Fig. 5. Effects of hypoxemia and hypercapnia on phasic genioglossus activity, and flow rate during propofol anesthesia (ED⁵⁰[median effective dose]). Arterial partial pressures of carbon dioxide and oxygen concentration were measured at time of assessment (mean and SEM). *  P < 0.05  versus condition 1 (paired  t test). CO²= carbon dioxide; et = end-tidal; O²= oxygen. (  A ) Phasic genioglossus activity. Genioglossus activity increased significantly during evoked hypoxemia and hypercapnia. (  B ) Flow rate (tidal volume/inspiratory time). Flow rate increased significantly during evoked hypoxemia and hypercapnia. (  C ) Minute ventilation. Minute ventilation decreased significantly during propofol anesthesia and increased subsequently during evoked hypoxemia and hypercapnia. *  P < 0.05  versus before evoked hypoxemia/ hypercapnia.