing
• ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension (2022)
• NHS England: National pulmonary hypertension service specification
• NICE NG202: Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s
• DVLA: Assessing fitness to drive — excessive sleepiness and OSA
• NICE NG42: Motor neurone disease — assessment and management
• BTS Guideline for home oxygen use in adults
• BTS Clinical statement on air travel
• BNF — for current doses

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8.01 At a Glance

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8.02 The Acutely Breathless Patient

ABCDE first. Look at the patient before the numbers:

• Airway: Can they speak? Stridor, gurgling, drooling or a hoarse voice suggest upper airway trouble.
• Breathing:
  • Respiratory rate — the most sensitive early sign of deterioration.
  • Work of breathing: accessory muscles, tripod position, inability to finish sentences.
  • SpO2, chest expansion, percussion, auscultation (wheeze, crackles, silent chest, absent breath sounds).
• Circulation: Heart rate, BP, perfusion, JVP, leg swelling.
• Disability: Drowsiness or confusion may mean hypoxia or rising CO2. Check pupils (opioids) and glucose.
• Exposure: Rash (anaphylaxis, meningococcal), calves (DVT), temperature.

Early tests:

• Arterial blood gas if SpO2 is low, the patient is drowsy, or CO2 retention is possible.
• Chest X-ray; ECG.
• Bloods: FBC, CRP, U&E, lactate; troponin and NT-proBNP if cardiac causes are possible; D-dimer only when PE is clinically unlikely.
• Peak flow in asthma (if the patient is able).
• Point-of-care ultrasound if trained: B-lines (pulmonary oedema), effusion, absent lung sliding (pneumothorax), dilated RV (PE).

Use NEWS2 to track deterioration. Use the SpO2 Scale 2 only for patients with confirmed hypercapnic respiratory failure and a prescribed target of 88–92%.

💡 Clinical Pearl: A normal SpO2 on high-flow oxygen does not mean the patient is safe. A patient who is drowsy, exhausted or "settling" with a rising CO2 may be about to arrest — check a blood gas and call for help.

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8.03 Respiratory Failure and Blood Gases

Respiratory failure means the lungs cannot keep blood oxygen up or CO2 down.

• Type 1 (hypoxaemic): PaO2 below 8 kPa with normal or low PaCO2. The problem is gas exchange — pneumonia, pulmonary oedema, PE, ARDS, asthma (early), pneumothorax.
• Type 2 (hypercapnic): PaCO2 above about 6.0–6.5 kPa (usually with low PaO2). The problem is not enough ventilation — COPD, exhaustion in severe asthma, obesity hypoventilation, neuromuscular disease, chest wall deformity, opioids and sedatives.

Reading a blood gas — four steps:

• 1. Oxygenation: Is the PaO2 low? Compare it with the inspired oxygen — roughly, the PaO2 in kPa should be about 10 less than the inspired oxygen percentage. A PaO2 of 12 kPa on 60% oxygen is a big gas exchange problem.
• 2. pH: Acidaemia (below 7.35) or alkalaemia (above 7.45)?
• 3. PaCO2 (normal 4.7–6.0 kPa): High CO2 with low pH is respiratory acidosis.
• 4. Bicarbonate (normal 22–26 mmol/L):
  • Acute type 2 failure: pH low, bicarbonate normal.
  • Chronic type 2 failure: pH near normal, bicarbonate high (the kidneys have compensated).
  • Acute-on-chronic: pH low despite a raised bicarbonate — the typical COPD exacerbation.

Also look at: Lactate, glucose, potassium, haemoglobin and carboxyhaemoglobin on the gas analyser.

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8.04 Oxygen Therapy

Oxygen is a drug. It must be prescribed with a target saturation range (BTS emergency oxygen guideline).

• Most acutely ill patients: Target 94–98%.
• At risk of hypercapnic respiratory failure: Target 88–92% until a blood gas is available. This includes:
  • COPD.
  • Severe obesity (obesity hypoventilation).
  • Neuromuscular disease and chest wall deformity.
  • Cystic fibrosis and bronchiectasis with previous CO2 retention.
• Critically ill (cardiac arrest, shock, sepsis, major trauma, anaphylaxis, CO poisoning): Start with 15 L/minute via a reservoir (non-rebreathe) mask, then titrate once stable.
• No oxygen needed if saturations are already in the target range — including uncomplicated MI and stroke.

Devices:

⚠️ Safety Pearl: Pulse oximeters can overestimate oxygen saturation in people with darker skin, and read falsely normal in carbon monoxide poisoning. If the clinical picture does not fit, check an arterial blood gas.

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8.05 NIV, CPAP and High-flow Oxygen

Non-invasive ventilation (NIV, "BiPAP") — two pressures through a tight mask: a higher inspiratory pressure (IPAP) that blows off CO2, and a lower expiratory pressure (EPAP) that keeps airways open.

• Main indication: Acute hypercapnic respiratory failure — pH below 7.35 and PaCO2 above 6.5 kPa that persist despite optimal medical treatment (BTS/ICS). Typically COPD, obesity hypoventilation, neuromuscular disease, chest wall deformity.
• Before starting: Agree and document the ceiling of treatment — is the patient for intubation if NIV fails?
• Typical settings: Start with IPAP about 15 cmH2O and EPAP 3–5 cmH2O. Increase IPAP to 20–30 cmH2O over 10–30 minutes as tolerated. Entrain oxygen to 88–92%.
• Monitoring: Blood gas at 1 hour and at 4 hours. No improvement in pH and PaCO2 means NIV is failing — escalate (or move to palliative care if that is the agreed ceiling).
• Contraindications and cautions:
  • Undrained pneumothorax.
  • Inability to protect the airway, vomiting, copious secretions.
  • Facial trauma or burns.
  • Recent upper GI surgery.
  • Severe shock.
• Not routinely used in asthma — intubation is safer if a patient with asthma is tiring.

CPAP (a single continuous pressure, usually 5–10 cmH2O): Keeps alveoli open and improves oxygenation. Used for type 1 failure — especially cardiogenic pulmonary oedema and some pneumonias. It does not directly remove CO2.

High-flow nasal oxygen (HFNO): Warmed, humidified oxygen at up to 60 L/minute.

• Delivers precise oxygen with a small amount of positive pressure.
• Comfortable — the patient can eat and talk.
• Useful in type 1 failure and after extubation.
• It can hide deterioration — set clear escalation criteria and review regularly.

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8.06 Acute Severe and Life-threatening Asthma

MLA / MRCP critical warning: A patient with a silent chest, exhaustion, falling effort or a normal/rising PaCO₂ in acute severe asthma may be approaching respiratory arrest. Seek immediate senior and critical-care support. Do not delay resuscitation for imaging or blood tests.

Mechanism: Airway inflammation, bronchospasm and mucus plugging narrow the airways. Air is trapped, the work of breathing soars, and the patient eventually tires. A rising or "normal" CO2 in acute asthma means exhaustion — a sign of life-threatening disease.

