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Effects of Continuous Positive Airway Pressure Treatment and Withdrawal in Patients With Obstructive Sleep Apnea on Arterial Stiffness and Central BP^*

^* From the Sleep Research Group, Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.

Correspondence to: Craig L. Phillips, BSc, Woolcock Institute of Medical Research, 431 Glebe Point Rd, Glebe, NSW 2037, Australia; e-mail: cphillip{at}mail.usyd.edu.au

Abstract

Background: Obstructive sleep apnea (OSA) is associated with increased BP and other cardiometabolic risk factors. The aim of the present study was to determine whether arterial stiffness and central BP (two important cardiovascular risk factors) would change, independent of peripheral BP following either the initiation of or withdrawal from nasal continuous positive airway pressure (CPAP) treatment in subjects with OSA.

Methods and results: Arterial stiffness and peripheral and central BP were measured at baseline, and then either at 2 months after starting CPAP therapy (intervention group, n = 20) or 7 nights after withdrawal from CPAP therapy (withdrawal group, n = 20) using pulse wave analysis. In the intervention group, there were reductions in arterial stiffness (ie, the aortic augmentation index fell by 2.5%) and central systolic BP (fell by 4.2 mm Hg) without a concomitant reduction in peripheral BP. The change in arterial stiffness was associated with CPAP compliance (r = –0.47). In contrast, in the withdrawal group there were no overall changes in arterial stiffness or BP. However, there was an early morning increase in diastolic BP and heart rate relative to late evening.

Conclusion: These results suggest that clinically important changes in arterial stiffness and central BP may occur following effective CPAP treatment of OSA without parallel changes in peripheral BP.

Key Words: augmentation index • central BP • continuous positive airway pressure • sleep apnea