Effects of (nCPAP) on cardiac function awake and asleep.

Continuous positive airway pressure (CPAP) leads to a fall in cardiac output (CO) when applied to individuals with normal cardiac function. However, some reports indicate that CPAP improves CO in selected patients with congestive heart failure, although other reports disagree. Nasal CPAP effectively reverses obstructive sleep apnoea, a condition in which vigorous inspiratory efforts against an occluded upper airway can induce falls in CO. The cardiovascular effects of CPAP in such patients will depend on the balance between the indirect cardiac benefits resulting from relief of apnoeas, and the direct effects of positive pressure on the heart itself.