Acute Medicine: Acute chest pain, breathlessness, collapse and blood gases

🩺 Acute chest pain, breathlessness, collapse and blood gases. These are among the commonest reasons for acute admission. The task is to rule out the killers quickly -ACS, PE, aortic dissection, tension pneumothorax, life-threatening asthma, cardiac syncope -and then treat or discharge safely. Detailed disease management is in the Cardiology and Respiratory Emergencies chapters; this page covers the front-door approach.
Your four questions for every patient: Could this be immediately life-threatening? What does the ECG (and blood gas) show? Which risk score or test will safely rule a diagnosis in or out? Can this patient go home safely -with what follow-up?

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Approach to Acute Chest Pain

• ECG within 10 minutes of arrival for anyone with chest pain -look for STEMI, ischaemia, arrhythmia, right heart strain, pericarditis.
• Life-threatening causes to consider first:

  Cause	Clues	Key test
  Acute coronary syndrome	Central pressure-like pain radiating to arm, jaw or neck; sweating; risk factors; exertional	ECG, high-sensitivity troponin
  Pulmonary embolism	Pleuritic pain, breathlessness, haemoptysis, tachycardia, hypoxia, DVT, risk factors	Wells score, D-dimer, CTPA
  Aortic dissection	Sudden, severe, tearing pain radiating to the back; BP difference between arms; neurological signs	CT aortogram
  Tension pneumothorax	Sudden breathlessness, absent breath sounds, deviated trachea, shock	Clinical -decompress
  Oesophageal rupture	Pain after forceful vomiting, surgical emphysema	CT chest with oral contrast
  Cardiac tamponade	Hypotension, raised JVP, muffled heart sounds	Echo

• Other causes -pericarditis (sharp, pleuritic, eased by sitting forward; saddle-shaped ST elevation, PR depression), myocarditis, pneumonia, pneumothorax, musculoskeletal (reproducible tenderness -but don't rely on it), GORD and oesophageal spasm, biliary colic, peptic ulcer, pancreatitis, shingles (before the rash), anxiety (diagnosis of exclusion).
• Initial management -ABCDE, oxygen if hypoxic (not routinely), analgesia, IV access, bloods (FBC, U&E, troponin, clotting, lipids, glucose), chest X-ray.
• Atypical presentations -women, older people and people with diabetes may have breathlessness, nausea, fatigue or no pain with ACS.

Suspected Acute Coronary Syndrome

• STEMI (ST elevation in 2 contiguous leads, or new LBBB with typical symptoms, or posterior MI -ST depression V1–V3 with dominant R waves):
  • Primary PCI if it can be delivered within 120 minutes of when fibrinolysis could have been given (and symptoms within 12 hours); otherwise fibrinolysis.
  • Aspirin 300 mg, second antiplatelet per PCI centre protocol, analgesia (IV opioid with antiemetic), oxygen only if SpO₂ under 94%.
• NSTEMI and unstable angina -diagnosed by symptoms, ECG changes (ST depression, T wave inversion) and high-sensitivity troponin:
  • High-sensitivity troponin pathways -a single very low troponin on arrival (if symptoms began over 3 hours earlier), or 0 and 1–3 hour samples (per local assay) -rule in or rule out MI quickly.
  • A rise and/or fall in troponin above the 99th centile is needed for MI; raised troponin also occurs in PE, sepsis, myocarditis, heart failure, CKD, tachyarrhythmias, stroke and after cardioversion (type 2 MI and myocardial injury).
  • Treatment -aspirin 300 mg, fondaparinux (unless angiography soon), second antiplatelet per protocol, beta-blocker, GTN; risk-stratify with GRACE -angiography within 72 hours for intermediate or higher risk (see the Cardiology chapters).
• HEART score (History, ECG, Age, Risk factors, Troponin -0–10) -helps identify low-risk chest pain suitable for early discharge (0–3 low risk).
• Discharge after ACS ruled out -consider other causes; outpatient testing for stable angina if symptoms suggest it (CT coronary angiography -NICE CG95).

