A prospective audit of blood usage post primary total knee arthroplasty.

The use of allogeneic blood is associated with many complications. A baseline audit performed in our institution in 2000 showed that 11% of patients undergoing primary total knee arthroplasty (TKA) required post-operative transfusion. Following this audit, patients undergoing primary TKA were no longer routinely cross matched, a Haemovigilance Nurse was employed in compliance with the National Blood Users Group guidelines, and post-operative cell salvage was introduced for patients with a preoperative haemoglobin level of less than 12 g/dl. A prospective audit was then performed over a nine month period, from 1st January to 30th September 2003, to assess the impact of these changes on our transfusion practice. Data was collected on 233 patients who had primary TKA performed during the period of our prospective audit. Patients were transfused if their blood loss exceeded a pre-calculated maximal allowable loss, or based on a 48 hour post-operative haemoglobin level. Seventeen of the 233 patients (7 %) received allogeneic blood. The average amount received was two units. Pre-operative anaemia and advanced patient age were predictive for increased risk of transfusion. Thirty six per cent of patients who were given a cell saver did not collect sufficient blood for re-transfusion. Ten per cent required further transfusion with allogeneic blood. There was no statistically significant difference in either the percentage of patients transfused or the volume of blood given to each patient between the two periods of audit. We did not find post-operative cell salvage to be an effective method of reducing allogeneic blood use.