There is a rapidly growing body of support for a prominent role of
platelet dysfunction in the pathophysiology of TIC. Historically,
platelet-specific transfusion and hemostatic management were based
on critical thresholds in platelet counts and less so on platelet
function. In trauma, platelet count does strongly influence hemostasis
and a low or decreasing platelet count in trauma patients does
predict greater mortality.13 However, platelet counts are typically
within the normal range during early TIC, indicating that their
consumption or dilution is not a major contributor to the early TIC
mechanism.13
Moderate or even mildly decreased platelet aggregation is strongly
associated with mortality. Kutcher et al used impedance aggregometry
to characterize platelet dysfunction in trauma patients on arrival
at the emergency department.14 They found that of 101 patients,
almost half (45.5%) showed decreased platelet aggregation in
response to ADP, thrombin receptor-activating peptide, arachidonic
acid (AA), and/or collagen. There was an astonishing 10-fold
increase in mortality in patients having any one of these platelet
aggregation deficits, and admission AA and collagen responsiveness
were sensitive and specific predictors of mortality. Solomon et
al showed similar results in 163 trauma patients of which 20
(12.3%) died15 and, again, even relatively minor defects in platelet
aggregation detected by multiple electrode aggregometry were
associated with mortality. They also found the platelet contribution
to clot firmness measured using rotational thromboelastometry
(ROTEM) to be significantly decreased in nonsurvivors. Using
thrombelastography modified to detect platelet-specific effects
(Platelet Mapping; Haemonetics) Wohlauer et al also found a
pronounced inhibition of clot strength when activated with ADP and
AA in 51 trauma patients sampled within 30 minutes of injury