Patients with obstructive sleep apnea have an abnormal peripheral vascularresponse to hypoxia

Patients with obstructive sleep apnea (OSA) have been reported to have an a ugmented presser response to hypoxic rebreathing. To assess the contributio n of the peripheral vasculature to this hemodynamic response, we measured h eart rate, mean arterial pressure (MAP), and forearm blood flow by venous o cclusion plethysmography in 13 patients with OSA and in 6 nonapneic control subjects at arterial oxygen saturations (Sa(O2)) of 90, 85, and 80% during progressive isocapnic hypoxia. Measurements were also performed during rec overy from 5 min of forearm ischemia induced with cuff occlusion. MAP incre ased similarly in both groups during hypoxia (mean increase at 80% Sa(O2): OSA patients, 9 +/- 11 mmHg; controls, 12 +/- 7 mmHg). Forearm vascular res istance, calculated from forearm blood flow and MAP decreased in controls ( mean change -37 +/- 19% at Sa(O2) 80%) but not in patients (mean change -4 +/- 16% at 80% Sa(O2)). Both groups decreased forearm vascular resistance s imilarly after forearm ischemia (maximum change from baseline -85%). We con clude that OSA patients have an abnormal peripheral vascular response to is ocapnic hypoxia.