AROUSAL AND CARDIORESPIRATORY RESPONSES TO HYPOXIA IN PRADER-WILLI-SYNDROME

Ventilatory responses to peripheral chemoreceptor stimuli are absent i n patients with Prader-Willi syndrome (PWS) during wakefulness. Becaus e arousal from sleep after rapidly developing hypoxia may require inta ct peripheral chemoreceptor function, we hypothesized that blunted hyp oxic arousal responses during sleep Stage 3/4 would be present in PWS. Thirteen patients with PWS (mean age, 23.4 +/- 3.7 +/- SEM yr; 46% ma le; body mass index [BMI], 28.9 +/- 1.6 kg/m(2)) and 11 matched contro l subjects (mean age 28.0 +/- 5.4 yr; 54% male; BMI, 28.8 +/- 3.1 kg/m (2)) were studied. An abrupt decrease in inspired Oz tension to 80 mm Hg was introduced until arousal occurred or for a maximum of 3 min. On e of the 13 patients with PWS and seven of the 11 control subjects wer e aroused by the hypoxic challenge (p < 0.02). During hypoxia, heart r ate increased by 9 +/- 2% in the PWS group versus 22 +/- 4% in the con trol group (p < 0.005). Respiratory rate did not change in the PWS gro up (4 +/- 2%; p = NS), but it increased by 13 +/- 2% in the control gr oup (p < 0.02). We conclude that abnormal arousal and cardiorespirator y responses to hypoxia are frequent in PWS. We postulate that intact p eripheral chemoreceptor function is an important component underlying arousal mechanisms to rapidly developing hypoxia during sleep.