Heather M. Stamey, RN, MBA, BSN1
Katherine R. Meyers, BS1
John T. Fordham, MBA1
Barry McKenzie, MD, FACS2
Sarah K. Spilman, MA3
1 St. Vincent Healthcare, Billings, MT
2 Surgical Associates, PC, Billings, MT
3 Diligent Research & Consulting, Urbandale, IA
Abstract
Introduction: Montana is a rural state with limited access to higher-level trauma care. This study’s purpose was to use geographic information system (GIS) methodology to assess access to the highest-level trauma centers by rotor-wing helicopter (RWH) and identify the demographic characteristics of regions without trauma access.
Methods: Maptitude® GIS software was used to identify Montana residents living within 60 minutes of a Level II trauma center as accessible by RWH transport. Demographic characteristics are reported to identify population groups lacking access to trauma care.
Results: Overall, 52% of residents had 60-minute access to a Level II trauma center by RWH. While Hispanics (59%), Asians (61%), and Blacks (65%) had greater than average access, 38% of American Indians lived within 60 minutes of a Level II trauma center as accessible by RWH.
Conclusion: Timely access to trauma care is significantly reduced in Montana, with dramatic disparities for American Indians. In rural areas of the state, a strong trauma system must be anchored by lower-level trauma centers able to provide prompt evaluation and stabilization for critically injured patients until they can be transferred to a higher level of care.
Keywords: rural trauma, trauma system, emergency medical services, geographic information system, health disparities, helicopter ambulance
Introduction
While 80-90% of all United States residents have 60-minute access to a higher-level trauma center, trauma access is much lower in Montana.1-4 Choi et al. reported that 53% of Montanans have 60-minute trauma access (air or ground emergency medical service (EMS)) to a Level I or Level II trauma center,1 and a recent study found that 63% of Montana residents lived within 60 driving minutes (ground EMS) of a Level II or Level III trauma center (highest levels of trauma care in the state).5
In frontier states where many residents live in sparsely populated regions, air ambulance EMS is an essential healthcare resource.6 Despite the need for access to definitive trauma care, there is ongoing debate and concern associated with the financial burden of RWH transport for patients.56
People who live in rural regions of the country often live a considerable distance from higher-level trauma centers or even hospitals with appropriate emergency capabilities.4, 7, 8 The ability to receive prompt intervention after a traumatic event can be significantly delayed due to distance from trauma care, limited EMS staffing, and geographic and/or weather barriers that impact or limit EMS transport.8-12
The challenges of rural trauma are further exacerbated by socioeconomic status, age, race, and health disparities in rural regions of the country.3, 8, 10, 13-18 When distance from trauma care is considerable, trauma care can be made more accessible by rotor-wing helicopter (RWH) to transport seriously injured trauma patients from the scene or via interfacility transfer to the appropriate level of care.2, 19, 20
JEMS: Understanding When to Request a Helicopter for Your Patient
RWH transport availability comes at a significant cost to the patient and can be more than $40,000.56 While RWH availability is essential to regions with geographic challenges and longer distances to higher-level trauma care, there are no uniform patient or system criteria dictating when the resource should be activated.6, 19, 21-23 In the most recent revision to the national field triage criteria for injured patients, the American College of Surgeons (ACS) declined to specify when air medical services should be activated.24
While many patients injured in rural areas can receive definitive care at a lower-level trauma center, patients with severe, life-threatening injuries need the expertise and resources available at the highest-level trauma centers.24-27
When those trauma centers are a significant distance from the scene of injury, however, opportunity for survival is dependent on a strong multi-level trauma system where patients can be stabilized at lower-level trauma centers or critical access hospitals before they are transported to definitive care.10, 27-31
Providers at these facilities must have the skills and knowledge to provide initial care for these patients, recognize quickly which patients need a higher level of care, and initiate life-saving interventions while waiting for transfer.25, 32-34 RWH EMS should be fully integrated into the state trauma system to ensure continuity of care from the time of injury to arrival at the definitive care facility.35
National literature has reported disparate access to trauma care in Montana compared to the rest of the nation.1, 4, 5, 7, 31 Previous work has examined ground EMS trauma access in Montana5, but no study of which we are aware has examined RWH trauma access in the state. This study’s purpose was to determine the proportion of residents in a rural state that had trauma access via RWH and to identify the demographic characteristics of those who lack trauma access.
