As a complication of the clinical course of disease, injury, or operation, the sudden and unanticipated onset of dyspnea, tachypnea, and cyanosis has achieved a well-deserved respect for serious portent and need for immediate and effective treatment. It is unfortunate, therefore, that accurate diagnosis of the causative factor or factors responsible for such disasters can be considerably more difficult to achieve than simple recognition that "something has gone wrong," so dramatically manifested by the initial symptoms. For surgical patients, additional difficulty in diagnosis may be superimposed by the intangibles of anesthesia, operation, serious trauma, and errors in parenteral fluid administration. Also, the diagnostic problem is not made easier by the variety of complex disturbed physiologic processes responsible for the principal signs and symptoms of acute cardiopulmonary insufficiency: (1) cyanosis; (2) tachypnea; (3) dyspnea; (4) tachycardia; and (5) hypotension. Congestive atelectasis is a descriptive term applied to an acute form of