Suspected Pulmonary Embolism

• Features -breathlessness (sudden), pleuritic chest pain, haemoptysis, tachycardia, tachypnoea, hypoxia, syncope, signs of DVT; may be subtle or absent; collapse or shock (massive PE).
• Risk factors -recent surgery or immobility, active cancer, previous VTE, pregnancy and post-partum, oestrogens (COC, HRT), long-haul travel, obesity, thrombophilia.
• Two-level Wells score (NICE NG158):
  • Clinical signs of DVT (3), PE the most likely diagnosis (3), HR over 100 (1.5), immobilisation or surgery in the past 4 weeks (1.5), previous DVT or PE (1.5), haemoptysis (1), active cancer (1).
  • Over 4 -PE likely → CTPA (immediately, or give interim anticoagulation if delayed).
  • 4 or less -PE unlikely → D-dimer -if positive, CTPA; if negative, PE is excluded.
• PERC rule -in low-probability patients, PE can be excluded without a D-dimer if all 8 criteria are met (age under 50, HR under 100, SpO₂ 94% or more, no haemoptysis, no oestrogen, no previous VTE, no unilateral leg swelling, no recent surgery or trauma).
• CTPA contraindicated (contrast allergy, severe CKD, pregnancy in some) -V/Q scan.
• Other tests -ECG (sinus tachycardia commonest; S1Q3T3 and RV strain less common), chest X-ray (often normal; excludes other causes), troponin and BNP (risk), echo (RV dilatation in massive PE), leg Doppler.
• Treatment:
  • Anticoagulation -DOAC (apixaban or rivaroxaban) for most; LMWH in pregnancy and some cancers; at least 3 months (longer if unprovoked or ongoing risk).
  • Massive PE (hypotension, shock) -thrombolysis (alteplase) unless contraindicated; embolectomy otherwise.
  • Outpatient treatment for low-risk patients (PESI or sPESI low, Hestia criteria) -ambulatory pathways.

Aortic Dissection and Other Killers

• Aortic dissection:
  • Sudden severe chest or back pain ("tearing", maximal at onset), may move; syncope, stroke, limb ischaemia, abdominal pain (mesenteric), paraplegia, new aortic regurgitation murmur, BP difference over 20 mmHg between arms, pulse deficits.
  • Risk factors -hypertension, Marfan and other connective tissue disorders, bicuspid aortic valve, cocaine, pregnancy, recent cardiac procedures.
  • Easily missed -may mimic MI (dissection into the right coronary -inferior STEMI) -don't thrombolyse if dissection is possible.
  • CT aortogram (or transoesophageal echo if unstable); chest X-ray may show a widened mediastinum (often normal).
  • Type A (ascending) -emergency surgery; type B -BP control (IV labetalol, target systolic 100–120 mmHg, HR under 60) ± TEVAR (see the Vascular and Cardiothoracic Surgery pages).
• Oesophageal rupture (Boerhaave's) -severe chest pain after vomiting, surgical emphysema (Hamman's crunch), shock; CT; nil by mouth, antibiotics, surgery.
• Spontaneous pneumothorax -sudden pleuritic pain and breathlessness; chest X-ray; aspiration or drain if symptomatic or large; tension needs immediate decompression (see the Respiratory Emergencies chapter).
• Myocarditis -chest pain, breathlessness, arrhythmia after viral illness; raised troponin; cardiac MRI.

Approach to Acute Breathlessness

• ABCDE with oxygen to target, SpO₂, ABG, ECG, chest X-ray, bloods (FBC, U&E, CRP, BNP, D-dimer if appropriate, troponin).
• Causes by speed of onset:
  • Seconds to minutes -PE, pneumothorax, anaphylaxis, foreign body, acute pulmonary oedema (flash), arrhythmia.
  • Hours to days -asthma, COPD exacerbation, pneumonia, heart failure, pleural effusion, metabolic acidosis (DKA, sepsis, AKI -"air hunger" with Kussmaul breathing).
  • Weeks to months -anaemia, ILD, lung cancer, effusions, neuromuscular weakness, heart failure, obesity.
• Examination clues:
  • Wheeze -asthma, COPD, anaphylaxis, cardiac asthma.
  • Bilateral crackles -pulmonary oedema, ILD, bilateral pneumonia.
  • Focal crackles and bronchial breathing -pneumonia.
  • Dull, reduced breath sounds -effusion, collapse.
  • Hyper-resonant, absent breath sounds -pneumothorax.
  • Clear chest with hypoxia -PE, early pneumonia, shunt.
  • Clear chest, normal SpO₂, fast deep breathing -metabolic acidosis, anxiety (diagnosis of exclusion).
• Bedside ultrasound (if trained) -B-lines (oedema), effusion, pneumothorax, LV and RV function.
• Neuromuscular causes (Guillain–Barré, myasthenia, MND) -breathlessness with weakness; FVC (not SpO₂) tracks respiratory muscle failure -refer to critical care if FVC falling or under 20 mL/kg.

