Fig. 2. Atelectasis 1 cm above the diaphragm in individual patients (filled circles) after induction of anesthesia and a period of apnea in relation to their end-tidal oxygen concentration (Feto2) just before the period of apnea. The results are compared with data (open circle) taken from Rothen et al. 3in which subjects were ventilated with 30% oxygen in nitrogen. Mean ± SD is presented above each group.