Severity: recognise the deteriorating patient

Severity (BTS/NICE/SIGN):

• Moderate: Increasing symptoms; PEF above 50–75% of best or predicted; no features of acute severe asthma.
• Acute severe — any one of:
  • PEF 33–50% of best or predicted.
  • Respiratory rate 25 or more.
  • Heart rate 110 or more.
  • Unable to complete sentences in one breath.
• Life-threatening — any one of:
  • PEF below 33%.
  • SpO2 below 92%, PaO2 below 8 kPa.
  • "Normal" PaCO2 (4.6–6.0 kPa).
  • Silent chest, cyanosis, poor respiratory effort.
  • Arrhythmia, hypotension.
  • Exhaustion, altered consciousness.
• Near-fatal: Raised PaCO2 and/or needing mechanical ventilation.

Management in hospital:

• Oxygen to SpO2 94–98%.
• Salbutamol 5 mg nebulised (oxygen-driven). Repeat every 15–30 minutes, or give continuously (5–10 mg/hour) if not improving.
• Ipratropium bromide 0.5 mg nebulised 4–6-hourly in acute severe or life-threatening asthma.
• Steroids: Prednisolone 40–50 mg orally (or hydrocortisone 100 mg IV 6-hourly if unable to swallow). Continue for at least 5 days.
• Magnesium sulfate 1.2–2 g IV over 20 minutes for life-threatening asthma, or acute severe asthma not responding to initial treatment.
• Senior decision only: IV aminophylline (omit the loading dose if already on oral theophylline; monitor levels) or IV salbutamol.
• No sedatives. Chest X-ray if pneumothorax or consolidation is suspected, or if ventilation is needed.
• Antibiotics: Not routinely — most exacerbations are viral.

ICU referral — transfer with a doctor able to intubate if there is:

• Deteriorating PEF.
• Persistent or worsening hypoxia, or hypercapnia.
• Exhaustion, drowsiness or confusion.
• Poor respiratory effort or respiratory arrest.

Discharge:

• PEF above 75% of best, with low diurnal variability.
• Stable on discharge medication for 12–24 hours; inhaler technique checked.
• Prednisolone to complete at least 5 days, plus inhaled steroid.
• Written asthma action plan.
• GP review within 2 working days; respiratory clinic within 4 weeks.

⚠️ Safety Pearl: A quiet chest in severe asthma is not improvement — it means almost no air is moving. Drowsiness, a silent chest or a normal CO2 in a breathless asthmatic needs ICU now.

Acute adult asthma pathway: BTS/SIGN (UK clinical pathway)

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8.07 COPD Exacerbation

Mechanism: A sustained worsening of breathlessness, cough or sputum, usually triggered by a viral or bacterial infection or pollution. Worsening airflow obstruction and air trapping increase the work of breathing. Tired breathing muscles let CO2 rise.

Assessment:

• Exclude pneumonia, pneumothorax, PE, heart failure and arrhythmia.
• ABG on arrival and after any oxygen change.
• Chest X-ray, ECG, FBC, U&E, CRP.
• Sputum culture if purulent.

Management:

• Controlled oxygen — target 88–92% via a 24% or 28% Venturi mask. Repeat the blood gas within 30–60 minutes.
• Nebulised bronchodilators: Salbutamol 2.5–5 mg and ipratropium 0.5 mg. If hypercapnic, drive the nebuliser with air, with nasal oxygen alongside.
• Prednisolone 30 mg daily for 5 days (NICE NG115).
• Antibiotics if sputum is purulent or there are signs of pneumonia (NICE NG114): e.g. amoxicillin, doxycycline or clarithromycin orally for 5 days; IV options if severe.
• NIV if pH below 7.35 and PaCO2 above 6.5 kPa persist despite these measures.
• Escalation plan: Decide early — and with the patient where possible — whether intubation and ICU are appropriate if NIV fails.
• Recovery:
  • Check inhaler technique.
  • Smoking cessation.
  • Pulmonary rehabilitation referral.
  • Review maintenance treatment.
  • Follow-up within 2 weeks.
  • Consider palliative care input in advanced disease.

💡 Clinical Pearl: In a COPD patient, high-flow oxygen can push the CO2 up and the pH down, causing drowsiness and respiratory arrest. But never withhold oxygen from a hypoxic patient — titrate to 88–92% and check the gas.

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8.08 Upper Airway Obstruction and Stridor

Stridor is a harsh, high-pitched noise from turbulent airflow through a narrowed upper airway. Inspiratory stridor suggests an obstruction at or above the larynx. It is a sign of severe narrowing — the airway may close completely without warning.

Causes:

• Anaphylaxis and angioedema.
• Infection: Supraglottitis (epiglottitis), deep neck space infection (quinsy, retropharyngeal abscess, Ludwig's angina), bacterial tracheitis.
• Foreign body — choking.
• Tumour — laryngeal, thyroid, mediastinal.
• Bleeding — neck haematoma after thyroid or carotid surgery.
• Burns and inhalation injury — soot, singed nasal hair, hoarse voice.
• Trauma; bilateral vocal cord palsy; laryngospasm.

Clinical pattern: Stridor, hoarse or muffled ("hot potato") voice, drooling, difficulty swallowing, tripod posture, anxiety, rising breathing effort.

Management:

• Call anaesthetics and ENT immediately — this is a potential difficult airway.
• Keep the patient sitting up, in the position they find most comfortable. Do not lie them flat or send them away for scans unaccompanied.
• High-flow oxygen.
• Nebulised adrenaline (e.g. 1 mg/mL, up to 5 mL nebulised) for temporary relief of airway swelling.
• Dexamethasone IV (e.g. 6.6–8 mg) for inflammatory swelling.
• Treat the cause:
  • IM adrenaline for anaphylaxis.
  • IV antibiotics (e.g. ceftriaxone) for supraglottitis.
  • Drainage for abscesses.
• Heliox (helium-oxygen) can reduce turbulent flow as a temporary bridge.
• Definitive airway in theatre if needed (awake fibreoptic intubation, or a surgical airway).

Choking (RCUK):

• Encourage coughing.
• If the cough becomes ineffective: up to 5 back blows, then up to 5 abdominal thrusts; repeat.
• If the patient becomes unconscious: start CPR.

Neck haematoma after thyroid surgery (DAS guidance) — remember "SCOOP":

• Skin exposure.
• Cut sutures.
• Open skin.
• Open muscles.
• Pack the wound.

This releases pressure on the airway at the bedside — do it immediately if the patient has stridor.

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8.09 Anaphylaxis

Mechanism: A severe, life-threatening, generalised hypersensitivity reaction. Mast cells release histamine and other mediators, causing airway swelling, bronchospasm, vasodilatation and capillary leak.

Common triggers:

• Drugs — antibiotics, NSAIDs, neuromuscular blockers, contrast.
• Foods — peanuts, tree nuts, shellfish.
• Insect stings.
• Latex.