Acute Asthma

Severity (BTS/SIGN)	Features (adults)
Moderate	Increasing symptoms; PEF 50–75% of best or predicted; no features of acute severe asthma
Acute severe	Any of: PEF 33–50%; RR 25 or more; HR 110 or more; unable to complete sentences
Life-threatening	Any of: PEF under 33%; SpO2 under 92%; PaO2 under 8 kPa; normal PaCO2 (4.6–6.0 kPa -tiring); silent chest, cyanosis, poor respiratory effort; arrhythmia, hypotension; exhaustion, altered consciousness
Near-fatal	Raised PaCO2 and/or needing mechanical ventilation

• Treatment:
  • Oxygen to SpO₂ 94–98%.
  • Nebulised salbutamol 5 mg (oxygen-driven), repeat or back-to-back if severe.
  • Nebulised ipratropium 500 micrograms (acute severe or life-threatening).
  • Steroids -prednisolone 40–50 mg orally (or IV hydrocortisone 100 mg) for at least 5 days.
  • IV magnesium sulfate 2 g over 20 minutes (acute severe or life-threatening not responding).
  • IV aminophylline (senior advice), IV salbutamol (rarely).
  • Critical care for life-threatening or near-fatal features, deterioration, exhaustion or rising CO₂.
• Before discharge -PEF over 75% of best, inhaler technique, personal asthma action plan, steroid course, GP review within 2 working days.

COPD Exacerbation

• Features -worsening breathlessness, cough, sputum volume or purulence; triggers -viral or bacterial infection, pollution, non-adherence, heart failure, PE.
• Assess -SpO₂, ABG (hypercapnia, acidosis), chest X-ray (pneumonia, pneumothorax), ECG, bloods, sputum culture.
• Treatment:
  • Controlled oxygen -target 88–92% (Venturi mask 24–28%) in patients at risk of hypercapnia; recheck ABG after 30–60 minutes.
  • Nebulised bronchodilators -salbutamol and ipratropium (air-driven if hypercapnic, with nasal oxygen alongside).
  • Prednisolone 30 mg daily for 5 days.
  • Antibiotics if sputum is purulent or pneumonia (per local guidance -e.g. amoxicillin, doxycycline or clarithromycin).
  • NIV -for acute hypercapnic respiratory failure (pH under 7.35 and PaCO₂ over 6.5 kPa) persisting despite optimal medical treatment (BTS).
• Ceiling of care -discuss early whether intubation would be appropriate if NIV fails.
• Before discharge -inhaler technique, smoking cessation, pulmonary rehabilitation, rescue packs, vaccinations, follow-up.

Acute Heart Failure

• Features -breathlessness (orthopnoea, paroxysmal nocturnal dyspnoea), pink frothy sputum, bilateral crackles, wheeze ("cardiac asthma"), raised JVP, peripheral oedema, third heart sound, hypoxia.
• Precipitants -ACS, arrhythmias (AF), uncontrolled hypertension, infection, fluid overload, non-adherence, NSAIDs, valve disease, thyroid disease, anaemia.
• Tests -ECG, troponin, BNP or NT-proBNP (normal level makes heart failure unlikely), chest X-ray (cardiomegaly, upper lobe diversion, Kerley B lines, effusions, bat-wing shadowing), echo (within 48 hours of admission -NICE), U&E.
• Treatment (NICE CG187):
  • Sit up; oxygen if hypoxic.
  • IV furosemide (e.g. 40–80 mg; higher if already on diuretics); monitor urine output, weight, U&E.
  • CPAP for severe pulmonary oedema with hypoxia or acidosis.
  • Nitrates (IV GTN) for hypertension, ischaemia or severe mitral or aortic regurgitation -avoid if hypotensive.
  • Don't routinely give opioids.
  • Treat the cause -PCI for ACS, rate control for AF, BP control.
  • Cardiogenic shock -inotropes and critical care (see page 3).
• Continue or start disease-modifying drugs (ACE inhibitor/ARNI, beta-blocker, MRA, SGLT2 inhibitor) for reduced ejection fraction once stable; specialist heart failure team input.

