Prehospital low‐titer group O whole blood in a multi‐agency civilian emergency medical system: Operational timelines, physiologic response, and stewardship across trauma and medical hemorrhage

Background Low‐titer group O whole blood (LTOWB) is increasingly used for prehospital hemorrhagic shock, yet real‐world data from multi‐agency EMS systems, particularly in medical hemorrhage, remain limited. This evaluation describes the first 11 months of a regional LTOWB program, focusing on operational timelines, physiologic response, protocol adherence, and product stewardship. Study Design and Methods In this quality‐improvement evaluation, all prehospital blood activations in the Pierce County EMS (PCEMS) region of Washington State were reviewed. Operational metrics included dispatch‐to‐blood time, scene time, transfusion location, and dispatch‐to‐ED interval. Physiologic response was assessed using systolic blood pressure (SBP), heart rate, and shock index (SI), with shock resolution defined as SI <1 on ED arrival. Protocol adherence and stewardship (utilization and waste) were obtained from EMS documentation and transfusion‐service logs. Results Eighty‐nine activations occurred, and all patients received prehospital transfusion (47 trauma, 42 medical hemorrhage). Timelines demonstrated early initiation: median dispatch‐to‐blood 21.3 min, scene time 14.3 mins, and dispatch‐to‐ED 36.6 min. Protocol adherence was high, with frequent LTOWB‐first transfusion, crystalloid avoidance, and TXA and calcium use. Among LTOWB recipients with serial vitals, SBP increased and SI decreased from initial assessment to post‐transfusion and ED arrival. Across agencies, 189 units (LTOWB and components) were issued; of 182 with known disposition, 135 (74.2%) were transfused and 47 expired, yielding a utilization of 74% and waste rate of 26%. Conclusions A regional multi‐agency EMS system achieved early LTOWB initiation, high protocol adherence, and physiologic improvement across trauma and medical hemorrhage, with stewardship metrics characteristic of early implementation.