ECMO Fly/No-Fly: Development of a Triage Tool to Identify ECMO Patients Appropriate for Helicopter Transport

Abstract

Objective Inter-facility transport of extracorporeal membrane oxygenation (ECMO) patients is usually by ground when within 300 miles of receiving facility. In suburban/rural environments, highway travel may not be possible and travel time may be disproportionately increased due to traffic conditions, type of roads traveled, weather, etc. Helicopter transport, when available, is more temporally consistent and can mitigate many of these travel barriers while minimizing out of hospital time; however, not all patients qualify for air transport. At our institution, where both ground ambulances and EC-145 helicopters are available for ECMO transport, we sought to develop a tool to identify potential ECMO patients for helicopter transfer as it could safely diminish out-of-hospital time. Methods Utilizing our ECMO database, we identified patient weight, estimated ground transport time, number of intravenous infusions, therapy type (veno-arterial vs. veno-venous ECMO), and mean arterial pressure (MAP) post-ECMO initiation as major factors affecting patient transport apart from travel distance. We then developed a weighted scale comprising of these variables with score ranging from 0 -15 (Figure). Patients with a score of 2-8 were considered eligible for helicopter transport (at the discretion of the ECMO team). Using this novel triage tool, we retrospectively reviewed our ECMO transports between 2017 and 2019 and determined which ground transfers were eligible for air transfer. Ground transport time was defined as total time that the patient spends in the ambulance and measured in statute miles based on roadway travel. Flight transport time was similarly defined as total time that the patient spends in the helicopter, and measured in nautical miles, as a straight line from sending to receiving hospital. Results 47 primary ECMO missions were performed, 6 by air and 41 by ground. Median ground transport time was 22 (7-54) minutes and median ground distance was 13 (3-54) statute miles. Median flight transport time was 18 (7-28) minutes and median flight distance was 15 (7-40) nautical miles/24 (13-58) statute miles. Of the ground transports, 22 (56.4%) patients had a triage score 8 or less (5 to 8) and were eligible for helicopter transfer. 17 patients had a triage score of 9 or greater (9-13) and were deemed ineligible for helicopter transfer. The most frequent factors leading to higher triage scores were high body weight and larger number of IV infusions. Upon review by the authors, this tool accurately predicted potential flight candidates. There were no differences in safety outcomes based on mode of transport. Conclusions ECMO patients appropriate for helicopter transfer can be predicted using this simple tool, minimizing patient travel distance and out-of-hospital time. Prospective validation, cost and feasibility analysis is warranted.