Intraoperative minimal acute normovolemic hemodilution in patients undergoing coronary artery bypass surgery

Efficacy of minimal acute normovolemic hemodilution (ANH) in avoiding homologous blood transfusion during cardiovascular surgery remains controversial. Postoperative bleeding and transfusion remain a source of morbidity and cost after open heart operations. Our objective was to evaluate the impact of minimal ANH on blood transfusion requirements during open cardiovascular surgery using cardiopulmonary bypass (CPB).

This study was a randomized controlled trial. One hundred one patients scheduled for elective coronary artery bypass graft (CABG) under cardiopulmonary bypass in October 2007 through March 2008 in Imam Khomeini hospital were randomly assigned to a control group (standard care, no = 47) or an ANH or study group (no = 54). We used minimal ANH (representing 10% of patients' blood volume). Mean 490 +/- 50 mL of fresh autologous blood was removed after induction of anesthesia and reinfused at the end of CPB. The blood transfusion guidelines were uniformly applied to all patients.

Significant decrease in the number of red blood cell units transfused per patient per group (1.39 +/- 1.0 and 2.551.9 +/- units; p < 0.0001) in the ANH group versus the control group was observed. Conversely, chest tube output, postoperative hematocrits, and platelet count did not differ between two groups. Percentage of patients in whom allogeneic red blood cells were transfused was 44% in study group versus 76% in control group; (p < 0.01). No patient was transfused with platelet concentrates or fresh frozen plasma.

Minimal ANH is safe and cost effective and its routine use in eligible patients is therefore justified. Intraoperative autologous blood donation in CABG surgery decreased perioperative allogeneic blood requirement. However, the removal and reinfusion of about one unit autologous blood had no effect on postoperative bleeding or platelet count.