Acute normovolemic hemodilution (ANH) is recognized as the easiest, the most economical and valuable autologous blood saved method among the types of autotransfusion. We studied whether this method could reduce the transfusion requirement of allogenic blood in total knee arthroplasty to investigate the efficacy of ANH.

The thirty patients were randomized and divided into two groups. In the ANH group (n = 15), 2 units of autologous blood were procured from a CVP catheter immediately before or after anesthetic induction, while Ringer's lactate and colloid solution were infused to maintain normovolemia via a different venous catheter. Perioperative changes of hemoglobin, hematocrit, platelets, prothrombin time (PT), transfusion requirements and the amount of postoperative drainage were compared.

There were no significant difference between the two groups in terms of perioperative changes of hemoglobin, hematocrit or platelets. And, there was significantly reduced demand for packed RBC transfusion in the ANH group (362.7±236.4 ml) compared with the control group (668.0±259.3 ml) (P <0.05). However, no significant difference was observed between the two groups in terms of postoperative drainage amount.

ANH can reduce transfusion requirements in total knee arthroplasty surgery if this is accompanied by appropriate patient selection and monitoring.