A. Bartels1, C. Jones1, A. Scott1, J. Coberly1, S. L. Barnes1, R. D. Hammer1, S. Ahmad1 1University Of Missouri,Columbia, MO, USA
Introduction:
Antiplatelet therapy is prevalent due to the important role platelets play in preventing and treating coronary artery disease and cerebrovascular accidents. These medications can potentiate bleeding complications associated with trauma; identification of chemical coagulopathy in trauma patients is important to guide initial resuscitation.
We previously conducted a retrospective review demonstrating the failure of the Platelet Function Assay (PFA)-100 to reliably detect aspirin and clopidogrel in traumatic brain injuries and cerebrovascular accidents. The overall sensitivity of the PFA-100 was 48.6% with a specificity of 74.8%.
The purpose of this study was to evaluate the effectiveness of thromboelastography with platelet mapping (TEG-PM) as an alternative to the PFA-100 in identifying antiplatelet medications in trauma patients.
Methods:
All TEG-PM studies from September 2013-2014 were collected. Admission diagnoses and home antiplatelet medications were reviewed. Trauma patients were selected and evaluated for concurrent PFA-100 tests to allow direct comparison of the two studies.
Results:
A total of 256 TEG-PM studies were performed. 106 were trauma patients and constituted our research group. Both TEG-PM and PFA-100 studies were performed on 21 patients.
TEG-PM identified aspirin with an overall sensitivity of 73.1% and specificity of 37%; clopidogrel was detected with 100% sensitivity and 12.7% specificity.
In the 21 patients who had both a TEG-PM and PFA-100, the overall sensitivity and specificity of the PFA-100 was 50% and 61.9%, respectively. Individually, the sensitivity of the PFA for ADP inhibition was 33.3%. There was 100% sensitivity and 8.3% specificity of the TEG-PM for ADP inhibition. Overall sensitivity and specificity for the TEG-PM was 94.4% and 25%, respectively.
Conclusion:
The overall sensitivity and specificity of the PFA-100 was similar to our previous study. TEG-PM was more sensitive for detecting clopidogrel than the PFA-100 in the same set of patients.
The high sensitivity of TEG-PM for detecting clopidogrel was also seen in the larger trauma group. A 100% negative predictive value of the TEG-PM for ADP inhibition is key and indicates its possible role as a screening tool for antiplatelet medications in the initial evaluation of trauma patients.
Interestingly, there is a low specificity of the TEG-PM for ADP inhibition – high levels of ADP inhibition are seen in trauma patients despite no known antiplatelet medication use. Acute traumatic coagulopathy (ATC) is a known phenomenon. The etiology of this inhibition is unclear; however, coagulopathy in the trauma patient remains an independent predictor of death and warrants further investigation.