Obstructive sleep apnea (OSA) and its associated complications recur rapidly after discontinuation of continuous positive airway pressure (CPAP), according to a new study.

Researchers at University Hospital Zurich (Switzerland) conducted a randomized controlled trial involving 41 OSA patients on CPAP to determine the effects of CPAP withdrawal. The patients were randomized to either continue CPAP or undergo CPAP withdrawal (subtherapeutic CPAP) for a period of two weeks. Polysomnography, sleepiness, psychomotor performance, endothelial function, blood pressure (BP), heart rate (HR), urinary catecholamines, blood markers of systemic inflammation, and metabolism were assessed.

The results showed that CPAP-withdrawal lead to a recurrence of OSA within a few days, together with a return of subjective sleepiness, but were not associated with significant deterioration of psychomotor performance within the two weeks. CPAP withdrawal was associated with a significant increase in morning systolic BP, morning diastolic BP, and morning heart rate. Endothelial function decreased significantly in the CPAP-withdrawal group compared to therapeutic CPAP. CPAP withdrawal was also associated with an increase in urinary catecholamines, but did not lead to an increase in markers of systemic inflammation, insulin resistance, or blood lipids. The study was published ahead of print on August 11, 2011, in the American Journal of Respiratory and Critical Care Medicine.

“We found that CPAP withdrawal was associated with a return of OSA by the first night,” said lead author Malcolm Kohler, MD, of University Hospital Zurich in Switzerland, and colleagues of the Sleep Disorders Center and Pulmonary Division. “Withdrawal usually leads to a rapid recurrence of OSA, a return of subjective sleepiness and is associated with impaired endothelial function, increased urinary catecholamines, blood pressure, and heart rate.”

A continuous positive airway pressure (CPAP) device delivers a stream of compressed air to a nose mask, keeping the airway open under air pressure so that unobstructed breathing becomes possible, thereby reducing, or preventing apneas and hypopneas. It is important to understand that it is the air pressure, and not the movement of the air, that prevents the apneas; this has the additional benefit of reducing or eliminating the extremely loud snoring that sometimes accompanies OSA. Given that it is a chronic health issue, ongoing care is usually needed to maintain CPAP therapy.

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