title: Agreements between the prothrombin times of blood treated In Vitro with heparinase during cardiopulmonary bypass (CPB) and blood sampled after CPB and systemic protamine.
abstract: The prothrombin time (PT) is useful for identifying coagulation factor deficits after cardiopulmonary bypass (CPB). However, long processing times and the need for fresh frozen plasma (FFP) to be thawed cause delays in factor replacement. We hypothesized that, by treating with heparinase, blood sampled toward the end of CPB can provide PT results that help to determine the requirement for FFP after CPB. Laboratory delays can be eliminated with point-of-care monitors. We studied 158 adults undergoing nonemergent cardiac surgery. Blood taken before separation from CPB was mixed with heparinase, and PT was measured in the laboratory with a HemoTec timer. Agreements between these results and laboratory measurements of blood taken after systemic protamine were compared by using Bland and Altman plots with the threshold of +/-1.0 s. We found that the laboratory PT measurements during CPB versus after CPB were compara-ble, but the limits of agreement exceeded these thresholds. Similarly, there was unsatisfactory agreement between the HemoTec and laboratory PT results measured before, during, and after CPB. For each PT measured during CPB, the corresponding confidence interval for the postprotamine PT was calculated. During CPB, a laboratory PT of < or =16 s or > or =18 s suggests a > or =83% or > or =93% probability of not requiring or potentially requiring, respectively, FFP after CPB. We conclude that the majority of PT measurements obtained from blood taken before weaning from CPB and treated in vitro with heparinase was associated with a high probability of whether or not FFP would be needed after CPB.
  
  
  CONCLUSIONS
  Coagulation dysfunction after cardiopulmonary bypass may contribute to bleeding. Obtaining coagulation tests and fresh frozen plasma requires time and delays treatment in patients who need fresh frozen plasma. We have devised a technique to provide early estimation of postbypass coagulation status.
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, People's Republic of China. hoamh@hotmail.com
authors.forename: Anthony M-H
authors.initials: AM
authors.lastname: Ho
authors.forename: Anna
authors.initials: A
authors.lastname: Lee
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ling
authors.forename: Alan
authors.initials: A
authors.lastname: Daly
authors.forename: Kevin
authors.initials: K
authors.lastname: Teoh
authors.forename: Theodore E
authors.initials: TE
authors.lastname: Warkentin
mesh_terms: D000368:Aged; D000465:Algorithms; D002315:Cardiopulmonary Bypass; D005260:Female; D006494:Heparin Antagonists; D019763:Heparin Lyase; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D011479:Protamines; D011517:Prothrombin Time; D015203:Reproducibility of Results
chemical_list: D006494:Heparin Antagonists; D011479:Protamines; D019763:Heparin Lyase