Howe et al developed an equation for predicting the change in hemoglobin associated with perioperative blood loss in orthopedic surgery. The goal is to prevent unnecessary transfusion by helping surgeons gauge the degree of blood loss. The authors are from the University of North Dakota in Grand Forks, North Dakota.

(1) estimated blood loss in liters

(2) intravenous fluids administered in liters (crystalloids)



• It does not appear that patients were transfused perioperatively. If blood is given, it can be accounted for by assuming 1 unit will raise the hemoglobin 1 g/dL in the adult.


change in hemoglobin in g/dL (preoperative minus postoperative hemoglobin) =

= (1.001 * (estimated blood loss in liters)) + (0.441 * (liters of intravenous fluids administered)) + 2.334



• In adult orthopedic surgery patients the estimated change in hemoglobin correlated with the actual change observed.

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