Some patients who undergo surgery require blood transfusions to compensate for the blood loss that occurs during the procedure. Often the blood used for the transfusion has been donated by a volunteer. The risks associated with receiving volunteer donor blood that has been screened by a competently managed modern laboratory are considered minimal, with the risk of contracting diseases such as HIV and hepatitis C being extremely low. However there is concern in many developing countries, where there is a high prevalence of such infections and transfusion services are inadequately equipped to screen donor blood as thoroughly. Although in developed countries the risks of acquiring a disease from transfused blood are low, the financial costs associated with providing a safe and reliable blood product are escalating. Therefore there is much attention being placed on alternative strategies to minimise the need for transfusions of donor blood.
'Cell salvage' or 'autotransfusion' is one technique designed to reduce the use of such transfusions. It involves the collection of a patient's own blood from surgical sites which can be transfused back into the same person during or after surgery, as required.
The authors undertook this systematic review to examine the evidence for the effectiveness of cell salvage in reducing the need for blood transfusions of donor blood in adults (over 18 years) undergoing surgery.
The authors found 75 studies investigating the effectiveness of cell salvage in orthopaedic (36 studies), cardiac (33 studies), and vascular (6 studies) surgery. Overall, the findings show that cell salvage reduces the need for transfusions of donated blood. The authors conclude that there appears to be sufficient evidence to support the use of cell salvage in cardiac and orthopaedic surgery. Cell salvage does not appear to cause any adverse clinical outcomes.
As the methodological quality of the trials was poor, the findings may be biased in favour of cell salvage. Large trials of high methodological quality that assess the relative effectiveness, safety, and cost-effectiveness of cell salvage in different surgical procedures should be the focus of future research in this area.
The results suggest cell salvage is efficacious in reducing the need for allogeneic red cell transfusion in adult elective cardiac and orthopaedic surgery. The use of cell salvage did not appear to impact adversely on clinical outcomes. However, the methodological quality of trials was poor. As the trials were unblinded and lacked adequate concealment of treatment allocation, transfusion practices may have been influenced by knowledge of the patients' treatment status potentially biasing the results in favour of cell salvage.
Concerns regarding the safety of transfused blood have prompted reconsideration of the use of allogeneic (from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques to minimise transfusion requirements.
To examine the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.
We identified studies by searching CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1950 to June 2009), EMBASE (1980 to June 2009), the internet (to August 2009) and bibliographies of published articles.
Randomised controlled trials with a concurrent control group in which adult patients, scheduled for non-urgent surgery, were randomised to cell salvage (autotransfusion) or to a control group who did not receive the intervention.
Data were independently extracted and the risk of bias assessed. Relative risks (RR) and weighted mean differences (WMD) with 95% confidence intervals (CIs) were calculated. Data were pooled using a random-effects model. The primary outcomes were the number of patients exposed to allogeneic red cell transfusion and the amount of blood transfused. Other clinical outcomes are detailed in the review.
A total of 75 trials were included. Overall, the use of cell salvage reduced the rate of exposure to allogeneic RBC transfusion by a relative 38% (RR 0.62; 95% CI 0.55 to 0.70). The absolute reduction in risk (ARR) of receiving an allogeneic RBC transfusion was 21% (95% CI 15% to 26%). In orthopaedic procedures the RR of exposure to RBC transfusion was 0.46 (95% CI 0.37 to 0.57) compared to 0.77 (95% CI 0.69 to 0.86) for cardiac procedures. The use of cell salvage resulted in an average saving of 0.68 units of allogeneic RBC per patient (WMD -0.68; 95% CI -0.88 to -0.49). Cell salvage did not appear to impact adversely on clinical outcomes.