Respiratory

Obstructive Sleep Apnoea

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is recurrent upper-airway narrowing or closure during sleep, causing sleep fragmentation and intermittent hypoxaemia; diagnosis uses sleep history and objective sleep testing, while treatment is tailored to symptoms, severity, comorbidity, safety risk and treatment adherence.

Definition

Obstructive sleep apnoea/hypopnoea syndrome is recurrent sleep-related narrowing or closure of the upper airway causing hypopnoeas or apnoeas, sleep fragmentation and intermittent hypoxaemia. Severity is determined using the apnoea–hypopnoea index or an equivalent objective sleep-study measure.

First principles

Sleep-related loss of pharyngeal tone permits collapse

The pharynx depends on dilator-muscle activity to remain open. During sleep this activity falls; an anatomically narrow airway, obesity, enlarged tonsils, retrognathia, alcohol or sedative exposure may then permit partial or complete collapse. The person continues making respiratory effort against obstruction, producing hypopnoea or apnoea, desaturation and a brief arousal that restores airway tone.

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