Of all the complications following surgical procedures, those involving the lungs are among the most feared and the most commonly reported.1 The incidence of atelectasis has been variously reported as causing from 3 to 70 per cent of all postoperative complications, with 40 per cent mortality among the persons affected.2 In operations of the upper part of the abdomen the morbidity from respiratory complications is said to be about 10 per cent.2 At the Kansas City Gen eral Hospital during two years in which careful records have been kept, the incidence of morbidity and mortality from respiratory complications is seen to be much lower (tables 1 and 2).3 All patients with atelectasis and massive pulmonary collapse in this series recovered speedily. Pneumonia was named as the cause of death or was associated with other causes in 24 of 125 postoperative deaths. In most cases the pneumonia