The Relation of Postoperative Atelectasis to the Solubility of Gas Filling the Lungs at Termination of Anesthesia

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Abstract
This study was undertaken to test the hypothesis that thorough ventilation of lungs with gas of low solubility at the termination of anesthesia protects against postoperative atelectasis. Two similar groups of patients were studied. Each group received a 10-min. period of test gas admini-stration at termination of anesthesia, one receiving room air, the other 100% O2, following which all patients breathed room air for the remainder of their convalescence. Atelectasis was defined as a fall in O2 partial pressure from preoperative to postoperative values without generalized hypoventilation or decreased inspired O2 concentration. Arterial blood studies were performed 1-hr. and 24-hrs. postoperatively. In addition, the clinical records of all patients were scrutinized for evidence of postoperative pulmonary complications. No difference in incidence of atelectasis or pulmonary complications was detected in either group. The hypothesis was, therefore, rejected.