***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: CONTEXT Allogeneic blood transfusions have immunomodulatory effects and have been associated with activation of human immunodeficiency virus ( HIV ) and cytomegalovirus ( CMV ) in vitro and of HIV in small pilot studies . Retrospective studies suggest that transfusions adversely affect the clinical course of HIV . Data in selected non-HIV-infected patients requiring blood transfusion have suggested clinical benefit with leukocyte-reduced red blood cells ( RBCs ) . OBJECTIVE To compare the effects of leukoreduced and unmodified RBC transfusions on survival , complications of acquired immunodeficiency syndrome , and relevant laboratory markers in HIV-infected patients . DESIGN AND SETTING Double-blind r and omized controlled trial conducted in 11 US academic medical centers from July 1995 through June 1999 , with a median follow-up of 12 months ( 24 months in survivors ) . PATIENTS A total of 531 persons infected with HIV and CMV , aged 14 years or older , who required transfusions for anemia ; 259 received leukoreduced transfusions and 262 received unmodified transfusions ( 10 did not receive the planned transfusion ) . MAIN OUTCOME MEASURES Survival and change in plasma HIV RNA level 7 days after transfusion , compared by type of transfusion . RESULTS At entry , the groups were similar in demographic , clinical , and relevant laboratory characteristics . A total of 3864 RBC units were transfused . Two hundred eighty-nine deaths occurred ( 151 with leukoreduced transfusion ; 138 with unmodified transfusion ) ; median survival was 13.0 and 20.5 months , respectively ( relative hazard [ RH ] , 1.20 ; 95 % confidence interval [ CI ] , 0.95 - 1.51 ; log-rank P = .12 ) . Analyses adjusted for prognostic factors suggested possible worse survival with leukoreduction ( RH , 1.35 ; 95 % CI , 1.06 - 1.72 ) . There was no difference in time to new opportunistic event/death or frequency of transfusion reactions . No changes in plasma HIV RNA level were seen in either group at days 7 , 14 , 21 , or 28 , even in patients not taking antiretroviral drugs . There were no differences in trends between groups in CMV DNA , CD4 cell counts , activated ( CD38 % or human leukocyte antigen-DR ) CD8 cell counts , or plasma cytokine levels . CONCLUSIONS We found no evidence of HIV , CMV , or cytokine activation following blood transfusion in patients with advanced HIV infection . Leukoreduction provided no clinical benefit in these patients . These data demonstrate the importance of conducting controlled studies of effects of leukoreduction in different patient population s , since smaller studies in other patient population s have suggested leukoreduction may be beneficial Background —Leukocytes in allogeneic blood transfusions are believed to be the cause of immunomodulatory events . A few trials on leukocyte removal from transfusions in cardiac surgery have been conducted , and they showed inconclusive results . We found in a previous study a decrease in mortality rates and number of infections in a subgroup of more heavily transfused patients . Methods and Results — Patients ( n= 496 ) undergoing valve surgery ( with or without CABG ) were r and omly assigned in a double-blind fashion to receive st and ard buffy coat – depleted ( PC ) or prestorage , by filtration , leukocyte-depleted erythrocytes ( LD ) . The primary end point was mortality at 90 days , and secondary end points were in-hospital mortality , multiple organ dysfunction syndrome , infections , intensive care unit stay , and hospital stay . The difference in mortality at 90 days was not significant ( PC 12.7 % versus LD 8.4 % ; odds ratio [ OR ] , 1.52 ; 95 % confidence interval [ CI ] , 0.84 to 2.73 ) . The in-hospital mortality rate was almost twice as high in the PC group ( 10.1 % versus 5.5 % in the LD group ; OR , 1.99 ; 95 % CI , 0.99 to 4.00 ) . The incidence of multiple organ dysfunction syndrome in both groups was similar , although more patients with multiple organ dysfunction syndrome died in the PC group . LD was associated with a significantly reduced infection rate ( PC 