***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 Preoperative treatment with thienopyridines is associated with increased  postoperative bleeding in cardiac surgery patients . Patients under treatment with thienopyridines  have different levels of platelet dysfunction and the effects of discontinuation are not totally predictable . The present study aim ed to determine if a preoperative assessment of platelet function in these patients could provide clinical ly relevant information regarding the risks of excessive postoperative bleeding and transfusion requirements . METHODS This is a retrospective analysis of prospect ively collected data . Patients ( n=87 ) under thienopyridine treatment until at least one week before cardiac surgery were enrolled in the study .  Platelet function was assessed preoperatively with multiple electrode aggregometry : the adenosine diphosphate ( ADP ) test and TRAP ( thrombin receptor-associated peptide ) test were performed for all patients . RESULTS Univariate analysis revealed that postoperative bleeding was associated ( p<0.1 ) with preoperative serum creatinine level , platelet count , CPB ( cardiopulmonary bypass ) duration , and results from the ADP test and the TRAP test . Multivariable linear regression analysis confirmed the CPB duration ( p=0.049 ) and ADP test ( p=0.007 ) as independently associated with postoperative bleeding . The relationship between the ADP test and postoperative bleeding was investigated with polynomial regression analysis , and a logarithmic equation provided the best fit . The accuracy of prediction was good ( area under the curve 0.71 , p=0.013 ) , with a cutoff value for the ADP test at 31 U ( sensitivity 72 % , specificity 66 % , negative predictive value 92 % , and positive predictive value 29 % ) . CONCLUSIONS The multiple electrode aggregometry ADP test in patients under thienopyridine treatment and undergoing cardiac surgery is associated with postoperative bleeding and platelet transfusion and provides an accurate preoperative prediction of postoperative bleeding risk Background Abnormal bleeding after cardiopulmonary bypass ( CPB ) is a common complication of cardiac surgery , with important health and economic consequences . Coagulation test – based algorithms may reduce transfusion of non-erythrocyte allogeneic blood in patients with abnormal bleeding . Methods The authors performed a r and omized prospect i ve trial comparing allogeneic transfusion practice s in 92 adult patients with abnormal bleeding after CPB . Patients with abnormal bleeding  were r and omized to one of two groups : a control group following individual anesthesiologist ’s transfusion practice s and a protocol group using a transfusion algorithm guided by coagulation tests . Results Among 836 eligible patients having all types of elective cardiac surgery requiring CPB , 92 patients developed abnormal bleeding after CPB ( incidence , 11 % ) . The transfusion algorithm group received less allogeneic fresh frozen plasma in the operating room after CPB ( median , 0 units ; range , 0–7 units ) than the control group ( median , 3 units ; range , 0–10 units ) ( P = 0.0002 ) . The median number of platelet units transfused in the operating room after CPB was 4 ( range , 0–12 ) in the algorithm group compared with 6 ( range , 0–18 ) in the control group ( P = 0.0001 ) . Intensive care unit ( ICU ) mediastinal blood loss was significantly less in the algorithm group . Multivariate analysis demonstrated that transfusion algorithm use result ed in reduced ICU blood loss . The control group also had a significantly greater incidence of surgical reoperation of the mediastinum for bleeding ( 11.8%vs . 0%;P = 0.032 ) . Conclusions Use of a coagulation test – based transfusion algorithm in cardiac surgery patients with abnormal bleeding after CPB  reduced non-erythrocyte allogeneic transfusions in the operating room and ICU blood loss Introduction : The current investigation aim ed to study the efficacy of hemostatic therapy guided either by conventional coagulation analyses or point-of-care ( POC ) testing in coagulopathic cardiac surgery patients . Methods : Patients undergoing complex cardiac surgery were assessed for eligibility . Those patients in whom diffuse bleeding was diagnosed after heparin reversal or increased blood loss during the first 24 postoperative hours were enrolled and r and omized to the conventional or  POC  group . Thromboelastometry and whole blood impedance aggregometry have been performed in the POC group . The primary outcome variable was the number of transfused units of packed erythrocytes during the first 24 h after inclusion . Secondary outcome variables included postoperative blood loss , use and costs of hemostatic therapy , and clinical outcome parameters . Sample size analysis revealed a sample size of at least 100 patients per group . Results : There were 152 patients who were screened for eligibility and 100 patients were enrolled in the study . After r and omization of 50 patients to each group , a planned interim analysis revealed a significant difference in erythrocyte transfusion rate in the conventional compared with the POC group [ 5 ( 4;9 ) versus 3 ( 2;6 ) units [ median ( 25th and 75th percentile ) ] , P < 0.001 ] . The study was terminated early . The secondary outcome parameters of fresh frozen plasma and platelet transfusion rates , postoperative mechanical ventilation time , length of intensive care unit stay , composite adverse events rate , costs of hemostatic therapy , and 6-month mortality were lower in the POC group . Conclusions : Hemostatic therapy based on POC testing reduced patient exposure to allogenic blood products and provided significant benefits with respect to clinical outcomes OBJECTIVE Anti-platelet therapy is associated with increased perioperative bleeding . Although current guidelines call for its caessation 5 - 10 days prior to cardiac surgery , this could constitute an increased risk of preoperative myocardial infa rct ion . The optimal safe period from discontinuation of anti-platelet therapy to surgery is as yet unknown for the individual patient . We investigated whether preoperative thromboelastography ( TEG ) with platelet mapping could predict bleeding tendency in patients ( on recent anti-platelet therapy ) undergoing coronary artery bypass grafting ( CABG ) . METHODS We prospect ively evaluated 59 patients on aspirin and clopidogrel therapy who underwent CABG .  Of them , 25 patients received aspirin alone . TEG with platelet mapping was performed immediately prior to surgery in all 59 patients . RESULTS During the first 24h post-surgery , 9/59 patients bled excessively ( 1216 + or - 310 ml in excessive bleeding vs 576 + or - 155 ml in non-bleeding patients ) . Of the patients bled excessively , eight received clopidogrel treatment prior to surgery . However , 26 of the remaining 34 patients receiving clopidogrel did not bleed significantly . Clopidogrel-induced platelet dysfunction diagnosed by platelet mapping discerned between patients who demonstrated excessive bleeding and those who did not ( 78 % - sensitivity , 84 % - specificity , p=0.004 ) . Aspirin-induced platelet dysfunction did not reflect a bleeding tendency . Of all patients , 85 % did not respond to a st and ard dose of clopidogrel , whereas 44 % did not respond to aspirin . CONCLUSIONS TEG with platelet mapping is able to predict excessive postoperative blood loss among patients who underwent CABG and recent anti-platelet therapy . The prevalence of non-responsiveness to anti-platelet therapy , including clopidogrel , is higher in patients undergoing coronary artery bypass grafting than in the general population . In this study , aspirin-induced platelet dysfunction did not influence postoperative blood loss Individual variability in the response to antiplatelet therapy ( APT ) , frequently administered preoperatively , has been established by various platelet function assays and could reflect bleeding tendency after coronary artery bypass surgery ( CABG ) . Our hypothesis is that multiple electrode whole-blood aggregometry ( MEA ) can identify patients at risk for excessive bleeding . We enrolled 211 patients ( 155 male and 56 female ) undergoing isolated CABG in a prospect i ve observational study . Patients were divided into four groups with respect to their preoperative APT management . MEA , using the ASPI and the ADP test , was performed prior to surgery . The primary endpoint was chest tube output ( CTO ) and the secondary endpoint was perioperative packed red blood cell concentrate ( PRBC ) administration . Patients were characterized as bleeders if their 24 h CTO exceeded the 75th percentile of distribution . 