Blood Loss During Hip and Knee Replacement Surgery

During the course of providing perioperative consultation for patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA), I've been struck by the discordance between measured intraoperative blood loss and the sometimes striking fall in the patient's hemoglobin level. In this U.K. study of 101 patients who underwent THA and 101 who underwent TKA, researchers estimated this "hidden" blood loss by calculating the perioperative change in blood volume and adjusting for measured blood loss and transfusions.

For TKA (usually performed with tourniquet), mean hemoglobin level fell from 13.9 to 10.9 g/dL; mean total blood loss was 1498 mL, of which 765 mL was hidden. For THA, mean hemoglobin level fell from 13.5 to 10.5 g/dL; m…