Pre-hospital and retrieval medicine in Scotland: a retrospective cohort study of the workload and outcomes of the emergency medical retrieval service in the first decade of national coverage.

Background: The Emergency Medical Retrieval Service (EMRS) has provided national pre-hospital critical care and aeromedical retrieval in Scotland since 2010. This study investigates trends in the service and patients attended over the last decade; and factors associated with clinical deterioration and pre-hospital death.

Methods: A retrospective cohort study was conducted of all service taskings over ten years (2011-2020 inclusive). The EMRS electronic database provided data on location, sociodemographic factors, diagnoses, physiological measurements, clinical management, and pre-hospital deaths. Binary logistic regression models were used to determine change in physiology in pre-hospital care, and factors associated with pre-hospital death. Geospatial modelling, using road and air travel time models, was used to explore transfer times.

Results: EMRS received 8,069 taskings over the study period, of which 2,748 retrieval and 3,633 pre-hospital critical care missions resulted in patient contact. EMRS was more commonly dispatched to socioeconomically deprived areas for pre-hospital critical care incidents (Spearman's rank correlation, r(8)=-0.75, p = 0.01). In multivariate analysis, systolic blood pressure < 90mmHg, respiratory rate < 6/min or > 30/min, and Glasgow Coma Score ≤ 14 were associated with pre-hospital mortality independent of demographic factors. Geospatial modelling suggested that aeromedical retrieval reduced the mean time to a critical care unit by 1 h 46 min compared with road/ferry transportation.

Conclusion: EMRS continues to develop, delivering Pre-Hospital and Retrieval Medicine across Scotland and may have a role in addressing health inequalities, including socioeconomic deprivation and geographic isolation. Age, specific distances from care, and abnormal physiology are associated with death in pre-hospital critical care.