Prehospital whole blood in the SWiFT hybrid type 1 trial: a qualitative implementation study guided by Normalization Process Theory

Background Prehospital transfusion of whole blood is a promising strategy for treating traumatic haemorrhage, but its introduction into civilian health systems requires coordinated change across blood manufacturing, hospital laboratory and prehospital services. The Study of Whole Blood in Frontline Trauma (SWiFT) was the first UK randomised trial comparing prehospital whole blood with component therapy (red blood cells and plasma), and included an embedded implementation study. The trial found that prehospital whole blood was not superior to component therapy on the primary clinical outcome, with a comparable safety profile. We explored how whole blood was introduced and operationalised across the service pathway, guided by Normalization Process Theory. Methods A qualitative implementation study (August 2021–January 2025) was embedded within the trial's type 1 hybrid effectiveness–implementation design. Data were collected across the pathway, from NHS Blood and Transplant manufacturing sites and hospital transfusion laboratories to ten air ambulance services, using observations, process mapping, focus groups and semi-structured interviews. Twenty-five interviews and three focus groups were conducted with prehospital clinicians, biomedical scientists, transfusion practitioners, haematologists and blood service staff. Data were analysed thematically (inductive–deductive) and mapped onto the four Normalization Process Theory constructs: coherence, cognitive participation, collective action and reflexive monitoring. Results Participants rapidly differentiated whole blood from component therapy and viewed it as clinically logical and procedurally clear. Strong cognitive participation was evident, with early champions, high staff buy-in and a shared commitment to evidence generation. Collective action involved significant but manageable adaptations to standard operating procedures, logistics, stock management and documentation, such as double-checking, revised packing and QR-coded randomisation cards. Reflexive monitoring was supported by frequent governance meetings, routine auditing of 'blood-on-board' boxes and iterative problem-solving around errors, wastage and stock distribution. Persistent challenges included O Rh-negative supply constraints, staff workload and concerns about trial-specific complexity versus future routine practice. Conclusions Prehospital whole blood was perceived as acceptable and operationally feasible across a multi-organisational service pathway, with strong engagement and adaptive reconfiguration of work. The analysis identified mechanisms supporting implementation, and supply, governance and sustainability issues that health services must address before wider adoption. Trial registration: ISRCTN23657907. Registered 7 December 2022.