Recognition (RCUK): Sudden onset and rapid progression of:

• Airway problems — swelling, hoarseness, stridor; and/or
• Breathing problems — wheeze, breathlessness, hypoxia; and/or
• Circulation problems — hypotension, collapse, tachycardia.

Skin or mucosal changes (urticaria, flushing, angioedema) are usually present, but are absent in up to 1 in 5.

Management (RCUK 2021):

• Remove the trigger (stop the infusion); call for help; lie flat with legs raised — or sit up if breathing is difficult.
• Adrenaline 500 micrograms IM (0.5 mL of 1 mg/mL, 1:1,000) into the anterolateral thigh. Repeat after 5 minutes if not improving.
• High-flow oxygen.
• IV fluid bolus (e.g. 500–1,000 mL crystalloid) for hypotension.
• Refractory anaphylaxis (no improvement after 2 IM doses): Start a low-dose IV adrenaline infusion with expert (critical care) help. Do not give IV adrenaline boluses unless experienced.
• Antihistamines and steroids are not first-line emergency treatment. A non-sedating oral antihistamine can help skin symptoms once stable.
• Mast cell tryptase: Take samples as soon as possible after treatment, at 1–2 hours, and at 24 hours or more (baseline).

After the event:

• Observation — duration depends on severity and response (RCUK). Longer if two or more doses of adrenaline were needed or if there is a risk of a biphasic reaction.
• Prescribe two adrenaline auto-injectors and train the patient to use them.
• Refer to an allergy clinic (NICE CG134).
• Report suspected drug reactions (Yellow Card).

⚠️ Safety Pearl: IM adrenaline is the treatment for anaphylaxis — give it early and repeat it. Delaying adrenaline to give chlorphenamine and hydrocortisone is a common and dangerous mistake.

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8.10 Angioedema without Urticaria

Mechanism: Swelling of the lips, tongue, face, throat or gut caused by bradykinin rather than histamine. Because it is not histamine-driven, it responds poorly to adrenaline, antihistamines and steroids, and comes on more slowly (hours). There is no urticaria or itch.

Causes:

• ACE inhibitors — the commonest. It can start years after starting the drug.
• Hereditary angioedema — C1-esterase inhibitor deficiency or dysfunction; family history, recurrent episodes, abdominal attacks; low C4.
• Acquired C1-inhibitor deficiency — lymphoma, autoimmune disease.
• Other drugs — gliptins, sacubitril/valsartan, tPA (alteplase).

Management:

• Airway assessment — tongue and floor-of-mouth swelling can obstruct the airway. Involve anaesthetics and ENT early.
• Stop the ACE inhibitor permanently — record it as an adverse reaction.
• Adrenaline can be tried, especially if anaphylaxis cannot be excluded.
• Specific treatment (specialist): C1-esterase inhibitor concentrate or icatibant (bradykinin receptor blocker) for hereditary angioedema. These are sometimes used off-label for severe ACE inhibitor angioedema. Fresh frozen plasma if neither is available.
• Check C4 and C1-inhibitor levels if hereditary or acquired angioedema is suspected.

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8.11 Tracheostomy and Laryngectomy Emergencies

Know which you are dealing with — check the bedhead sign:

• Tracheostomy: The upper airway is still connected to the lungs. You may be able to oxygenate via the mouth and nose as well as the stoma.
• Laryngectomy: The trachea has been brought out to the neck, and there is no connection between the mouth and the lungs. Oxygenate and ventilate via the stoma only.

Blocked or displaced tracheostomy (National Tracheostomy Safety Project):

• Call for help — anaesthetics and ENT.
• Apply high-flow oxygen to both the face and the stoma (unless laryngectomy).
• Use waveform capnography to check airflow.
• Check patency:
  • Remove any speaking valve or cap.
  • Remove the inner tube — many blockages are in the inner tube.
  • Try to pass a suction catheter.
• If the catheter will not pass: deflate the cuff.
• If still not breathing or no improvement: remove the tracheostomy tube. Then oxygenate via the face or the stoma. If not breathing, start CPR and ventilate via the mouth (covering the stoma) or via the stoma.
• Secondary steps (experienced staff): Oral intubation, or intubation via the stoma.

Bleeding from a tracheostomy: Minor bleeding is common. Major bleeding a few days to weeks after insertion may be a tracheo-innominate artery fistula — over-inflate the cuff, apply pressure, and call surgeons immediately.

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8.12 Community-acquired Pneumonia

Mechanism: Infection of the alveoli, which fill with pus and fluid. The usual organisms are:

• Streptococcus pneumoniae — the commonest.
• Haemophilus influenzae.
• Atypical organisms: Mycoplasma, Legionella, Chlamydophila.
• Staphylococcus aureus — especially after influenza.
• Viruses: Influenza, SARS-CoV-2, RSV.

Clinical pattern: Cough, fever, breathlessness, pleuritic pain; crackles or bronchial breathing. Older people may present with confusion or falls only.

Severity (NICE NG250) — CURB-65, one point each:

• Confusion (new).
• Urea above 7 mmol/L.
• Respiratory rate 30 or more.
• Blood pressure: systolic below 90 or diastolic 60 or less.
• Age 65 or over.

Score 0–1 is low risk (below 3% mortality); 2 is intermediate (3–15%); 3–5 is high (above 15%). Use clinical judgement too — very low saturations, pleural complications or frailty raise the risk whatever the score.

Timing: Confirm the diagnosis (including chest X-ray) and start antibiotics within 4 hours of presentation — sooner (within 1 hour) if the patient has sepsis.

Investigations (moderate or high severity):

• Blood cultures if sepsis is suspected.
• Sputum culture.
• Pneumococcal urinary antigen.
• Legionella urinary antigen if there are risk factors (travel, hotels, air conditioning, outbreaks).
• Viral PCR in season.
• CRP baseline.

Antibiotics (NICE NG250, adults; usually a 5-day course):

• Use erythromycin instead of clarithromycin in pregnancy.
• Review IV antibiotics by 48 hours and switch to oral when possible.
• Severe pneumonia: NICE NG250 suggests considering corticosteroids (IV hydrocortisone first). Note the MHRA warning about combining fluoroquinolones with steroids (tendon rupture).
• Influenza in season: Antivirals (e.g. oseltamivir) for hospitalised patients.

Do not discharge if, in the past 24 hours, there are two or more of:

• Temperature above 37.5°C.
• Respiratory rate 24 or more.
• Heart rate above 100.
• Systolic BP 90 or below.
• SpO2 below 90% on air.
• Abnormal mental state.
• Unable to eat without help.

Complications:

• Sepsis and AKI.
• Respiratory failure and ARDS.
• Parapneumonic effusion and empyema — suspect with persistent fever or a non-falling CRP.
• Lung abscess.
• AF.

Follow-up: A repeat chest X-ray at about 6 weeks for people at risk of lung cancer (e.g. smokers over 50) or with persisting symptoms.

