Variables affecting the change in systemic blood pressure in response to nasal CPAP in obstructive sleep apnea patients.

We hypothesized that an improvement in systemic blood pressure (BP) during continuous positive airway pressure (CPAP) treatment of obstructive sleep apnea (OSA) would be related to severity of hypertension (HTN), morphometric parameters such as body mass index, and level of CPAP adherence. We tested this hypothesis with a retrospective review of 85 consecutive OSA patients who had completed diagnostic and CPAP titration polysomnograms and were equipped with a CPAP-adherence monitoring system for a minimum of 1 month of observation. Sphygmomanometer-obtained BP readings were compared at baseline and after 4-6 weeks of CPAP therapy. Presentation BP was significantly and strongly associated with the change in BP seen with treatment. Those with an elevated systolic and diastolic BP and those with an elevation of either systolic or diastolic BP showed a significant fall in BP on CPAP. Those with a BP below the hypertensive range of 140/90 on presentation did not have a significant drop in BP with CPAP. There were no significant changes in systolic, diastolic, or mean BP when patients were categorized by the severity of HTN, as determined by the number of antihypertensive medications prescribed or if they were categorized by the degree of CPAP adherence, objectively determined by the average use of more or less than 4 h/night. We conclude that HTN at initial presentation is among the most important indicators of potential benefit of CPAP administration on BP.