Sepsis platelets are hyporeactive. Platelet reactivity assays are shown at the following time points: I: admission day; II: day 5 to 7; and III: day of ICU discharge. (A-F) Platelet integrin activation (A,C,E) and P-selectin exposure (B,D,F) were measured upon stimulation with ADP (5 µM) (A-B), CRP-XL (0.01 µg/mL) (C-D), or convulxin (0.01 µg/mL) (E-F) in whole blood by flow cytometry. (G-L) Light transmission aggregometry was performed using washed platelets (500 000/µL). Maximum (max.) aggregation is depicted upon stimulation with CRP-XL (0.1 µg/mL) (G-H), rhodocytin (10 nM) (I-J), or TRAP-6 (10 µM) (K-L). Representative curves are shown in panels G, I, and K. CRP-XL samples were measured for 5 minutes, and rhodocytin or TRAP-6 samples for 10 minutes. Graphs show median ± IQR. Differences were analyzed by Kruskal-Wallis test (A-L). *P < .05; **P < .01; ***P < .001; ****P < .0001.