31.6 % versus LD 21.6 % ; OR , 1.64 ; 95 % CI , 1.08 to 2.49 ) . In both groups , intensive care unit stay and hospital stay were similar , and postoperative complications increased with the number of transfused units . Conclusions —Mortality at 90 days was not significantly different ; however , a beneficial effect of LD in valve surgery was found for the secondary end points of in-hospital mortality and infections OBJECTIVE In elective orthopaedic hip- and knee replacement surgery patients , we studied the effect of implementation of a uniform transfusion policy on RBC usage . STUDY DESIGN AND METHODS A r and omized , controlled study . A new uniform , restrictive transfusion policy was compared with st and ard care , which varied among the three participating hospitals . Only prestorage leucocyte-depleted RBC(s ) were used . Primary end-point was RBC usage , related to length of hospital stay . Secondary end-points were Hb levels , mobilization delay and postoperative complications . RESULTS Six hundred and three patients were evaluated .  Adherence to the protocol was over 95 % . Overall mean RBC usage was 0.78 U/patient in the new policy group and 0.86 U/patient in the st and ard care policy group ( mean difference 0.08;95 % CI [ -0.3 ; 0.2 ] ; P = 0.53 ) . In two hospitals , the new transfusion policy result ed in a RBC reduction of 30 % ( 0.58U RBC/patient ) ( P = 0.17 ) and 41 % ( 0.29 U RBC/patient ) ( P = 0.05 ) respectively . In the third hospital , however , RBC usage increased by 39 % ( 0.31 U RBC/patient ) ( P = 0.02 ) with the new policy , due to a more restrictive st and ard care policy in that hospital . Length of hospital stay was not influenced by either policy . CONCLUSIONS Implementation of a uniform transfusion protocol for elective lower joint arthroplasty patients is feasible , but does not always lead to a RBC reduction . Length of hospital stay was not affected Perioperative blood transfusions are reported to be related to cancer recurrence and reduced survival . Different underlying mechanisms have been proposed , and allogeneic leucocytes in transfused blood have been suggested to contribute to this phenomenon BACKGROUND Blood cardioplegia ( BCP ) is widely used for myocardial protection during open heart operation . However , BCP may have a chance to induce neutrophil-mediated myocardial injury during aortic cross-clamping . We clinical ly evaluated the myocardial protective effect of leukocyte-depleted blood cardioplegia ( LDBCP ) for initial and intermittent BCP administration in pediatric patients . METHODS Fifty patients undergoing open heart operation for congenital heart disease between January 1997 and March 1999 were review ed . Twenty-five were administered LDBCP for myocardial protection during ischemic periods ( LDBCP group ) , and the remaining 25 were given BCP without leukocyte depletion ( BCP group ) . RESULTS The difference in plasma concentrations of malondialdehyde between coronary sinus effluent blood and arterial blood just after reperfusion in the LDBCP group ( 1.68 + /- 0.56 micromol/L ) was significantly lower than that in the BCP group ( 2.35 + /- 0.62 micromol/L ; p < 0.01 ) . The LDBCP group showed significantly lower plasma concentrations of human heart fatty acid-binding protein at 50 minutes after reperfusion ( LDBCP group , 103.5 + /- 38.7 IU/L ; BCP group , 144.8 + /- 48.8 IU/L ; p < 0.01 ) and the peak value of creatine kinase-MB during the first 24 postoperative hours ( LDBCP group , 17.0 + /- 8.5 IU/L ; BCP group , 26.0 + /- 11.6 IU/L ; p < 0.01 ) than did the BCP group . The maximum dose of catecholamine was significantly smaller in the LDBCP group ( LDBCP group , 3.20 + /- 2.18 microg x kg(-1 ) x min(-1 ) ; BCP group , 5.60 + /- 2.83 microg x kg(-1 ) x min(-1 ) ; p < 0.01 ) . CONCLUSIONS These results suggest the usefulness of LDBCP for protection from the myocardial injury that can be induced by BCP administration during aortic cross-clamping Introduction Microvascular alterations impair tissue oxygenation during sepsis . A red blood cell ( RBC ) transfusion increases oxygen ( O2 ) delivery but rarely improves tissue