***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: BACKGROUND AND OBJECTIVES Red cell transfusion is commonly used in orthopaedic surgery . Evidence suggests that a restrictive transfusion strategy may be safe for most patients . However , concern has been raised over the risks of anaemia in those with ischaemic cardiac disease .  Perioperative silent myocardial ischaemia ( SMI ) has a relatively high incidence in the elderly population undergoing elective surgery . This study used Holter monitoring to compare the effect of a restrictive and a liberal red cell transfusion strategy on the incidence of SMI in patients without signs or symptoms of ischaemic heart disease who were undergoing lower limb arthroplasty . MATERIAL S AND METHODS We performed a multicentre , controlled trial in which 260 patients undergoing elective hip and knee replacement surgery were enrolled and r and omized to transfusion triggers that were either restrictive ( 8 g/dl ) or liberal ( 10 g/dl ) . Participants were monitored with  continuous ambulatory electrocardiogram ( ECG ) ( Holter monitoring ) , preoperatively for 12 h and postoperatively for 72 h. The tapes were analysed for new ischaemia by technicians blinded to treatment . The total ischaemia time in minutes was divided by the recording time in hours and an ischaemic load in min/h was calculated . Haemoglobin levels were measured preoperatively , postoperatively in the recovery room , and on days one , three and five after surgery . RESULTS The mean postoperative haemoglobin concentration was 9.87 g/dl in the restrictive group and 11.09 g/dl in the liberal group . In the restrictive group , 34 % were transfused a total of 89 red cell units , and in the liberal group 43 % were given a total of 119 red cell units . A postoperative episode of silent ischaemia was experienced by 21/109 ( 19 % ) patients in the restrictive group and by 26/109 ( 24 % ) patients in the liberal group [ mean difference -4.6 % ; 95 % confidence interval ( CI ) : -15.5 % to 6 % , P = 0.41 ) . There was no significant difference ( P = 0.53 ) between the overall ischaemic load in the restrictive group ( median 0 min/h , range 0 - 4.18 ) and the liberal group ( median 0 min/h , range 0 - 19.48 ) . In those patients who did experience postoperative SMI , the mean ischaemic load was 0.48 min/h in the restrictive group and 1.51 min/h in the liberal group ( ratio 0.32 , 95 % CI : 0.14 - 0.76 , P = 0.011 ) . The median postoperative length of hospital stay in the restrictive group was 7.3 days [ range 5 - 11 ; interquartile range ( IQR ) 6 - 8 ] compared with 7.5 days ( range 5 - 13 ; IQR 7 - 8 ) in the liberal group . The numbers were not large enough to conclude equivalence . CONCLUSIONS In patients without preoperative evidence of myocardial ischaemia undergoing elective hip and knee replacement surgery , a restrictive transfusion strategy seems unlikely to be associated with an increased incidence of SMI . A proportion of these patients experience moderate SMI , regardless of the transfusion trigger . Use of a restrictive transfusion strategy did not increase length of hospital stay , and use of this strategy would lead to a significant reduction in red cell transfusion in orthopaedic surgery . Our data did not indicate any potential for harm in employing such a strategy in patients with no prior evidence of cardiac ischaemia who were undergoing elective orthopaedic surgery Thresholds for red blood cell transfusion  following cardiac surgery vary by hospital and surgeon . The TITRe2 multi-centre r and omised controlled trial aims to r and omise 2000 patients from 17 United Kingdom centres , and tests the hypothesis that a restrictive transfusion threshold will reduce postoperative morbidity and health service costs compared to a liberal threshold . Patients consent to take part in the study pre-operatively but are only r and omised if their haemoglobin falls below 9 g/dL during their post-operative hospital stay . The primary outcome is a binary composite outcome of any serious infectious or ischaemic event in the first three months after r and omisation . Many challenges have been encountered in the set-up and running of the study 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 OBJECTIVES Perioperative transfusions are known to increase morbidity and mortality after  coronary artery bypass grafting ( CABG ) . The aims of the study were ( 1 ) to identify the clinical profile of the patient subset at highest risk from transfusion and ( 2 ) to disclose causative relationship and dose-dependency of transfusion on hospital mortality . METHODS A prospect i ve observational design was employed on a cohort of 1047 consecutive patients ( median age 63.2 ± 9.3 , 18.8 % female , 30.6 % diabetics , 31.9 % urgent/emergent , 15.3 % with low preoperative left ventricular ejection fraction ( LVEF ) ) who underwent on-pump isolated CABG between January 2004 and December 2007 .  