Discussion
This study examined blood component use in trauma patients after implementation of a new MTP protocol. The major observation is that the majority (63%) of the severely injured patients received component therapy at a ratio of 1:1 to 1:2 FFP/RBC, with low use of type AB plasma and no need for rescue rFVIIa. The MTP patients received significantly fewer total blood components than the historic rFVIIa cohort. MTP was not associated with any increase in lung injury or infectious complications.
The patients who received less than the optimal FFP/RBC ratio per our institutional MTP had a much higher ISS and very high mortality. Some studies point to improved prehospital trauma care, which results in more severely injured trauma patients who are transported to hospitals but die shortly after arrival. The nonsurvivors in our study who received a low FFP/RBC ratio died within 3 hours after hospital arrival. Survival bias is introduced as patients who died early were pegged at a low FFP/RBC ratio. Patients who survived longer were able to receive more component therapy.
Death due to trauma has a trimodal distribution: early deaths occur within hours and are considered preventable with optimal trauma care to prevent exsanguination. With the improvement in trauma resuscitation, studies have shown a shift in the distribution toward survival from early death. However, there is increased morbidity associated with cellular damage due to ischemia reperfusion injury subsequently resulting in multiple organ dysfunction, such as acute respiratory distress syndrome, renal failure, cardiac dysfunction, infection, and sepsis.
Several studies have shown improvement in survival with a high ratio of FFP/RBC resuscitation, starting with combat casualties and later extrapolated to civilian trauma. The relationship between volume of blood loss, reduction of coagulation factors, platelet levels, and the functionality of the hemostatic system is difficult to establish in trauma patients despite mathematical modeling. Routine coagulation studies such as INR and PTT may not reflect ongoing coagulopathy. The body's physiologic response to injury often results in acidosis and hypothermia, and, together with coagulopathy, this triad is a vicious circle and often results in exsanguination. Two important factors in restoring hemostasis are time to coagulation factor replacement and amount replaced. Timely and adequate replacement of coagulation factors results in better control of bleeding in the setting of damage-control surgery. Most trauma hospitals now have institutional algorithms that include fixed FFP/RBC ratios and universal group AB plasma availability. FFP and thawed plasma contain all the coagulation factors, including procoagulants and anticoagulants including antifibrinolytic factors. The optimal FFP/RBC ratio is not known. Although military data suggest 1:1, more recent civilian trauma experience suggests that the optimal ratio is closer to 1:2. Davenport et al reported that the hemostatic effects of FFP may be maximal at ratios of 1:2 in a prospective study quantifying the changes in clot strength by rotational thromboelastography with different ratios. When this ratio is achieved early, it may preempt secondary dilutional coagulopathy and lead to an overall decrease in blood component use, with no increase in the observed incidence of lung injury or nosocomial infection.
rFVIIa induces hemostasis at the site of tissue injury by complexing with exposed tissue factor to activate factor X and enhancing factor Xa production on activated platelets to generate additional thrombin. It obviates the concern for volume overload with large-volume plasma administration and is associated with decreased blood component use and even cost. However, thrombosis is a major complication of rFVIIa use, and there is no proven mortality benefit. Our institutional practice of using low-dose rFVIIa probably accounts for the low baseline incidence of thrombosis in the historic cohort of trauma patients who had received rescue rFVIIa after massive transfusion.
Since the institution of an MTP at our institution incorporating a higher FFP/RBC ratio, the use of rFVIIa has decreased tremendously. We estimate that the overall lower blood component utilization and avoidance of rFVIIa use leads to an average cost savings of $13,270 per MTP patient based on blood charges by suppliers, including the technical component Figure 1. It seems that earlier incorporation of plasma in blood component resuscitation may indeed mitigate trauma-induced coagulopathy, in conjunction with damage-control surgery or embolization. However, with all the limitations imposed by the retrospective nature of our study, there is no evidence that MTP has improved mortality in this subset of severely injured patients.
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Figure 1.
Comparison of blood component use and cost between current massive transfusion protocol (MTP) and historic recombinant factor VII (rFVII) cohorts. CRYO, cryoprecipitate; FFP, fresh frozen plasma; PLT, platelets.
The limitations of our study are in keeping with those of any small single-institution retrospective analysis. These limitations should not discourage trauma centers from examining their empiric practice of adopting new MTPs because trauma demographics and blood component practice and transport within hospitals vary. For instance, our institution has a relatively high proportion of blunt trauma, thawed plasma had been in use for some time before the current MTP, and the blood bank is located in proximity to the operating room. Reliance on type AB plasma should be monitored because it is a scarce resource and because there is an anecdotal association between type AB plasma use and morbidity. Although a recent report suggests that cryoprecipitate may be associated with improved outcomes, our experience suggests that fibrinogen replacement is often adequate with the current MTP (data not shown). The optimal use of cryoprecipitate merits further study before its universal incorporation into an MTP. Finally, the timing of early plasma administration, within the first 6 hours, is critical. We will be prospectively monitoring the exact timing of plasma administration in an ongoing effort to optimize our MTP.