Background The Emergency Medical Retrieval Service (EMRS) provides an aeromedical retrieval service to remote and rural communities. Most of these facilities are unable to deliver Critical Care Interventions (CCI). CCI are delivered by the EMRS team prior to transfer of the patient to definitive care. This study addresses correlation between total on-scene times (TOST) and level of intervention delivered, and whether there is any variation in TOST between medical and trauma emergencies.

Methods Prospective data were collected on EMRS secondary retrievals over a 5-year period from GP-led facilities. Data were collected on the CCI undertaken by EMRS during TOST prior to transfer of the patient. Interventions undertaken were scored using TISS-76. Correlation was analysed using Spearman's coefficient and differences between groups analysed using Mann–Whitney tests. Statistical significance was defined as p<0.01.

Results EMRS retrieved 308 patients suitable for inclusion. Complete data were available for 97% of patients (n=300). Underlying diagnosis was trauma in 26% (n=72) and medical in 74% (n=228). There was a significant correlation between TOST and TISS-76 for all EMRS patients. Spearman's coefficient of rank correlation was (ρ)=0.616 with p<0.0001. The median TOST for the medical group was 60 min and for the trauma group 60 min (point estimate for difference 0 min, 95% CI 10 to 10, p=0.951).

Conclusion This study demonstrates a significant relationship between TOST on-scene by the retrieval team and the level of intervention delivered to patients. The present data do not support the assertion that there is a difference in TOST for medical and trauma patients.