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Obstructive sleep apnoea syndrome
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Exam Tips
- Differentiate OSA (sleep-study diagnosis) from OSAS/OSAHS (OSA plus clinically significant symptoms such as daytime sleepiness).
- High-yield triad in adults: loud snoring, witnessed apnoeas, daytime sleepiness; in children, think behavioural change/hyperactivity rather than sleepiness alone.
- Do not rely on Epworth score alone to rule out disease; combine history (including partner collateral) with objective sleep testing.
- Always ask about driving risk and document safety advice in symptomatic patients.
- Adenotonsillar hypertrophy is the classic paediatric cause; obesity is a major adult driver.
Definition
Obstructive sleep apnoea syndrome (OSAS, often termed OSAHS) is a sleep-related breathing disorder in which recurrent partial or complete upper-airway collapse during sleep causes hypopnoeas or apnoeas with sleep fragmentation and intermittent hypoxaemia. The syndrome implies clinically important consequences (for example excessive daytime sleepiness, fatigue, cognitive impairment, or safety risk), distinguishing it from asymptomatic obstructive sleep apnoea found on sleep studies.
Pathophysiology
During sleep, reduced pharyngeal dilator muscle tone allows a structurally vulnerable upper airway (for example from obesity, enlarged soft tissues, or craniofacial narrowing) to collapse repeatedly when negative inspiratory pressure exceeds airway stability. Each event causes airflow reduction/cessation, oxygen desaturation, hypercapnic tendency, and transient cortical arousal that restores tone but fragments sleep architecture. Repetition across the night drives sympathetic overactivity, oxidative stress, endothelial dysfunction, and non-dipping nocturnal blood pressure; this explains links with hypertension, arrhythmia, stroke risk, and daytime neurocognitive symptoms. In children, adenotonsillar hypertrophy is a dominant anatomical driver (see Figure: upper-airway collapse and arousal cycle in standard respiratory physiology texts).
Risk Factors
- Obesity (including central obesity) and increased neck circumference (>40.6 cm in adults)
- Increasing age
- Male sex (approximately 2-3:1 male: female in adults)
- Family history of OSA/OSAS
- Smoking and alcohol use
- Supine sleep position
- Craniofacial or upper-airway factors (retrognathia, micrognathia, macroglossia, narrow oropharynx, deviated septum)
- Adenotonsillar hypertrophy (especially in children aged about 2-8 years)
- Hypothyroidism, type 2 diabetes, polycystic ovary syndrome, acromegaly
- Down syndrome, neuromuscular disease (for example cerebral palsy), achondroplasia, Prader-Willi syndrome
- Cardiovascular/cerebrovascular disease (heart failure, atrial fibrillation, prior stroke/TIA) and moderate-severe asthma
Clinical Features
Symptoms
- Loud habitual snoring
- Witnessed apnoeas, nocturnal gasping or choking
- Excessive daytime sleepiness, fatigue, unrefreshing sleep
- Impaired concentration, memory difficulty, mood change/depressive symptoms
- Morning headache (often settles within hours)
- Nocturnal awakenings, nocturia, nocturnal reflux symptoms
- Driving sleepiness, near-misses or road traffic incidents
- In children: restless sleep, unusual sleep posture (neck extension), nocturnal enuresis, behavioural problems, hyperactivity, poor school performance, mouth breathing, rarely faltering growth
Signs
- Raised BMI/central adiposity
- Large neck circumference
- Hypertension (including possible non-dipping pattern)
- Craniofacial abnormalities (retrognathia/micrognathia)
- Upper-airway obstruction signs (adenotonsillar enlargement, nasal obstruction, mouth breathing, nasal speech)
- Signs of cardiopulmonary comorbidity (for example heart failure, pulmonary hypertension, COPD overlap)
Investigations
Clinical screening tools (STOP-Bang, Epworth Sleepiness Scale):Higher STOP-Bang score increases pre-test probability; Epworth may show daytime somnolence but normal score does not exclude OSAS
Overnight respiratory polygraphy (home or lab):Documents apnoea-hypopnoea index/oxygen desaturation events consistent with obstructive sleep-disordered breathing
Polysomnography (full sleep study, gold standard when diagnostic uncertainty/complexity):Recurrent obstructive events with sleep fragmentation and desaturation; helps phenotype severity and alternative sleep disorders
Overnight oximetry:Repetitive desaturation pattern supports sleep-disordered breathing but is less definitive than polygraphy/polysomnography
Targeted baseline tests (for differentials/comorbidity): TFTs, HbA1c/glucose, FBC/U&Es; ABG if hypoventilation suspected:May identify contributors such as hypothyroidism, metabolic disease, or daytime hypercapnia (suggesting overlap/obesity hypoventilation)
Management
Lifestyle Modifications
- Weight reduction and exercise; treat obesity as disease-modifying therapy
- Avoid alcohol (particularly evening intake) and sedative-hypnotics/opioids where possible
- Smoking cessation
- Sleep hygiene and regular sleep schedule
- Positional therapy for positional OSA (avoid supine sleep)
- Driving and occupational safety counselling; urgent specialist referral if sleepiness affects driving/work
Pharmacological Treatment
No routine drug therapy for primary airway collapse in OSAS
There is no first-line medication that reverses upper-airway collapse. Manage contributing conditions and avoid respiratory depressants (benzodiazepines, opioids, excess alcohol) where clinically feasible; residual sleepiness pharmacotherapy is specialist-led only.
Surgical / Interventional
- Adenotonsillectomy in children with adenotonsillar hypertrophy (often first-line and frequently curative in uncomplicated paediatric disease)
- Continuous positive airway pressure (CPAP) in symptomatic adults and selected children; mandibular advancement device as alternative in appropriate dentition/milder disease
- Selected upper-airway surgery (for example uvulopalatopharyngoplasty) in carefully chosen cases
- Maxillomandibular advancement in severe craniofacial structural disease
- Bariatric surgery in severe obesity when indicated by obesity pathway criteria
Complications
- Road traffic collisions and workplace accidents from impaired vigilance
- Systemic hypertension and non-dipping nocturnal blood pressure
- Cardiac arrhythmias (including atrial fibrillation)
- Stroke (incident and recurrent risk increases with severe untreated disease)
- Heart failure progression and possible pulmonary hypertension
- Type 2 diabetes/metabolic dysfunction association
- Depression and reduced quality of life
- In children: behavioural/cognitive impairment, poor educational performance, and rare faltering growth
Prognosis
Prognosis is generally good with effective treatment and adherence, with improvement in daytime alertness, quality of life, and functional outcomes. CPAP can produce modest blood-pressure reduction and may improve cardiovascular risk markers; in children, adenotonsillectomy resolves symptoms in most uncomplicated cases.
Sources & References
🏥BMJ Best Practice(1)
✅NICE Guidelines(1)
- Obstructive sleep apnoea syndrome[overview]
📖Textbook References(20)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 590)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1293)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 539)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 590)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 564)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 641)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1299)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1301, 1302)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1301)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1299, 1300)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1839)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 540, 541)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 539)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 539)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 539)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 549, 550)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 539)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 539)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 174, 175)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 697)[context]