Postoperative bleeding is a common sequela of hypothermic cardiopulmonary bypass (CPB). Although normothermic CPB has been proposed to decrease postoperative coagulation problems, other studies have disputed this. This study was aimed at comparing the hemostatic parameters, postoperative bleeding and blood transfusion requirements between patients who underwent coronary artery bypass graft (CABG) surgery under normothermic CPB and those who underwent CABG under hypothermic CPB.
We reviewed the hospital records of 45 patients who underwent normothermic CPB (Group 1) and 178 patients who underwent hypothermic CPB (Group 2) at the Philippine Heart Center from January 2001 to December 2002. The two groups were comparable in terms of demographic criteria and clinical profile. The mean ages for Group 1 and Group 2 were 60 and 62 years, respectively. Male preponderance, NYHA functional class, LV ejection fraction, history of myocardial infarction, presence of smoking history, hypertension, diabetes and dyslipidemia were similar. Perioperative data revealed a higher percentage of usage of the left internal mammary artery (97% vs. 77%, p=0.002) and a greater number of grafted coronary vessels (3.67 vs. 3.23, p=0.023) in the hypothermic group (Group 2). The mean temperature was 34.55°C for Group 1 and 28°C for Group 2. The aortic cross clamp time was similar in the two groups but the CPB time was shorter in Group 1 (134 minutes vs. 164 minutes, p0.001. Postoperative hemostatic parameters were similar, except for a slightly higher PTT in Group 2 (42.65 vs. 46.95, p=0.02). Total chest tube drainage was not significantly different between the two groups. Blood transfusion requirements were similar between the two groups except for a greater number of fresh whole blood units transfused in Group 1 (2.91 units vs. 1.6 units, p=0.002).
In summary, the use of normothermic CPB did not significantly alter the postoperative hemostatic parameters, postoperative blood loss and blood transfusion requirement compared to hypothermic CPB. However, normothermia was associated with a shorter duration of CPB.