REPEATED VITAL CAPACITY MANEUVERS AFTER CARDIOPULMONARY BYPASS - EFFECTS ON LUNG-FUNCTION IN A PIG MODEL

Respiratory failure following cardiopulmonary bypass (CPB) is a major complication after cardiac surgery. A vital capacity inflation of the lungs, performed before the end of CPB, may improve gas exchange, but the necessity to repeat it is unclear. Therefore, we studied 18 pigs u ndergoing hypothermic CPB. A vital capacity manoeuvre (VCM) was perfor med in two groups and consisted of inflating the lungs for 15 s to 40 cm H2O at the end of CPB. In one group, VCM was repeated every hour. T he third group served as controls. Atelectasis was studied by CT scan. Intrapulmonary shunt increased after bypass in the controls and impro ved spontaneously 3 h later without returning to baseline values. From 3 to 6 h after CPB, there was no more improvement and more than 10% a telectasis remained at 6 h. In contrast, the two groups treated before termination of CPB with VCM showed only minor atelectasis and no abno rmal changes in gas exchange directly after bypass or later. We conclu de that the protective effect of VCM remained for 6 h after bypass, an d there was no extra benefit on gas exchange by repeating the VCM.