Obstructive sleep apnoea

Sleep apnoea is quantified by the Apnoea Hypopnoea Index, which is the total number of apnoeas and hypopnoeas during sleep divided by hours of sleep. Sleep apnoea can be further subdivided into: obstructive sleep apnoea (OSA), due to upper airway instability, usually with snoring; and central sleep apnoea, due to episodic loss of respiratory drive and secondary hypoventilation. In adults, snoring, OSA and symptomatic OSA are more common in men than women and have increased over the past 20 years by 14–55% due to increasing population age, obesity and co-existent medical problems. Snoring and OSA are due to sleep-related loss of upper airway dilator muscle tone (e.g. genioglossus) in the oropharynx. Patients with known OSA should bring their own continuous positive pressure airway machine to the hospital. A suspected diagnosis of OSA can be confirmed with ambulatory cardiopulmonary or attended polysomnography.