Univariate and multivariate regression analysis and post-hoc risk stratification , by means of propensity scoring and binary segmentation , were adopted . RESULTS The following independent risk factors were identified : age , body surface area ( BSA ) , preoperative glomerular filtration rate , preoperative haemoglobin , surgical priority , length of cardiopulmonary bypass , intraoperative haemodilution and early postoperative blood loss . The patient population was stratified in quintiles of transfusional risk , by means of propensity scoring . As to modifiable risk factors , patients in the highest quintiles of risk were those with BSA ( < 1.73 , preoperative haemoglobin < 12 g/dl , intraoperative haemoglobin < 8.0 g/dl and those undergoing cardiopulmonary bypass > 90 ' ) . Binary segmentation was performed to avoid any association between red cell transfusion and worse outcomes being causative and dose-dependent . A dose-dependent pattern was disclosed , with patients receiving > 5 units being at highest risk . CONCLUSIONS High exposure to blood transfusions may be prevented by preoperative patient stratification and by the close tailoring of management strategies on planning and implementing surgical timing , as well as by cardiopulmonary bypass technique Transfusion-related  acute lung injury ( TRALI ) is the leading cause of transfusion-related morbidity and mortality . Both antibodies and bioactive lipids that have accumulated during storage of blood have been implicated in TRALI pathogenesis . In a single-center , nested , case-control study , patients were prospect ively observed for onset of TRALI according to the consensus definition . Of 668 patients , 16 patients ( 2.4 % ) developed TRALI . Patient-related risk factors for onset of TRALI were age and time on the cardiopulmonary bypass . Transfusion-related risk factors were total amount of blood products ( odds ratio [ OR ] = 1.2 ; 95 % confidence interval [ CI ] , 1.03 - 1.44 ) , number of red blood cells stored more than 14 days ( OR = 1.6 ; 95 % CI , 1.04 - 2.37 ) , total amount of plasma ( OR = 1.2 ; 95 % CI , 1.03 - 1.44 ) , presence of antibodies in donor plasma ( OR = 8.8 ; 95 % CI , 1.8 - 44 ) , and total amount of transfused bioactive lipids ( OR = 1.0 ; 95 % CI , 1.00 - 1.07 ) . When adjusted for patient risk factors , only the presence of antibodies in the associated blood products remained a risk factor for TRALI ( OR = 14.2 ; 95 % CI , 1.5 - 132 ) . In-hospital mortality of TRALI was 13 % compared with 0 % and 3 % in transfused and nontransfused patients , respectively ( P < .05 ) . In conclusion , the incidence of TRALI is high in cardiac surgery patients and associated with adverse outcome . Our results suggest that cardiac surgery patients may benefit from exclusion of blood products containing HLA/HNA antibodies BACKGROUND Patients undergoing major arterial reconstruction  have traditionally been transfused with red blood cells to keep hemoglobin concentrations above 10 g/dL in order to prevent anemia-induced myocardial ischemia . There are no data to support this practice . The hypothesis that vascular patients will tolerate a hemoglobin concentration of 9 g/dL was examined . METHODS Ninety-nine patients undergoing elective aortic and infrainguinal arterial reconstructions  were prospect ively r and omized preoperatively to receive transfusions to maintain a hemoglobin level of either 10 g/dL or 9 g/dL. RESULTS Despite significantly different postoperative hemoglobin levels of 11.0 + /- 1.2 versus 9.8 + /- 1.3 g/dL ( P < 0.0001 ) , there were no differences in mortality or cardiac morbidity rates or length of hospital stay . There were no differences in hemodynamic parameters . Oxygen delivery was lower in the group with lower hemoglobin levels , but there was no difference in O2 consumption between the groups . CONCLUSIONS A lower hemoglobin concentration was tolerated without adverse clinical outcome . Patients did not compensate for anemia by increased myocardial work , but by increasing O2 extraction in the peripheral tissues Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more BACKGROUND The hemoglobin threshold at which postoperative red-cell transfusion is warranted is controversial . We conducted a r and omized trial to determine whether a higher threshold for blood transfusion would improve recovery in patients who had undergone surgery for hip fracture . METHODS We enrolled 2016 patients who were 50 years of age or older , who had either a history of or risk factors for cardiovascular disease , and whose hemoglobin level was below 10 g per deciliter after hip-fracture surgery . We r and omly assigned patients to a liberal transfusion strategy ( a hemoglobin threshold of 10 g per deciliter ) or a restrictive transfusion strategy ( symptoms of anemia or at physician discretion for a hemoglobin level of < 8 g per deciliter ) . The primary outcome was death or an inability to walk across a room without human assistance on 60-day follow-up . RESULTS A median of 2 units of red cells were transfused in the liberal- strategy group and none in the restrictive- strategy group . The rates of the primary outcome were 35.2 % in the liberal- strategy group and 34.7 % in the restrictive- strategy group ( odds ratio in the liberal- strategy group , 1.01 ; 95 % confidence interval [ CI ] , 0.84 to 1.22 ) , for an absolute risk difference of 0.5 percentage points ( 95 % CI , -3.7 to 4.7 ) . The rates of in-hospital acute coronary syndrome or death were 4.3 % and 5.2 % , respectively ( absolute risk difference , -0.9 % ; 99 % CI , -3.3 to 1.6 ) , and rates of death on 60-day follow-up were 7.6 % and 6.6 % , respectively ( absolute risk difference , 1.0 % ; 99 % CI , -1.9 to 4.0 ) . The rates of other complications were similar in the two groups . CONCLUSIONS A liberal transfusion strategy , as compared with a restrictive strategy , did not reduce rates of death or inability to walk independently on 60-day follow-up 
    Output:
    
INTERPRETATION Evidence from r and omised controlled trials in cardiac surgery refutes findings from observational studies that liberal thresholds for red blood cell transfusion are associated with a substantially increased risk of mortality and morbidity .