Sleep-Disordered Breathing, Postoperative Delirium, and Cognitive Impairment.

Sleep-disordered breathing (SDB) is highly prevalent in the general population and has been associated with cognitive impairment in older individuals. Delirium is an acute decline in cognitive function and attention that often occurs after surgery, especially in older individuals. Several recent studies suggest an association between SDB and postoperative delirium. The aim of this systematic review is to examine the current literature on SDB, postoperative delirium, and cognitive impairment and to discuss the pathophysiology and perioperative considerations. A literature search was performed of Medline (1946-2016), Medline In-Process (June 2016), Embase (1947-2016), Cochrane Central Register of Controlled Trials (May 2016), and Cochrane Database of Systematic Reviews (2005 to June 2016). Inclusion criteria for studies were (1) polysomnography confirmed SDB; (2) postoperative delirium or cognitive impairment confirmed by a validated diagnostic tool; and (3) publications in the English language. All study designs including randomized controlled trials and observational studies were included. The literature search identified 2 studies on SDB and postoperative delirium, 15 studies on SDB and cognitive impairment, and 5 studies on the effect of continuous positive airway pressure on cognitive impairment and delirium in older individuals. SDB was associated with cognitive impairment, and this systematic review revealed that SDB may be a risk factor for postoperative delirium, especially in older individuals. Although the pathophysiology of SDB and postoperative delirium is unclear and effective treatments for SDB to reduce the incidence of delirium have not been studied extensively, preliminary evidence suggests that continuous positive airway pressure therapy may lower the risk of delirium. Health care professionals need to be aware that undiagnosed SDB may contribute to postoperative delirium. Preoperative screening for SDB and strategies to reduce the risk for postoperative delirium may be helpful in older individuals. Further studies are needed to clarify the relationship between SDB and postoperative delirium and elucidate the pathophysiology of postoperative delirium through SDB.