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8.13 Hospital-acquired and Aspiration Pneumonia

Hospital-acquired pneumonia (HAP): Onset 48 hours or more after admission. Gram-negative organisms (Pseudomonas, Klebsiella, E. coli) and MRSA are more likely.

• Send a microbiology sample before antibiotics, and start antibiotics within 4 hours of suspicion.
• Non-severe, low resistance risk: e.g. co-amoxiclav orally (NICE NG250); alternatives include doxycycline or co-trimoxazole.
• Severe or higher risk of resistance (e.g. recent antibiotics, ICU, known resistant organisms): IV piperacillin-tazobactam, a cephalosporin or meropenem, guided by local microbiology.
• MRSA suspected: Add vancomycin or teicoplanin.
• Review at 5 days and stop if stable.

Aspiration:

• Aspiration pneumonitis: Chemical injury from stomach contents. Abrupt breathlessness and hypoxia within hours of vomiting or a seizure. Often does not need antibiotics at first — supportive care.
• Aspiration pneumonia: Infection from inhaled mouth organisms — in people with swallowing problems, reduced consciousness, alcohol excess, stroke or dementia. Typically affects the right lower lobe (or the posterior segments if lying down). Treat as CAP or HAP according to setting; routine extra anaerobic cover is not usually needed.
• Prevention:
  • Swallow assessment (speech and language therapy).
  • Sit upright for meals.
  • Oral care.
  • Review sedating drugs.
• Recurrent aspiration in frailty or dementia: Discuss goals of care and "eating and drinking with acknowledged risks".

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8.14 Acute Chest Syndrome in Sickle Cell Disease

Definition: A new infiltrate on chest X-ray in a person with sickle cell disease, plus one or more of:

• Chest pain.
• Fever.
• Tachypnoea or wheeze.
• Cough.
• Hypoxia.

It is a leading cause of death in sickle cell disease. It often develops during a painful crisis.

Triggers: Infection (including atypical organisms), fat embolism from bone marrow infarction, and hypoventilation from rib pain or opioids.

Management:

• Urgent haematology involvement; HDU or ICU if deteriorating.
• Oxygen to keep SpO2 at 95% or more (or at the patient's baseline).
• Analgesia — enough to allow deep breathing, but watch for opioid-induced hypoventilation.
• Incentive spirometry.
• Careful IV fluids (avoid overload).
• Antibiotics covering typical and atypical organisms (e.g. a cephalosporin plus a macrolide).
• Blood transfusion: Top-up or exchange transfusion for severe or worsening disease (falling saturations, multilobar involvement).

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8.15 Tension Pneumothorax

Mechanism: Air enters the pleural space with each breath but cannot escape (a one-way valve). Pressure builds, the lung collapses, the mediastinum is pushed across, and venous return to the heart falls — causing shock and cardiac arrest.

Who: Trauma; ventilated patients (including NIV); after central line insertion or other procedures; occasionally spontaneous.

Clinical pattern:

• Severe, rapidly worsening breathlessness and hypoxia.
• Tachycardia and hypotension; raised JVP.
• Absent breath sounds and hyper-resonance on the affected side.
• Tracheal deviation away from the affected side — a late sign.
• Ventilated patients: Rising airway pressures, falling saturations, hypotension.

Management — a clinical diagnosis; do not wait for an X-ray:

• High-flow oxygen.
• Needle decompression with a large cannula (14G):
  • In the 4th or 5th intercostal space just anterior to the mid-axillary line (preferred in adults — the chest wall is thinner), or
  • The 2nd intercostal space in the mid-clavicular line.
• Finger thoracostomy (in trauma or ventilated patients, by trained staff) is more reliable.
• Then insert a chest drain — needle decompression is only temporary, and cannulas can kink or dislodge.

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8.16 Spontaneous Pneumothorax

• Primary spontaneous pneumothorax (PSP): No known lung disease. Typically tall, thin young men; smoking (including cannabis) greatly increases the risk.
• Secondary spontaneous pneumothorax (SSP): Underlying lung disease — COPD, asthma, cystic fibrosis, interstitial lung disease, TB, Pneumocystis pneumonia, cancer. Patients are less able to tolerate it, so it is more dangerous.

Clinical pattern: Sudden pleuritic chest pain and breathlessness. There may be reduced breath sounds and hyper-resonance, but small pneumothoraces can be silent. Confirm with chest X-ray (or CT or ultrasound).

BTS 2023 approach: Management is now guided by symptoms and patient priorities, not just size.

• Look for high-risk features:
  • Haemodynamic instability.
  • Significant hypoxia.
  • Bilateral pneumothorax.
  • Underlying lung disease.
  • Age 50 or over with a significant smoking history.
  • Haemothorax.
  These patients usually need a chest drain and admission.
• PSP with minimal symptoms and no high-risk features: Conservative management can be considered whatever the size, with clear safety-netting and follow-up.
• PSP with symptoms: After discussion with the patient:
  • Needle aspiration.
  • An ambulatory device (allows outpatient care).
  • A chest drain.
• SSP: Usually admission and a chest drain. Needle aspiration or an ambulatory device may be suitable for selected patients.
• Chest drain technique:
  • Small-bore (Seldinger), inserted in the "triangle of safety" — the lateral edge of pectoralis major, the anterior edge of latissimus dorsi, and the 5th intercostal space.
  • Use ultrasound guidance where fluid is present.
  • Do not clamp a bubbling drain.
• Persistent air leak or recurrence: Refer to thoracic surgery (pleurodesis or bullectomy). Surgery is also offered after a first pneumothorax in high-risk occupations (e.g. pilots, divers).

Discharge advice:

• Stop smoking — this greatly reduces recurrence.
• Do not fly until the pneumothorax has fully resolved on imaging (and usually for 1–2 weeks after).
• Avoid diving permanently, unless definitive surgery has been done.
• Return immediately if breathlessness worsens.

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8.17 Pleural Infection and Large Effusions

Pleural infection (complicated parapneumonic effusion or empyema): Infection spreads from pneumonia into the pleural fluid, which may become loculated and full of pus.

• Suspect it when pneumonia does not settle — persistent fever, rising or non-falling CRP, new effusion.
• Ultrasound-guided pleural aspiration for:
  • Appearance (pus?).
  • pH (use a blood gas analyser).
  • Glucose, LDH, protein.
  • Gram stain and culture.
• Drain it (small-bore chest drain) if there is:
  • Frank pus.
  • Organisms on Gram stain or culture.
  • Pleural fluid pH below 7.2 in a suspected infected effusion.
• Antibiotics: Cover the pneumonia organisms plus anaerobes (e.g. co-amoxiclav, or per local guidance). Courses are typically several weeks.
• If the collection persists: Intrapleural tPA plus DNase (MIST2). Thoracic surgery (VATS) if this fails.
• Prognosis: The RAPID score (Renal, Age, Purulence, Infection source, Dietary factors) helps predict outcome.

