The objectives of the project are to investigate the roles of the various hypotheses that have been implicated in pulmonary adjustments and in development of pulmonary edema and pulmonary insufficiency. The hypotheses to be tested in the project are roles of: 1. pulmonary thromboembolization; 2. adrenergic mechanisms; 3. pulmonary hypoperfusion; and 4. vasoactive factors in the etiology of pulmonary edema and pulmonary insufficiency.