Sleep, sleep studies and sleep-disordered breathing: basic knowledge for the anesthesiologist

To provide a basic understanding of sleep physiology, the pathophysiology of sleep-disordered breathing and the processes applied in undertaking and assessing sleep studies.

It has become increasingly apparent that obstructive sleep apnoea is associated with heightened perioperative risk. Furthermore, the condition still remains under-diagnosed in patients presenting for surgery.

This review describes the physiology of sleep including sleep stages, sleep monitoring, the normal hypnogram and investigation from simple overnight pulse oximetry to full polysomnography. The pathophysiology of sleep-disordered breathing is discussed; from simple snoring through obstructive sleep apnoea to obesity hypoventilation syndrome. The relationship to metabolic syndrome is explored.Salient points in the interpretation of sleep study reports are presented.