A clinical study on the effects of pulsatile cardiopulmonary bypass on the blood endotoxin levels.

Levels of endogenous endotoxins have been reported to increase after cardiopulmonary bypass. Endotoxin levels have also been implicated in multiple organ failure and may contribute to the immunocompromised state seen after bypass. We evaluated the effects of pulsatile cardiopulmonary bypass circulation on endogenous endotoxin levels. The study population consisted of 15 consecutive adult patients who underwent cardiac operations with cardiopulmonary bypass. Pulsatile flow was used during aortic crossclamping in eight patients (group I) and nonpulsatile flow was used in the remaining seven patients (group II). Changes in blood endotoxin levels were monitored during aortic crossclamping, after release of the clamp, and after weaning from bypass. The blood endotoxin level at each stage was expressed as a percentage of the level at the beginning of bypass. Group I patients a significantly lower blood endotoxin percentage than group II (from 20 to 120 minutes after the initiation of aortic crossclamping). In group I, the blood endotoxin percentage was nearly constant during aortic crossclamping. After release of aortic crossclamping, group I also had a lower blood endotoxin percentage than group II. Endogenous endotoxin levels appear to increase in the presence of intestinal congestion and ischemia. Improvement in intestinal circulation by pulsatile cardiopulmonary bypass may prevent increases in endogenous endotoxin levels by reducing these factors.