Effect of surgery with cardiopulmonary bypass on alveolar-capillary barrier function in human beings

The rate of clearance of technetium /sup 99m/-labeled diethylenetriamine pentaacetate (/sup 99m/TcDTPA) was measured from the lung into the blood (T1/2LB) in 9 patients before and after operation with cardiopulmonary bypass (CPB). Two hours postoperatively, T1/2LB fell from 49.3 +/- 13.6 minutes to 24.0 +/- 12.8 minutes. In addition, alveolar-arterial oxygen tension difference P(A-a)O2 had increased from 73 +/- 28 mm Hg to 164 +/- 37 mm Hg. The rates of clearance of /sup 99m/TcDTPA had returned to preoperative times by 7 days after operation, although there was still a significant elevation in P(A-a)O2. This study has shown an increased clearance from the lung of a low-molecular-weight molecule following operation with CPB. This finding should allow a more rational approach to elucidating the mechanisms of injury to the gas-blood interface in the lung following this type of operation