Respiratory: Sleep and Breathing (Complete)

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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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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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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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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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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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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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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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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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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Drug Reference Table

Drug / use	Key points
Apixaban VTE treatment	10 mg twice daily for 7 days, then 5 mg twice daily; after 6 months, 2.5 mg twice daily can be used for extended prevention.
Rivaroxaban VTE treatment	15 mg twice daily for 21 days, then 20 mg daily with food; 10 mg daily option for extended prevention.
Warfarin	INR 2–3; preferred in antiphospholipid syndrome.
LMWH	Pregnancy; some cancer-associated VTE; severe renal impairment (adjusted).
Riociguat	Inoperable or residual CTEPH, and PAH (specialist); not with PDE5 inhibitors or nitrates.
Endothelin receptor antagonists (ambrisentan, bosentan, macitentan)	PAH (specialist); teratogenic - pregnancy prevention; bosentan needs LFT monitoring; anaemia, oedema.
PDE5 inhibitors (sildenafil, tadalafil)	PAH (specialist); never with nitrates.
Prostacyclin pathway (selexipag, iloprost, epoprostenol, treprostinil)	PAH (specialist); IV epoprostenol for severe disease - line infections, rebound if interrupted.
CPAP	Moderate or severe OSA, or mild OSA with symptoms (NICE NG202).
Home NIV	Obesity hypoventilation, neuromuscular and chest wall disease, persistent hypercapnia after COPD admission.
Modafinil / pitolisant / sodium oxybate	Narcolepsy (specialist).
Acetazolamide	Prevention of acute mountain sickness; tingling, frequent urination; avoid in sulfonamide allergy (caution).
Dexamethasone	High altitude cerebral oedema (with descent and oxygen).
Nifedipine	High altitude pulmonary oedema treatment and prevention.

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Spot the Diagnosis

Clue	Diagnosis
Still breathless 6 months after PE, mismatched defects on V/Q scan	CTEPH
Young woman, exertional syncope, loud P2, right axis deviation, normal lungs	Idiopathic pulmonary arterial hypertension
Limited systemic sclerosis, anticentromere antibodies, falling TLCO	Systemic sclerosis-associated PAH
Recurrent nosebleeds, lip telangiectasia, brain abscess, low SpO2	Pulmonary AVM (HHT)
Cirrhosis, breathless and desaturating when sitting up	Hepatopulmonary syndrome
Lorry driver, snoring, falls asleep at traffic lights, AHI 42	Severe OSA - must not drive; inform DVLA
BMI 46, PaCO2 7.8 kPa awake, bicarbonate 34, leg oedema	Obesity hypoventilation syndrome
MND, morning headaches, orthopnoea, FVC 45%	Respiratory muscle weakness - NIV
Heart failure with EF 30%, waxing and waning breathing at night	Cheyne–Stokes central sleep apnoea
Falls asleep suddenly, collapses when laughing	Narcolepsy with cataplexy
Trekker at 4,000 m, breathless at rest, crackles, cyanosed	High altitude pulmonary oedema
Trekker at 4,500 m, confused and ataxic	High altitude cerebral oedema

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Exam-style Scenarios

1. 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.

2. 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.

3. 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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Key Points

• 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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Guidelines and Further Reading

• 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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