Effect of CPAP, weight loss, or CPAP plus weight loss on central hemodynamics and arterial stiffness

Obesity and obstructive sleep apnea tend to coexist. Little is known about the effects of obstructive sleep apnea, obesity, or their treatment on central aortic pressures and large artery stiffness. We randomized 139 adults with obesity (body mass index >30 kg/m²) and moderate-to-severe obstructive sleep apnea to (1) continuous positive airway pressure (CPAP) therapy (n=45), (2) weight loss (WL) therapy (n=48), or (3) combined CPAP and WL (n=46) for 24 weeks. We assessed the effect of these interventions on central pressures and carotid-femoral pulse wave velocity (a measure of large artery stiffness), measured with arterial tonometry. Central systolic pressure was reduced significantly only in the combination arm (-7.4 mm Hg; 95% confidence interval, -12.5 to -2.4 mm Hg; P=0.004), without significant reductions detected in either the WL-only (-2.3 mm Hg; 95% confidence interval, -7.5 to 3.0; P=0.39) or the CPAP-only (-3.1 mm Hg; 95% confidence interval, -8.3 to 2.0; P=0.23) arms. However, none of these interventions significantly changed central pulse pressure, pulse pressure amplification, or the central augmentation index. The change in mean arterial pressure (P=0.008) and heart rate (P=0.027) induced by the interventions was significant predictors of the change in carotid-femoral pulse wave velocity. However, after adjustment for mean arterial pressure and heart rate, no significant changes in carotid-femoral pulse wave velocity were observed in any group. In obese subjects with obstructive sleep apnea, combination therapy with WL and CPAP is effective in reducing central systolic pressure. However, this effect is largely mediated by changes in mean, rather than central pulse pressure. WL and CPAP, alone or in combination, did not reduce large artery stiffness in this population.