Randomized Placebo-controlled Trial of Continuous Positive Airway Pressure on Blood Pressure in the Sleep Apnea–Hypopnea Syndrome

Arterial blood pressure rises at apnea termination, and there is increasing evidence that the sleep apnea-hypopnea syndrome (SAHS) is associated with daytime hypertension but no randomized controlled trial evidence of whether SAHS treatment reduces blood pressure exists. We, therefore, conducted a randomized placebo-controlled cross-over study of the effects of 4 wk of continuous positive airway pressure (CPAP) or oral placebo on 24-h blood pressure in 68 patients (55 males, 13 females; median apnea-hypopnea index AHI, 35) not receiving hypotensive medication. Ambulatory blood pressure was recorded for the last 48 h of each treatment. Epworth Sleepiness Score (ESS) and Functional Outcomes of Sleep Questionnaire (FOSQ) were also recorded. All patients were normotensive. There was a small decrease in 24-h diastolic blood pressure (placebo, 79.2 SE 0.9 mm Hg; CPAP, 77.8 SE 1.0 mm Hg; p = 0.04) with the greatest fall occurring between 2:00 A.M. and 9:59 A.M. The observed decrease in 24-h diastolic blood pressure was greater in two a priori groups, CPAP use > or = 3.5 h per night (81.5 SE 1.2 mm Hg; 79.6 SE 1.2 mm Hg; p = 0.03) and those with more than twenty 4% desaturations per hour (82.4 SE 2.1 mm Hg; 77.4 SE 2.1 mm Hg; p = 0.002). Systolic pressure also fell in the latter group (133.1 SE 2.8 mm Hg; 129.1 SE 2.1 mm Hg; p = 0.009). Desaturation frequency was the best predictor of diastolic blood pressure fall with CPAP (r = 0.38; p = 0.002). Both ESS and FOSQ domains improved. Thus, CPAP can reduce blood pressure in patients with SAHS, particularly in those with nocturnal oxygen desaturation, but the decrease is small.