Low-Titer O + Whole Blood Implementation in the EMS System for Metropolitan Oklahoma City and Tulsa: Significance, Success, & Sharing Lessons Learned

OBJECTIVES: Over 300 emergency medical services (EMS) organizations across the United States have implemented transfusion programs for traumatic injuries using packed red blood cells, platelets, plasma, or whole blood before hospital arrival. Beginning in December of 2022, the EMS System for Metropolitan Oklahoma City (OKC) and Tulsa began carrying low-titer O-positive whole blood (LTOWB) for adult patients in traumatic hemorrhagic shock, specifically those exhibiting elevated shock indexes. We aim to describe establishing our prehospital LTOWB program and its first two years of operations across OKC and Tulsa. METHODS: We used an observational study design and retrospective descriptive analysis of patients receiving LTOWB by paramedic transfusion from the Emergency Medical Services Authority Ambulance Service, Oklahoma City Fire Department, or Tulsa Fire Department between December 1, 2022, and February 1, 2025. Descriptive analysis and univariate logistic regression quantify the relationship of patient characteristics against survival to hospital arrival and survival to hospital discharge outcomes. RESULTS: Penetrating trauma was the most common mechanism of injury recorded for patients receiving EMS LTOWB (71.6%). Following LTOWB transfusion, prehospital vital signs (systolic blood pressure, heart rate, and shock index) significantly improved (p < 0.05). Systolic blood pressure improvement conferred 9.7 times greater odds of survival to hospital arrival (95% CL 1.6-58.6). Occurrence of prehospital traumatic circulatory arrest was significantly related to lower odds of survival to hospital arrival and survival to hospital discharge (OR 1.01 and OR 1.04, respectively). CONCLUSIONS: Transfusion of LTOWB in a large, urban EMS system in the Southwestern United States confers a positive benefit to patients with measurable improvement in median systolic blood pressure, heart rate, and shock index. Continuous review of cases and misses empowered our system in dynamic protocol adjustments to best meet our population's needs. Patients often had secondary deterioration during transit, illustrating that blood transfusion "bought" temporary time during transport of critically injured patients to definitive care.