***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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    ***EXAMPLES*** 
    Input: BACKGROUND Operative treatment of craniosynostosis is associated with substantial blood loss , often requiring transfusion of packed red blood cells ( PRBC ) and coagulation products . AIMS The aim of this prospect i ve study was to analyze  thromboelastographic ( TEG ) parameters and platelet fibrinogen product to determine predictors of substantial blood loss , and the need for PRBC transfusion and coagulation products . METHODS With IRB approval , we enrolled 120 children undergoing craniosynostosis repair with a st and ardized anesthetic , fluid management , and TEG measurements at predefined times . Outcomes of interest were intraoperative blood loss , and need for PRBC transfusion and coagulation products  . Multivariable logistic regression and receiver operating characteristic ( ROC ) curve analysis was applied to determine independent predictors of substantial blood loss and need for coagulation products . RESULTS One hundred and eighteen children were included in the analysis . Forty-four required PRBC transfusion ( median 26 ml·kg(-1 ) ; IQR : 22 - 42 ) with median blood loss of 56 ml·kg(-1 ) ( IQR : 43 - 83 ) . Factors associated with the PRBC transfusion included type of surgery , duration of surgery , and three TEG parameters , α-angle , MA , and K-time ( all P < 0.001 ) . A predictive algorithm was developed by subgroup analysis of cranial vault reconstruction ( CVR ) patients for substantial intraoperative blood loss ( defined as ≥60 ml·kg(-1 ) ) and need for coagulation products with ROC-derived cut-off values : platelet fibrinogen product , < 343 ; α-angle , < 62 ° ; MA , < 55 mm ; K-time , > 2.1 min . The best prognostic combination included at least two of these four predictors ( sensitivity 89 % , specificity 90 % ) . Multivariable regression identified MA as the only independent predictor of coagulation product administration ( P < 0.001 ) and ROC analysis identified MA < 46 mm as the optimal cut-off ( sensitivity 86 % , specificity 94 % ) . CONCLUSIONS Risk for substantial intraoperative blood loss can be assessed using TEG parameters and platelet fibrinogen product , whereas the need for coagulation products is strongly related to low MA . Patients susceptible to substantial blood loss can be risk stratified based on their TEG/platelet fibrinogen product profile Bleeding remains a serious complication of cardiac surgery . Studies indicate that preoperative fibrinogen concentration is an independent predictor of blood loss during coronary artery bypass graft ( CABG ) surgery . This study evaluates whether fibrinogen concentration is a better predictor of blood usage than the prothrombin time ( PT ) and activated partial thromboplastin time ( aPTT ) tests . Patients not taking clopidogrel bisulfate who underwent CABG surgery during a 3-month period at a 350-bed community hospital were included in this prospect i ve study . The parameters evaluated included patient ’s age , preoperative coagulation test results ( PT , international normalized ratio [ INR ] , aPTT , fibrinogen ) , and number of blood components transfused . A probability value of less than 0.05 was deemed significant . Thirty-five patients were included in this study .  Mean blood usage was 6 units . Patient ’s age approached significance as a predictor of blood usage , and fibrinogen levels trended toward significance more than the other coagulation parameters . In this study , the increased age of the patient and low plasma concentrations of fibrinogen were associated with increased blood usage . Although no indicators clearly demonstrated statistical significance , the vast difference in the probability values for patients ’ ages and fibrinogen levels indicated that there was a trend toward significance in blood usage for CABG patients . Further studies with larger patient population s are indicated 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 BACKGROUND We sought to assess predictability of excessive bleeding using thrombelastography ( TEG ) , multiplate impedance aggregometry , and conventional coagulation tests including fibrinogen in patients undergoing coronary artery bypass graft ( CABG ) surgery . METHODS A total of 170 patients were enrolled in this prospect i ve observational study . TEG , Multiplate aggregometry , and coagulation tests were sample d on the day before surgery . Excessive bleeding was defined as > 1000 mL over 18 hours . RESULTS  Multiplate-adenosine diphosphate ( ADP ) measurements were significantly lower in patients with excessive bleeding , 85.5AU ± 32.8 versus 108.5AU ± 30.0 , p = 0.012 . Bivariate analysis revealed body mass index , myocardial infa rct ion , and multiplate-ADP as predictors of bleeding . In multivariable linear regression analysis , multiplate-ADP remained a significant predictor of bleeding ( β : -6.2 [ confidence interval : -12.0 to -0.3 ] , p = 0.035 ) . The lowest interval of multiplate-ADP ( < 50 AUC ) was associated with significantly more bleeding and need for platelet concentrate transfusion . Fibrinogen levels < 2.5 g/L were also found to be associated with excess bleeding ( p = 0.020 ) . CONCLUSIONS Multiplate impedance aggregometry identified patients at risk for excessive bleeding after CABG . Low fibrinogen levels were associated with increased bleeding . Neither routine TEG parameters nor conventional coagulation tests were correlated with bleeding OBJECTIVE To assess the predictive value of variables possibly associated with blood loss  after coronary artery bypass grafting ( CABG ) .  