Pre-hospital fibrinogen levels in major trauma patients transported by helicopter emergency medical service: determining who might benefit

Abstract

Background

Low fibrinogen contributes to poor outcomes in patients with traumatic coagulopathy. Upon Emergency Department (ED) arrival, some major trauma patients are coagulopathic, and have low fibrinogen levels, though who is not clear. In helicopter transported trauma patients, who are transfused blood during transport, we seek to identify prehospital clinical variables that are associated with ED hypofibrinogenemia.

Methods

We conducted a health records review of consecutive helicopter EMS transported patients to two trauma centers who received one or more units of packed red blood cells (pRBCs) during transport. Primary outcome was first ED fibrinogen level which, for statistical analyses, was transformed to a binomial variable (<1.6g/L and > 1.6g/L) based on provincial transfusion thresholds. Direct multivariate logistic regression was used. 65 patients were evaluated for outcomes associations. The independent variables: systolic blood pressure (sBP)<90 with EMS before resuscitation; sBP <90 after crystalloid  administration but before pRBCs, sBP<90 after pRBC infusion; shock index (SI); and sBP. Odds ratios and 95% confidence intervals were reported for all significant associations.

Results

Ongoing sBP<90 after pRBC was a significant predictor of low fibrinogen, p = .03: with 7.4(1.2 – 45.89) times greater odds of fibrinogen < 1.6g/l. This variable also was a significant predictor of INR > 1.5, p = .013. Those with sBP<90 after pRBC had a 17.5(1.8 – 169.2) greater odds of having an INR > 1.5. An ED arrival SI ≥ 1.5 had 8.93(1.9 – 42.6) times greater odds of having fibrinogen < 1.6 g/l than those with an ED SI < 1, p = .006. Compared with ED SI 1 – 1.49 group, those with an EDSI ≥ 1.5 had 6.9 times greater odds of having fibrinogen < 1.6 g/l, p = .02, OR = 6.9(1.3 – 36.1). Outcomes (alive/14-day mortality from hemorrhage or multi-organ failure/ Mortality other causes) for sBP<90 post pRBC were 20/34(58.8%)/7/34(20.5%)/7/34 (20.5%) compared to not persistently hypotensive: 29/31(93.5%)/1/31(3%)/1/31(3%)

Implications and lessons learned

In major trauma patients transported by helicopter EMS who received prehospital  transfusion, persistent hypotension after prehospital blood transfusion and initial ED shock index ≥ 1.5 were both associated with low initial ED fibrinogen levels. Identification of those trauma patients more likely to have low fibrinogen provides earlier opportunity for targeted intervention with fibrinogen replacement.