title: Prediction of excessive bleeding after coronary artery bypass graft surgery: the influence of timing and heparinase on thromboelastography.
abstract: OBJECTIVE
  To compare the ability of thromboelastography, when done at either 10 or 60 minutes after protamine reversal of heparin, to predict excessive bleeding after coronary artery bypass graft (CABG) surgery and to investigate, with the use of heparinase, whether heparin contamination was responsible for the difference, if any.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  University hospital, single institution.
  
  
  METHODS
  Patients undergoing elective CABG surgery (n = 40).
  
  
  METHODS
  Blood samples for thromboelastography and routine coagulation tests were collected before induction of anesthesia and at 10 and 60 minutes after protamine reversal of heparin. Blood loss and blood product use were recorded postoperatively.
  
  
  RESULTS
  Of 40 patients undergoing elective CABG surgery, 10 fulfilled the criteria for excessive postoperative bleeding. The sensitivity of thromboelastography to identify patients who bled was better at 60 minutes than at 10 minutes after protamine reversal of heparin (100% v 70%). There was greater specificity (83% v 40% at 10 minutes; 73% v 20% at 60 minutes) and positive predictive value (58% v 28% at 10 minutes; 55% v 29% at 60 minutes) when heparinase was added. At both times, thromboelastography showed only moderate correlation with total blood loss and the use of fresh frozen plasma or platelets or both. Conventional coagulation tests did not predict excessive postoperative bleeding.
  
  
  CONCLUSIONS
  This study suggests that timing and the use of heparinase influence the predictive ability of thromboelastography, but its usefulness as a sole predictor of post-CABG surgery bleeding is limited.
authors.affiliation: Department of Anaesthesia, National University Hospital, Singapore.
authors.forename: Lian K
authors.initials: LK
authors.lastname: Ti
authors.forename: Keng-Fatt
authors.initials: KF
authors.lastname: Cheong
authors.forename: Fun-Gee
authors.initials: FG
authors.lastname: Chen
mesh_terms: D000368:Aged; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D005260:Female; D019763:Heparin Lyase / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019106:Postoperative Hemorrhage / Q000175:diagnosis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013916:Thrombelastography; D013997:Time Factors
chemical_list: D019763:Heparin Lyase