Journal Watch: Helicopter Transport Triage

Reviewed This Month

Trauma System Resource Preservation: A Simple Scene Triage Tool Can Reduce Helicopter Emergency Medical Services Overutilization in a State Trauma System. 

Authors: Udekwu P, Schiro S, Toschlog E, Farrell M, McIntyre S, Winslow J 3rd. 

Published in: Trauma Acute Care Surg, 2019 Aug; 87(2): 315–21. 

This month we review a manuscript that examines use of helicopter emergency medical services (HEMS). As we all are aware, the goal of using HEMS is to improve outcomes for patients with time-sensitive injuries. The current literature supports the use of HEMS for severely injured patients. However, when low-risk patients are transported by HEMS, there can be a substantial bill attached to their care and transport, sometimes leading to financial hardship. 

Previously published literature indicates many EMS agencies utilize the CDC guidelines for HEMS triage. However, this has been shown to lead to substantial overtriage. Another option discussed in the available literature is the Air Medical Prehospital Triage (AMPT) score. However, the AMPT is a complex score that includes both objective and subjective criteria. Moreover, its feasibility for use has not been evaluated. So the question is, can we simply and effectively triage patients in the field to identify those who will benefit from HEMS and those who should not be transported by helicopter?

Reducing Overtriage

The objectives of this month’s study included “evaluation for changes in statewide scene HEMS utilization in all ages, a contemporary evaluation of scene clinical variables and their association with mortality and ED disposition, and an assessment of HEMS overtriage and costs.” The authors had two hypotheses: 1) that contemporary HEMS utilization was associated with substantial overtriage, resulting in increased costs and patient risk of financial harm, and 2) that increased costs and risks could be mitigated by the application of a simple scene-based rule derived from easily accessible clinical information. 

To complete this study, the authors used data from the North Carolina trauma registry. They identified all patients transported from scenes and admitted to trauma centers from 2013–2015. Time-sensitive injuries were defined as “ED death, disposition to an operating room, and invasive procedure or intensive care unit.” The authors performed logistic regression modeling to evaluate the influence of scene variables on in-hospital mortality in ground EMS (GEMS) and HEMS patients. The authors also created a logistic regression model for patients at low risk of mortality. The variables analyzed included age, transport mode, GCS motor component score, scene pulse rate, scene respiratory rate, scene blood pressure, and blunt or penetrating mechanism. 

They compared outcomes in low- and high-risk patients. Low-risk patients were defined as those age 16–69 with blunt injuries, systolic blood pressure of 90 mm Hg or more, pulse rate of 60–160 bpm, respiratory rate of 10–29 breaths per minute, and a GCS motor component score of 6. 

One of the more interesting parts of this analysis was how the authors evaluated cost. They simply performed an Internet search using the terms helicopter, EMS, cost, and value to estimate the financial impact of HEMS transportation. Medicare beneficiary data was used to estimate GEMS costs. 

Results

There were 45,527 GEMS patients and 4,662 HEMS patients transported from scenes identified in the registry. The average age for GEMS patients was 48.2 years, versus 40.4 for HEMS patients (p<0.001). HEMS patients had a higher median injury severity score (14.0 vs. 8.3, p<0.001) and higher median scene pulse rate (94 vs. 90, p<0.001). GEMS patients had a higher average GCS motor score (5.7 vs. 5.2, p<0.001) and higher median systolic blood pressure (138 vs. 130, p<0.001), and a higher percentage of GEMS patients survived (96.0% vs. 91.7%, p<0.001). 

There was no statistically significant difference in mortality rate when comparing low-risk HEMS and GEMS patients (0.6% vs. 0.4%, p=0.415). Of all HEMS patients 34.8% were categorized as low-risk. Of those, 64.1% did not have a study-defined time-sensitive injury, and 7.8% were discharged home. 

The authors reported that the average charge for HEMS transport was $40,766, with a net revenue of $12,875 per patient transport. Further, they reported the average cost for GEMS was $224 to $2,204. The authors then estimated the total revenue for all low-risk patients in this study at $20.9 million. This estimate included $13.4 million for low-risk patients without a study-defined time-sensitive injury and $3.5 million for HEMS patients discharged straight home from EDs. Finally the authors reported that transporting all low-risk patients in this study by GEMS would cost $3.6 million, representing a savings of $17.3 million. 

The authors concluded that “implementing a simple decision tool designating nongeriatric adult patients with a blunt injury mechanism, normal Glasgow Coma Scale motor score, systolic blood pressure greater than 90 mm Hg, pulse rate of 60–120 bpm, and respiratory rate of 10–29 breaths per minute to ground transportation would result in substantial savings without an increase in mortality and reduce risk of patient financial harm.”

Conclusion

This study has some limitations. Most notably the authors did not address transport distance, terrain, or scene access. The authors noted their analysis of cost was an “oversimplification” because it did not correct for the benefits gained by sparing GEMS resources. They also did not compare the risk of death to crews and patients in HEMS and GEMS transports. The authors were clear in noting that these results were specific to North Carolina EMS and may not be generalizable to other regions, specifically those with centrally controlled HEMS and GEMS dispatch. 

This is an interesting and important article but certainly not the definitive study identifying simple HEMS triage methods and comparing costs associated with HEMS and GEMS transport. However, this study will generate new research questions and novel methods to evaluate HEMS triage and cost. 

Antonio R. Fernandez, PhD, NRP, FAHA, is research director at the EMS Performance Improvement Center and an assistant professor in the Department of Emergency Medicine at the University of North Carolina–Chapel Hill. He is on the board of advisors of the Prehospital Care Research Forum at UCLA.