Crystalloid to packed red blood cell transfusion ratio in the massively transfused patient: When a little goes a long way

BACKGROUND: Massive transfusion (MT) protocols have emphasized the importance of ratio-based transfusion of plasma and platelets relative to packed red blood cells (PRBCs); however, the risks attributable to crystalloid resuscitation in patients requiring MT remain largely unexplored. We hypothesized that an increased crystalloid:PRBC (C:PRBC) ratio would be associated with increased morbidity and poor outcome after MT. METHODS: Data were obtained from a multicenter prospective cohort study evaluating outcomes in blunt injured adults with hemorrhagic shock. Patients requiring MT (≥10 units PRBCs in first 24 hours) were analyzed. The C:PRBC ratio was computed by the ratio of crystalloid infused in liters (L) to the units of PRBCs transfused in the first 24 hours postinjury. Logistic regression modeling was used to characterize the independent risks associated with the 24-hour C:PRBC ratio, after controlling for important confounders and other blood component transfusion requirements. RESULTS: Logistic regression revealed that the 24-hour C:PRBC ratio was significantly associated with a greater independent risk of multiple organ failure (MOF), acute respiratory distress syndrome (ARDS), and abdominal compartment syndrome (ACS). No association with mortality or nosocomial infection was found. A dose-response analysis revealed that patients with a C:PRBC ratio >1.5:1 had over a 70% higher independent risk of MOF and over a twofold higher risk of ARDS and ACS. CONCLUSION: In patients requiring MT, crystalloid resuscitation in a ratio greater than 1.5:1 per unit of PRBCs transfused was independently associated with a higher risk of MOF, ARDS, and ACS. These results suggest overly aggressive crystalloid resuscitation should be minimized in these severely injured patients. Further research is required to determine whether incorporation of the C:PRBC ratio into MT protocols improves outcome.