REDUCTION OF ALLOGENEIC BLOOD-TRANSFUSIONS AFTER OPEN-HEART OPERATIONS BY LOWERING CARDIOPULMONARY BYPASS PRIME VOLUME

Background. Despite recent advances in blood conservation techniques, up to 30% to 80% of patients undergoing open heart operations require allogeneic blood transfusions. A prospective, randomized study was per formed to test the effect of lowering cardiopulmonary bypass prime vol ume (as an additional component of an integrated blood conservation st rategy) on clinical outcome and allogeneic blood transfusion. Methods. One hundred fourteen patients undergoing open heart operations were r andomized to either full prime (FP) volume (1,400 mL of Plasmalyte sol ution) or reduced prime (RP) volume (600 to 890 mL). The reduction of prime volume was achieved by slowly draining the cardiopulmonary bypas s circuit into a cell-saving device before the initiation of bypass. F irm transfusion thresholds were observed. Results. There were no signi ficant differences between the groups with respect to baseline charact eristics, body surface area, type and urgency of the procedures, perfu sion technique, and hematologic profile. Mortality (FP, 1.7%; RP, 0%; p approximate to 1.0) and overall morbidity (FP, 28.1%; RP, 22.8%; p = 0.53) were similar However, transfusion requirements were significant ly lower in the RP group: total donor exposure, 3.8 +/- 10.1 versus 1. 0 +/- 2.4 units (p = 0.044); percentage of patients transfused, 54% (n = 31) versus 35% (n = 20) (p = 0.036). Twenty-four-hour chest tube dr ainage was similar: 455 +/- 223 mt far FP versus 472 +/- 173 mt for RP (p = 0.66). The lowest hematocrit on bypass was significantly higher in the RP group: 29.3% +/- 4% versus 26.3% +/- 5.3% (p = 0.009). Concl usions. Lowering cardiopulmonary bypass prime volume resulted in a sig nificant decrease in allogeneic blood product use. because postoperati ve 24-hour chest tube drainage was similar in both groups, and hematoc rit during bypass was higher in the RP group, the reduction in allogen eic blood transfusions appears to be related to a decrease in prime-in duced hemodilution, this technique is effective, simple, and safe. It therefore should be strongly considered for patients undergoing operat ions using normothermic or near-normothermic cardiopulmonary bypass wh o are at high risk for allogeneic blood transfusion. (C) 1998 by The S ociety of Thoracic Surgeons.