Continuous positive airway pressure lowers blood pressure in hypertensive patients with obstructive sleep apnea

Summary Question of the study Obstructive sleep apnea (OSA) and hypertension are frequently associated and probably causally related. We investigated the influence of continuous positive airway pressure (CPAP) on blood pressure (BP) in OSA. Patients and Methods Fourty-four patients in whom CPAP-therapy had been successfully applied for treatment of OSA (median apnea-hypopopnea-index [AHI] 57.5/h) were included. Non-invasive 24-hour BP was measured at 15  min intervals before and with CPAP. Results After 1 – 3 days of CPAP, 24-hour systolic and diastolic BP in the hypertensive patients (n = 32) decreased from a median of 141 (129 – 173, 25 % – 75 % interquartile range) mmHg to 136 (118 – 157) mmHg (p = 0.004) and from 90 (80 – 107) mmHg to 88 (77 – 99) mmHg (p = 0.001), respectively, but was unchanged in the normotensives (n = 10). After 4 – 6 months of CPAP, 24-hour systolic and diastolic BP in a hypertensive subgroup (n = 19) decreased from a median of 140 (131 – 142) mmHg to 131 (122 – 143) mmHg (p = 0.01) and from 88 (86 – 94) mmHg to 84 (80 – 87) mmHg (p = 0.02), respectively, but was unchanged in a normotensive subgroup (n = 8). After long-term CPAP, there was a small weight reduction in the hypertensive patients. Subgroup analysis of 13 hypertensives with stable weight confirmed a significant BP-reduction. Conclusions In OSA with associated hypertension, CPAP has a specific BP-lowering effect. This suggests that both disorders are causally related.