Obstructive Sleep Apnea

Obstructive sleep apnoea (OSA) is recurrent partial (hypopnoea) or complete (apnoea) collapse of the upper airway during sleep, with intermittent hypoxia and sleep fragmentation.

Prevalence 10 to 30% of adults for AHI 5 or more, 6 to 17% with symptoms; higher in men, with age, obesity, and after menopause.

Severity by apnoea hypopnoea index (AHI): mild 5 to 15, moderate 15 to 30, severe over 30 events per hour.

Risk factors: obesity, male sex, age, neck circumference over 40 cm, craniofacial abnormalities, tonsillar hypertrophy, nasal obstruction, hypothyroidism, acromegaly, alcohol, sedatives, smoking, family history.

Consequences: daytime sleepiness, motor vehicle accidents, resistant hypertension, atrial fibrillation, heart failure, stroke, coronary disease, pulmonary hypertension, insulin resistance, mood disorders, nocturnal arrhythmia.

• Loud snoring, witnessed apnoeas, gasping or choking, nocturia, morning headache, unrefreshing sleep, excessive daytime sleepiness (Epworth score over 10), impaired concentration, irritability, erectile dysfunction.
• Examination: BMI, neck circumference, Mallampati score, retrognathia, large tonsils, hypertension.
• Children: hyperactivity, poor school performance, enuresis, adenotonsillar hypertrophy.

• Screening questionnaires: STOP BANG (3 or more suggests risk), Epworth Sleepiness Scale.
• Type 1 polysomnography in a sleep laboratory or home sleep apnoea test (type III) for uncomplicated suspected moderate to severe OSA; polysomnography for significant comorbidity (heart failure, COPD, neuromuscular disease, hypoventilation).
• AHI and oxygen desaturation index, nadir saturation, arousal index.
• Further evaluation: awake blood gas if hypoventilation suspected, TSH, haemoglobin, upper airway examination (nasal endoscopy), drug induced sleep endoscopy for surgical planning.

• Lifestyle: weight loss (10% reduces AHI by about 26%), avoidance of alcohol and sedatives before bed, lateral sleeping position, smoking cessation, treat nasal obstruction.
• CPAP is first line for moderate to severe OSA and symptomatic mild OSA: auto titrating pressures 4 to 20 cmH2O, humidification, mask fitting, adherence monitoring (4 hours or more on 70% of nights). Improves sleepiness, blood pressure (2 to 3 mmHg), quality of life.
• Mandibular advancement devices for mild to moderate OSA or CPAP intolerance (custom made).
• Surgical options: tonsillectomy/adenotonsillectomy in children (first line), nasal surgery, uvulopalatopharyngoplasty, maxillomandibular advancement (success about 85%), hypoglossal nerve stimulation (BMI under 35, AHI 15 to 65, no complete concentric collapse).
• Pharmacotherapy: tirzepatide 10 to 15 mg weekly for OSA with obesity (reduces AHI 50 to 60%); solriamfetol 75 to 150 mg or modafinil 200 to 400 mg for residual sleepiness; pitolisant; combined aroxybutynin/atomoxetine under investigation. Acetazolamide 250 mg for central component.
• Bariatric surgery for BMI over 35 with OSA.
• Driving advice: do not drive when drowsy; occupational reporting as required by law until controlled.
• Perioperative precautions; manage hypertension (spironolactone useful in resistant hypertension with OSA).
• Follow up at 4 to 12 weeks after starting CPAP and annually.