RESULTS	Atelectasis in a transverse scan near the diaphragm after induction of anesthesia and apnea was 9.8 + / - 5.2 cm2 ( 5.6 + / - 3.4 % of the total lung area ; mean + / - SD ) , 1.3 + / - 1.2 cm2 ( 0.6 + / - 0.7 % ) , and 0.3 + / - 0.3 cm2 ( 0.2 + / - 0.2 % ) in the groups breathing 100 , 80 , and 60 % oxygen , respectively ( P < 0.01 ) .\