The Effect of Normothermic Cardiopulmonary Bypass on Postoperative Bleeding in CABG

Background- CABG is the most common type of cardiac surgery which generally is done under cardiopulmonary bypass (CPB). Hypothermic CPB was introduced in cardiac surgery in order to protect organs against hypoperfusion. Hypothermia is associated with many adverse effects on the vital organs, which result in impairment of organ and systemic function. Normothermia on the other hand is more in agreement with the physiology of human organs. The aim of this study is to evaluate the effect of body temperature during CPB on postoperative bleeding. Methods- One hundred patients were randomized into normothermic (35-37o C, N=50) and mild hypothermic (28-32o C, N=50) CPB groups and compared with respect to blood loss, transfusion requirements and platelet level in primary coronary artery bypass grafting. The patients’ hemoglobin levels, leukocyte counts and platelet counts were measured before operation, immediately upon arrival in the intensive care unit, 4 hours afterwards and 6 days after surgery. The volume of blood shed through mediastinal and pleural drainage tubes were recorded at 6, 12 and 24 hours after operation. Results- There were no differences in preoperative characteristic including patient age, sex, number of occluded vessels, weight, height, hemoglobin and hematocrit level, platelet and WBC levels. Normothermic patients tended to bleed less at 24 hours (warm, 288±30ml vs. cold, 580±100ml). Platelet levels were preserved better in normothermic patients than in hypothermic patients. The warm group had a reduced blood loss by 40 percent after 6, 34% after 12 and 30% after 24 hours as compared with blood loss in hypothermical ly-perfused patients. Conclusion- These data suggest that normothermic systemic perfusion reduced postoperative blood loss and preserved platelets (Iranian Heart Journal 2006; 7 (2):31-36).