Fig. 1. Individual and mean (± SD) values for upper airway cross-sectional area, anteroposterior dimension, and transverse dimension at the level of the soft palate, base of the tongue, and tip of the epiglottis in expiration. Baseline images of the airway were acquired during infusion of propofol at a rate of 50–80 μg · kg⁻¹· min⁻¹(light anesthesia). Image acquisitions were repeated after the depth of anesthesia was increased by administering a bolus dose of propofol and increasing the rate of infusion to 240 μg · kg⁻¹· min⁻¹(deep anesthesia). *P < 0.005 compared with light anesthesia. **P < 0.0001 compared with light anesthesia.