Severity of hemorrhage and the survival benefit associated with plasma: Results from a randomized prehospital plasma trial

BACKGROUND Recent randomized clinical trial evidence demonstrated a survival benefit with the use of prehospital plasma in patients at risk of hemorrhagic shock. We sought to characterize the survival benefit associated with prehospital plasma relative to the blood transfusion volume over the initial 24 hours. We hypothesized that the beneficial effects of prehospital plasma would be most robust in those with higher severity of hemorrhage. METHODS We performed a prespecified secondary analysis using data derived from a prospective randomized prehospital plasma trial. Blood component transfusion volumes were recorded over the initial 24 hours. Massive transfusion (MT) was defined a priori as receiving >= 10 units of red cells in 24 hours. We characterized the 30-day survival benefit of prehospital plasma and the need for MT and overall 24-hour red cell transfusion volume utilizing Kaplan-Meier survival analysis and Cox proportional hazard regression. RESULTS There were 501 patients included in this analysis with 230 randomized to prehospital plasma with 104 patients requiring MT. Mortality in patients who received MT were higher compared with those that did not (MT vs. NO-MT, 42% vs. 26%, p = 0.001). Kaplan-Meier survival curves demonstrated early separation in the NO-MT subgroup (log rank p = 0.008) with no survival benefit found in the MT group (log rank p = 0.949). Cox regression analysis verified these findings. When 24-hour red cell transfusion was divided into quartiles, there was a significant independent association with 30-day survival in patients who received 4 to 7 units (hazard ratio, 0.33, 95% confidence interval, 0.14-0.80, p = 0.013). CONCLUSION The survival benefits of prehospital plasma was demonstrated only in patients with red cell requirements below the transfusion level of MT. Patients who received 4 to 7 units of red cells demonstrated the most robust independent survival benefit attributable to prehospital plasma transfusion. Prehospital plasma may be most beneficial in those patients with moderate transfusion requirements and mortality risk.