Preoperative blood volume deficit influences blood transfusion requirements in females and males undergoing coronary bypass graft surgery

Study Objective: To evaluate whether preoperative blood volume and postoperative blood loss influence blood transfusion in females and males undergoing coronary artery bypass graft (CA-BG) surgery. Design: Prospective study. Setting: Anesthesiology department of a teaching hospital. Patients: 57 CABG patients (21 females and 36 males). Measurements: Blood volume was determined using the radioactivity dilution method. Preoperatively, each patient received intravenous (IV) injection of 1 mL Albumin I-131 tracer having 25 microcuries of radioactivity. Five-milliliter blood samples were collected at different intervals. From these samples, hematocrit (Hct) value, preoperative total blood volume, red blood cell (RBC) volume, and plasma volume were determined. Postoperatively, some consenting patients received another 1 mL dose of the tracer, and the postoperative blood volumes were determined. If a patient received a blood transfusion, the units of packed red blood cells (PPLBCs), platelets, or fresh frozen plasma (FFP) transfused were recorded. For each patient we recorded the gender, age, weight, height, body surface area (BSA), preoperative Hct, duration of surgery, and discharge Hct. Results: Preoperatively, the mean total blood volume, RBC volume, and plasma volume, respectively, were 2095 mL/m(2), 631 mL/m(2), and 1, 465 mL/m(2) in females, and 2,580 mL/m(2), 878 mL/m(2), and 1, 702 mL/m(2) in males. The preoperative blood volumes were significantly lower (p < 0.01) in females than in males. There was no significant difference between males and females in the extent of blood loss during CABG. Intraoperatively, females received PRBC transfusion of 1.38 units, significantly more (p < 0.01) than the 0.39 units received by males. During the entire hospital stay, females received 4.33 units of PRBC, significantly more than (p < 0.02) the 1.33 units received by males. Significantly more (p < 0.01) females (12 of 21) received intraoperative PRBC transfusion than did males (6 of 36). Multiple logistic regression analysis of the data showed that PRBC transfusion was significantly correlated with the preoperative total blood volume and RBC volume. Conclusion: The greater need for blood transfusion in females than in males during CABG is primarily attributable to significantly lower preoperative total blood volume and RBC volume in females. (c) 2002 by Elsevier Science Inc.