Mortality of civilian patients with suspected traumatic haemorrhage receiving pre-hospital transfusion of packed red blood cells compared to pre-hospital crystalloid

Abstract

Background: Major haemorrhage is a leading cause of mortality following major trauma. Increasingly, Helicopter Emergency Medical Services (HEMS) in the United Kingdom provide pre-hospital transfusion with blood products, although the evidence to support this is equivocal. This study compares mortality for patients with suspected traumatic haemorrhage transfused with pre-hospital packed red blood cells (PRBC) compared to crystalloid. Methods: A single centre retrospective observational cohort study between 1 January 2010 and 1 February 2015. Patients triggering a pre-hospital Code Red activation were eligible. The primary outcome measure was all-cause mortality at 6hours (h)and 28days(d), including a sub-analysis of patients receiving a major and massive transfusion. Multivariable regression models predicted mortality. Multiple Imputation was employed, and logistic regression models were constructed for all imputed datasets. Results: The crystalloid (n=103) and PRBC (n=92) group were comparable for demographics, Injury Severity Score (p=0.67) and mechanism of injury (p=0.73). Observed 6h mortality was smaller in the PRBC group (n=10, 10%) compared to crystalloid group (n=19, 18%). Adjusted OR was not statistically significant (OR 0.48, CI 0.19-1.19, p=0.11). Observed mortality at 28days was smaller in the PRBC group (n=21, 26%) compared to crystalloid group (n=31, 40%), p=0.09. Adjusted OR was not statistically significant (OR 0.66, CI 0.32-1.35, p=0.26). A statistically significant greater proportion of the crystalloid group required a major transfusion (n=62, 60%) compared to the PRBC group (n=41, 40%), p=0.02. For patients requiring a massive transfusion observed mortality was smaller in the PRBC group at 28days (p=0.07). Conclusion: In a single centre UK HEMS study, in patients with suspected traumatic haemorrhage who received a PRBC transfusion there was an observed, but non-significant, reduction in mortality at 6h and 28days, also reflected in a massive transfusion subgroup. Patients receiving pre-hospital PRBC were significantly less likely to require an in-hospital major transfusion. Further adequately powered multi-centre prospective research is required to establish the optimum strategy for pre-hospital volume replacement in patients with traumatic haemorrhage.