Scientific Article

Predicting Blood Usage in Cardiac Surgery—The Transfusion Predictor Product

Address correspondence to: Mr. Michael McDonald, Perfusion Services, Unit 2, 91 Tulip Street, Cheltenham, Victoria, 3192, Australia. E-mail: mmcdonald@perfusionservices.com.au.

Abstract

Blood cross-matched for patients undergoing cardiac surgery is used infrequently and represents a significant cost. We investigated the ability to predict the need for intraoperative transfusion. We hypothesized that red blood cell volume is a predictor because dilution is the primary cause for transfusion requirement intraoperatively. A total of 401 consecutive patients having cardiothoracic surgery requiring the use of cardiopulmonary bypass were retrospectively analyzed by revision of their perfusion record. This sample included 82% elective, 17% urgent, and 1% emergency procedures. The product of body surface area and preoperative hemoglobin gave us gHb/l/m², which are the units of the Transfusion Predictor Product (TPPu). Mean patient age was 66.9 ± 10.7 years, and 112 (28%) were women. Mean TPP was 257.2 ± 45.5^u. 52 patients (13%) received red blood cells intraoperatively. At less than TPP 211.7^u, one standard deviation below the mean value, 32 patients of 69 (46%) received blood transfusion intraoperatively (p < 0.001). At a TPP greater than 211.7^u, 20 patients of 322 (6%) had blood transfusion intraoperatively. Patients with a TPP > 211.7^u do not require routine cross-matching of blood. Cross-matching for these patients should be individualized on the basis of predicted duration of CPB and/or other types of patient comorbidity.