***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 Perioperative anemia leads to increased morbidity and mortality and potentially inhibits rehabilitation after hip fracture surgery . As such , the optimum transfusion threshold after hip fracture surgery is unknown . PATIENTS AND METHODS A total of 120 elderly , cognitively intact hip fracture patients admitted from their own home were r and omly assigned to receive transfusion at a hemoglobin threshold of 10.0 g per dL ( liberal ) versus 8.0 g per dL ( restrictive ) in the entire perioperative period . Patients were treated according to a well-defined multimodal rehabilitation program . Primary outcome was postoperative functional mobility measured with the cumulated ambulation score ( CAS ) . RESULTS Patients in the liberal group received transfusions more frequently than those in the restrictive group ( 44 patients vs. 22 patients ; p < 0.01 ) and received more transfusions during hospitalization ( median , 2 units [ interquartile range , 1 - 2 ] vs. 1 [ 1 - 2 ] ; p < 0.0001 ) . There were no significant differences in postoperative rehabilitation scores ( CAS : median , 9 [ 9 - 15 ] vs. 9 [ 9 - 13.5 ] ; p = 0.46 ) or in length of stay ( median , 18 days vs. 16 days , respectively ; p = 0.46 ) . There were fewer patients in the liberal transfusion group with cardiovascular complications ( 2 % vs. 10 % ; p = 0.05 ) and a lower mortality ( 0 % vs. 8 % ; p = 0.02 ) . CONCLUSION Although a liberal transfusion trigger did not result in increased ambulation scores , restrictive transfusion thresholds should be treated with caution in elderly high-risk hip fracture patients , until their safety has been proved in larger r and omized studies 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 Background Red blood cell ( RBC ) transfusion is commonly used to increase oxygen transport in patients with sepsis . However it does not consistently increase oxygen uptake at either the whole-body level , as calculated by the Fick method , or within individual organs , as assessed by gastric intra-mucosal pH. Aim This study evaluates the hemodynamic and oxygen utilization effects of hemoglobin infusion on critically ill septic patients . Methods Fifteen septic patients undergoing mechanical ventilation whose hemoglobin was < 10 g% were eligible . Ten patients ( APACHE II : 25.5 ± 7.6 ) received an infusion of 1 unit of packed RBC over 1 h while se date d and paralyzed . The remaining five control patients ( APACHE II : 24.3 ± 6.0 ) received a 5 % albumin solution ( 500 ml ) over 1 h. Hemodynamic data , gastric tonometry and calorimetry were obtained prior to and immediately after RBC transfusion or 5 % albumin infusion . Results Transfusion of RBC was associated with an improvement in left ventricular systolic work index ( 38.6 ± 12.6 to 41.1 ± 13.0 g/min/m2 ; P = 0.04 ) . In the control group there was no significant change in the left ventricular systolic work index ( 37.2 ± 14.3 to 42.2 ± 18.9 g/min/m2 ) . An increase in pulmonary vascular resistance index ( 203 ± 58 to 238 ± 49 dyne/cm5/m2 ; P = 0.04 ) was also observed , while no change was produced by colloid infusion ( 237 ± 87.8 to 226.4 ± 57.8 dyne/cm5/m2 ) . Oxygen utilization did not increase either by Fick equation or by indirect calorimetry in either group . Gastric intramucosal pH increased only in the control group but did not reach statistical significance . Conclusion Hemoglobin increase does not improve either global or regional oxygen utilization in anemic septic patients . Furthermore , RBC transfusion may hamper right ventricular ejection by increasing the pulmonary vascular resistance index 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 CONTEXT Post hoc analysis of a previous trial has suggested that prone positioning may improve survival in patients with severe hypoxemia and with acute respiratory distress syndrome ( ARDS ) . OBJECTIVE To assess possible outcome benefits of prone positioning in patients with moderate and severe hypoxemia who are affected by ARDS . DESIGN , SETTING , AND PATIENTS The Prone-Supine II Study , a multicenter , unblinded , r and omized controlled trial conducted in 23 centers in Italy and 2 in Spain . Patients were 342 adults with ARDS receiving mechanical ventilation , enrolled from February 2004 through June 2008 and prospect ively stratified into subgroups with moderate ( n = 192 ) and severe ( n = 150 ) hypoxemia . INTERVENTIONS Patients were r and omized to undergo supine ( n = 174 ) or prone ( 20 hours per day ; n = 168 ) positioning during ventilation . MAIN OUTCOME MEASURES The primary outcome was 28-day all-cause mortality . Secondary outcomes were 6-month mortality and mortality at intensive care unit discharge , organ dysfunctions , and the complication rate related to prone positioning . RESULTS Prone and supine patients from the entire study population had similar 28-day ( 31.0 % vs 32.8 % ; relative risk [ RR ] , 0.97 ; 95 % confidence interval [ CI ] , 0.84 - 1.13 ; P = .72 ) and 6-month ( 47.0 % vs 52.3 % ; RR , 0.90 ; 95 % CI , 0.73 - 1.11 ; P = .33 ) mortality rates , despite significantly higher complication rates in the prone group . Outcomes were also similar for patients with moderate hypoxemia in the prone and supine groups at 28 days ( 25.5 % vs 22.5 % ; RR , 1.04 ; 95 % CI , 0.89 - 1.22 ; P = .62 ) and at 6 months ( 42.6 % vs 43.9 % ; RR , 0.98 ; 95 % CI , 0.76 - 1.25 ; P = .85 ) . The 28-day mortality of patients with severe hypoxemia was 37.8 % in the prone and 46.1 % in the supine group ( RR , 0.87 ; 95 % CI , 0.66 - 1.14 ; P = .31 ) , while their 6-month mortality was 52.7 % and 63.2 % , respectively ( RR , 0.78 ; 95 % CI , 0.53 - 1.14 ; P = .19 ) . CONCLUSION Data from this study indicate that prone positioning does not provide significant survival benefit in patients with ARDS or in subgroups of patients with moderate and severe hypoxemia . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00159939 CONTEXT Anemia is a common problem in critically ill patients admitted to intensive care units ( ICUs ) , but the consequences of anemia on morbidity and mortality in the critically ill is poorly defined . OBJECTIVES To prospect ively define the incidence of anemia and use of red blood cell ( RBC ) transfusions in critically ill patients and to explore the potential benefits and risks associated with transfusion in the ICU . DESIGN Prospect i ve observational study conducted November 1999 , with 2 components : a blood sampling study and an anemia and blood transfusion study . SETTING AND PATIENTS The blood sampling  study included 1136 patients from 145 western European ICUs , and the anemia and blood transfusion study included 3534 patients from 146 western European ICUs . Patients were followed up for 28 days or until hospital discharge , interinstitutional transfer , or death . MAIN OUTCOME MEASURES Frequency of blood drawing and associated volume of blood drawn , collected over a 24-hour period ; hemoglobin levels , transfusion rate , organ dysfunction ( assessed using the Sequential 
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In line with this , the up date d systematic review including data from several recent trials showed no associations with mortality or other adverse events when comparing restrictive to liberal RBC transfusion strategies , however , restrictive transfusion strategies reduce the exposure of patients to RBC transfusions and reduce number of transfused RBC units .