DESIGN A prospect i ve study . SETTING A university hospital . PARTICIPANTS Eighty-nine patients scheduled for elective CABG .  INTERVENTIONS Blood sample s were drawn before and after surgery . Chest tube drainage was measured hourly until removal of drains . MEASUREMENTS AND MAIN RESULTS Activation of coagulation and fibrinolysis , routine clotting tests , and expression of platelet surface antigens were analyzed using flow cytometry . A significant correlation was found among blood loss and activated partial thromboplastin time , fibrinogen , prothrombin fragment 1 + 2 , D-dimers , platelet count , GPIb and P-selectin expression on platelets , use of internal thoracic artery , cross-clamp time , and thrombin-antithrombin III complex . In a multiple regression model , glycoprotein ( GP ) Ib expression on platelets , platelet count , use of internal thoracic artery , and D-dimers were significantly associated with blood loss . Logistic regression analysis showed that GPIb and D-dimers predicted an increased blood loss with a positive predictive value of 73 % and a negative predictive value of 91 % . CONCLUSIONS Postoperative D-dimers and GPIb expression may be useful to exclude nonsurgical causes in bleeding patients after CABG BACKGROUND Congenital heart disease ( CHD ) is associated with complex coagulation abnormalities . Platelet aggregability has not been investigated in detail in children with acyanotic and cyanotic malformations undergoing open heart surgery . The method of whole-blood multiple electrode aggregometry ( MEA ) appears suitable for rapid platelet analysis in children , for example , because of small sample volumes . We investigated perioperative evolution of platelet aggregation by means of MEA in children with CHD . METHODS Fifty children with acyanotic or cyanotic malformations were included in a prospect i ve observational study . Laboratory testing was assessed before anaesthesia , and during and after surgery until the fifth postoperative day . MEA was performed in hirudin-anticoagulated blood using adenosine diphosphate ( ADP ) , arachidonic acid , and thrombin receptor-activating peptide for platelet activation . Surgical variables , bleeding volumes , and transfusion requirements were documented during hospital stay . RESULTS Mean platelet count was within the normal range in all patients with no intergroup differences . Before surgery , aggregation to all agonists was within the age-adjusted normal range in cyanotic children and was statistically significantly higher compared with acyanotic children . Platelet aggregation decreased significantly during surgery in both groups followed by a slow recovery not reaching baseline levels . Bleeding and platelet transfusions were higher in the cyanotic group . Transfusion requirements correlated with ADP-induced platelet aggregation . CONCLUSIONS These results indicate higher blood loss , despite better platelet aggregation in cyanotic patients compared with acyanotic patients .  MEA alone might not be suitable for predicting increased perioperative blood loss BACKGROUND The bleeding time is frequently used to screen primary haemostasis before surgical procedures , although it poorly predicts the risk of hemorrhage . The platelet function analyzer ( PFA ) , which is also used to screen primary haemostasis , has a higher sensitivity and other advantages , like patient friendliness , higher degree of objectivity and analytical reliability , but needs more extensive clinical validation . METHODS We compared the predictive values of the PFA-CTs ( closure times ) and bleeding time for bleeding events after  renal biopsy .  We prospect ively evaluated the complications in patients that underwent a renal biopsy and were screened with PFA in advance ( n=170 ) . For comparison we used a historical cohort of patients screened with the bleeding time ( n=132 ) . RESULTS When the PFA-CTs were normal , 26.0 % of the patients had a mild bleeding event after the biopsy , which did not differ from the event rate with a normal bleeding time ( 29.4 % ) . When one or both PFA-CTs were prolonged , 51.3 % of the patients had post-biopsy bleeding events independently of the measures to correct the closure time(s ) , significantly more than with either a prolonged bleeding time ( 26.7 % ) or normal PFA-CTs ( 26.0 % ) . CONCLUSION For bleeding events , the PFA has a higher positive and similar negative predictive value compared to the bleeding time . Taken into account the additional advantages of the PFA like patient friendliness and better analytical qualities , we prefer the PFA over the bleeding time as a screening tool for primary haemostasis before performing a renal biopsy 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 = −0.20 
    Output:
    
In conclusion , while useful in the diagnosis and management of patients with overt bleeding  , whole blood coagulation and platelet function tests as well as st and ard coagulation tests demonstrated limited ability to predict perioperative bleeding in unselected patients .