Community-acquired Pneumonia

• Features -cough, fever, purulent sputum, pleuritic pain, breathlessness, focal chest signs; older people may present with confusion only.
• CURB-65 (in hospital -one point each):
  • Confusion (new -AMTS 8 or less).
  • Urea over 7 mmol/L.
  • Respiratory rate 30 or more.
  • Blood pressure -systolic under 90 or diastolic 60 or less.
  • Age 65 or more.
• Interpretation -0–1 low severity (consider home treatment); 2 moderate (hospital); 3–5 high severity (consider critical care if 4–5). Use alongside clinical judgement (CRB-65 in the community).
• Tests -chest X-ray, FBC, U&E, CRP; blood cultures, sputum culture, pneumococcal and Legionella urinary antigens (moderate to high severity); viral PCR (influenza, COVID-19, RSV) in season.
• Antibiotics (NICE NG138, local guidelines) -within 4 hours of diagnosis (1 hour if sepsis):
  • Low severity -amoxicillin (doxycycline or clarithromycin if allergic) for 5 days.
  • Moderate -amoxicillin ± clarithromycin (atypical cover).
  • High severity -co-amoxiclav plus clarithromycin (or local alternatives).
• Review -failure to improve: empyema, abscess, resistant organisms, wrong diagnosis (PE, cancer, heart failure); chest X-ray at 6 weeks for smokers and over-50s with persistent symptoms.

Interpreting Arterial Blood Gases

• Normal values (approximate):

  Measurement	Normal range
  pH	7.35–7.45
  PaO2	Over 10 kPa on room air (expected on oxygen is about FiO2% minus 10 kPa)
  PaCO2	4.7–6.0 kPa
  Bicarbonate (HCO3)	22–26 mmol/L
  Base excess	−2 to +2
  Lactate	Under 2 mmol/L

• A systematic approach:
  • How is the patient? -and what is the FiO₂?
  • Oxygenation -is the patient hypoxaemic (PaO₂ under 8 kPa = respiratory failure)?
  • pH -acidaemia (under 7.35) or alkalaemia (over 7.45)?
  • PaCO₂ -respiratory component (high CO₂ = respiratory acidosis; low = respiratory alkalosis).
  • Bicarbonate and base excess -metabolic component (low = metabolic acidosis; high = metabolic alkalosis).
  • Which is primary? -the one that matches the pH direction.
  • Compensation -is the other system moving to correct it (partial if pH still abnormal; full compensation rarely returns pH completely to normal)?
  • Anion gap in metabolic acidosis (see page 6); lactate, glucose, electrolytes.
• Venous blood gas -useful for pH, bicarbonate, lactate, potassium and glucose (not for oxygenation; venous CO₂ slightly higher).
• Mixed disorders are common (e.g. salicylate -respiratory alkalosis plus metabolic acidosis; COPD with diuretics -respiratory acidosis plus metabolic alkalosis).

Respiratory Failure

Type	Blood gas	Causes	Treatment
Type 1 (hypoxaemic)	PaO2 under 8 kPa, normal or low PaCO2	Pneumonia, pulmonary oedema, PE, ARDS, ILD, asthma (early)	Oxygen, CPAP or high-flow, treat cause
Type 2 (hypercapnic)	PaO2 under 8 kPa, PaCO2 over 6 kPa	COPD, obesity hypoventilation, neuromuscular disease, chest wall deformity, sedative or opioid overdose, exhaustion (severe asthma)	Controlled oxygen, NIV, reverse drugs, intubation if appropriate

• Acute vs chronic type 2:
  • Acute -high PaCO₂ with low pH (no time to compensate).
  • Chronic (compensated) -high PaCO₂, normal pH, high bicarbonate (kidneys retain bicarbonate over days).
  • Acute-on-chronic -high PaCO₂, high bicarbonate, but low pH -needs NIV.
• Oxygen-induced hypercapnia -in at-risk patients, excess oxygen worsens CO₂ retention (V/Q mismatch, Haldane effect) -target 88–92%; don't stop oxygen abruptly (rebound hypoxaemia).
• Signs of hypercapnia -drowsiness, confusion, headache, bounding pulse, warm peripheries, flapping tremor (asterixis).

