Haemostatic changes in the pulmonary blood during cardiopulmonary bypass

Pulmonary injury may result from the use of cardiopulmonary bypass (CPB). We investigated changes in the haemostatic system in the pulmonary vein during CPB compared with blood that circulated through the bypass circuit. Paired samples were taken from the pulmonary vein and central venous pressure (CVP) line during the peri-operative period from ten patients. Plasma levels of factor VII (P < 0.001), prekallikrein (P < 0.05), antithrombin III (P < 0.001) and heparin cofactor II (P < 0.005) were decreased in the pulmonary vein after 20 min of bypass compared with pre-operative levels. In the pulmonary vein there was a significant increase in neutrophil expressed CD11b (P < 0.001), neutrophil elastase: alpha 1-antitrypsin complexes (P < 0.001), endothelin-1(P < 0.001) and thrombin-antithrombin complexes (P < 0.001) by the end of bypass compared with pre-operative levels. There was no significant change in monocyte expressed CD11b, factor XII or C1-esterase inhibitor in the pulmonary vein for the study period. None of these variables were significantly different in the pulmonary vein compared with CVP line. In the pulmonary vein plasma levels of activated factor VII decreased following heparin administration (P < 0.001) in the majority of patients which was coincidental to an increase (P < 0.001) in tissue factor pathway inhibitor (TFPI). This increase in TFPI was significantly higher in the pulmonary vein compared with CVP line (P < 0.05) There was a decrease in neutrophil count by 20 min on CPB in both the pulmonary vein and CVP line (P < 0.001) and this did not return to pre-operative levels in the pulmonary vein. Soluble thrombomodulin levels decreased by 20 min on CPB in the CVP line (P < 0.05) but tended to increase in the pulmonary vein, although this was not statistically significant. In conclusion we found evidence of thrombin generation and possible endothelial damage together with increased neutrophil activation and adhesion molecule expression in the pulmonary vein during CPB which may play an important role in the development of post-CPB pulmonary injury.