Large effusion causing breathlessness:

• Therapeutic aspiration relieves symptoms. Remove no more than about 1.5 L at once, and stop if the patient develops chest tightness or coughing (re-expansion pulmonary oedema).
• A massive effusion with mediastinal shift can compromise breathing and circulation — urgent drainage.
• Recurrent malignant effusions: Indwelling pleural catheter or talc pleurodesis.
• Haemothorax (after trauma or procedures): Large-bore drain and surgical review.

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8.18 Pulmonary Embolism

Mechanism: A blood clot, usually from the leg or pelvic veins, lodges in the pulmonary arteries. Small clots cause pleuritic pain and breathlessness. Large clots strain the right ventricle and cause shock.

Risk factors:

• Recent surgery or immobility.
• Cancer.
• Previous VTE.
• Pregnancy and the postpartum period.
• Oestrogen (COCP, HRT).
• Thrombophilia.
• Long-haul travel.
• Obesity.

Clinical pattern: Breathlessness, pleuritic pain, haemoptysis, syncope; tachycardia, tachypnoea, hypoxia, signs of DVT. It can be subtle — the chest X-ray is often normal.

Diagnosis (NICE NG158):

• Calculate the two-level Wells score.
• PE likely (Wells above 4): CTPA immediately. If it is delayed, start interim anticoagulation.
• PE unlikely (Wells 4 or less): D-dimer. If positive, CTPA; if negative, PE is excluded.
• PERC rule: Can be used to avoid testing in low-risk patients. All criteria must be met:
  • Age under 50.
  • Heart rate below 100.
  • SpO2 95% or more.
  • No haemoptysis.
  • No oestrogen use.
  • No previous VTE.
  • No unilateral leg swelling.
  • No recent surgery or trauma.
• Renal impairment or contrast allergy: V/Q scan.
• Pregnancy: Leg ultrasound first if there are leg symptoms; then V/Q or CTPA after discussion. Treat with LMWH while waiting.

Treatment:

• Anticoagulation: Usually a DOAC:
  • Apixaban 10 mg twice daily for 7 days, then 5 mg twice daily.
  • Rivaroxaban 15 mg twice daily for 21 days, then 20 mg once daily.
• Exceptions:
  • LMWH for pregnancy.
  • Warfarin for antiphospholipid syndrome.
  • Severe renal impairment — LMWH, unfractionated heparin or warfarin.
• Outpatient treatment for low-risk patients (e.g. PESI class I–II, or Hestia criteria) with good follow-up.
• High-risk (shocked) PE: Thrombolysis — see the Cardiac Emergencies chapter.
• Duration: At least 3 months. Longer for unprovoked PE or ongoing risk factors, balancing bleeding risk.
• Unprovoked PE: History, examination and basic tests for cancer. Do not routinely do extensive cancer screening or thrombophilia testing.

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8.19 Massive Haemoptysis

Why it is dangerous: The threat is drowning in blood rather than blood loss — only a few hundred mL can fill the airways. Definitions vary (e.g. more than 200–600 mL in 24 hours), but any haemoptysis causing breathing difficulty, hypoxia or instability is massive.

Causes:

• Bronchiectasis and cystic fibrosis.
• Lung cancer.
• TB and aspergilloma.
• Lung abscess, necrotising pneumonia.
• Vasculitis (GPA) and other alveolar haemorrhage.
• PE.
• Anticoagulants and clotting problems.
• Arteriovenous malformation.
• Trauma.

Management:

• Call for help: Senior, anaesthetics, respiratory, interventional radiology, thoracic surgery.
• Position the patient with the bleeding side down (if known) to protect the good lung.
• High-flow oxygen; suction.
• Large-bore IV access; crossmatch; FBC and clotting.
• Reverse anticoagulation and correct clotting.
• Tranexamic acid — IV (e.g. 1 g) or nebulised.
• Intubation with a large tube if the airway is threatened. The tube can be advanced into the non-bleeding main bronchus to protect the good lung.
• CT angiography (if stable) to find the source.
• Bronchial artery embolisation — the main definitive treatment.
• Bronchoscopy (to find and control bleeding); surgery for selected causes.

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8.20 Diffuse Alveolar Haemorrhage

• What it is: Bleeding into the alveoli throughout both lungs, usually from inflamed small vessels (capillaritis).
• Causes:
  • ANCA-associated vasculitis (GPA, MPA).
  • Anti-GBM disease (Goodpasture's).
  • SLE.
  • Drugs, cocaine, bone marrow transplant, severe clotting disorders.
• Clinical pattern:
  • Breathlessness, hypoxia.
  • Haemoptysis — absent in up to a third.
  • Falling haemoglobin.
  • Bilateral infiltrates on chest X-ray.
  • Often with kidney involvement — a "pulmonary-renal syndrome" (haematuria, proteinuria, AKI).
• Tests:
  • Urine dipstick (blood and protein).
  • ANCA, anti-GBM, ANA, dsDNA, complement.
  • CT chest; bronchoscopy (increasingly bloody lavage samples).
  • Kidney biopsy.
• Management (respiratory, renal and rheumatology urgently):
  • Oxygen and ventilatory support.
  • High-dose IV methylprednisolone.
  • Rituximab or cyclophosphamide.
  • Plasma exchange for anti-GBM disease.

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8.21 Acute Pulmonary Oedema

Cardiogenic pulmonary oedema is covered in detail in the Cardiac Emergencies chapter. From a respiratory point of view:

• Look for clues it is cardiac rather than pneumonia or ARDS:
  • History of heart disease; orthopnoea; raised JVP; peripheral oedema.
  • Bilateral perihilar shadowing, upper lobe diversion, effusions, Kerley B lines.
  • Raised NT-proBNP.
  • Bilateral B-lines on lung ultrasound.
  • Poor LV function on echo.
• Treatment:
  • Sit up; oxygen to target.
  • IV furosemide.
  • CPAP for persistent hypoxia (NIV if hypercapnic).
  • Nitrates if hypertensive.
  • Treat the trigger (ACS, AF, hypertension).
• Other causes of "wet lungs":
  • Fluid overload in AKI.
  • Transfusion-associated circulatory overload (TACO) and transfusion-related acute lung injury (TRALI).
  • Neurogenic pulmonary oedema after head injury or subarachnoid haemorrhage.
  • Re-expansion oedema after drainage.
  • High altitude.

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8.22 ARDS

Mechanism: Acute respiratory distress syndrome is widespread inflammation of the lungs that makes the alveolar–capillary barrier leaky. Protein-rich fluid floods the alveoli, causing stiff lungs and severe hypoxia — not due to heart failure.

Diagnosis (Berlin definition):

• Onset within 1 week of a known insult, or new or worsening respiratory symptoms.
• Bilateral opacities on imaging, not fully explained by effusions, collapse or nodules.
• Not fully explained by heart failure or fluid overload (echo if no risk factor).
• PaO2/FiO2 ratio (on PEEP of at least 5 cmH2O):
  • Mild: 200–300 mmHg (26.7–40 kPa).
  • Moderate: 100–200 mmHg (13.3–26.7 kPa).
  • Severe: 100 mmHg or less (13.3 kPa or less).

