Effects of continuous positive airway pressure therapy on daytime and nighttime arterial blood pressure in patients with severe obstructive sleep apnea and endothelial dysfunction

Purpose A nocturnal non-dipping or rise in blood pressure (BP) is associated with poor cardiovascular outcome. This study aimed to test whether continuous positive airway pressure (CPAP) therapy can reduce nocturnal BP and normalize the 24-h BP profile in patients with severe obstructive sleep apnea (OSA) and erectile dysfunction as a surrogate for endothelial dysfunction (ED). Patients and methods Eighteen consecutive patients with OSA and ED on stable antihypertensive medication (age 55.8 +/- 9.5 years, body mass index 35.5 +/- 3.8 kg/m(2), apnea-hypopnoea index 66.1 +/- 27.4/h) were treated with CPAP for 6 months (average daily use 5.8 +/- 2.3 h). Twenty-four hour BP recordings were performed using a portable monitoring device. Rising was defined as an increase, whereas non-dipping was defined as a fall in nocturnal BP of less than 10% compared to daytime values. Serum noradrenaline levels as markers of sympathetic activity were measured at baseline and at 6 month follow up. Results Compared to baseline, nocturnal systolic and diastolic BP were significantly reduced after CPAP therapy (128.5 +/- 14 to 122.9 +/- 11 mmHg,p = 0.036; 76.2 +/- 9 to 70.5 +/- 5 mmHg,p = 0.007). The frequency of non-dipping and rising nocturnal systolic BP, as well as mean nocturnal heart rate, was reduced after CPAP treatment (73 to 27%,p = 0.039;20 to 7%,p = 0.625; from 81.5 +/- 10 to 74.8 +/- 8 beats per minutep = 0.043). Serum levels of noradrenaline were significantly lower after CPAP therapy (398 +/- 195 ng/l vs. 303 +/- 135 ng/l,p = 0.032). Conclusion In patients with severe OSA and clinically apparent ED, CPAP therapy was associated with a decrease in nocturnal BP and serum noradrenaline levels, as well as a normalization of the 24-h BP profile