Phys · respiratory
Obstructive Sleep Apnoea
Also known as obstructive sleep apnoea · sleep apnea · OSA · OSAHS · sleep-disordered breathing · apnoea-hypopnoea index · AHI · CPAP · Epworth Sleepiness Scale · hypoglossal nerve stimulation · mandibular advancement splint · STOP-BANG · upper airway resistance syndrome
Consultant-physician-depth guide to obstructive sleep apnoea (OSA) — pathophysiology of upper airway collapse, clinical features and Epworth Sleepiness Scale, cardiometabolic associations, diagnosis by polysomnography with AHI severity grading, STOP-BANG screening, and the full management ladder (lifestyle, CPAP, oral appliances, hypoglossal nerve stimulation, bariatric surgery) — structured for FRACP DWE and DCE preparation.
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Target exams
Red flags
- Excessive daytime sleepiness in a commercial driver or safety-critical worker — mandatory fitness-to-drive assessment and reporting
- Severe OSA with nocturnal desaturation, pulmonary hypertension, or cor pulmonale — untreated disease carries a significant cardiovascular and mortality risk
- Resistant hypertension with a non-dipping nocturnal blood pressure pattern — screen for OSA, which is present in up to 80 percent of such patients
- New or worsening atrial fibrillation, especially with obesity — untreated OSA promotes recurrence after cardioversion or ablation
- Morbid obesity with daytime hypercapnia and somnolence — overlap syndrome of OSA and obesity hypoventilation syndrome needs bilevel support, not CPAP alone
Obstructive Sleep Apnoea
The answer first
Obstructive sleep apnoea (OSA) is a chronic sleep-related breathing disorder characterised by repetitive collapse of the upper airway during sleep, producing intermittent hypoxia, recurrent arousals, and fragmented sleep. It is among the commonest chronic diseases a physician will encounter, and its burden is dominated by two consequences: excessive daytime sleepiness with impaired cognition and a markedly elevated motor vehicle accident risk, and a cluster of cardiometabolic associations — resistant hypertension, atrial fibrillation, heart failure, type 2 diabetes, and stroke. [1]
Three facts must land before everything else: [1]
- Diagnosis rests on polysomnography and the apnoea-hypopnoea index (AHI). An AHI of 5 to 15 is mild, 15 to 30 moderate, and over 30 severe. The AHI is the single number that determines severity, drives the treatment decision, and is the most commonly tested fact in written exams. [1]
- CPAP is first-line for moderate-to-severe OSA and is highly effective for symptoms, blood pressure, and quality of life — but adherence is the central challenge, and CPAP has not been shown to prevent hard cardiovascular events in patients who already have established cardiovascular disease (the SAVE trial) [5].
- Driving is a medico-legal obligation. In Australia, a physician who diagnoses clinically significant excessive daytime sleepiness in a driver has a duty to counsel the patient and, if the patient continues to drive, to report to the licensing authority. This is a high-yield ethics and communication point that candidates consistently under-weight.
References7ShowHide
- [1]Johns MW A new method for measuring daytime sleepiness: the Epworth sleepiness scale Sleep, 1991.PMID 1798888
- [2]Peppard PE, Young T, Barnet JH, Palta M, Hagen EW, Hla KM Increased prevalence of sleep-disordered breathing in adults Am J Epidemiol, 2013.PMID 23589584
- [3]Yaggi HK, Concato J, Kernan WN, Lichtman JH, Brass LM, Mohsenin V Obstructive sleep apnea as a risk factor for stroke and death N Engl J Med, 2005.PMID 16282178
- [4]Marin JM, Carrizo SJ, Vicente E, Agusti AG Long-term cardiovascular outcomes in men with obstructive sleep apnoea-hypopnoea with or without treatment with continuous positive airway pressure: an observational study Lancet, 2005.PMID 15781100
- [5]McEvoy RD, Antic NA, Heeley E, et al. CPAP for Prevention of Cardiovascular Events in Obstructive Sleep Apnea N Engl J Med, 2016.PMID 27571048
- [6]Strollo PJ Jr, Soose RJ, Maurer JT, et al. Upper-airway stimulation for obstructive sleep apnea N Engl J Med, 2014.PMID 24401051
- [7]Chung F, Yegneswaran B, Liao P, et al. STOP questionnaire: a tool to screen patients for obstructive sleep apnea Anesthesiology, 2008.PMID 18431116