A safe, simple and cost-effective protocol for blood transfusion in primary total knee replacement

Patients undergoing total knee replacement (TKR) in the UK usually have either blood cross-matched or have an auto-transfusion of drained blood postoperatively. A previous retrospective audit of blood requirements in patients who had undergone primary TKR showed that a large amount of cross-matched blood was wasted as the CT ratio (ratio of number of units of blood cross-matched to number of units transfused) of 4.9:1 was obtained. The range recommended by the Blood Transfusion Society is 2:1 to 3:1.

A protocol was introduced to group and save plus antibody screen for all patients and to cross-match 2 units of blood pre-operatively in patients with either a haemoglobin of less than 12.5 g/dl or with multiple red cell antibodies in their blood. The trigger point for blood transfusion postoperatively was also reduced from 9.0 g/dl to 8.0 g/dl, unless the patient was clinically symptomatic.

A further prospective study involving 50 patients was carried out using the new protocol. Five patients required cross-matching pre-operatively, three with haemoglobin less than 12.5 g/dl and two with multiple red cell antibodies. Postoperatively, the patients with haemoglobin of less than 12.5 g/dl required blood transfusion of 2 units each, reducing the CT ratio to 1.7:1. The patients with red cell antibodies did not require a blood transfusion.

The benefits from above protocol are 2-fold: patient safety, as risks of transfusion are avoided; and cost saving, in regards to haematology technician time and auto-transfusion sets which cost around pound 70 each.