Catheter-induced clotting and thrombin generation in control, HRG-depleted, or FXII-depleted human plasma. (A) Plasma was incubated for 15 minutes at 37°C in the absence or presence of catheter segments before initiating clotting by addition of 20 mM CaCl₂. Absorbance was monitored, and plasma recalcification times were determined as the time to half maximal absorbance. Bars represent the mean ± SD of 4 determinations. ^∗P < .05 and ^∗∗∗P < .001 comparison of the plasma recalcification time in the absence of catheter segments (red bars); ^##P < .01 and ^###P < .001 comparisons of the plasma recalcification time in the presence of catheter segments (blue bars); ^††P < .01 and ^†††P < .001 as indicated by the lines (one-way ANOVA and Holm-Sidak method). (B-E) Plasma was incubated in the absence or presence of catheter segments for 15 minutes at 37°C, and thrombin generation was initiated by the addition of 20 mM CaCl₂ and was quantified by monitoring the hydrolysis of 1 mM Z-GGR-AMC. Representative thrombin generation profiles in the absence (B) or presence (C) of catheter segments. Mean lag time (D) and peak thrombin (E) in the absence (red bars) or presence (blue bars) of catheter segments are shown. Bars represent mean ± SD from 5 determinations each performed in duplicate. ^∗P < .05 comparison of the control plasma in the absence of catheter segments. ^#P < .05 and ^##P < .01 comparisons of the control plasma in the absence of catheter segments; P > .05 (one-way ANOVA and Holm-Sidak method).