A RANDOMISED PROSPECTIVE STUDY OF POST OPERATIVE BLOOD SALVAGE WITH AUTOLOGOUS RETRANSFUSION IN PRIMARY TOTAL HIP REPLACEMENT

Abstract

The rate of homologous blood transfusion (HBT) following primary total hip replacement (THR) can be as high as 30–40% and is not without risk. Postoperative blood salvage (POS) with autologous blood transfusion may minimize the necessity for HBT but the clinical, haematological and economic benefits have yet to be clearly demonstrated for primary THR.

The aim of this randomized prospective study was, therefore, to determine if the use of post-operative salvage affects post-operative haemoglobin and haematocrit values and reduces the rate of homologous blood transfusion. Secondary outcome measures included length of hospital stay and patient satisfaction. A cost analysis was also conducted on the basis of the results obtained.

The patients were randomized during the operation (at the point of reduction of the primary THR) to receive either two Medinorm vacuum drains or the autologous retransfusion system. A power calculation estimated that 72 patients would be required in each group to detect a significant difference of 0.7 gdL-1 in post operative haemoglobin level (at 80% power with an value of 0.05). This assumed a standard deviation of 1.5 gdL-1 obtained from a previous retrospective study.

There were 82 patients in the Medinorm vacuum drain group and 76 patients in the autologous retransfusion group. In the group with the autologous system, 76% of the patients were retransfused with a mean of 252mls. There was no significant difference between the groups when comparing haemoglobin and haematocrit values. However, significantly fewer patients in the group with the autologous system had a postoperative haemoglobin value less than 9.0 gdL-1 (8% vs. 20%, p = 0.035). Furthermore, significantly fewer patients with the autologous retransfusion system required a transfusion of homologous blood (8% vs. 21%, p = 0.022). There was a small overall cost saving in this group.

This study has shown that use of an autologous retransfusion system for primary THR reduces the necessity for HBT and is cost effective. POS also results in significantly fewer patients dropping their post-operative haemoglobin level below 9.0 gdL-1. As a result our unit routinely uses the autologous retransfusion system for primary THR.