Oxygen, CPAP, High-flow and NIV

Support	How it works	Main uses
Controlled oxygen (Venturi)	Fixed FiO2 (24–60%)	COPD, risk of hypercapnia
High-flow nasal oxygen	Heated, humidified oxygen up to 60 L/min -precise FiO2, small PEEP effect, flushes dead space	Type 1 respiratory failure (pneumonia), post-extubation, palliative breathlessness
CPAP (continuous positive airway pressure)	Constant pressure keeps alveoli open -improves oxygenation	Type 1 failure -acute pulmonary oedema, pneumonia (including COVID-19), obstructive sleep apnoea
NIV / BiPAP (bilevel)	Higher inspiratory pressure (IPAP) plus expiratory pressure (EPAP) -improves ventilation (removes CO2)	Type 2 failure -COPD exacerbation (pH under 7.35, PaCO2 over 6.5), obesity hypoventilation, neuromuscular disease, chest wall disease
Invasive ventilation	Intubation and mechanical ventilation in ICU	Failure of NIV, reduced consciousness, inability to protect airway, severe hypoxia

• NIV contraindications (relative) -untreated pneumothorax, facial trauma or burns, vomiting, inability to protect the airway, copious secretions, recent upper GI surgery, severe hypoxaemia, haemodynamic instability.
• NIV needs a plan -escalation decision (is the patient for intubation if NIV fails?), ABG at 1–2 hours (improvement in pH and PaCO₂), monitoring in an appropriate area.
• Signs NIV is failing -worsening pH or PaCO₂, falling consciousness, exhaustion.

Transient Loss of Consciousness

• Transient loss of consciousness (TLoC) -usually syncope (reflex, orthostatic or cardiac), epileptic seizure, or psychogenic non-epileptic seizure (see the Older Person chapter on Falls and the Neurology and Cardiology chapters).
• Initial assessment (NICE CG109) -detailed history (before, during, after; witness account), examination (including lying and standing BP, heart murmurs, neurology), 12-lead ECG for everyone.
• Features suggesting syncope -triggers (standing, pain, heat, micturition), prodrome (light-headed, sweating, nausea, visual greying), brief loss, rapid recovery (some brief jerks are common -convulsive syncope).
• Features suggesting a seizure -tongue bitten (especially the side), head turning to one side, unusual posturing, prolonged jerking, prolonged confusion afterwards, déjà vu or aura, cyanosis.
• Red flags -urgent cardiac assessment (within 24 hours):
  • ECG abnormality -conduction disease (heart block, bifascicular block), long QT, Brugada pattern, WPW, ventricular arrhythmia, LVH (HCM), ischaemia.
  • Heart failure or structural heart disease (murmur).
  • TLoC during exertion or while lying down.
  • Family history of sudden cardiac death under 40.
  • New or unexplained breathlessness; palpitations before collapse.
  • Age over 65 with TLoC without prodrome.
• Uncomplicated reflex syncope -explain, reassure, avoid triggers, counter-pressure manoeuvres; no driving restriction for simple faints while standing (DVLA).
• Orthostatic hypotension -drug review, fluids (see the Older Person chapter).
• Driving -give DVLA advice for all TLoC presentations.

Palpitations

• Assess -ABCDE; are there adverse features (shock, syncope, ischaemia, heart failure)? -see page 2.
• ECG during symptoms is key -sinus tachycardia, AF, flutter, SVT, ectopics, VT.
• History -onset and offset (sudden -re-entry SVT; gradual -sinus), rate, regularity (tap it out), triggers (caffeine, alcohol, stimulants, exercise), associated symptoms (syncope, chest pain), drugs, thyroid symptoms, family history.
• Bloods -FBC (anaemia), U&E, magnesium, calcium, TFTs, glucose, troponin if ischaemic symptoms.
• Common causes -ectopic beats (benign), sinus tachycardia (anxiety, anaemia, thyrotoxicosis, fever, dehydration, PE, pregnancy), AF, SVT.
• New AF -rate control, anticoagulation (CHA₂DS₂-VASc), look for triggers (sepsis, thyroid, alcohol, PE); cardioversion if onset under 48 hours or unstable.
• Red flags -syncope, exertional symptoms, family history of sudden death, structural heart disease, broad complex tachycardia, pre-excitation (WPW) -cardiology referral.
• Outpatient monitoring -ambulatory ECG (24-hour to 7-day), event recorders, implantable loop recorder (infrequent symptoms).

