The blood supply in the UK is one of the safest anywhere but it remains an expensive resource. The use of allogeneic transfusion has in recent years been re-evaluated due to concerns raised over the risks of transfusion transmitted infections, immunologic reactions and human error catastrophes. Recent attention has focused on the transmission of variant Creutzfeldt-Jakob Disease (vCJD). This is a rare and fatal human neurodegenerative condition which is transmitted by a prion from meat infected with BSE.
In 2004 a report published in The Lancet demonstrated that vCJD can be transmitted by blood transfusions1 and at the time of writing there have been four known such cases. This led the UK to exclude donors who have, or think they may have, received a blood transfusion since 1980 from donating blood. This step was implemented by all four of the UK Blood Services on 2nd August 2004.2
The increased cost of blood products, combined with the potential risk of transmission of disease and donor shortages, has been the driving force in medical circles to conserve blood supplies through the judicious use of allogeneic blood and to adopt alternatives to minimize patient exposure to the risks of such transfusions.
The use of red cell salvage techniques to complement a blood conservation program is accepted practice. This form of autologous blood transfusion involves the collection and re-infusion of the patient's own blood. Post operative cell salvage is a subtype of autologous blood transfusion. In this technique the blood from the operative site is collected post operatively through conventional drains and subsequently re-infused back to the same patient. This form of autologous blood transfusion is especially useful in joint replacement surgery such as total knee replacements and total hip replacements.
Total knee replacement (TKR) surgery can result in substantial blood loss.3 It is estimated that 50% of the true total loss occurs during the post-operative period which suggests salvage and re-infusion of shed blood presents an effective means of reducing the requirement for allogeneic blood.
A pilot study was conducted in a large district general hospital in the North East of England, that issues approximately 11,500 units of blood per annum. The hospital has an established and proactive transfusion team and has already successfully introduced intraoperative red cell salvage. It was decided to pilot the use of CellTrans™ (Summit Medical) autologous blood transfusion system.
Prior to the introduction of autologous blood transfusion systems, a preliminary study was undertaken to develop and validate criteria in order to target the use of the drains to patients most likely to benefit from their use. A study of 200 patients admitted for knee arthroplasty identified a transfusion rate of 26%. A total of 108 units of bank blood were used in this cohort, with a mean of 2 units per patient transfused. This equated to approximately £15,800 for the units of blood used. It was discovered the mean procedural drop in Hb was 4.8 g/dl (range 2.3 - 8.8 g/dl). This allowed the formulation of inclusion criteria for patients most likely to benefit from autologous drains.
Patients considered for inclusion in the pilot must
- be under the care of a Consultant Orthopaedic Surgeon with experience in blood conservation techniques and familiar with the CellTrans™ drain
- be undergoing bilateral or revision knee surgery
- be undergoing primary knee replacement where the pre-op Hb <50 g/l above the patient's individual transfusion trigger established by the anaesthetist
- be assessed for contraindication and consent gained by an anaesthetist who would decide on patient suitability.
In order to validate these criteria, the criteria were applied to the pre-study cohort. It was established that all of the transfused patients met the criteria. Of those meeting the criteria, 13% would have avoided transfusion. None of the patients who would have been excluded from receiving drains were transfused. Of the 200 patients studied, 35% met the criteria.
Prior to commencing the study, an operating policy was developed and ratified along with a data collection tool. Staff competencies were developed and ratified and education sessions were delivered by the manufacturer to 100 staff. A number of key trainers were identified and given appropriate training.
During the pilot period, 50 patients met the inclusion criteria and received autologous drains. Of this group, 33 underwent unilateral knee arthroplasty, 13 bilateral and 4 revision procedures. The mean volume of blood re-infused was 600 mls and the average procedural drop was 2.9 g/dl.
Evaluation of the pilot demonstrated a reduction in the overall transfusion rate from 26% to 3% with only 4 of the 50 patients requiring bank blood. This reduction was more dramatic in those undergoing bilateral and revision procedures where blood use was reduced from >95% to 12%. There were no adverse events noted in the pilot period, and staff were instructed not to reinfuse blood if there were any uncertainties regarding the procedure.
The cost of the blood used during the pilot combined with the additional cost of the drains was £6230. This represented a cost saving of £7500 when compared with the expected use of blood within this group.
The conclusions from the pilot were that:
- Post-operative autologous transfusion is a safe and efficient way to reduce patient's exposure to donor blood
- The use of drains directed at a target population is an appropriate strategy
The key factor in the successful introduction of post operative blood salvage is continued staff training
References
- Peden AH, Head MW, Ritchie DL, Bell JE, Ironside JW (2004). “Preclinical vCJD after blood transfusion in a PRNP codon 129 heterozygous patient”. Lancet. 2004, 364 (9433): 527-529
- National Blood Service http://www.blood.co.uk/pages/b10faq.html
- Lotke PA, Faralli VJ, Orenstein EM and Ecker ML. Blood loss after total knee replacement. Effects of tourniquet release and continuous passive motion. JBJS.1991:73,(7); 1037-1040.