Causes:

• Direct lung injury: Pneumonia (including COVID-19), aspiration, inhalation injury, drowning, lung contusion.
• Indirect: Sepsis, acute pancreatitis, major trauma, burns, massive transfusion, TRALI, drugs.

Management (ICU):

• Treat the cause — antibiotics, source control.
• Lung-protective ventilation: Tidal volume about 6 mL/kg of predicted body weight, plateau pressure 30 cmH2O or less, and adequate PEEP.
• Prone positioning for at least 12–16 hours a day in moderate or severe ARDS (PaO2/FiO2 below 150 mmHg).
• Conservative fluid strategy once shock has resolved.
• Neuromuscular blockade in selected early severe cases.
• Referral for ECMO in severe refractory hypoxia, in suitable patients.
• Steroids: Dexamethasone for COVID-19 requiring oxygen. Use in other ARDS remains debated — follow ICU guidance.

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8.23 Neuromuscular Respiratory Failure

Mechanism: The lungs are normal but the breathing muscles are weak, so ventilation fails and the patient cannot cough or protect the airway.

Causes:

• Guillain–Barré syndrome.
• Myasthenic crisis.
• Motor neurone disease.
• High cervical spinal cord injury.
• Botulism; critical illness polyneuropathy and myopathy.
• Muscular dystrophies; severe hypokalaemia or hypophosphataemia.

Why it is dangerous: Oxygen saturation and blood gases stay normal until very late. By the time SpO2 falls or CO2 rises, the patient may be about to arrest.

Monitor:

• Forced vital capacity (FVC) every few hours — the key measurement. Peak flow is not useful. Patients with facial weakness may need a face mask attachment.
• Single breath count (counting aloud on one breath — below about 15–20 is worrying).
• Weak cough, difficulty swallowing, nasal speech (bulbar weakness).
• Paradoxical abdominal movement; inability to lie flat (diaphragm weakness).
• Neck flexion weakness.

Refer to ICU — the "20/30/40 rule":

• FVC below 20 mL/kg (or falling by 30% or more).
• Maximum inspiratory pressure weaker than −30 cmH2O.
• Maximum expiratory pressure below 40 cmH2O.
• Also refer for bulbar dysfunction with aspiration risk, or a rising CO2.

Specific treatment:

• GBS: IV immunoglobulin (0.4 g/kg daily for 5 days) or plasma exchange. Watch for autonomic instability (arrhythmias, BP swings).
• Myasthenic crisis:
  • IV immunoglobulin or plasma exchange.
  • Stop drugs that worsen myasthenia — aminoglycosides, macrolides, quinolones, magnesium, beta-blockers, some anaesthetic agents.
  • Steroids are started cautiously, because they can worsen weakness at first.
• MND: Discuss NIV and goals of care early, ideally before a crisis.

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8.24 Opioids, Carbon Monoxide and Smoke

Opioid toxicity:

• Signs: Reduced consciousness, slow breathing (respiratory rate below 8–10), pinpoint pupils, hypoxia and hypercapnia.
• Causes: Overdose, accumulation in renal impairment (morphine, codeine), transdermal patches, combinations with gabapentinoids or benzodiazepines.
• Management:
  • Support the airway; bag-mask ventilation if needed.
  • Naloxone 400 micrograms IV or IM, repeated as needed.
  • In opioid-dependent or palliative patients, titrate small IV doses (e.g. 20–100 micrograms) to restore breathing without causing severe pain or withdrawal.
  • Naloxone wears off in 30–90 minutes, sooner than many opioids — observe closely and use an infusion for long-acting opioids (methadone, modified-release).
• Benzodiazepines: Supportive care. Flumazenil is not routinely used — it can cause seizures, especially in mixed overdoses or long-term users.

Carbon monoxide (CO) poisoning:

• Mechanism: CO binds haemoglobin far more strongly than oxygen, starving tissues of oxygen.
• Sources: Faulty boilers and heaters, fires, car exhausts, barbecues indoors.
• Symptoms: Headache, nausea, dizziness, confusion — often several household members or pets affected, worse at home. Severe: seizures, coma, arrhythmias, MI.
• Diagnosis:
  • Pulse oximetry reads falsely normal.
  • Measure carboxyhaemoglobin (COHb) on a venous or arterial blood gas (co-oximetry).
  • Levels may already have fallen if oxygen was given, so interpret with the history.
• Treatment:
  • 100% oxygen via a tight reservoir mask (15 L/minute) — this shortens CO's half-life from about 5 hours to about 1 hour.
  • ECG and troponin.
  • Discuss hyperbaric oxygen for selected severe cases with TOXBASE or NPIS.
  • Warn about the source (gas safety) and other people at risk.

Smoke inhalation:

• Airway burns: Facial burns, singed nasal hair, soot in the mouth, hoarse voice or stridor — early intubation before swelling closes the airway.
• CO poisoning: High-flow oxygen.
• Cyanide poisoning (burning plastics): Unexplained high lactate, collapse — give hydroxocobalamin.

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8.25 Drug Reference Table

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8.26 Spot the Emergency

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8.27 Exam-style Scenarios

1. A 24-year-old with asthma has RR 30, HR 125 and PEF 30% of best. She cannot complete sentences. SpO2 is 91%.
Answer: Life-threatening asthma (PEF below 33%, SpO2 below 92%).

• Oxygen to 94–98%; salbutamol 5 mg and ipratropium 0.5 mg nebulised (oxygen-driven).
• Prednisolone 40–50 mg (or hydrocortisone 100 mg IV).
• Magnesium sulfate 1.2–2 g IV over 20 minutes.
• Arterial blood gas; senior and ICU review now.

2. A 72-year-old with COPD is breathless. On 28% oxygen after nebulisers and steroids: pH 7.28, PaCO2 8.9 kPa, PaO2 7.8 kPa.
Answer: Acute-on-chronic hypercapnic respiratory failure.

• Start NIV (pH below 7.35, PaCO2 above 6.5 despite treatment).
• Agree the ceiling of treatment before or as you start.
• Repeat the blood gas at 1 hour and 4 hours.
• Antibiotics if purulent sputum; look for pneumonia or pneumothorax.

3. An 80-year-old has cough and fever. She is confused; urea 9 mmol/L, RR 32, BP 95/55.
Answer: High-severity CAP (CURB-65 = 5).

• Sepsis bundle; oxygen; fluids.
• IV co-amoxiclav plus clarithromycin within 1 hour (septic).
• Blood cultures, pneumococcal and legionella antigens.
• Consider steroids and senior review of ICU appropriateness.

4. A 21-year-old man has sudden pleuritic pain. Chest X-ray shows a large left pneumothorax; he is comfortable at rest with SpO2 98%.
Answer: Primary spontaneous pneumothorax with minimal symptoms and no high-risk features.