Chest Pain, Breathlessness and Collapse at a Glance

Problem	Key test or score	Key action
Chest pain	ECG within 10 minutes; hs-troponin pathway	Rule out ACS, PE, dissection
STEMI	ST elevation, new LBBB, posterior changes	Primary PCI within 120 minutes
PE likely	Wells over 4	CTPA (interim anticoagulation)
PE unlikely	Wells 4 or less	D-dimer; CTPA if positive
Aortic dissection	Tearing pain, arm BP difference	CT aortogram; no thrombolysis
Acute severe asthma	PEF 33–50%, RR 25+, HR 110+, can't finish sentences	Salbutamol, ipratropium, prednisolone, magnesium
Life-threatening asthma	PEF under 33%, SpO2 under 92%, normal CO2, silent chest	Critical care
COPD with acidosis	pH under 7.35, PaCO2 over 6.5	NIV; target 88–92%
Pulmonary oedema	BNP, chest X-ray, echo	IV furosemide, CPAP, nitrates
Pneumonia	CURB-65	0–1 home; 2 hospital; 3+ consider critical care
Syncope red flags	Abnormal ECG, exertional, family history, heart disease	Cardiology within 24 hours

Spot the Diagnosis

Clue	Diagnosis
Sharp chest pain better leaning forward with widespread saddle ST elevation	Pericarditis
ST depression V1–V3 with tall R waves and chest pain	Posterior MI
Troponin rise in a patient with sepsis and fast AF, no chest pain	Type 2 MI / myocardial injury
Pleuritic pain, HR 110 and SpO2 91% with a clear chest X-ray after knee surgery	PE -CTPA
Tearing pain to the back with a 30 mmHg arm BP difference	Aortic dissection
Inferior STEMI with a new early diastolic murmur and back pain	Dissection involving the right coronary -no thrombolysis
Chest pain and surgical emphysema after forceful vomiting	Boerhaave's syndrome
Asthma with PaCO2 5.4 kPa, PEF 28% and quiet chest	Life-threatening asthma
pH 7.28, PaCO2 8.9, HCO3 32 in COPD	Acute-on-chronic type 2 respiratory failure -NIV
pH 7.40, PaCO2 7.2, HCO3 33 in stable COPD	Compensated chronic respiratory acidosis
pH 7.50, PaCO2 3.2, PaO2 9 in a breathless young woman	Respiratory alkalosis -consider PE (not just anxiety)
Fast deep breathing with clear chest, normal SpO2, glucose 28	DKA -Kussmaul breathing
Pink frothy sputum, bilateral crackles and BNP 4,000	Acute pulmonary oedema
CURB-65 score of 4	High-severity pneumonia -consider critical care
Collapse during exercise with an ejection systolic murmur	Aortic stenosis or HCM -urgent cardiology
Collapse after standing in a hot queue with prodrome and quick recovery	Vasovagal syncope
Collapse with a bitten lateral tongue and 20 minutes of confusion	Epileptic seizure
Sudden-onset regular palpitations at 180 that stop suddenly	Re-entry SVT

Exam-style Scenarios

1. A 58-year-old man has 40 minutes of central crushing chest pain radiating to his jaw. ECG shows 3 mm ST elevation in II, III and aVF.
Answer: Inferior STEMI.

• Aspirin 300 mg, analgesia with antiemetic, oxygen only if hypoxic; activate the primary PCI pathway; antiplatelet per cath lab protocol.
• Right-sided leads (V4R -RV infarction -avoid nitrates, give fluids if hypotensive); watch for bradycardia and heart block (atropine, pacing).
• Check for features of aortic dissection before antithrombotic escalation if the story is atypical.

2. A 35-year-old woman on the combined pill has 2 days of pleuritic chest pain and breathlessness. HR 108, SpO₂ 94%, no leg swelling. Chest X-ray is normal.
Answer: Suspected PE.

• Two-level Wells -PE most likely diagnosis (3) + HR over 100 (1.5) = 4.5 -PE likely → CTPA.
• Start interim anticoagulation (e.g. apixaban or LMWH) if CTPA is delayed and no contraindication.
• If confirmed -DOAC for at least 3 months; stop the combined pill (alternative contraception); assess for outpatient management (sPESI 0).

