[Change in plasma microparticle procoagulant activity after traumatic brain injury].

Objective: To observe the serial changes of plasma microparticle procoagulant activity in patients with traumatic brain injury (TBI) and evaluate its correlations with outcome and pathophysiology of TBI.

Methods: A total of 139 consecutive patients with isolated moderate or severe head trauma and 40 age- and sex-matched healthy controls were enrolled. Plasma samples were obtained on entry in healthy controls, as well as on admission and at day 1, day 2, day 3, day 5, and day 7 after TBI in the patients. Its concentration was measured by a prothrombinase assay.

Results: Fifty patients (36.0%) died from TBI in a month. After TBI, plasma microparticle procoagulant activity in the patients increased during the 6-hour period immediately, peaked in 24 hours and decreased gradually thereafter. It was substantially higher than that of healthy controls during the 7-day period using analysis of covariate (P < 0.01). A multivariate analysis selected plasma microparticle procoagulant activity (OR 1.432, 95% CI 1.194-1.719, P < 0. 01) as an independent predictor for 1-month mortality. Plasma microparticle procoagulant activities of non-survivals were statistically significantly higher than those of survivals (P = 0.01), and plasma microparticle procoagulant activities of patients with severe TBI were obviously higher than those of patients with moderate TBI (P = 0.002) using repeated-measures analysis. Plasma microparticle procoagulant activities of patients were negatively associated with Glasgow coma scale scores using Spearman correlation coefficient (P < 0.05). A multivariate linear regression selected plasma D-dimer level (P = 0.012) and plasma C-creative protein level (P = 0.019) related to plasma microparticle procoagulant activities. A receiver operating characteristic curve identified the cutoff levels of plasma microparticle procoagulant activities (12.2 U/ml) predicting 1-month mortality of patients with the high sensitivity (72.0%) and specificity values (85.4%). Areas under curve (AUC) of plasma resistin level (AUC = 0.847 +/- 0.037) was smaller than those of GCS scores (AUC = 0.917 +/- 0.023), but this difference failed to reach statistical significance (P = 0.104).

Conclusion: Increased activity of plasma microparticle procoagulant is found after traumatic brain injury. It may contribute to inflammatory reaction and coagulation cascade and is associated with a poor clinical outcome.