Haemodynamic effects of short-term nasal continuous positive airway pressure therapy in sleep apnoea syndrome: Monitoring by a finger arterial pressure device

Abstract

We have evaluated the effects of short-term nasal continuous positive airway pressure (nCPAP) therapy on systemic blood pressure and heart rate in patients with obstructive sleep apnoea syndrome. Twenty-five consecutive patients were examined during baseline conditions (No-CPAP) and during one night of nCPAP treatment (CPAP). The mean value and the variation coefficient of cardiovascular variables, examined by a finger arterial pressure device (Finapres), were determined in wakefulness and sleep. Without nCPAP an increase in blood pressure from wakefulness to sleep was observed in all patients from 138 ± 3 mmHg to 146 ± 3 and 155 ± 4 mmHg, and from 80 ± 1 mmHg to 82 ± 2 and 84 ± 2 mmHg, respectively, for systolic and diastolic values in non rapid eye movement (NREM) and rapid eye movement (REM) sleep. Conversely, heart rate decreased from 75 ± 2 beats·min-1 to 70 ± 2 and 69 ± 2 beats·min-1. In addition, variability of heart rate and blood pressure was greatly increased compared with the awake state. Short-term nCPAP therapy significantly reduced systolic pressure from 144 ± 3 mmHg to 137 ± 3 and 143 ± 4 mmHg during NREM and REM sleep, respectively, associated with a decrease in heart rate (from 69 ± 2 to 65 ± 2 beat·min-1). In total sleep and in all sleep stages a significantly reduced variability (p<0.001) was found. No changes were observed for diastolic pressure during CPAP night compared with baseline conditions. The fall in systolic blood pressure without changes in diastolic pressure could be explained by a persistent vasoconstriction besides the removal of apnoeas. An additional mechanical effect of CPAP on the cardiovascular system is discussed.