Correlates of preoperative hematocrit value in patients undergoing coronary artery bypass.

The patient's preoperative red cell volume and hematocrit value are among the strongest predictors of need for postoperative transfusion. We have determined the factors that correlate with preoperative hematocrit value. We performed multiple regression analysis with preoperative hematocrit value as the dependent variable. The factors that were significantly correlated with preoperative hematocrit value, in order of their decreasing contribution to variability, were sex, date of operation, preoperative hospital stay, weight, left ventricular end-diastolic pressure, age, smoking history, and recent myocardial infarction (less than 6 weeks). Factors that did not contribute significantly to predicting preoperative hematocrit value included ejection fraction, emergency operation, previous streptokinase use, number of coronary arteries diseased, body mass index (obesity), diabetes, height, body surface area, and history of percutaneous transluminal coronary angioplasty. The patient most likely to have a low preoperative hematocrit value can be characterized as a small, elderly, female nonsmoker with a recent myocardial infarction and elevated left ventricular end-diastolic pressure. The prevalence of low preoperative hematocrit value is increasing with time independent of other factors.