Blood is a costly commodity with side-effects that can be avoided by eliminating unnecessary transfusion. The purpose of this study was to prospectively audit the amount of blood we were transfusing in elective joint surgery and to then institute a new, more scientifically based post-operative protocol to see if we could reduce our transfusion requirements.

We prospectively audited 79 patients undergoing primary knee or hip arthroplasty (38 knees and 41 hips) in our unit and found that 66% (58% of knees and 73% of hips) had at least one unit of blood transfused postoperatively, with a mean transfusion requirement of 1. 3 units per patient (1. 1 for knees, range 0–6; 1. 5 for hips, range 0–4).

We then devised a new protocol for post-operative blood transfusion. This new protocol requires the calculation of the volume of blood that each individual patient can safely lose (maximum allowable blood loss – MABL) based upon their weight and pre-operative haematological indices. Total blood loss up to this volume is replaced with colloid. In the first 24 hours, if a patient’s total blood loss reaches their MABL they have their haematocrit measured at the bedside using the Microspin™ system. If their haematocrit is low (< 0. 30 for males, < 0. 27 for females) they are transfused blood. We set our ‘transfusion trigger’ after the first 24 hours at 8. 5 g/dl. Blood is transfused if the formal haemoglobin check on days 1, 2 or 3 is less than this.

We conducted a further audit of 82 patients (35 knees, 47 hips) following the institution of this protocol. Under the new protocol only 24% of patients required blood (11 % of knees, 34% of hips) with a mean transfusion requirement of 0. 56 units per patient (0. 26 for knees, range 0–4; 0. 79 for hips, range 0–4).

The use of clinical audit and the institution of strict guidelines for transfusion can effectively change transfusion practice and result in the delivery of improved patient care. Our transfusion protocol is a simple and effective method of keeping blood transfusion to a minimum and is particularly useful in a unit that does not have the facility to use autologous blood or re-infusion drains for elective orthopaedic surgery.