Assessing the Appropriateness of Helicopter Emergency Medical Services for Non- Traumatic Emergencies in Kochi prefecture, Japan

Background Although the effectiveness of helicopter emergency medical services (HEMS) in trauma care is well documented, assessment of the appropriateness of HEMS requests, especially in non-traumatic cases, remain limited. This study aimed to describe HEMS dispatches in non-trauma emergencies and evaluate undertriage and overtriage based on clinical necessity and transport time. Methods We conducted a retrospective cohort study in the western Kochi Prefecture, Japan, from 2017 to 2021. Adults (≥ 18 years) with moderate to severe non-traumatic conditions requiring emergency transport during HEMS operating hours were included. HEMS necessity was classified as “absolute” (treatment unavailable at the local hospital) or “relative” (critical condition with potential benefit from shorter transport time). Undertriage and overtriage were determined by comparing the actual HEMS dispatch requests with these criteria. Results Of the 2,312 patients analyzed, 63 had HEMS requests. Among the 2249 ground EMS dispatches, 248 cases met HEMS necessity criteria—two met absolute and 246 met relative necessity criteria—resulting in an undertriage rate of 11.0%. Of the 63 HEMS requests, 56 did not meet necessary criteria, yielding an overtriage rate of 88.9%. One-third involved ineligible conditions and the rest were unnecessary because of the longer transport time. Conclusions In non-traumatic emergencies, total transport time may be a better criterion for HEMS dispatch than diagnosis or severity alone. Revising dispatch protocols to include transport efficiency and regional contexts may help reduce inappropriate HEMS use.