• BTS 2023: conservative management can be offered regardless of size, with safety-netting and early follow-up.
• Alternatives after shared decision-making: needle aspiration or an ambulatory device.
• Smoking cessation; no flying until resolved; avoid diving.

5. A 55-year-old woman, 10 days after a hip replacement, has sudden breathlessness. HR 115, SpO2 91%, BP 128/80; Wells score 7.5.
Answer: PE likely.

• Immediate CTPA; start interim anticoagulation if there is any delay.
• If confirmed and stable: DOAC (e.g. apixaban) for at least 3 months (provoked).
• If she becomes shocked: thrombolysis.

6. A man with bronchiectasis coughs up 300 mL of fresh blood and is hypoxic.
Answer: Massive haemoptysis.

• Lie him bleeding side down; high-flow oxygen; suction.
• Large-bore access, crossmatch, reverse any anticoagulation; tranexamic acid.
• Call anaesthetics (intubation with a large tube), respiratory and interventional radiology.
• CT angiography, then bronchial artery embolisation.

7. A 40-year-old with GBS has FVC 1.2 L (weight 75 kg) and a weak cough. SpO2 is 97% on air.
Answer: Impending neuromuscular respiratory failure — FVC 16 mL/kg (below 20 mL/kg).

• Refer to ICU now for elective intubation; normal saturations are falsely reassuring.
• IV immunoglobulin.
• Monitor for autonomic instability.

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8.28 Key Points

• Respiratory rate is the earliest sign of deterioration. A drowsy, tiring patient may have a rising CO2.
• Prescribe oxygen to a target: 94–98% for most; 88–92% if at risk of hypercapnia; reservoir mask at 15 L/minute if critically ill.
• NIV is for hypercapnic acidosis (pH below 7.35, PaCO2 above 6.5) — agree the ceiling of care first.
• Life-threatening asthma: SpO2 below 92%, PEF below 33%, silent chest, normal or rising CO2, exhaustion. Give magnesium and call ICU.
• COPD: controlled oxygen, nebulisers, prednisolone 30 mg for 5 days, antibiotics if purulent sputum.
• CAP: CURB-65 plus judgement; antibiotics within 4 hours (1 hour if septic); 5-day courses.
• Tension pneumothorax is a clinical diagnosis — decompress without waiting for an X-ray.
• BTS 2023: minimally symptomatic primary pneumothorax can be managed conservatively, whatever its size.
• Drain pleural infection if there is pus, organisms, or pH below 7.2.
• PE: Wells score, then CTPA or D-dimer; DOAC for most; thrombolysis if shocked.
• Anaphylaxis: IM adrenaline 500 micrograms, repeat at 5 minutes. Antihistamines and steroids are not first-line.
• Stridor: sit up, call anaesthetics and ENT, nebulised adrenaline and dexamethasone.
• Laryngectomy patients can only be oxygenated through the neck stoma.
• Neuromuscular weakness: measure FVC — saturations stay normal until the end.
• CO poisoning gives falsely normal SpO2 — measure carboxyhaemoglobin.

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8.29 Guidelines and Further Reading

• BTS Guideline for oxygen use in healthcare and emergency settings
• BTS/ICS Guideline for the ventilatory management of acute hypercapnic respiratory failure in adults
• BTS/NICE/SIGN: Management of acute asthma in adults in hospital
• NICE NG115: COPD in over 16s and NICE NG114: COPD (acute exacerbation) — antimicrobial prescribing
• NICE NG250: Pneumonia — diagnosis and management
• BTS Guideline for pleural disease (2023)
• NICE NG158: Venous thromboembolic diseases
• Resuscitation Council UK: Emergency treatment of anaphylaxis (2021); choking algorithm
• NICE CG134: Anaphylaxis — assessment and referral after emergency treatment
• National Tracheostomy Safety Project: Emergency tracheostomy and laryngectomy algorithms
• Difficult Airway Society: Guidelines for management of neck haematoma after thyroid surgery
• British Society for Haematology: Management of acute chest syndrome in sickle cell disease
• TOXBASE and the National Poisons Information Service
• BNF — for current doses

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8.30 Respiratory Arrest and Ventilatory Collapse

Signs: absent or ineffective respirations, severe bradypnoea, unresponsiveness or loss of airway protection. In asthma/COPD, falling respiratory rate with fatigue may precede arrest.

• Act: call resuscitation team, assess pulse, open/protect airway, provide bag-mask ventilation with oxygen by trained responders and follow adult life-support protocols.
• Causes: CNS depressants/opioids, severe obstruction, neuromuscular disease, severe hypercapnia, seizures or arrest due to systemic illness.
• Specific reversal: naloxone for suspected opioid-induced respiratory depression according to local practice without delaying airway support.

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8.31 Emergency Pleural Procedures and Safety

• Pleural aspiration: use ultrasound and appropriate consent, monitoring, asepsis and operator training; assess bleeding risk and anticoagulants.
• Intercostal drain: confirm site with imaging/ultrasound when not an immediate emergency; use the safe triangle and local procedural standards; secure, connect and document output.
• Complications: bleeding, organ injury, infection, re-expansion pulmonary oedema, dislodgement and persistent air leak.
• Escalation: suspected tension pneumothorax is an exception: do not wait for imaging before emergency decompression.

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8.32 Discharge Safety after an Acute Respiratory Admission

• Clinical stability: improving work of breathing, safe oxygenation with documented plan, stable vital signs, oral intake and capacity for medicines/support.
• Medicines: document indication, dose and duration of antimicrobials/steroids; review inhalers, technique and interactions.
• Continuity: oxygen and NIV arrangements, pulmonary rehab when indicated, smoking cessation, written asthma/COPD plans, review and cancer safety-netting.
• Patient-centred: discuss advance planning or escalation where appropriate, especially for recurrent advanced lung disease.

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9.01 Bronchiolitis in Infants

Cause: usually RSV, producing small-airway oedema, mucus and obstruction in infants; symptoms peak around days 3–5.

• Presentation: preceding coryza, cough, tachypnoea, recession, crackles/wheeze and reduced feeding; very young infants may have apnoea.
• Diagnosis: clinical. Routine chest X-ray, blood testing, antibiotics, bronchodilators and corticosteroids are not indicated for uncomplicated bronchiolitis.
• Management: supportive care, feeding/hydration assessment, nasal suction when appropriate and supplemental oxygen according to age, comorbidity and local NICE NG9 thresholds.
• Red flags: apnoea, cyanosis, exhaustion, severe recession, dehydration or deteriorating oxygenation require urgent hospital assessment.

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9.02 Upper Respiratory Tract Infection and Acute Bronchitis

Acute bronchitis is usually viral and resolves without antibiotics; cough may persist for several weeks. URTI includes rhinitis, pharyngitis, laryngitis and influenza-like illness.

