Predictors of transfusion risk in elective knee surgery

Two hundred seventy-nine patients undergoing primary unilateral total knee replacement and 280 patients undergoing primary bilateral total knee replac ements were reviewed retrospectively. Patients' height, weight, hemoglobin level before donation, hemoglobin level before surgery, autologous donation , number and type of transfusions whether autologous or allogeneic, and hem oglobin at discharge were collected from hospital and clinic records. The a verage drop in hemoglobin was 3.85 g/dL in the group of patients undergoing unilateral total knee replacement and 5.42 g/dL in the group of patients u ndergoing bilateral total knee replacements. The preoperative hemoglobin an d blood volume seemed to be very strong, statistically significant predicto rs of transfusion risk in single and bilateral knee replacements, In unilat eral total knee replacement, patients with a hemoglobin of greater than 13 g/dL had only an 8% chance of transfusion and if they donated autologous bl ood, 66% of the blood was wasted, Preoperative anemia was a strong predicto r of transfusion risk in patients undergoing unilateral and bilateral total knee replacements and carried a very high allogeneic transfusion exposure risk, even in patients who had donated blood preoperatively. A nomogram was developed using blood volume and predonation hemoglobin to predict transfu sion risk and need to predeposit autologous blood in patients undergoing un ilateral and bilateral total knee replacements.