Objective: To determine total blood loss and transfusion requirements during primary total hip replacement (THR) surgery; and, to identify predictors of increased blood loss.
Methods: This was a prospective cohort study of 295 consecutive patients undergoing primary THR at a 700-bed teaching hospital in Boston, Massachusetts. The main outcome measures were the total blood loss, which was defined (in units) as the initial hematocrit minus final hematocrit divided by 3 plus the number of units transfused, and the number of autologous and homologous units of blood transfused.
Results: The mean total blood loss was 3.6 units, and the mean total units transfused was 2.1. Univariate predictors of greater total blood loss (at P < 0.05) included being male, receiving general anesthesia, and higher American Society of Anesthesiologists (ASA) class. In multiple linear regression models which controlled for demographic and clinical variables (age, race, marital status, education, smoking history, obesity, underlying disease, payor status, cemented prosthesis, comorbidity, and season of operation), being male, receiving general anesthesia, and having an ASA score of 3 predicted greater total blood loss.
Conclusion: Preoperative characteristics can help determine which patients should donate either more or less than the customary 2 units of blood.