O2 uptake in patients with sepsis . Possible causes include RBC alterations due to prolonged storage or residual leukocyte-derived inflammatory mediators . The aim of this study was to compare the effects of two types of transfused RBCs on microcirculation in patients with sepsis . Methods In a prospect i ve r and omized trial , 20 patients with sepsis were divided into two separate groups and received either non-leukodepleted ( n = 10 ) or leukodepleted ( n = 10 ) RBC transfusions . Microvascular density and perfusion were assessed with sidestream dark field ( SDF ) imaging sublingually , before and 1 hour after transfusions . Thenar tissue O2 saturation ( StO2 ) and tissue hemoglobin index ( THI ) were determined with near-infrared spectroscopy , and a vascular occlusion test was performed . The microcirculatory perfused boundary region was assessed in SDF images as an index of glycocalyx damage , and glycocalyx compounds ( syndecan-1 , hyaluronan , and heparan sulfate ) were measured in the serum . Results No differences were observed in microvascular parameters at baseline and after transfusion between the groups , except for the proportion of perfused vessels ( PPV ) and blood flow velocity , which were higher after transfusion in the leukodepleted group . Microvascular flow index in small vessels ( MFI ) and blood flow velocity exhibited different responses to transfusion between the two groups ( P = 0.03 and P = 0.04 , respectively ) , with a positive effect of leukodepleted RBCs . When within-group changes were examined , microcirculatory improvement was observed only in patients who received leukodepleted RBC transfusion as suggested by the increase in De Backer score ( P = 0.02 ) , perfused vessel density ( P = 0.04 ) , PPV ( P = 0.01 ) , and MFI ( P = 0.04 ) . Blood flow velocity decreased in the non-leukodepleted group ( P = 0.03 ) . THI and StO2 upslope increased in both groups . StO2 and StO2 downslope increased in patients who received non-leukodepleted RBC transfusions . Syndecan-1 increased after the transfusion of non-leukodepleted RBCs ( P = 0.03 ) . Conclusions This study does not show a clear superiority of leukodepleted over non-leukodepleted RBC transfusions on microvascular perfusion in patients with sepsis , although it suggests a more favorable effect of leukodepleted RBCs on microcirculatory convective flow . Further studies are needed to confirm these findings .Trial registration Clinical Trials.gov , The frequency of infection in 197 patients undergoing elective colorectal surgery and having either no blood transfusion , transfusion with whole blood , or filtered blood free from leucocytes and platelets  was investigated in a prospect i ve r and omized trial . Natural killer cell function was measured before operation and 3 , 7 and 30 days after surgery in 60 consecutive patients . Of the patients 104 required  blood transfusion ; 48 received filtered blood and 56 underwent whole blood transfusion . Postoperative infections developed in 13 patients transfused with whole blood ( 23 per cent , 9.5 per cent confidence interval 13–32 per cent ) , in one patient transfused with blood free from leucocytes and platelets ( 2 per cent , 9.5 per cent confidence interval 0.05–11 per cent ) and in two non‐transfused patients ( 2 per cent , 95 per cent conjidence interval 0.3‐8per cent ) ( P < 0.01 ) . Natural killer cell function was significantly ( P < 0.001 ) impaired up to 30 days after surgery in patients transfused with whole blood . These data provide a strong case against the use of whole blood transfusion in patients undergoing elective colorectal surgery We performed a prospect i ve , r and omized trial in CMV seronegative marrow recipients to determine if filtered blood products were as effective as CMV-seronegative blood products for the prevention of transfusion-transmitted CMV infection after marrow trans 
    Output:
    
There is no clear evidence for supporting or rejecting the routine use of leukoreduction in all patients requiring PRBC transfusion for preventing TRALI , death , infection , non-infectious complications and other adverse events .