Prediction of transfusion requirements in surgical patients: a review

SUMMARY Preoperative estimation of transfusion requirements in patients scheduled for surgery is critical to optimize blood management, including costs, and to appropriately select patients who can benefit from alternatives to allogeneic blood transfusion. Three groups of methods for transfusion requirement prediction have been developed. The simplest methods are those that identify patients at risk of requiring transfusion support on the basis of the surgical procedure they are scheduled for and one or two clinical parameters. Preoperative hemoglobin concentration (or red blood cell mass) and age are the most reliable parameters that have emerged from the studies. A second group of methods includes approaches based on the calculation of a risk score obtained by totaling predefined values assigned to the presence or absence of a number of predictors proven to be relevant in affecting transfusion requirements in a given surgical setting. The third group is based on mathematical approaches that define transfusion requirements by comparing the two elements that determine them: the reduction in red blood cell mass induced by surgery (blood loss) and the maximum red blood cell mass that a patient, according to their clinical condition, can tolerate to lose. Experiences reported to date show these methods can all be helpful in clinical practice for predicting transfusion requirements in the individual patient. Selection of the strategy to be used depends on the precision required, the intended use and hospital organization.