Post-operative outcomes of CABG patients given blood transfusion based on Society of Thoracic Surgeons Guidelines on Blood Transfusion.

Background. The worldwide practice in cardiac surgery regarding blood transfusion is towards a more conservative approach. The aim of the present study is to compare the postoperative outcome in terms of mortality and duration of mechanical ventilation among patients undergoing first-time CABG using the STS Guidelines' threshold in transfusion and the current practice at PHC.

Methods. All adult patients aged 18-65 years undergoing elective cardiac surgery including
aortocoronary bypass, heart valve replacement and correction of congenital cardiac anomaly at the Philippine Heart Center starting September 2008 until August 2009 were included in the study. Patients were randomized to Group 1, Restricted group and Group 2, Liberal group. Decisions regarding intraoperative and post-operative blood transfusion for the Liberal group were made by the attending surgeon and anesthesiologist. For the Restricted Group, decisions on blood transfusion were based on the STS Guidelines that is packed red cells will only be transfused for hemoglobin values less than 7 gm/dl. Postoperative outcome in terms of duration of mechanical ventilation and mortality were evaluated.

Results. A total of 71 patients were enrolled in the study. Thirty-four were randomly assigned to the restricted transfusion group and 37 to the liberal transfusion group. The average age of patients included in the restricted group was 44 years while patients of the liberal group had an average age of 47 years. Pre-operative factors were homogenous for both groups. Preoperative hemoglobin and hematocrit values were significantly higher for the restricted group. The amount of packed red cells transfused was significantly higher in the liberal group, 2.35 ± .53 units, compared to the restricted group, 0.18 ± 0.75 units. (p-value = 0.00.) Comparison of mediastinal drainage revealed lesser amount in the restricted group, 132.21 ± 63.10 ml, than the liberal group, 195.27 ± 81.10 ml (p-value= 0.01). Duration of mechanical ventilation was shorter among the restricted group with only 14.7% requiring >48 hours of MV compared to 43.24% for the liberal group (p value=0.18). Mediastinal chest tubes were removed earlier in the restricted group with only 11.76% having CT >48 hours compared to 45.94% patients in the liberal group, (p value=O.OO). Other outcome variables such as post-op dialysis, inotropic support >48hrs, sepsis, arrhythmia and hospital stay was not different for both groups. Nomortality was recorded for both groups.

Conclusion. Adherence to the STS Guideline recommendation of 7gm/dL cut-off for PRBC transfusion may benefit the patient in terms of lesser mediastinal drainage, shorter duration of mechanical ventilationand earlier removal of chest tubes. No mortality was noted for both groups.