Paramedic-initiated helivac to tertiary hospital for primary percutaneous coronary intervention: a strategy for improving treatment delivery times

Abstract

Background: In regions of New Zealand without coronary catheterisation laboratory (CCL) facilities, patients presenting with ST-elevation myocardial infarction (STEMI) are often subjected to prolonged delays before receiving primary percutaneous coronary intervention (PPCI) if it is the chosen reperfusion strategy. Therefore, we aimed to trial a new process of paramedic-initiated helivac of STEMI patients from the field directly to the CCL.

Methods: Utilising a prospective observational approach, over a 48-month period, paramedics identified patients with a clinical presentation and electrocardiogram features consistent with STEMI and transported them directly to the regional air ambulance base for helivac to the CCL (flight time 30-35 minutes). These patients were compared to two historic STEMI cohorts either transported by paramedics to the region's local hospital or self-presenting, prior to helivac. The primary outcome measures were: first medical contact-to-balloon (FMCTB) time and accuracy of paramedic diagnosis. Secondary outcome measures were mortality at 30 days and six months, and hospital length of stay (LOS).

Results: A total of 92 patients underwent helivac for PPCI (mean age of 64 years, SD ±10.3). Median FMCTB time was 155 minutes (IQR 27) for the historic cohorts (n=57), versus 102 minutes (IQR 16) for the experimental cohort (n=35, P<0.001). Paramedic diagnosis showed a sensitivity of 97% (95% CI: 85 to 99) and a specificity of 100% (95% CI: 84 to 100) with no inappropriate CCL activations. No significant difference was observed between groups in terms of 30 day and 6-month mortality. Hospital LOS was significantly shorter among the experimental cohort (P=0.01).

Conclusions: Paramedic-initiated helivac of STEMI patients from the field directly to the CCL for PPCI is safe and feasible and can significantly improve time-to-treatment to within benchmark timeframes, resulting in reduced hospital LOS.

Keywords: ST-elevation myocardial infarction (STEMI); air ambulances; ambulances; emergency medical services (EMS); percutaneous coronary intervention (PCI).

Figure 1

Description of patient groups for comparison. STEMI, ST-elevation myocardial infarction; ED, emergency department; NRHT, Northland Rescue Helicopter Trust; CCL, cardiac catheterisation laboratory; PPCI, primary percutaneous coronary intervention; ICP, intensive care paramedic.

Figure 2

Helicopter patient transfer flight path, Whangarei to Auckland, North Island of New Zealand. The designated flight path is an approximate distance of 155 km with an average duration of 30 minutes. NRH, Northland Rescue Helicopter.

Figure 3

Spatial distribution of all patients helivaced to Auckland City Hospital—Cardiac Intervention Unit (ACH-CIU): pre- and post-implementation phases. Patient spatial distribution is shown relative to the catchment area boundary in the trial’s post-implementation phase. This boundary was designated as a 20-minute transport time to the helipad. NRH, Northland Rescue Helicopter.