Blood component ratios in massively transfused, blunt trauma patients--a time-dependent covariate analysis.

BACKGROUND: This study evaluated critical thresholds for fresh frozen plasma (FFP) and platelet (PLT) to packed red blood cell (PRBC) ratios and determined the impact of high FFP:PRBC and PLT:PRBC ratios on outcomes in patients requiring massive transfusion (MT).

METHODS: Retrospective review of a cohort of massively transfused blunt trauma patients admitted to a Level I trauma center. MT was defined as transfusion of ≥10 units of PRBC within 24 hours of admission. Critical thresholds for FFP:PRBC and PLT:PRBC ratios associated with mortality were identified using Cox regression with time-dependent variables. Impacts of high blood component ratios on 12-hour and 24-hour survival were evaluated.

RESULTS: During the 10-year study period, a total of 229 blunt trauma patients required a MT. At 12 hours and 24 hours after admission, a FFP:PRBC ratio threshold of 1:1.5 was found to have the strongest association with mortality. At 12 hours, 58 patients (25.4%) received a low (<1:1.5) and 171 patients (74.6%) a high (≥1:1.5) FFP:PRBC ratio. Patients in the low ratio group had a significantly higher mortality compared with those in the high ratio group (51.7% vs. 9.4%; adjusted hazard ratio [95% confidence interval] = 1.18 [1.04-1.34]; adjusted p = 0.008). A similar statistically significant difference was found at 24 hours after admission. For PLTs, a PLT:PRBC ratio of 1:3 was identified as the best cut-off associated with both 12-hour and 24-hour survival. At 12 hours, 79 patients (34.5%) received a low (<1:3) and 150 patients (65.5%) a high (≥1:3) PLT:PRBC ratio. After adjusting for differences between the ratio groups, no statistically significant survival advantage associated with a high PLT:PRBC ratio was found (40.5% vs. 9.3%; adjusted hazard ratio [95% confidence interval] = 1.11 [0.99-1.26]; adjusted p = 0.082).

CONCLUSION: For massively transfused blunt trauma patients, a plasma to PRBC ratio of ≥1:1.5 was associated with improved survival at 12 hours and 24 hours after hospital admission. However, for PLTs, no statistically significant survival benefit with increasing ratio was observed. The results of this analysis highlight the need for prospective studies to evaluate the clinical significance of high blood component ratios on outcome.