Effect of CPAP on Blood Pressure in Patients With OSA/Hypopnea: Systematic Review and Meta-Analysis
What is the effect of reducing blood pressure (BP) by continuous positive airway pressure treatment (CPAP) compared to other treatments?
Four databases were searched for all randomized controlled trials assessing the effect of CPAP on BP in patients with obstructive sleep apnea (OSA).
A total of 1,599 reports were included in the initial search; of these, only 31 met criteria. A mean difference in systolic BP of 2.6 ± 0.6 mm Hg and in diastolic BP of 2.0 ± 0.4 mm Hg was observed, favoring treatment with CPAP (p < 0.001). The mean difference in systolic and diastolic BP was, respectively, 2.2 ± 0.7 and 1.9 ± 0.6 mm Hg during daytime and 3.8 ± 0.8 and 1.8 ± 0.6 mm Hg during nighttime. Subjects with a higher apnea-hypopnea index (AHI) or who experience daytime somnolence were found to have better BP response to CPAP. Thus, an increase in AHI of 10/hour from baseline, a systolic BP decrease of approximately 1 mm Hg, could be expected in subjects treated by CPAP. No firm conclusion was met comparing the effect of CPAP to oral devices on BP.
The authors concluded that CPAP significantly reduces BP in patients with OSA, but with a low effect size.
Hypoxia due to repeated episodes of apnea found in OSA leads to activation of the renin-angiotensin-aldosterone system, only one of many mechanisms explaining the association of OSA and hypertension (HTN). CPAP is the preferred treatment to counteract these episodes of hypoxia. Effect of BP lowering seen here is equivalent to one-half of the magnitude observed with drug therapy for HTN in meta-analyses. More studies are needed to determine whether CPAP can reduce HTN over time, to determine the number of medications needed to treat HTN, or to directly compare CPAP’s effect at lowering BP with drug therapy.
Keywords: Continuous Positive Airway Pressure, Renin-Angiotensin System, Blood Pressure Determination, Hypertension, Sleep Apnea, Obstructive, Sleep Apnea Syndromes
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