***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 Desmopressin-induced release of tissue plasminogen activator from endothelial cells may explain the absence of its hemostatic effect in patients undergoing cardiac surgery . Prior administration of the antifibrinolytic drug tranexamic acid might unmask such an effect , and combination therapy might thereby improve postoperative hemostasis . Methods and Results A double-blinded design r and omly allocated 163 adult patients undergoing coronary revascularization , valve replacement , both procedures , or repair of atrial septal defect to four treatment groups : placebo , tranexamic acid given as 10 mg/kg over 30 minutes followed by 1 mg . kg−1 . hr−1 for 12 hours initiated before skin incision , desmopressin given as 0.3 μg/kg over 20 minutes after protamine infusion , and both drugs . One surgeon performed all operations . Blood loss consisted of mediastinal tube drainage over 12 hours . Follow-up visits sought evidence of myocardial infa rct ion and stroke  . Desmopressin decreased neither the 12-hour blood loss nor the amount of homologous red cells transfused . Tranexamic acid alone significantly reduced 12-hour blood loss , by 30%1 ( mean , 318 versus 453 ml ; Conclusions Desmopressin exerts no hemostatic effect , with or without prior administration of antifibrinolytic drug . Prophylactic tranexamic acid alone appears economical and safe in decreasing blood loss and transfusion requirement after cardiac surgery Intraoperatively administered , tranexamic acid ( TA ) does not reduce bleeding in total hip replacement ( THR ) . Therefore , its prophylactic use was attempted in the present study because this has been shown to be more effective in cardiac surgery . We investigated 40 patients undergoing THR in a prospect i ve , r and omized , double-blinded study . Twenty patients received TA given in two bolus doses of 10 mg/kg each , the first just before surgical incision and the second 3 h later . In addition , a continuous infusion of TA , 1.0 mg · kg−1 · h−1 for 10 h , was given after the first bolus dose . The remaining 20 patients formed a control group . Both groups used preoperative autologous blood donation and intraoperative autotransfusion . Intraoperative bleeding was significantly less ( P = 0.001 ) in the TA group compared with the control group ( 630 ± 220 mL vs 850 ± 260 mL ) . Postoperative drainage bleeding was correspondingly less ( P = 0.001 ) ( 520 ± 280 vs 920 ± 410 mL ) . Up to 10 h postoperatively , plasma D-dimer concentration was halved in the TA group compared with the control group . One patient in each group had an ultrasound-verified late deep vein thrombosis . In conclusion , we found TA , administrated before surgical incision , to be efficient in reducing bleeding during THR . Implication s In a prospect i ve , double-blinded study of 40 patients undergoing total hip replacement , the preoperative administration of tranexamic acid  reduced bleeding by 35 % , probably by decreasing induced fibrinolysis . Whether tranexamic acid therapy can replace predonation of autologous blood or intraoperative autotransfusion requires further study Pediatric patients who undergo posterior spinal fusion surgery to correct scoliosis often require multiple blood transfusions . Tranexamic acid is a synthetic antifibrinolytic drug that reduces transfusion requirements in cardiac surgery and total knee arthroplasty . We evaluated the efficacy of prophylactic tranexamic acid to reduce perioperative blood transfusion requirements in a prospect i ve , double-blinded , placebo control study . Forty patients , 9–18 yr of age , were r and omized to either tranexamic acid ( initial dose of 10 mg/kg and infusion of 1 mg · kg−1 · h−1 ) or placebo ( isotonic saline ) . Perioperative management was st and ardized . A uniform transfusion threshold for noncell saved red blood cells was 7.0 g/dL. The total amount of blood transfused in the perioperative period was significantly reduced in the Tranexamic group ( P = 0.045 ) . No thrombotic complications were detected in either group . The administration of prophylactic tranexamic acid in patients with scoliosis undergoing posterior spinal fusion surgery has the potential to reduce