Continuous positive airway pressure (CPAP) for 12 weeks among patients with obstructive sleep apnea and hypertension resistant to three or more drugs resulted in a decrease in 24-hour mean and diastolic blood pressures and an improvement in nocturnal blood pressure patterns, a study found.
More than 70% of patients with resistant hypertension have obstructive sleep apnea, researchers noted. So, to assess CPAP on blood pressure values and nocturnal blood pressure patterns, researchers enrolled 194 patients in an open-label, randomized, multicenter clinical trial in 24 teaching hospitals in Spain from June 2009 to October 2011.
Results appeared in the Dec. 11 issue of JAMA, the Journal of the American Medical Association.
The mean apnea-hypopnea index was 40.4 (SD, 18.9) and patients took an average of 3.8 antihypertensive drugs. Baseline 24-hour mean blood pressure was 103.4 mm Hg; systolic blood pressure was 144.2 mm Hg; and diastolic blood pressure was 83 mm Hg.
At baseline, average nighttime blood pressure decreased at least 10% compared with the average daytime blood pressure among 25.8% of patients. The percentage of patients using CPAP for 4 or more hours per day was 72.4%.
Compared with the control group, those who used CPAP achieved a greater decrease in 24-hour mean blood pressure (3.1 mm Hg; 95% CI, 0.6 to 5.6; P=0.02) and 24-hour diastolic blood pressure (3.2 mm Hg; 95% CI, 1.0 to 5.4; P=0.005). The decrease in 24-hour systolic blood pressure was not statistically significant (3.1 mm Hg; 95% CI, −0.6 to 6.7; P=0.10). More patients in the CPAP group displayed a nocturnal blood pressure dipper pattern at the 12-week follow-up than did the control group (35.9% vs 21.6%; adjusted odds ratio [OR], 2.4; 95% CI, 1.2 to 5.1; P=0.02).
There was a significant positive correlation between the number of hours of CPAP use and the decrease in 24-hour mean blood pressure (r=0.29, P=0.006), systolic blood pressure (r=0.25; P=0.02), and diastolic blood pressure (r=0.30, P=0.005). Authors noted that their work corroborates the relationship seen in other studies between the number of hours of CPAP use per night and its effect on blood pressure, especially in patients who use it at least 4 hours per night.
The authors wrote, “In line with the published evidence, our results confirm that there is a clinically and statistically significant reduction in both 24-hour mean and diastolic blood pressure levels, especially during the night and in those patients with acceptable CPAP adherence.”