Background

In the literature are different data about the allogenic blood transfusion rate after total knee replacement. The common intention in orthopedic surgery is to reduce the requirement for allogenic blood transfusions by optimizing the blood management. The aim of this study is to determine the efficacy of the mechanical autotransfusion system OrthoPAT® to reduce the postoperative allogenic blood transfusion (ABT) rate.

Background: In the literature are different data about the allogenic blood transfusion rate after total knee replacement. The common intention in orthopedic surgery is to reduce the requirement for allogenic blood transfusions by optimizing the blood management. The aim of this study is to determine the efficacy of the mechanical autotransfusion system OrthoPAT (Haemonetics Corp., MA, USA) to reduce the postoperative allogenic blood transfusion rate.

Method: According to the preliminary performed power analysis we did a prospective controlled study including 104 patients which were randomized in a group A (OrthoPAT for intra- and postoperative blood salvage and retransfusion, n = 52 patients) and a control group B (no retransfusion system was used, n = 52 patients) All patients had a primary osteoarthritis of the knee and were operated on without use of a tourniquet. We implanted in all patients a cemented posterior stabilized total knee prosthesis design (LPS-Flex Mobile, Zimmer, IN, USA). In group A the autotransfusion system was used for 6 hours (intra- and postoperatively) and the collected blood was retransfused. The retransfused blood is anticoagulanted, filtered and centrifuged to separate waste products. Red cells are washed with saline and reconcentrated to a high haematocrit. The preoperative data for cardiopathy, angiopathy, preoperative anemia or anticoagulant treatment showed no significant differences for group A and B. Because of missing data we finally were able to use the results of 98 patients: 48 group A and 50 in group B. The indications for a blood transfusion were influenced by the clinical symptoms of anemia, the hemoglobin value (hemoglobin < 8.0 g/dl) and the anamnesis of cardiovascular diseases. Evaluation was done with the medical history and the pre-/postoperative hemoglobin values, postoperative blood loss and postoperative need of allogenic blood transfusion.

Results: The two groups showed no significant differences relating to the demographic data or the medical history. 16 patients (33 %) of the retransfusion group who in mean received 281 ml of salvaged blood needed allogenic blood transfusion compared with 22 patients (44 %) of the control group B (p = 0,306). The hemoglobin values of group A versus the control group showed after the donation of the salvaged blood a significant difference (p = 0,027) but no longer at the 3rd and 5th day postoperative.

Conclusions: The use of the autotransfusion system seems to reduce the postoperative allogenic blood transfusion rate but not statistical significant. At the 3rd and 5th day postoperatively no significant differences of the hemoglobin values could be stated comparing group A with group B. For us this was a clue showing that the quality of the erythrocytes after the reclamation was reduced.