Materials and Methods
Study Setting
A geographic and demographic study of RWH access to Level II trauma centers in Montana was conducted. At the time of the study, Montana had zero Level I trauma centers and four Regional Trauma Centers (equivalent to Level II trauma centers, all verified by the ACS).36
As of January 1, 2023, the state had six licensed air medical services with RWH bases; three bases were located at Level II trauma centers, one was located at a State Area Trauma Hospital (state-verified, equivalent to Level III trauma center), and two were located at airports near State Area Trauma Hospitals.37 Three types of RWHs are used in the state: Eurocopter 145 (speed 140 knots), Eurocopter 135 (speed 136 knots), and Bell 407 (speed 133 knots).
Study Design and Variables
The software program Maptitude® (Caliper Corporation, Newton, MA, 2022) was used for Geographic Information System (GIS) analysis. All map features, including federal interstates and American Indian reservations, are embedded within the software, as is the United States 2020 Census and American Community Survey data for population, age, race, and ethnicity.
Race was categorized as American Indian or Alaska Native (hereafter American Indian); Asian; Black or African American (hereafter Black); Native Hawaiian or Other Pacific Islander; White; Other Race; or Two or More Racial Categories. Ethnicity was categorized as Hispanic Origin or Non-Hispanic Origin. The geographic unit of analysis was the zip code, and distance was calculated using the centroid of the zip code from the RWH base station.
Trauma centers were identified by mapping the street addresses and the buffer function in Maptitude was used to calculate the number of residents with 60-minute trauma access. The study did not meet institutional review board review criteria.
The primary outcome of trauma access was defined as the number of Montana residents with RWH air access to a Level II trauma center in 60 minutes or less. This includes the ability of RWH to launch from the base station, retrieve the patient from the scene, and transport the patient to a Level II trauma center.
Using median response times for RWH transports in Montana in 2021, RWH transport time included median EMS lift-off time (9 minutes) and median on-scene time (23 minutes).38 For all calculations, it was assumed that RWH traveled at 133.5 knots.1 Models did not account for geography or weather.
JEMS: Case Report: Prehospital Whole Blood Transfusion by Texas Helicopter Air Ambulance Crew
For the RWH bases located at Level II trauma centers, trauma access within 60 minutes was considered ability to fly from and back to a Level II trauma center (two-way trip). Given that the aforementioned estimates for median lift-off and on-scene time accounted for 32 minutes, it was calculated that a RWH could travel 71.7 total nautical miles (one-way 35.8 miles) in the remaining 28 minutes.
For the RWH bases located at a Level III trauma center or nearby airports, trauma access within 60 minutes was considered the ability to fly from the base to a Level II trauma center (one-way trip). After accounting for the median estimates for lift-off and on-scene time, the RWH could cover 71.7 total nautical miles (one-way) in the remaining 28 minutes.
Maps were used to identify which zip codes were located along the travel path, including a two-way trip from a RWH based at a Level II trauma center or a one-way trip from a RWH based at an airport base or Level III trauma center.
Statistical Analyses
- Demographic data for the state and the regions with trauma access were computed within the GIS software.
- Proportions are reported as frequencies and percentages.
Results
Locations of the RWH bases and their 60-minute coverage areas are shown in Figure 1, and Figure 2 highlights the zip codes in which a patient could be reached by RWH and transported to a level II trauma center within 60 minutes. Nearly 1.1 million residents lived in Montana in 2020, and demographic analyses indicated that 558,845 residents (52%) had access to a Level II trauma center within 60 minutes via RWH.
