The effect of emergency medical system transport time on in route clinical decline in a rural system

BACKGROUND The emergency medical system (EMS) Field Triage Decision Scheme (FTDS) exists to direct certain injured patients to high-level care facilities. In rural states, this may require long transport durations, with uncertainty about the effects on clinical decline. We investigate adherence to the FTDS and the effect of transport duration on clinical decline in helicopter emergency medical system (HEMS) and ground emergency medical system (GEMS) transport in the Commonwealth of Kentucky. METHODS This institutional review board-approved study retrospectively analyzed deidentified data from the 2017 National EMS Information System for Kentucky. Patients were classified using step 1 FTDS criteria (respiratory rate [RR], <10 or >29 breaths per minute; systolic blood pressure (SBP), <90 mm Hg; or Glasgow Coma Scale [GCS] score, <14 points), by mode of transport (HEMS or GEMS), and by arrival at an appropriate center (levels I-III trauma center). Clinical decline was defined in both groups as an in route decrease in GCS of 2 points or greater, a SBP decrease of 1 SD or greater into or within the low range, an RR increase of 1 SD or greater into or within the high range, or an RR decrease of 1 SD or greater into or within the low range. RESULTS Almost half (46.3%) of step 1 patients were transported to an inappropriate center; the most common reason recorded was "closest facility" (57.8%). The percent of step 1 patients who declined in route increased with prehospital time in both HEMS and GEMS (p < 0.001). Overall, 12.2% of step 1 patients declined during transport, most commonly because of decreasing GCS (median change,-5 points; interquartile range,-3 to-9, in GCS declining patients). Helicopter EMS patients were more likely to meet step 1 criteria at the scene (29.9% vs. 5.8% GEMS, p < 0.001) and to decline (27.8% vs. 6.1% GEMS, p < 0.001). CONCLUSION This study demonstrates that, in a rural state, injured patients meeting FTDS step 1 criteria reach levels I to III trauma centers only about half the time. The FTDS step 1 criteria identified patients at higher risk of further prehospital clinical decline. Rather than decline after 1 hour, these data show that an increasing proportion of patients experience clinical decline throughout prehospital transport. LEVEL OF EVIDENCE Therapeutic, Level IV.