Prehospital Blood Transfusion in Swedish Trauma Care: Feasibility and Early Clinical Outcomes — a Prospective Cohort Study

Background Prehospital blood transfusion has been introduced increasingly in civilian trauma systems, but evidence regarding its clinical impact remains inconsistent. In Sweden, prehospital transfusion capability is relatively newly implemented, and its role within the national trauma system is not yet defined. This study evaluated feasibility and early clinical outcomes associated with prehospital transfusion in severely injured trauma patients treated at a regional trauma center in Sweden. Methods This prospective observational cohort study included trauma patients aged 15 years or older admitted to Karolinska University Hospital between November 2022 and December 2024 who received blood products prehospitally or within two hours of hospital arrival. Prehospital and arrival physiological parameters, laboratory markers of shock and coagulopathy, time intervals, occurrence of massive transfusion, and mortality up to 90 days were compared. Logistic regression examined associations with massive transfusion, and Cox proportional hazard models evaluated mortality, adjusting for age, sex, injury severity, prehospital transport time, and systolic blood pressure. Results Of 152 included patients, 55 received prehospital transfusion. A higher proportion of men were transfused prehospitally, while age and injury severity (Injury Severity Score ≥ 26 in 56% vs 49%) were similar between groups. Prehospital physiological parameters did not differ, but a larger proportion of patients in the prehospital transfusion group presented with shock on arrival (40% vs 25%). No significant differences were observed in laboratory indicators of circulatory impairment or coagulation abnormalities. Time to first emergency procedure was shorter in the prehospital transfusion group (24 vs 67 minutes). Prehospital transfusion was associated with a lower occurrence of massive transfusion (52% vs 66%; adjusted odds ratio 0.4, 95% confidence interval 0.2–0.8). Mortality up to 90 days did not differ between groups. Conclusion In this Swedish trauma system with short prehospital transport times, prehospital transfusion was feasible and associated with reduced massive transfusion requirements, but not improved survival. Further research is needed to define which patient subgroups benefit most. Trial registration: ClinicalTrials.gov, NCT05573841. Registered 11 October 2022.