As shown in Table 1, proportions of trauma access were similar across age categories, with 53% of pediatric residents (age < 18 years), 52% of adult residents (age 18+ years), and 51% of geriatric residents (age > 65 years) having trauma access via RWH.
Table 1. Access to Trauma Care by Demographic Profile
| State Totals | Trauma Access Totals | |||
| Montana Total | % of State Total | Trauma Access Total | % with Trauma Access* | |
| Population | 1,077,941 | 558,845 | 52% | |
| Pediatric Residents (age < 18 years) | 232,808 | 22% | 122,271 | 53% |
| Adult Residents (age 18+ years) | 845,133 | 78% | 436,574 | 52% |
| Geriatric Residents (age > 65 years) | 202,444 | 19% | 102,405 | 51% |
| Racial Categories | ||||
| American Indian | 65,450 | 6% | 24,662 | 38% |
| Asian | 8,972 | < 1% | 5,473 | 61% |
| Black | 6,236 | < 1% | 4,022 | 65% |
| Native Hawaiian or Other Pacific Islander | 581 | < 1% | 277 | 48% |
| White | 938,192 | 87% | 490,516 | 52% |
| Other Race | 10,155 | < 1% | 5,733 | 57% |
| Two or More Racial Categories | 48,355 | 4% | 28,163 | 58% |
| Ethnic Categories | ||||
| Hispanic Origin | 43,875 | 4% | 25,682 | 59% |
| Non-Hispanic Origin | 1,034,066 | 96% | 533,163 | 52% |
When comparing trauma access among racial categories, most groups had similar or greater access to trauma care when compared to the state average, including residents of Hispanic origin (59%), Asians (61%), and Blacks (65%). While individuals identifying as American Indian comprise 6% of the state population, findings indicate that 38% of American Indian residents have 60-minute access to the highest level of trauma center by RWH.
Discussion
A GIS-based methodology was used to explore RWH access to Level II trauma centers in Montana. Results indicate that nearly one-half of Montanans are unable to reach a Level II trauma center by RWH within 60 minutes, making it clear that many Montana residents live in communities with significant time and distance barriers to trauma care.
These findings are nearly identical to Choi et al. (2022), which found that 53% of Montanans had access by air or ground to the highest-level trauma centers within 60 minutes in 2019.1 Importantly, 60-minute access in Montana has not improved since 2019 despite opening a new RWH base in Bozeman in 2021.39 When utilizing methodology from previous analyses (citation blinded for this review), post-hoc analyses show that 32% of Montanans have 60-minute access to a Level II trauma center by ground EMS.
Therefore, 20% of Montanans do not live within 60-minutes (drive time) of a trauma center but have access to trauma care within 60-minutes because of RWH services.
Given the vast geography of Montana and the locations of the highest-level trauma centers, study maps illustrate that many regions of the state lack trauma access. This is especially the case in eastern Montana, where there are no RWH bases or Level II or III trauma centers.
The primary care, urgent care, and emergency department settings serve as essential resources in regions without trauma access.40-42 In regions without higher-level trauma care, the strength of the state trauma system becomes an integral resource in the care of injured residents who may receive evaluation and treatment at lower-level trauma centers or critical access hospitals before transferring to a higher level of trauma care.
There is concerted effort in Montana to operate a strong trauma system that facilitates regional collaboration in setting protocols, educating healthcare professionals and community members, and auditing cases to identify recurrent issues and opportunities for improvement.36 In a study of the Montana trauma system in the late 1990s, there was a statistically significant reduction in preventable death after implementation of the trauma system.31
JEMS: Reduce Inappropriate Helicopter Utilization in EMS
These data, however, have not been updated in the last two decades. Additional analysis is warranted to determine if the trauma system mitigates mortality and morbidity in regions of the state that lack trauma access.
One of the starkest study findings is the significant disparity in trauma access for American Indians, indicating that nearly two-thirds of this population could not access a Level II trauma center by RWH within 60 minutes.