3. A 23-year-old with asthma is breathless and can say only a few words. RR 30, HR 120, SpO₂ 93%, PEF 35% of best. ABG: PaO₂ 9.1 kPa, PaCO₂ 4.2 kPa.
Answer: Acute severe asthma.

• Oxygen to 94–98%; back-to-back salbutamol 5 mg nebs (oxygen-driven) plus ipratropium 500 micrograms; prednisolone 40–50 mg.
• If not improving -IV magnesium 2 g; senior and critical care involvement; repeat ABG (a rising or normal CO₂ means tiring -life-threatening).
• Before discharge -PEF over 75%, steroid course, inhaler technique, asthma action plan, follow-up.

4. A 72-year-old woman with COPD is drowsy and breathless. On 4 L/min oxygen: SpO₂ 96%, pH 7.26, PaCO₂ 9.4 kPa, PaO₂ 10.2 kPa, HCO₃ 31.
Answer: Acute-on-chronic hypercapnic (type 2) respiratory failure.

• Reduce oxygen to target 88–92% (Venturi 24–28%); nebulised bronchodilators (air-driven), prednisolone 30 mg, antibiotics if purulent sputum or pneumonia.
• NIV (pH under 7.35, PaCO₂ over 6.5 despite treatment) -agree a ceiling of care (intubation if NIV fails?).
• Repeat ABG at 1–2 hours; look for triggers (pneumonia, pneumothorax on chest X-ray, PE, heart failure).

5. A 68-year-old man collapsed without warning while sitting watching TV and recovered within a minute. ECG shows sinus rhythm with right bundle branch block and left axis deviation (bifascicular block).
Answer: Syncope with red flags -possible intermittent complete heart block.

• Urgent cardiology assessment (within 24 hours) -admit for cardiac monitoring; echo.
• Likely pacemaker if bradyarrhythmia confirmed (or loop recorder).
• Advise not to drive until assessed (DVLA); check medications (rate-limiting drugs).

Key Points

• Chest pain -ECG within 10 minutes; think ACS, PE, dissection, tension pneumothorax, oesophageal rupture, tamponade.
• STEMI -primary PCI within 120 minutes; posterior MI shows ST depression in V1–V3.
• High-sensitivity troponin pathways rule MI in or out quickly; troponin rises for many non-ACS reasons.
• PE -Wells over 4 → CTPA; 4 or less → D-dimer; PERC in low-risk patients.
• Aortic dissection -tearing pain to the back, arm BP difference -don't thrombolyse; CT aortogram.
• Breathlessness with a clear chest and hypoxia -think PE.
• Life-threatening asthma -PEF under 33%, SpO₂ under 92%, normal or rising CO₂, silent chest.
• COPD -target 88–92%; NIV for pH under 7.35 and PaCO₂ over 6.5 despite treatment.
• Acute pulmonary oedema -sit up, IV furosemide, CPAP, nitrates if BP allows; find the cause.
• CURB-65 -0–1 home, 2 hospital, 3 or more severe.
• ABG -oxygenation, pH, CO₂, bicarbonate, primary disorder, compensation.
• Type 1 failure -low O₂, normal or low CO₂; type 2 -low O₂, high CO₂.
• CPAP improves oxygenation (pulmonary oedema); NIV improves ventilation (COPD); untreated pneumothorax contraindicates NIV.
• Syncope -ECG for all; red flags (abnormal ECG, exertional, lying down, family history, heart disease) need cardiology within 24 hours.

Guidelines and Further Reading

• NICE CG95: Recent-onset chest pain of suspected cardiac origin
• NICE NG185: Acute coronary syndromes; ESC: Guidelines for the management of acute coronary syndromes (2023)
• NICE NG158: Venous thromboembolic diseases -diagnosis, management and thrombophilia testing
• BTS/SIGN 158: British guideline on the management of asthma (and BTS/NICE/SIGN joint asthma guideline 2024)
• NICE NG115: COPD in over 16s; BTS: Guideline for acute hypercapnic respiratory failure (NIV)
• NICE CG187: Acute heart failure
• NICE NG138: Pneumonia (community-acquired) -antimicrobial prescribing; BTS: Community-acquired pneumonia guidelines
• NICE CG109: Transient loss of consciousness in over 16s
• BTS: Guideline for oxygen use in adults in healthcare and emergency settings
• BNF -for current doses