title: Platelets are dominant contributors to hypercoagulability after injury.
abstract: BACKGROUND
  Venous thromboembolic (VTE) disease has a high incidence following trauma, but debate remains regarding optimal prophylaxis. Thrombelastography (TEG) has been suggested to be optimal in guiding prophylaxis. Thus, we designed a phase II randomized controlled trial to test the hypothesis that TEG-guided prophylaxis with escalating low-molecular weight heparin (LMWH), followed by antiplatelet therapy would reduce VTE incidence.
  
  
  METHODS
  Surgical intensive care unit trauma patients (n = 50) were randomized to receive 5,000 IU of LMWH daily (control) or to TEG-guided prophylaxis, up to 5,000 IU twice daily with the addition of aspirin, and were followed up for 5 days. In vitro studies were also conducted in which apheresis platelets were added to blood from healthy volunteers (n = 10).
  
  
  RESULTS
  Control (n = 25) and TEG-guided prophylaxis (n = 25) groups were similar in age, body mass index, Injury Severity Score, and male sex. Fibrinogen levels and platelet counts did not differ, and increased LMWH did not affect clot strength between the control and study groups. The correlation of clot strength (G value) with fibrinogen was stronger on Days 1 and 2 but was superseded by platelet count on Days 3, 4, and 5. There was also a trend in increased platelet contribution to clot strength in patients receiving increased LMWH. In vitro studies demonstrated apheresis platelets significantly increased clot strength (7.19 ± 0.35 to 10.34 ± 0.29), as well as thrombus generation (713.86 ± 12.19 to 814.42 ± 7.97) and fibrin production (274.03 ± 15.82 to 427.95 ± 16.58).
  
  
  CONCLUSIONS
  Increased LMWH seemed to increase platelet contribution to clot strength early in the study but failed to affect the overall rise clot strength. Over time, platelet count had the strongest correlation with clot strength, and in vitro studies demonstrated that increased platelet counts increase fibrin production and thrombus generation. In sum, these data suggest an important role for antiplatelet therapy in VTE prophylaxis following trauma, particularly after 48 hours.
  
  
  METHODS
  Therapeutic study, level III.
authors: Department of Surgery, University of Colorado Denver, Aurora, Colorado, USA.
authors: Jeffrey N
authors: JN
authors: Harr
authors: Ernest E
authors: EE
authors: Moore
authors: Theresa L
authors: TL
authors: Chin
authors: Arsen
authors: A
authors: Ghasabyan
authors: Eduardo
authors: E
authors: Gonzalez
authors: Max V
authors: MV
authors: Wohlauer
authors: Anirban
authors: A
authors: Banerjee
authors: Christopher C
authors: CC
authors: Silliman
authors: Angela
authors: A
authors: Sauaia
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000008:administration & dosage; D001777:Blood Coagulation; D001792:Blood Platelets / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage*; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D010976:Platelet Count; D011379:Prognosis; D011446:Prospective Studies; D013916:Thrombelastography; D019851:Thrombophilia / Q000097:blood* / Q000150:complications / Q000188:drug therapy; D013927:Thrombosis / Q000097:blood / Q000209:etiology* / Q000517:prevention & control; D014947:Wounds and Injuries / Q000097:blood / Q000150:complications* / Q000175:diagnosis
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D010975:Platelet Aggregation Inhibitors