Obstructive Sleep Apnoea
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Direct answer
Obstructive sleep apnoea (OSA) is repeated collapse of the pharyngeal airway during sleep, producing apnoeas and hypopnoeas that fragment sleep and drop oxygen saturation. The patient, usually middle-aged and overweight, snores loudly, has witnessed pauses in breathing and falls asleep easily by day. Diagnosis is confirmed by polysomnography, graded by the apnoea-hypopnoea index, and treated first with weight loss and continuous positive airway pressure (CPAP), with surgery reserved for selected anatomical obstruction.
What you must remember
- Mechanism: during sleep the pharyngeal dilator muscles relax, and a narrowed airway — from obesity, macroglossia, large tonsils and adenoids, retrognathia or nasal obstruction — collapses repeatedly.
- Clinical features: loud habitual snoring, witnessed apnoeic pauses, restless sleep, excessive daytime sleepiness, morning headache and dry mouth, irritability and poor concentration; the Epworth sleepiness scale quantifies sleepiness.
- Examination: body mass index and neck circumference, nasal patency, tonsil size, tongue position and any retrognathia; in children, adenotonsillar hypertrophy dominates the picture.
- Diagnosis: polysomnography (sleep study) records sleep stages, airflow, respiratory effort, oxygen saturation and heart rate; an apnoea-hypopnoea index above five events per hour with symptoms defines the disease, graded as mild, moderate or severe.
- Consequences of untreated OSA: systemic hypertension, increased cardiovascular and cerebrovascular risk, type 2 diabetes association, daytime accidents and reduced quality of life.
- Management ladder: weight reduction, alcohol and sedative avoidance, positional therapy; CPAP as the gold standard for moderate to severe disease; mandibular advancement appliances for mild cases with dental fit; and surgical options — adenotonsillectomy in children, septoplasty or other nasal surgery to aid therapy, uvulopalatopharyngoplasty in selected adults, and tracheostomy as the definitive bypass in extreme cases.
- Follow-up: symptom review, adherence to CPAP and repeat assessment after significant weight change; anaesthesia in OSA patients carries higher airway risk and needs planning.
Common confusion
Simple snoring without apnoeas, somnolence or desaturation is not OSA, though it may share the same anatomy. Also distinguish obstructive from central sleep apnoea: in the obstructive type, respiratory effort continues against a closed airway, whereas in central apnoea both effort and airflow cease — a distinction the sleep study traces and one that changes treatment entirely.
Exam-focused takeaway
For theory, define OSA, list risk factors and clinical features, describe the polysomnographic diagnosis with the apnoea-hypopnoea index, and give the management ladder from lifestyle measures through CPAP to site-directed surgery. In viva, expect the Epworth scale, why adenotonsillectomy helps children and why CPAP, not surgery, is first line for most adults. In the posting, take a snoring history from the spouse — the witnessed apnoea account often makes the diagnosis before any test.
Frequently asked questions
How is obstructive sleep apnoea defined?
Recurrent upper airway collapse during sleep causing apnoeas and hypopnoeas with arousals and desaturation, an apnoea-hypopnoea index above five per hour with typical symptoms.
What is the Epworth sleepiness scale?
A short questionnaire scoring the tendency to doze in eight situations, used to grade excessive daytime sleepiness and monitor response to treatment.
What is the first-line treatment for moderate to severe OSA?
Weight loss wherever applicable plus CPAP therapy at night, which splints the airway open and reverses apnoeas and desaturation.
Which operation most helps children with OSA?
Adenotonsillectomy, because adenoid and tonsillar hypertrophy is the dominant cause in children.
What is the role of uvulopalatopharyngoplasty?
It enlarges the oropharyngeal airway by resecting redundant palatal and tonsillar tissue in carefully selected adults with palatal-level obstruction, after a sleep study.
Why must OSA be treated rather than ignored?
Untreated OSA worsens systemic hypertension and cardiovascular risk, impairs daytime function and driving safety, and degrades overall quality of life.