Prehospital Resuscitation with Type O Whole Blood for Trauma and Hemorrhage
Clinical Snapshot
PICO Framework
| P — Population | Adult trauma patients with hemorrhagic shock transported by air medical services |
| I — Intervention | Prehospital transfusion with up to 2 units of low-titre type O whole blood |
| C — Comparator | Prehospital transfusion with as-indicated blood components (plasma, red blood cells, or both) |
| O — Outcomes | Primary: all-cause mortality at 30 days post-randomisation. Secondary: adverse events, and (observational substudy) outcomes by whole blood storage age (1–14 days vs 15–21 days) |
Bottom Line
The TOWAR trial is the largest pragmatic cluster-RCT to date comparing prehospital whole blood with component therapy in trauma patients with haemorrhagic shock. Across 44 air medical bases and 1020 patients, whole blood did not reduce 30-day mortality compared with blood components (25.9% vs 20.5%; adjusted OR 1.24; 95% CI 0.87–1.76; P=0.24). The point estimate numerically favoured components, though the wide confidence interval precludes definitive conclusions in either direction. An embedded observational substudy found no clinically meaningful effect of blood storage age on outcomes. These findings challenge the hypothesis that whole blood confers a survival advantage over optimised component therapy in the prehospital setting. For Australian aeromedical services, this trial does not support transitioning from established component-based prehospital transfusion programmes to whole blood. The logistical complexity and cost of whole blood supply chains are not justified by the current evidence. Clinicians and service directors should await further evidence, including subgroup analyses from the full publication, before revising prehospital transfusion protocols. The null result does not diminish the importance of early prehospital blood product administration per se — only the specific product choice.
Key Findings
P Value: P = 0.24 (non-significant)
Effect Size: Adjusted odds ratio 1.24 (favouring blood components over whole blood)
Primary Outcome: 30-day all-cause mortality: 25.9% in the whole-blood group vs 20.5% in the blood component group
Nnt Or Sensitivity: No NNT calculable for benefit; absolute risk difference approximately +5.4 percentage points higher mortality with whole blood (not statistically significant). Observational substudy: storage age 15–21 days vs 1–14 days adjusted OR 0.99 (95% CI 0.74–1.32), indicating no storage age effect.
Confidence Interval: 95% CI: 0.87 to 1.76
Clinical Application
Implementation of prehospital whole blood programmes requires significant logistical infrastructure: cold-chain maintenance on aircraft, blood banking agreements for low-titre type O whole blood supply, crew training, and wastage management. These barriers are substantial for most services. Component therapy (packed red cells and/or plasma) remains operationally simpler and is already deployed by many aeromedical services. Australian aeromedical retrieval services (CareFlight, RFDS, Ambulance Victoria HEMS, NSW Ambulance HEMS) have been progressively introducing prehospital blood products, primarily packed red cells and fresh frozen plasma. The Australian and New Zealand Trauma Society (ANZTS) and RACGP trauma guidelines emphasise early haemorrhage control and damage control resuscitation. The TGA regulates blood products under the Therapeutic Goods Act; whole blood for prehospital use would require specific TGA approval and supply chain arrangements with the Australian Red Cross Lifeblood. This trial's null result does not support a wholesale transition from component therapy to whole blood in Australian aeromedical services. PBS considerations are not directly applicable as blood products are supplied through the National Blood Authority (NBA) under the National Blood Agreement, not the PBS. Existing Australian programmes using components should not be dismantled based on this evidence. Adult trauma patients with hemorrhagic shock transported by air medical retrieval services. Most applicable to patients with penetrating or blunt trauma requiring prehospital blood product resuscitation prior to definitive surgical haemorrhage control.
Abstract
BACKGROUND: Blood transfusion before arrival at a hospital reduces mortality from traumatic hemorrhage and shock. Whether transfusion with whole blood is more beneficial than transfusion with blood components is uncertain, as are the effects of the length of time that blood products are in storage between donation and transfusion. METHODS: In this pragmatic, multicenter, phase 3, cluster-randomized trial, we assigned 44 air medical bases in a 2:1 ratio to the use of up to 2 units of whole blood or as-indicated blood components (plasma, red cells, or both) for prehospital transfusion in trauma patients during 1-month blocks. The primary outcome was death from any cause within 30 days after randomization. An observational substudy assessed outcomes according to the storage age of whole blood. RESULTS: Of 1020 eligible patients transported to hospitals by the air bases, 715 were assigned to receive whole blood and 305 to receive blood components; 695 and 298, respectively, were included in the primary analysis. Mortality at 30 days was 25.9% in the whole-blood group and 20.5% in the component group (adjusted odds ratio, 1.24; 95% confidence interval [CI], 0.87 to 1.76; P = 0.24). No substantial between-group differences in adverse events were observed. In the observational substudy, 30-day mortality was 27.1% among 210 patients who received whole blood with a storage age of 15 to 21 days and 26.4% among 443 patients who received whole blood with a storage age of 1 to 14 days (adjusted odds ratio, 0.99; 95% CI, 0.74 to 1.32). CONCLUSIONS: In injured patients with hemorrhagic shock, the use of whole blood for prehospital transfusion did not result in lower 30-day mortality than the use of blood components. (Funded by the Defense Health Agency Research Technology Portfolio Management, Combat Casualty Portfolio; TOWAR ClinicalTrials.gov number, NCT04684719.).
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