title: A small amount can make a difference: a prospective human study of the paradoxical coagulation characteristics of hemothorax.
abstract: BACKGROUND
  The evacuated hemothorax has been poorly described because it varies with time, it has been found to be incoagulable, and its potential effect on the coagulation cascade during autotransfusion is largely unknown.
  
  
  METHODS
  This is a prospective descriptive study of adult patients with traumatic chest injury necessitating tube thoracostomy. Pleural and venous samples were analyzed for coagulation, hematology, and electrolytes at 1 to 4 hours after drainage. Pleural samples were also analyzed for their effect on the coagulation cascade via mixing studies.
  
  
  RESULTS
  Thirty-four subjects were enrolled with a traumatic hemothorax. The following measured coagulation factors were significantly depleted compared with venous blood: international normalized ratio (>9 vs 1.1) (P < .001) and activated partial thromboplastin time (aPTT) (>180 vs 24.5 seconds) (P < .001). Mixing studies showed a dose-dependent increase in coagulation dilutions through 1:8 (P < .05).
  
  
  CONCLUSIONS
  An evacuated hemothorax does not vary in composition significantly with time and is incoagulable alone. Mixing studies with hemothorax plasma increased coagulation, raising safety concerns.
authors.affiliation: Division of Trauma and Emergency Surgery, Department of Surgery, University of Texas Health Science Center, 7703 Floyd Curl Drive, Mail Code 7840, San Antonio, TX 78229, USA. Electronic address: smithwz@livemail.uthscsa.edu.
authors.forename: W Zachary
authors.initials: WZ
authors.lastname: Smith
authors.forename: Hannah B
authors.initials: HB
authors.lastname: Harrison
authors.forename: Marc A
authors.initials: MA
authors.lastname: Salhanick
authors.forename: Russell A
authors.initials: RA
authors.lastname: Higgins
authors.forename: Alfonso
authors.initials: A
authors.lastname: Ortiz
authors.forename: John D
authors.initials: JD
authors.lastname: Olson
authors.forename: Martin G
authors.initials: MG
authors.lastname: Schwacha
authors.forename: Chantal R
authors.initials: CR
authors.lastname: Harrison
authors.forename: Jayson D
authors.initials: JD
authors.lastname: Aydelotte
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Stewart
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Dent
mesh_terms: D000328:Adult; D001777:Blood Coagulation / Q000502:physiology*; D001804:Blood Transfusion, Autologous / Q000379:methods*; D004322:Drainage / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006491:Hemothorax / Q000097:blood / Q000209:etiology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011446:Prospective Studies; D013898:Thoracic Injuries / Q000097:blood / Q000150:complications* / Q000601:surgery; D013908:Thoracotomy / Q000379:methods*; D016896:Treatment Outcome; D014945:Wound Healing
keywords: Autotransfusion; Coagulation; Disseminated intravascular coagulation; Hemothorax; Pleural blood