Early Platelet Dysfunction in Sepsis: An ICU Pilot Study.

Platelets are critical for hemostasis and play an active role in immune responses to infection. While thrombocytopenia in sepsis is associated with poor outcomes, platelet dysfunction remains less explored. This prospective observational pilot study investigated the relationship between platelet dysfunction and sepsis severity using multiple platelet function tests. Ten adults with sepsis or septic shock admitted to the ICU of "Fondazione Policlinico Universitario A. Gemelli" and seven healthy controls were enrolled. Blood samples were collected at admission (T0), after 48 h (T1), and after 7 days (T2). Controls were sampled only at T0. Besides platelet count, hemostatic platelet function was assessed by light transmission aggregometry (LTA), thromboelastography (TEG), and platelet activation markers (P-selectin and PAC-1 expression), whereas immune platelet function was assessed by investigation of platelet-leukocyte aggregates and soluble plasma levels of CD40L. Platelet function was correlated with procalcitonin levels and SOFA scores. While thrombocytopenia developed after 48 h, hemostatic and immune platelet dysfunctions were already evident at T0. Platelet function abnormalities were correlated with sepsis severity, as reflected by higher SOFA scores and elevated procalcitonin levels, particularly at T0. Early platelet dysfunction, preceding thrombocytopenia, may represent a potential early indicator of sepsis severity and support timely intervention for hemostatic and immune platelet-dependent abnormalities in septic patients.