RCT of prehospital whole blood in life-threatening traumatic haemorrhage

The Study of Whole Blood in Frontline Trauma (SWiFT) trial was a pragmatic, multicentre, unblinded, randomised, controlled trial across 10 air ambulance services in England, comprising physician-paramedic clinical teams. It sought to determine whether prehospital transfusion of up to 2 units of whole blood was superior to standard blood components in reducing the risk of death or massive transfusion within 24 hours in patients with life-threatening traumatic haemorrhage.

Blood boxes were randomly assigned in a 1:1 ratio and packed with either whole blood or standard blood components. Participants in the whole blood group were transfused up to 2 units of whole blood (group O, with low levels of anti-A and anti-B antibodies) whilst the standard-care group received up to 2 units of red cells and 2 units of plasma (thawed or lyophilized). 

Of the 942 randomised, after exclusion of pre-specified patients (with nontraumatic haemorrhage or traumatic cardiac arrest at the time of ambulance service arrival), 616 participants (314 whole blood and 302 standard care) were included in the analysis. The primary outcome was a composite of death from any cause or massive transfusion (≥ 10 units of any blood component in adults or ≥ 40 mL/kg in paediatric participants) within 24 hours after randomisation. This occurred in 48.7% of participants in the whole blood group and 47.7% in the standard care group, revealing no statistically significant difference (adjusted relative risk, 1.02; 95% confidence interval [CI] 0.80 to 1.31; P = 0.84).

Mortality at all timepoints was also similar between the two groups, as was the percentage of participants who received a massive transfusion within 24 hours. Slightly more serious adverse events occurred in the standard care group (37 events) than in the whole blood group (31 events). Prothrombin times exceeded the normal range in 40.7% of participants in the whole blood group versus 30.5% in the standard care arm.  

Overall, the study found that prehospital transfusion of up to two units of whole blood was not superior to standard blood components in reducing the risk of death or massive transfusion within 24 hours in patients with life-threatening traumatic haemorrhage.  

The authors noted that the dose of whole blood (up to 2 units) may have been insufficient to demonstrate an effect and that future research is needed to clarify whether specific populations might benefit.   

Reference: 

• Smith JE, Cardigan R, Sanderson E, Silsby L, Rourke C, Barnard EBG, Basham P et al for the Swift Trial Group. Prehospital Whole Blood In Traumatic Hemorrhage – A Randomized Controlled Trial. The New England Journal of Medicine; Published March 17, 2026. https://www.nejm.org/doi/abs/10.1056/NEJMoa2516043