Relationship between plasma neutrophil elastase and respiratory index of patients who had undergone cardiac surgery with cardiopulmonary bypass.

To evaluate the effects of cardiopulmonary bypass (CPB) on the release of polymorphonuclear leukocyte elastase (PMN-E) and postoperative pulmonary function, the perioperative plasma levels of PMN-E in α1-antitrypsin complex (EAC) and hydrogen peroxide concentration in the expired breath were measured in eight patients who underwent cardiac surgery with CPB, and the relationship between EAC levels and the respiratory index (RI) was studied. Although PMN, EAC, and the ratio of EAC to neutrophil (E/N) were elevated significantly after surgery, alveolar-arterial oxygen difference (A-aDO2) and respiratory index (A-aDO2/PaO2) did not change when compared with those of the preoperative period. Hydrogen peroxide concentration in the expired breath also did not change (below 2.5 μmol·l(-1)) during the perioperative period. These results suggest that the elevation of EAC immediately after cardiac surgery using CPB, which lasted less than 2h, was not a cause of postoperative pulmonary disorder. However, there was a significant positive correlation between E/N ratio and respiratory index (r=0.67,P<0.01). Thus excessive release of PMN-E during CPB may be implicated in the etiology of postoperative respiratory dysfunction.