perioperative blood transfusion requirements UNLABELLED Perioperative bleeding following coronary artery bypass grafting ( CABG ) is associated with increased blood product usage . Although aprotonin is effective in reducing perioperative blood loss , excessive cost prohibits routine utilization . Epsilon aminocaproic acid ( EACA ) and tranexamic acid ( TA ) are inexpensive antifibrinolytic agents , which , when given prophylactically , may reduce blood loss . The present study was undertaken to compare the efficacy of TA and EACA in reducing perioperative blood loss . METHODS The study population consisted of first-time CABG patients . Patients were allocated in a prospect i ve double-blind fashion : ( 1 ) group EACA ( loading dose 15 mg/kg , continuous infusion 10 mg/kg per hour for 6 hours , N = 20 ) ; ( 2 ) group TA ( loading dose 15 mg/kg , continuous infusion 1 mg/kg per hour for 6 hours , N = 20 ) ; ( 3 ) control group ( infusion of normal saline for 6 hours , N = 19 ) . RESULTS Treatment groups were similar preoperatively . No significant difference in intraoperative blood loss or perioperative use of blood products was noted . D-dimer concentration was elevated in the control group compared to the EACA and TA groups ( p < 0.05 ) . Group TA had less postoperative blood loss than the EACA and control groups at 6 and 12 hours postoperatively ( p < 0.05 ) . TA had reduced total blood loss ( 600 + /- 49 mL ) postoperatively compared to EACA ( 961 + /- 148 mL ) and control ( 1060 + /- 127 mL , p < 0.05 ) . CONCLUSION TA and EACA effectively inhibited fibrinolytic activity intraoperatively and throughout the first 24 hours postoperatively . TA was more effective in reducing blood loss postoperatively following CABG . This suggests that TA may be beneficial as an effective and inexpensive antifibrinolytic in first-time CABG patients BACKGROUND The transfusion of allogeneic red blood cells and allogeneic coagulation products is associated with risk to the patient and the depletion of an increasingly scarce re source . This prospect i ve , r and omized , double-blind , placebo-controlled trial investigated practice s to avoid transfusion in patients undergoing first-time cardiac surgery . METHODS Patients were r and omized to one of three treatment groups : an aprotinin group , a tranexamic acid group , and a control group receiving normal saline . Intra-operative cell salvage was used for all patients . The primary outcomes were the number of patients exposed to allogeneic red blood cells , allogeneic coagulation products or any allogeneic transfusion ( allogeneic red blood cells and /or allogeneic coagulation products ) . RESULTS Patients were 2.5 times more likely to receive any allogeneic transfusion in the tranexamic group than in the aprotinin group ( 21 patients out of 60 compared with nine out of 60 , respectively ) . The relative risk of any allogeneic transfusion comparing aprotinin with tranexamic acid was 0.43 ( 95 % confidence interval 0.21 - 0.86 ; P=0.019 ) . Patients in the control group were four times more likely to receive any allogeneic transfusion when compared with the aprotinin group ( 37 patients out of 60 compared with nine out of 60 , respectively ) . The relative risk of any allogeneic transfusion comparing aprotinin with control was 0.24 ( 95 % confidence interval 0.13 - 0.46 ; P<0.001 ) . CONCLUSIONS When used in addition to intra-operative cell salvage , aprotinin is the most efficacious pharmacological therapy for reducing patient exposure to any allogeneic transfusion during first-time cardiac surgery Background : Excessive bleeding often occurs during pediatric scoliosis surgery and is attributed to numerous factors , including accelerated fibrinolysis . The authors hypothesized that administration of tranexamic acid would reduce bleeding and transfusion requirements during scoliosis surgery . Methods : Forty-four patients scheduled to undergo elective spinal fusion were r and omly assigned to receive either 100 mg/kg tranexamic acid before incision followed by an infusion of 10 mg · kg−1 · h−1 during surgery ( tranexamic acid group ) or 0.9 % saline ( placebo group ) . General anesthesia was administered according to a st and ard protocol . Blood loss , transfusion requirements , coagulation parameters , and complications were assessed . Results : In the tranexamic acid group , blood loss was reduced by 41 % compared with placebo ( 1,230 ± 535 vs. 2,085 ± 1,188 ml ; P < 0.01 ) . The amount of blood transfused did not differ between groups ( 615 ± 460 vs. 940 ± 718 ml ; P = 0.08 ) . Administration of tranexamic acid was a multivariate predictor of blood loss , as was American Society of Anesthesiologists physical status and preoperative platelet count . No apparent adverse drug effects occurred in any patient . Conclusion : Intraoperative administration of tranexamic acid significantly reduces blood loss during spinal surgery in children with scoliosis We performed a r and omized , double-blind study on the effect of tranexamic acid on blood loss and blood transfusions in 40 primary total hip arthroplasties .  Tranexamic acid , 10 mg/kg body weight , or placebo , was given intravenously just before the operation . Blood loss during the operation and postoperatively into the drains was recorded , as also were blood hemoglobin concentrations . Ultrasound examination 1 week postoperatively was done to estimate the blood loss due to remaining hematomas . Total ( operation + drain ) blood loss was 0.76 ( 95 % CI 0.63 - 0.89 ) L in the tranexamic acid group as compared to 1.0 ( CI 0.81 - 1.2 ) L in the placebo group ( p = 0.03 ) . The number of blood transfusions during the day of operation was 2 vs. 10 ( p = 0.07 ) and the total number during the hospital stay was 5 vs. 13 ( p = 0.2 ) . 1 patient in each group had a pulmonary embolism Tranexamic acid was used to reduce postoperative drainage and allogenic blood transfusion requirements in patients undergoing on-pump primary coronary bypass surgery . Over 12 months , 222 patients participated in this prospect i ve , r and omized , placebo-controlled , double-blind study conducted at a tertiary center . Half of the patients were r and omly allocated to receive tranexamic acid as a bolus ( 10 mg·kg−1 ) prior to sternotomy , followed by an infusion ( 1 mg·kg−1·hr−1 ) up to the time of starting of protamine . The other  111 patients  received a saline bolus and infusion  . Postoperative drainage and transfusion requirements were measured in all patients . Markers of graft patency , hemostasis , hemodynamic stability , and fibrinolysis were evaluated . Chest closure time , renal function parameters , allergic reactions , incidence of stroke , re-exploration , and hospital mortality were also noted . Postoperative drainage was significantly less and blood conservation considerably better when tranexamic acid was used . Post-bypass hemostasis was achieved faster , fibrinolysis was less , and there was no evidence of increased incidence of graft occlusion in the group given tranexamic acid The administration of tranexamic acid ( TA ) prior to cardiopulmonary bypass ( CPB ) has been associated with reduced bleeding during and after cardiac surgery . In a prospect i ve , r and omized , controlled , double-blind clinical trial , adult patients undergoing repeat open heart surgery received TA ( n = 17 ) or an equal volume of saline placebo ( n = 13 ) . In the TA group , a 20-mg/kg intravenous ( IV ) initial dose of TA at skin incision was followed by an infusion of 2 mg centered dot kg-1 centered dot h-1 , which continued for the duration of the surgical procedure . Identical transfusion guidelines were followed in both groups . Routine coagulation tests , D-dimer levels , mediastinal tube drainage , and transfusion requirements were compared . Cumulative postoperative mediastinal tube drainage measured at 24 h was 649 + /- 391 mL ( mean + /- SD ) in the TA group compared with 923 + /- 496 mL in the placebo group ( P < 0.01 ) . Forty-eight- and 72-h mediastinal tube drainage were also significantly less in the TA group ( P < 0.01 ) . Seven of 17 TA patients received no transfusion of allogene 
    Output:
    
The effect of TXA  on blood loss did not vary over the range of doses assessed ( 5·5 - 300 mg/kg ) .
CONCLUSION TXA  reduces blood loss in surgical patients by about one-third .
A total dose of 1 g appears to be sufficient for most adults .
There is no evidence to support the use of high doses