Hypothermic Cardiopulmonary Bypass in CABG surgery, it is the time to revise our protocols

Background: Hypothermia during coronary artery bypass grafting (CABG) procedures using cardiopulmonary bypass (CPB) technique is a defensive maneuver. Since most surgeons worldwide are accustomed to the use of "mild" hypothermia for such procedures, this study hope to discover whether "moderate" hypothermia had a more significant impact on lowering tissue oxygen consumption during cardiac surgery, taking into account that the risks of exposing the patient to "mild" hypothermia are similar to the risks of moderate hypothermia. Furthermore, the study sought to weigh the benefits of "mild" hypothermia against those of normothermia with regards to their impact on tissue oxygen consumption. purposes: To evaluate the total body oxygen consumption under different ranges of body temperature during surgery performed with the aid of CPB, ending with recommendations regarding the range of temperature that yield a preferential clinical outcome as a result of lower oxygen consumption. Methods: between December 2014 and April 2015, 70 consecutive patients (55 males and 15 females), undergoing coronary artery bypass grafting surgery (CABG), allocated into three groups regarding the core temperature (Group 1 with normothermia 35-37°C, Group 2 with mild hypothermia 32-35°C, Group 3 with moderate hypothermia 28-32°C). Results: There were no significant changes in Group 1 and Group 2 during CPB, however, for Group 3, there was a remarkable decrease in the oxygen consumption (VO2). Conclusions: Moderate hypothermia rather than mild hypothermia proves to be of more benefit to the tissues when compared to normothermic conditions, as it significantly reduces tissue oxygen consumption. Moreover, even normothermia was found to be superior to mild hypothermia due to the latter’s adverse effects while maintaining similar results with regards to oxygen consumption.