24 h CTO value of 11.33 ml/kg presented 75th percentile of distribution , thus cut-off value for “ bleeder category ” . The proportion of patients characterized as bleeders was significantly different among the groups in regard to preoperative APT ( p = 0.039 ) . Significant differences in both ASPI ( p < 0.001 ) and ADP ( p = 0.038 ) tests were observed between different preoperative APT groups . Significant correlations between the ASPI test ( r = −0.170 , p = 0.014 ) and ADP test ( r = −0.206 , p = 0.003 ) with 24 h CTO were found . The receiver operating curve revealed an ASPI test value of < 20 area under curve ( AUC ) units ( AUC 0.603 , p = 0.023 ) and an ADP test < 73 AUC ( AUC 0.611 , p = 0.009 ) as a “ bleeder ” determinant . The proportion of patients transfused with PRBC did not significantly differ among the groups in regard to preoperative APT ( p = 0.636 ) . Comparison of the ASPI test values between patients with respect to PRBC administration revealed lower values in the ASPI test in a group of patients transfused with PRBC ( mean , 27.88 vs. 40.32 AUC , p = 0.002 ) . Our study showed that MEA is a useful method of predicting CABG patients with excessive postoperative bleeding BACKGROUND : The majority of pediatric cardiac surgery patients receive blood transfusions . We hypothesized that the routine use of intraoperative thromboelastometry to guide transfusion decisions would reduce the overall proportion of patients receiving transfusions in pediatric cardiac surgery . METHODS : One hundred pediatric cardiac surgery patients were included in the study . Fifty patients ( study group ) were prospect ively included and compared with 50 procedure- and age-matched control patients ( control group ) .  In the study group , thromboelastometry , performed during cardiopulmonary bypass , guided intraoperative transfusions . Intraoperative and postoperative transfusions of packed red blood cells , fresh frozen plasma , platelets , and fibrinogen concentrates , and postoperative blood loss and hemoglobin levels were compared between the 2 groups . RESULTS : The proportion of patients receiving any intraoperative or postoperative transfusion of packed red blood cells , fresh frozen plasma , platelets , or fibrinogen concentrates was significantly lower in the study group than in the control group ( 32 of 50 [ 64 % ] vs 46 of 50 [ 92 % ] , respectively ; P < 0.001 ) . Significantly fewer patients in the study group received transfusions of packed red blood cells ( 58 % vs 78 % , P = 0.032 ) and plasma ( 14 % vs 78 % , P < 0.001 ) , whereas more patients in the study group received transfusions of platelets ( 38 % vs 12 % , P = 0.002 ) and fibrinogen concentrates ( 16 % vs 2 % , P = 0.015 ) . Neither postoperative blood loss nor postoperative hemoglobin levels differed significantly between the study group and the control group . CONCLUSIONS : The results suggest that routine use of intraoperative thromboelastometry in pediatric cardiac surgery to guide transfusions is associated with a reduced proportion of patients receiving transfusions and an altered transfusion pattern Background Bleeding is a frequent complication during surgery . The intraoperative administration of blood products , including packed red blood cells , platelets and fresh frozen plasma ( FFP ) , is often live saving . Complications of blood transfusions contribute considerably to perioperative costs and blood product re sources are limited . Consequently , strategies to optimize the decision to transfuse are needed . Bleeding during surgery is a dynamic process and may result in major blood loss and coagulopathy due to dilution and consumption . The indication for transfusion should be based on reliable coagulation studies . While hemoglobin levels and platelet counts are available within 15 minutes , st and ard coagulation studies require one hour . Therefore , the decision to administer FFP has to be made in the absence of any data . Point of care testing of prothrombin time ensures that one major parameter of coagulation is available in the operation theatre within minutes . It is fast , easy to perform , inexpensive and may enable physicians to rationally determine the need for FFP . Methods / Design The objective of the POC-OP trial is to determine the effectiveness of point of care prothrombin time testing to reduce the administration of FFP . It is a patient and assessor blind , single center r and omized controlled parallel group trial in 220 patients aged between 18 and 90 years undergoing major surgery ( any type , except cardiac surgery and liver transplantation ) with an estimated blood loss during surgery exceeding 20 % of the calculated total blood volume or a requirement of FFP according to the judgment of the physicians in charge . Patients are r and omized to usual care plus point of care prothrombin time testing or usual care alone without 
    Output:
    
Platelet function tests demonstrated significant variability in their ability to predict blood loss and transfusion requirements .
We conclude that incorporation of point-of-care platelet function tests into transfusion management algorithms is associated with a reduction in blood loss and transfusion requirements in cardiac surgery patients