Timing and location of blood product transfusion and outcomes in massively transfused combat casualties

Background: Hemostatic resuscitation using blood components in a 1:1:1 ratio of platelets:fresh frozen plasma:red blood cells (RBCs) is based on analyses of massive transfusion (MT, 10 RBC units in 24 hours). These 24-hour analyses are weakened by survival bias and do not describe the timing and location of transfusions. Mortality outcomes associated with early (first 6 hours) resuscitation incorporating platelets, for combat casualties requiring MT, have not been reported. Methods: We analyzed records for 8,618 casualties treated at the United States military hospital in Baghdad, Iraq, between January 2004 and December 2006. Patients (n = 414) requiring MT, not receiving fresh whole blood, and surviving at least 1 hour (reducing survival bias) were divided into 6-hour apheresis platelet (aPLT) transfusion ratio groups: LOW (aPLT:RBC, ≤0.1, n = 344) and HIGH (aPLT:RBC, >0.1, n = 70). Baseline characteristics of groups were compared. Factors influencing survival on univariate analysis were included in Cox proportional hazards models of 24-hour and 30-day survival. Results: Patients received aPLT in the emergency department (4%), operating room (45%), intensive care unit (51%). The HIGH group presented with higher (p < 0.05) admission International Normalized Ratio (1.6 vs. 1.4), base deficit (8 vs. 7), and temperature (36.7 vs. 36.4). Overall mortality was 27%. At 24 hours, the HIGH group showed lower mortality (10.0% vs. 22.1%, p = 0.02). Absolute differences in 30-day mortality were not significant (HIGH, 18.6%; LOW, 28.8%, p = 0.08). On adjusted analysis, the HIGH group was independently associated with increased survival: LOW group mortality hazard ratios were 4.1 at 24 hours and 2.3 at 30 days compared with HIGH group (p = 0.03 for both). Increasing 6-hour FFP:RBC ratio was also independently associated with increased survival. Conclusion: Early (first 6 hours) hemostatic resuscitation incorporating platelets and plasma is associated with improved 24-hour and 30-day survival in combat casualties requiring MT. Level of Evidence: Therapeutic study, level III.