Comparison of blood reinfusion techniques used during coronary artery bypass grafting

A comparison of intraoperative autologous blood conservation techniques was carried out in 100 patients undergoing coronary artery bypass grafting. To facilitate comparisons of similar groups, patients were stratified into high-risk and low-risk groups based on the ratio of preoperative bleeding time to preoperative red blood cell volume. Our previous work suggested that patients with an elevated ratio have increased risk of excessive postoperative blood transfusion. We used this ratio to stratify the 100 patients to either the high-risk (39 patients) or low-risk (61 patients) strata. Within each stratum, patients were randomized to one of three groups: no intraoperative autologous blood conservation (control group), infusion of autologous platelet-rich plasma obtained from intraoperative plasmapheresis (PRP group), and infusion of autologous whole blood harvested immediately before cardiopulmonary bypass (whole blood group). Variables of postoperative blood loss and transfusion requirements were measured in each patient. Analysis of variance showed significant differences in blood product transfusions between groups. Patients in the high-risk stratum required significantly more blood product transfusions than those in the low-risk stratum (5.4 ± 0.7 versus 2.0 ± 0.6 units per patient; p < 0.001). In the high-risk stratum, PRP patients required significantly less postoperative blood transfusion compared with patients in the high-risk control group (2.9 ± 2.1 versus 8.1 ± 2.2 units per patient; p = 0.05). In the low-risk stratum, no intraoperative blood infusion method resulted in significant improvement in postoperative blood use. We conclude that intraoperative autologous blood reinfusion methods are not helpful in low-risk patients but, for high-risk patients, infusion of autologous PRP is associated with significantly less postoperative blood transfusion. This suggests that the added cost of intraoperative autologous blood conservation techniques is justified in patients at high risk for excessive postoperative blood transfusion but not in patients at low risk.