EFFECT OF NASAL CONTINUOUS POSITIVE AIRWAY PRESSURE DURING SLEEP ON 24-HOUR BLOOD-PRESSURE IN OBSTRUCTIVE SLEEP-APNEA

Ambulatory blood pressure (BP) was measured noninvasively (Oxford Medi log ABP) at 15-minute intervals for 24 hours before and after 8 weeks of treatment with nasal continuous positive airway pressure (nCPAP) in 19 men with obstructive sleep apnea (OSA). We included both normotens ive and hypertensive patients, but hypertensives were studied after wi thdrawal of antihypertensive drugs. Ambulatory BP before and after tre atment was compared using patients as their own controls. Treatment wi th nCPAP was successfully established in 14 of the 19 patients (74%). Blood pressure fell significantly in patients who were successfully tr eated: 24-hour mean BP (systolic/diastolic) decreased from 141 +/- 18/ 89 +/- 11 mm Hg to 134 +/-19/85 +/- 13 mm Hg (p < 0.05). The reduction in 24-hour mean systolic BP occurred during both day and night, but a significant fall in mean diastolic BP was only observed during the da y. The mean blood pressure fell in both normotensive and hypertensive patients. Patients who were inadequately treated with nCPAP had no red uction in mean 24-hour BP. Effective treatment of sleep apnea with nCP AP was associated with a significant fall in both systolic and diastol ic BP independent of changes in body weight or alcohol consumption, su ggesting that sleep apnea was an independent factor contributing to el evated nighttime and daytime BP in these patients.