10. Obstructive Sleep Apnoea

📄Definition

OSA is a disorder characterised by recurrent episodes of upper airway obstruction during sleep, causing intermittent hypoxia, fragmented sleep, and excessive daytime sleepiness.

🔬 Pathophysiology

🧠 Mnemonic: SNORE

  • Soft tissue collapse (pharyngeal muscles relax during sleep)

  • Narrowing of upper airway

  • Obstruction leads to apnoea (cessation) or hypopnoea (reduction)

  • Resulting in arousals + oxygen desaturation

  • Excessive daytime sleepiness due to poor restorative sleep

📋 Risk Factors

🧠 Mnemonic: THROAT FAT

  • Thyroid (hypothyroidism)

  • Heavy alcohol use

  • Retrognathia or craniofacial abnormalities

  • Obesity (most common)

  • Adult male

  • Tonsillar hypertrophy

  • Family history

  • Age >40

  • Tobacco smoking

📋Clinical Features

🧠 Mnemonic: STOPBANG
Used as a screening tool too:

  • Snoring (loud, disruptive)

  • Tiredness (daytime somnolence)

  • Observed apnoeas during sleep

  • Pressure (hypertension)

  • BMI >35

  • Age >50

  • Neck circumference >40 cm

  • Gender = Male

Other symptoms:

  • Morning headaches

  • Poor concentration

  • Irritability

  • Nocturia

🩺 Physical Examination Findings

  • Obesity (BMI >30)

  • Large neck circumference

  • Tonsillar hypertrophy

  • Crowded oropharynx (Mallampati grade)

  • Retrognathia

  • Signs of pulmonary hypertension (if severe)

🔍 Investigations

🧠 Mnemonic: SLEEP TEST

  • Screening: STOP-BANG or Epworth Sleepiness Scale

  • Limited channel home oximetry (initial test in many)

  • ECG – may show bradycardia, arrhythmias

  • Echo if pulmonary HTN suspected

  • Polysomnography (gold standard): records AHI (Apnoea-Hypopnoea Index)

  • TFTs – check for hypothyroidism

  • Especially screen for hypertension, diabetes

  • Sugar (HbA1c) – metabolic syndrome

  • Tests for other sleep disorders (if unclear)

🧾 Management

🧠 Mnemonic: CPAP REST

  • CPAP = 1st-line for moderate to severe OSA (AHI >15)

  • Positional therapy for supine-only OSA

  • Alcohol & sedative avoidance

  • Patient education on risks (e.g. driving, DVLA rules)

  • Referral to sleep/ENT specialist

  • Exercise & weight loss (essential)

  • Surgery (e.g. UPPP, tonsillectomy) if structural cause

  • Treat underlying (e.g. hypothyroidism, nasal obstruction)

⚠️ Complications

  • Daytime accidents (especially driving)

  • Cardiovascular: hypertension, MI, stroke, arrhythmias

  • Poor glucose control

  • Depression

  • Pulmonary hypertension / cor pulmonale

🧐 Differentials

🧠 Mnemonic: SNORES

  • Simple snoring

  • Narcolepsy

  • Obesity hypoventilation syndrome

  • Restless legs syndrome

  • Epilepsy (nocturnal)

  • Seizure or parasomnias

📌 PARA Revision Tips

  • Always check STOPBANG and Epworth Sleepiness Scale

  • CPAP is gold standard for moderate to severe OSA

  • Know DVLA rules – inform if excessive daytime sleepiness

  • Don’t forget screening for CV/metabolic risks

  • Polysomnography is diagnostic gold standard (AHI classification)

🔎 Last updated in line with NICE NG202 – OSA
Published: November 2021 • Last reviewed: July 2025
🔒 PASSMAP ensures all content is NICE-aligned and reviewed for Physician Associate Registration Assessment (PARA) success.

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