Effects of Ventilation on Lung Function after Normothermic Ischemia

Abstract

The effects of atelectasis and hyperinflation were compared on immediate postischemic lung function and architecture, following normothermic ischemia. Thirty Sprague-Dawley rats were divided into 3 groups; 2 groups were subjected to 60 minutes of normothermic ischemia. The lungs were atelectatic in 10 (group A), they were hyperinflated to a pressure of 10 cm H2O in 10 (group B), and 10 rats served as nonischemic controls (group C). After 5 minutes of reperfusion, left pneumonectomies were performed and the lungs were examined histopathologically. There were no statistically significant differences in pulmonary venous blood oxygen tension or pH in the 3 groups. There was a significant difference between the compliance data of groups A and B (p < 0.05) and a highly significant difference between the compliance data of groups A and C (p < 0.001). Alveolar edema, perivascular edema, peribronchiolar edema, vascular congestion, and intrapulmonary hemorrhage were more frequent and more severe in the atelectatic group than in the hyperinflated group. The results indicate that postischemic injury occurred at an early stage in atelectatic lungs before any change in blood gas values and that superior postischemic preservation was achieved in lungs maintained in a hyperinflated state.