Background Obstructive sleep apnea (OSA) is associated with increased blood pressure (BP) and other cardio-metabolic 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 blood pressure following either initiation 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 (intervention group, n=20) or 7 nights after withdrawal from CPAP (withdrawal group, n=20) using pulse wave analysis. In the intervention group there were reductions in arterial stiffness (aortic augmentation index fell by -2.5%) and central systolic BP (- 4.2 mmHg) 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.

Phillips C, Yee B, Yang Q, Villaneuva A, Hedner J, Berend N, Grunstein R.

Sleep Research Group, Woolcock Institute of Medical Research, University of Sydney, Camperdown, Sydney, NSW, Australia.