Aspects of retransfusion of shed blood in cardiac surgery

Abstract: The use of cardiotomy suction during open heart surgery with cardiopulmonary bypass (CPB) has a long tradition and often regarded as mandatory. Recently, studies have described potentially negative effects of cardiotomy suction with activation of the complement system, enhanced inflammatory response, hemolysis and coagulopathy. Emboli of various matters has also been studied. Whether they affect the function of various organs is an ongoing debate. Renal dysfunction after cardiac surgery is a well known complication. Monitoring of renal function is important, both for the guidance of renal intervention and for the prediction of outcome. Cystatin C has been suggested as a more sensitive marker of glomerular filtration rate (GFR) than creatinine, which today is the most commonly used marker of GFR. In study I and II, we studied the distribution and the kinetics of lipid microemboli during cardiac surgery in a porcine model. The organ that received most emboli was the kidney. Within the brain, the grey matter received most emboli. A high degree of first-pass trapping in the capillaries was found. No immediate renal excretion of lipid material was seen. In study III, we evaluated cystatin C with iohexol clearance in a clinical study on patients scheduled for coronary artery bypass grafting (CABG). We found that cystatin C is suitable for monitoring renal function in cardiac surgery. In study IV, the final part of this thesis, we launched a clinical trial including 150 patients, where we compared outcome between CABG with and without cardiotomy suction. There were a few differences, all favoring surgery without the use of cardiotomy suction. No difference was found regarding renal function. We could conclude that CABG with CPB can be conducted safely without using cardiotomy suction and retransfusion of shed blood, as long as the surgeon is vigilant on the blood loss and prepared to use cardiotomy suction when needed.