Findings and Conclusion To our knowledge , this is the first meta- analysis to compare the clinical results between PAT and a control in joint replacement patients .
This meta- analysis has proven that the use of a PAT reinfusion system reduced significantly the dem and for ABT , the number of patients who require ABT and the cost of hospitalization after total knee and hip arthroplasty .
This study , together with other previously published data , suggests that PAT drains are beneficial .
Background Total hip or knee arthroplasty is an elective procedure that is usually accompanied by substantial blood loss , which may lead to acute anemia .
As a result , almost half of total joint arthroplasty patients receive allogeneic blood transfusions ( ABT ) .
Many studies have shown that post-operative auto-transfusion ( PAT ) significantly reduces the need for  ABT  , but other studies have question ed the efficacy of this method .
Effect of autologous salvaged blood on postoperative natural killer cell precursor frequency
BACKGROUND Immunosuppression after major surgery increases the risk of infections . Natural killer cells play a pivotal part in defence against infection . We aim ed to investigate the immunomodulatory effects of different types of postoperative blood transfusion by use of a new assay for measuring the frequency of peripheral blood natural killer precursor cells ( NKpf assay ) . METHODS We measured the natural killer cell precursor ( NKp ) frequency before and 5 days after surgery in 120 patients undergoing joint replacement surgery . The patients were assigned to one of five groups according to the type of transfusion received : non-transfused ( n=32 ) , allogeneic non-leukodepleted blood ( eight ) , allogeneic leukodepleted blood ( 30 ) , autologous predeposited blood ( ten ) , and autologous salvaged blood collected within the first 24 h after surgery ( 40 ) . We also measured interferon gamma and interleukin 10 concentrations before and after surgery . FINDINGS The mean postoperative NKp frequency for all patients was lower than the preoperative values , except in patients receiving autologous salvaged blood , which was higher than all other groups ( p<0.0001 ) . Postoperative NKp frequencies for patients receiving allogeneic or autologous predeposited blood responded similarly ( p=0.99 ) , but these patients had lower NKp frequencies than did the non-transfused group ( p<0.0001 ) . Postoperative interferon gamma concentrations were higher in the autologous salvaged blood group ( p<0.0001 ) than in other groups , which did not differ from each other . Interleukin 10 concentrations were similar across all groups ( p=0.49 ) . INTERPRETATION Immunosuppression associated with surgery and blood loss was reflected in a reduced frequency of NKp and decreased interferon gamma . This immunosuppression was reversed by transfusion of autologous salvaged blood , suggesting that this fluid contained immunostimulants
Findings and Conclusion To our knowledge , this is the first meta- analysis to compare the clinical results between PAT and a control in joint replacement patients .
This meta- analysis has proven that the use of a PAT reinfusion system reduced significantly the dem and for ABT , the number of patients who require ABT and the cost of hospitalization after total knee and hip arthroplasty .
This study , together with other previously published data , suggests that PAT drains are beneficial .
Background Total hip or knee arthroplasty is an elective procedure that is usually accompanied by substantial blood loss , which may lead to acute anemia .
As a result , almost half of total joint arthroplasty patients receive allogeneic blood transfusions ( ABT ) .
Many studies have shown that post-operative auto-transfusion ( PAT ) significantly reduces the need for  ABT  , but other studies have question ed the efficacy of this method .