Quantification of hypercoagulable state after blunt trauma: microparticle and thrombin generation are increased relative to injury severity, while standard markers are not.
BACKGROUND
Major trauma is an independent risk factor for developing venous thromboembolism. While increases in thrombin generation and/or procoagulant microparticles have been detected in other patient groups at greater risk for venous thromboembolism, such as cancer or coronary artery disease, this association has yet to be documented in trauma patients. This pilot study was designed to characterize and quantify thrombin generation and plasma microparticles in individuals early after traumatic injury.


METHODS
Blood was collected in the trauma bay from 52 blunt injured patients (cases) and 19 uninjured outpatients (controls) and processed to platelet poor plasma to allow for (1) isolation of microparticles for identification and quantification by flow cytometry, and (2) in vitro thrombin generation as measured by calibrated automatic thrombography. Data collected are expressed as either mean ± standard deviation or median with interquartile range.


RESULTS
Among the cases, which included 39 men and 13 women (age, 40 ± 17 years), the injury severity score was 13 ± 11, the international normalized ratio was 1.0 ± 0.1, the thromboplastin time was 25 ± 3 seconds, and platelet count was 238 ± 62 (thousands). The numbers of total (cell type not specified) procoagulant microparticles, as measured by Annexin V staining, were increased compared to nontrauma controls (541 ± 139/μL and 155 ± 148/μL, respectively; P < .001). There was no significant difference in the amount of thrombin generated in trauma patients compared to controls; however, peak thrombin was correlated to injury severity (Spearman correlation coefficient R, 0.35; P = .02).


CONCLUSIONS
Patients with blunt trauma have greater numbers of circulating procoagulant microparticles and increased in vitro thrombin generation. Future studies to characterize the cell-specific profiles of microparticles and changes in thrombin generation kinetics after traumatic injury will determine whether microparticles contribute to the hypercoagulable state observed after injury.
Department of Surgery, Mayo Clinic, Rochester, MN, USA. park.myung@mayo.edu
Myung S
MS
Park
Barbara A L
BA
Owen
Beth A
BA
Ballinger
Michael G
MG
Sarr
Henry J
HJ
Schiller
Scott P
SP
Zietlow
Donald H
DH
Jenkins
Mark H
MH
Ereth
Whyte G
WG
Owen
John A
JA
Heit
D000328:Adult; D017304:Annexin A5 / Q000097:blood; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D010865:Pilot Projects; D011446:Prospective Studies; D011517:Prothrombin Time; D012307:Risk Factors; D013917:Thrombin / Q000378:metabolism*; D019851:Thrombophilia / Q000097:blood*; D013925:Thromboplastin / Q000378:metabolism; D015599:Trauma Severity Indices; D054556:Venous Thromboembolism / Q000097:blood / Q000453:epidemiology*; D014947:Wounds and Injuries / Q000097:blood* / Q000150:complications*
D017304:Annexin A5; D015415:Biomarkers; D013925:Thromboplastin; D013917:Thrombin