Acute normovolaemic haemodilution decreases postoperative allogeneic blood transfusion after total knee replacement

We hypothesized that the success of postoperative blood conservation afteracute normovolaemic haemodilution (NVHD) is influenced by the extent ofintraoperative bleeding and surgical trauma, and the timing of autologousblood transfusion. As total knee replacement is associated with minimalintraoperative but extensive postoperative blood loss, this procedure isideally suited to acute NVHD. Therefore, to test our hypothesis, 30patients undergoing elective total knee replacement were enrolled in aprospective, randomized, controlled study. In groups NVHD-2 and NVHD-6,before induction of anaesthesia patients were bled to a target packed cellvolume (PCV) of 28-30%, and in the post-anaesthesia care unit autologousblood was transfused over a 2-h period terminating after operation at 2 and6 h, respectively. In the control group, NVHD was not performed. Afteroperation, platelets, fibrinogen, prothrombin and partial thromboplastintime, and liver function, urea and electrolytes were measured and comparedwith preoperative baseline values. Significantly (P < 0.024) moreallogeneic blood was transfused in the control group (21 u.) compared witheither group NVHD-2 (7 u.) or group NVHD-6 (5 u.). In the control group,despite the allogeneic blood transfusion, postoperative PCV decreased untilday 4 after operation. Coagulation profile, liver function and urea andelectrolytes concentrations were unaffected by the method of treatment. Weconclude that for total knee replacement, acute NVHD is an effective bloodconservation strategy. However, there was no difference in allogeneic bloodadministration between the two NVHD groups. Coagulation and liver function,and urea and electrolyte concentrations were unaffected by treatment.