title: Technical report: analysis of citrated blood with thromboelastography: comparison with fresh blood samples.
abstract: OBJECTIVE
  Thromboelastography (TEG) evaluates the visco-elastic properties of whole blood to assess clot formation and hemostasis. When blood cannot be analyzed immediately, it is stored in citrated tubes to be analyzed after recalcification. In this study, we evaluated the results of TEG analysis performed on citrated blood and compared these results to values obtained from activated (kaolin and tissue factor) and non activated, fresh blood samples, obtained at various time intervals (one, two, and three hours).
  
  
  METHODS
  Four blood samples were collected from each of ten healthy volunteers. The following TEG analyses were performed on each sample: reaction time (r), k time (k), alpha angle (alpha), and maximum amplitude (MA). Studies were done using fresh, non citrated blood, obtained within five minutes of collection, and using citrated blood, one, two, and three hours after collection. Samples were analyzed, with and without activation, using kaolin and tissue factor.
  
  
  RESULTS
  Tissue factor activated and non activated, citrated samples had shorter r and k times (P=0.03, P=0.008, P<0.0001, and P<0.0001, respectively) and higher alpha angle and MA values (P<0.0001, P<0.0001, P=0.79, and P=0.03, respectively) compared to fresh, non citrated samples. These findings were consistent with a hypercoagulable state. Conversely, citrated samples, activated with kaolin, yielded results similar to those obtained from fresh, non citrated samples. The TEG measurements were similar among citrated samples stored from one to three hours.
  
  
  CONCLUSIONS
  Our results demonstrate that TEG measures, performed on citrated blood samples, yield results that are consistent with a hyperocoagulable state. Using kaolin to activate citrated samples, on the other hand, yields results similar to those obtained from non citrated, fresh blood samples.
authors.affiliation: Department of Anesthesia, Toronto General Hospital, University Health Network, and Department of Health Policy, Management and Evaluation, University of Toronto, 200 Elizabeth St., EN3-424, Toronto, Ontario M5G 2C4, Canada. marcin.wasowicz@uhn.on.ca
authors.forename: Marcin
authors.initials: M
authors.lastname: Wasowicz
authors.forename: Coimbatore
authors.initials: C
authors.lastname: Srinivas
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Meineri
authors.forename: Brie
authors.initials: B
authors.lastname: Banks
authors.forename: Stuart A
authors.initials: SA
authors.lastname: McCluskey
authors.forename: Keyvan
authors.initials: K
authors.lastname: Karkouti
mesh_terms: D000328:Adult; D001777:Blood Coagulation / Q000187:drug effects* / Q000502:physiology; D001800:Blood Specimen Collection / Q000379:methods; D002951:Citrates / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007616:Kaolin / Q000494:pharmacology; D008297:Male; D013916:Thrombelastography / Q000187:drug effects* / Q000379:methods; D019851:Thrombophilia / Q000139:chemically induced; D013925:Thromboplastin / Q000502:physiology; D013997:Time Factors; D016896:Treatment Outcome; D014914:Whole Blood Coagulation Time
chemical_list: D002951:Citrates; D007616:Kaolin; D013925:Thromboplastin