Platelet function in major trauma: A 5‐day trajectory analysis by injury pattern

BACKGROUND: Platelet dysfunction is recognized as an important component of trauma-induced coagulopathy. However, both its trajectory and its relationship with specific injury patterns remain incompletely understood. METHODS: This retrospective study included severely injured patients who underwent Multiplate™ impedance aggregometry from emergency room (ER) admission through day 5 in the intensive care unit (ICU). Patients were stratified into isolated traumatic brain injury (TBI), major trauma without TBI (MT), and major trauma with TBI (TBI + MT). To eliminate the influence of platelet count on platelet function testing, platelet numbers were normalized to 250 G/L. RESULTS: Seventy-four patients were included (15 TBI, 28 MT, 31 TBI + MT). Platelet counts declined significantly over 5 days (p < 0.0001). Unadjusted platelet function (ASPI, ADP, TRAP) was significantly reduced on all days compared with ER admission (all p < .0001). After adjustment for platelet count, only ASPI and ADP remained reduced, and only on day 1. Unadjusted injury-pattern differences were observed solely on day 1: ASPI and ADP were higher in TBI than MT (both p < .05), and TRAP was highest in TBI compared with MT and TBI + MT (p < .05). After platelet-count adjustment, all differences resolved except for ASPI on day 1 (p < .05). CONCLUSIONS: Platelet function declined markedly within the first 24 h after trauma, independent of platelet count, indicating an early qualitative dysfunction in addition to thrombocytopenia. Beyond this early phase, no further changes were observed in survivors during the one-week observation period. We found no consistent association between injury patterns, including TBI, and sustained dysfunction.