UC Irvine

Background

The cardiovascular effects of positive airway pressure (PAP) therapy in obstructive sleep apnea (OSA) patients are not clear because of confounding by comorbid conditions.

Methods and results

Prospective interventional study of PAP therapy and withdrawal. Apnea Hypopnea Index (AHI; events/hour of sleep) was determined from polysomnography. Central aortic blood pressures (BPs), Aortic Augmentation Index (AAIx), and central (PWVc-f) and peripheral pulse wave (PWVc-r) velocities were determined by applanation tonometry. Echocardiography and brachial artery reactivity testing were performed at baseline, after 4 and 12 weeks of PAP therapy, and 1 week after PAP withdrawal. The 84 participants were mean (SD) 41.1 (7.6) years old and had 39.8 (24.5) AHI events/hour. After 4 weeks post-PAP initiation and sustained after 12 weeks, subjects experienced decreases in central systolic BP (P=0.008), diastolic BP, mean BP, AAIx, and PWVc-r, and brachial artery dilation (all P<0.001), as well as improvements in left ventricular diastolic function and systemic and pulmonary vascular resistance. In adjusted models, PAP use (hours/night) predicted reductions in diastolic BP (β=-0.65 [SE, 0.32] mm Hg/hour; P=0.045), AAIx (β=-0.53 [0.27] %/hour; P=0.049) and PWVc-r (β=-0.13 [0.05] m·s(-1)/hour; P=0.007), and improved brachial artery flow-mediated dilation (β=0.31 [0.14] %/hour use; P=0.015). After 1 week of PAP withdrawal, brachial diameter, diastolic BP, mean BP, AAIx, and heart rate increased (P≤0.05).

Conclusions

PAP therapy reduces arterial tone and improves endothelial and diastolic function in young to middle-aged adults. This positive effect is observed after 4 weeks and depends on hours of use, but reverts quickly with PAP withdrawal.

Clinical trial registration

URL: https://clinicaltrials.gov/. Unique identifier: NCT01317329.