A comparison of pulmonary function in puppies undergoing total cardiopulmonary bypass with bubble or membrane oxygenators.

Twenty-six puppies, 4 to 6 weeks of age, underwent preoperative determination of alveolar ventilation, venoarterial shunting, static pulmonary compliance, and diffusion capacity. The animals were divided into four groups: Group I underwent a left thoracotomy alone for 3 hours and served as a control; Group II underwent total cardiopulmonary bypass for 1 hour with a membrane oxygenator; Group III underwent total cardiopulmonary bypass for 1 hour with a bubble oxygenator; and Group IV underwent total cardiopulmonary bypass for 3 hours with a membrane oxygenator. After the operation, pulmonary function studies were repeated in each animal. It was found that pulmonary function deteriorated in all groups. Alveolar ventilation and venoarterial shunting grew worse in the two groups that had been supported by the membrane oxygenator, whereas decrease in compliance seemed to be related to duration of the procedure. Diffusing capacity decreased equally in all groups.