Fig. 2.
Measures of the hypoxic ventilatory response (HVR) during the intermittent hypoxia protocol completed during wakefulness and sleep. Average values of the HVR determined for the initial two episodes and the final two episodes of the intermittent hypoxia protocol in men and women of the OSA and control groups are shown. Note that the HVR was greater during wakefulness compared with sleep. Moreover, note that there was a progressive increase in the HVR from the initial two episodes to the final two episodes during wakefulness but not sleep. Furthermore, note that progressive augmentation of the HVR was greater in the OSA group compared with control in both men and women. SaO2, Arterial oxygen saturation. Values are means ± SE. ‡Significantly different from initial episodes. †Significantly different from sleep.