• Assess: duration, fever, focal chest signs, hypoxaemia, immunosuppression and systemic illness; distinguish pneumonia when there are focal findings or concerning physiological observations.
• Treatment: fluids, symptom relief, smoking advice and safety-netting. Do not use antibiotics routinely for uncomplicated viral infection; apply NICE antimicrobial guidance when bacterial infection is suspected.
• Escalate: suspected pneumonia, respiratory distress, dehydration, stridor or significant comorbidity.

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9.03 Croup, Epiglottitis and Paediatric Stridor

• Croup: viral laryngotracheitis in young children with barking cough, hoarse voice and inspiratory stridor; oral dexamethasone is standard treatment, with nebulised adrenaline for severe disease in monitored settings.
• Epiglottitis: severe toxicity, high fever, drooling, dysphagia and a child sitting forward; urgent anaesthetic/ENT assistance and controlled airway management take precedence over throat examination.
• Foreign body: abrupt choking or unilateral wheeze; apply age-appropriate choking/resuscitation algorithms and seek urgent specialist assessment where needed.

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9.04 Paediatric Asthma: Differences from Adult Pathways

Young children may have viral-induced wheeze without persistent asthma; objective testing becomes more useful from approximately age 5.

• Under 5: diagnosis largely clinical, monitored treatment trials, review response and competing diagnoses.
• Aged 5–11: use age-appropriate objective assessment and ICS-containing preventer strategies following NG245.
• Aged 12 and over: the adult/adolescent AIR/MART approach applies where indicated and licensed.
• Acute attack: age-specific BTS/SIGN guidance; prescribe bronchodilator doses and oxygen target according to paediatric protocol rather than copying adult doses.

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9.05 Recurrent Infection: Immunodeficiency and Structural Disease

Recurrent pneumonia in the same lobe suggests local obstruction or anatomical abnormality; infection in different lobes suggests systemic susceptibility, aspiration or bronchiectasis.

• History: childhood onset, sinopulmonary disease, fertility, chronic diarrhoea, family history, immunosuppressants, HIV and aspiration.
• Investigations: quantitative immunoglobulins, HIV testing with consent, sputum culture, CT chest for bronchiectasis, and sweat/genetic testing when CF or PCD is suspected.
• MRCP associations: hypogammaglobulinaemia, common variable immunodeficiency, primary ciliary dyskinesia (sometimes situs inversus) and CFTR-related disease.

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9.06 Respiratory Prevention and Vaccination

• Smoking cessation: the most effective intervention to slow COPD progression; use behavioural support and licensed cessation medicines after individual assessment.
• Vaccination: influenza, COVID-19, pneumococcal, RSV and pertussis schedules change; check current UKHSA Green Book and NHS eligibility by age, pregnancy and risk group rather than memorising a fixed list.
• Other prevention: reduce occupational exposures, optimise inhaler technique, pulmonary rehabilitation, hand hygiene, adequate nutrition, and contact management for TB or pertussis when indicated.

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10.01 Fast Differentials: Obstructive, Restrictive and Vascular

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10.02 Arterial Blood Gas Interpretation: Worked Patterns

Method: establish primary disturbance, check whether compensation is plausible, interpret oxygen in the context of FiO₂ and then look for mixed disorders. These values are illustrative, not diagnostic by themselves.

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10.03 Imaging Pattern Recognition for MRCP

• Lobar opacity + air bronchograms: consolidation.
• Unilateral white-out with mediastinum pushed away: large pleural effusion; pulled toward the opacity suggests collapse/volume loss.
• Apical cavity: reactivation TB, abscess, malignancy or fungus; microbiology and risk factors matter.
• Peripheral basal honeycombing: UIP pattern; IPF only after exclusions and multidisciplinary review.
• Upper lobe fibrosis + eggshell calcification: silicosis; bilateral hilar lymphadenopathy: sarcoidosis (differential includes lymphoma/TB).
• Mosaic attenuation / air trapping: small-airway disease, hypersensitivity pneumonitis or vascular disease depending on expiratory CT and perfusion.

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10.04 Selected Respiratory Drug and Dose Reference

Adult teaching examples only: check BNF, renal function, contraindications and current local protocols before prescribing.

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10.05 Common UKMLA and MRCP Traps

1. Normal PaCO₂ in severe asthma can signify impending respiratory failure.
2. Normal chest radiograph does not exclude PE, early infection or severe asthma.
3. Low FVC alone does not prove restriction; confirm with TLC.
4. D-dimer cannot confirm PE; apply a clinical pretest probability strategy.
5. Purulent sputum without systemic features does not automatically mean pneumonia.
6. IPF and UIP: a UIP CT pattern has other causes; exclude exposures and connective tissue disease.
7. Pneumothorax: symptoms/physiology, not radiographic size alone, determine appropriate management.
8. Oxygen should be titrated to a target rather than automatically maximised in known CO₂ retainers.
9. Thoracentesis: ultrasound guidance improves safety; pleural pH helps triage parapneumonic effusions.
10. Clubbing in COPD warrants an alternative diagnosis such as malignancy or bronchiectasis.

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10.06 Integrated Short Cases for MLA and MRCP

1. Young adult, sudden dyspnoea, unilateral absent breath sounds, shock: suspected tension pneumothorax; treat immediately without waiting for X-ray.
2. Older patient, confusion, RR 32, fever, new lobar infiltrate: assess pneumonia severity, oxygen, sepsis and antibiotic pathway; confusion may be the presenting feature.
3. COPD, pH 7.28, PaCO₂ 9 kPa despite controlled oxygen and bronchodilators: consider NIV if appropriate, check contraindications and escalation plan.
4. Wheeze, silent chest, exhausted, PaCO₂ 5.4 kPa: life-threatening asthma; urgent ICU/senior review.
5. Post-operative tachycardia, pleuritic pain, hypoxaemia: risk-stratify and investigate PE.
6. Subacute dry cough, clubbing, basal crackles, HRCT honeycombing: evaluate fibrotic ILD, exposures and CTD; discuss at ILD MDT.
7. Chronic cough with large volumes of purulent sputum and recurrent infections: evaluate bronchiectasis and its underlying cause.

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10.07 Sources and Guideline Checkpoints

Source articles: Seven user-supplied HTML files, including the complete Respiratory Emergencies chapter, form the principal text. Other presentations, paediatric and revision notes broaden MLA/MRCP coverage; a separate line-by-line clinical audit has not been performed.

• GMC MLA content map — current framework for UKMLA assessments from September 2026.
• BTS/NICE/SIGN NG245 — asthma diagnosis and long-term management; acute asthma uses separate BTS/SIGN pathways.
• BTS/SIGN acute adult asthma pathway.
• NICE NG115 — COPD; NICE NG250 — pneumonia.
• NICE NG158 — VTE/PE; BTS Pleural Disease 2023.
• BTS emergency oxygen guideline; NICE NG9 — bronchiolitis.

Clinical safety: Prescribing, oxygen/NIV protocols, anticoagulation, invasive procedures and cancer pathways are updated over time. This educational chapter is not a replacement for the current BNF, NHS trust protocols or senior clinical judgement.

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