Assessment of rVIIa as a universal haemostatic agent in a model of haemodilution

Haemostatic failure, secondary to large volume fluid replacement, is a major component to the mortality and morbidity associated with blunt trauma. Progressive bleeding in multiply injured patients is due to both dilution effects and specific inhibitory effects on platelet function of the colloids used. Recombinant factor VIIa (rVIIa) is seen increasingly as a possible universal haemostatic agent that could act to reverse or prevent haemostatic failure associated with dilution and the direct effects of the colloids within the 'Golden' hour of haemorrhagic shock.

We have conducted a pilot preclincal study to evaluate the potential role of rVIIa as a universal haemostatic agent in a model of large volume fluid replacement using thrombelastography (TEG). TEG is a method of global haemostasis assessment, providing information on the rate of clot formation, clot strength and durability.

Whole blood samples from normal donors were tested undiluted (100%) or diluted (50% and 80%) with standard colloid replacement solutions (Haemacel, Albumin, Gelofusine, Hydroxyethyl starch) and N/Saline. Global haemostasis was assessed in the TEG, ± 90 μg/kg rVIIa added. In undiluted blood (100%) there were no statistically significant changes in any TEG parameter when rVIIa was added. At dilutions of > 50% addition of rVIIa significantly improved the kinetics of clot formation and rate of platelet reactivity, P < 0.05, although time to the start of coagulation and final clot strength were not significantly different. The beneficial effects of addition of rVIIa did not differ between different fluid replacement solutions.

Addition of rVIIa therefore appears to improve markers of global haemostasis in this model of large volume fluid replacement. Further work is required to assess its potential value as a universal haemostatic agent in the setting of blunt trauma and large volume fluid replacement.