Sixty percent of Montanans identifying as American Indian reside on reservations,43 and the maps (Figures 1 and 2) show that much of Montana’s federal reservation lands are outside the areas of trauma access. Lack of access to trauma care can further exacerbate other health-related disparities in this population, 11, 17, 44-46 and this is a significant public health issue that deserves further investigation.
Study methods utilized many assumptions that may not hold true for all trauma incidents. First, estimates assumed that the RWH flight could be completed without refueling at an airport or other RWH base. While this does not impact the distance calculations of how far the RWH can travel within 60 minutes, it may inflate the importance of the 60-minute time frame.
While 60 minutes was chosen as the time benchmark to replicate national research,1-3, 12, 47, 48 the median total RWH flight time in 2021 was 1 hour and 40 minutes.38 This slightly longer time period can also be accomplished on a single tank of fuel and would increase the estimated number of Montanans that can be promptly transported to a Level II trauma center.
Second, assumptions did not account for geography or weather, which are significant factors in flight plans and the decision to launch the RWH. 23, 49-52 Crew and patient safety are the most important considerations in the decision to deploy the RWH, and inclement weather is one of the main limiting factors of RWH utilization.51, 52
Additionally, RWH may not be able to land in mountainous areas or fly over mountain passes that exceed an altitude of 10,000 feet.52 In Montana, these geographic restrictions further limit RWH transport, especially in the western and southwestern regions of the state, and geography was not considered in the study methodology. Future work should control for these factors when assessing flight times and trauma accessibility.
Third, RWH flight between the Level II trauma centers in Missoula, Great Falls, and Billings cannot be completed in under 60 minutes (see Figure 1), so it is common practice in Montana to transport injured patients by ground to the closest trauma center and then transfer patients by RWH to the highest level of care in the state (Level II trauma center at the time of the study).
While stable patients may be transported to higher level trauma centers by ground ambulances, this puts stress on the limited paid or volunteer EMS personnel and may leave a region without EMS coverage if the ambulance must travel a significant distance to transport the patient. RWH is therefore a significant resource to expedite transfer and allow ground EMS resources to remain in the area. It is also important to note that the state of Montana did not have Level I trauma centers at the time of analysis; the closest Level I trauma centers were in Utah and Colorado.
This precludes direct scene transport or RWH interfacility transfer to a Level I trauma center given the significant distance that must be traveled. As such, the state follows national guidelines for the field triage of injured patients24 and directs RWHs to take patients at high risk for serious injury to the “highest-level trauma center available within the geographic constraints of the regional trauma system” (page e52), with Level II being the highest-level of trauma center at the time of study.
Additionally, Montana air transportation destination guidelines53 allow RWH to take high-priority patients to any Level I, II, or III trauma center in the state, a practice that underscores the importance of interfacility transfer and RWH services in ensuring rural trauma access.
Finally, a fixed-wing ambulance (FWA) has a greater range than RWH and is an essential resource for inter-facility transport, especially when a patient must be transported to a Level I trauma center.54, 55 Given the extended time that it takes to mobilize an FWA crew, patients are typically taken to a nearby trauma center via RWH or ground EMS and then FWA is used to facilitate interfacility transfer to a higher level of care. Ground EMS, RWH, and FWA are all essential modes of transport in the regional trauma system.
Limitations
This study has several limitations. First, some zip codes are relatively large in terms of square miles; software calculations reflect zip code demographic averages and may fail to identify areas without trauma access in these regions with large zip codes.
Second, trauma access was computed with average flight speeds and RWH response times but did not account for weather, geography and elevation, or other delays. Findings should therefore be considered a conservative estimate.
JEMS: Coordinating a Ground-Air Intercept: Lessons Learned
Third, the methodology does not consider mode of transport criteria, nor do we exclude patients who live close to a trauma center when RWH would not be considered. Residents who live very close to a Level II trauma center are included in the proportion of Montanans with trauma access, even if RWH would not be the mode of transport.
Finally, RWH bases in nearby states were not included in the analyses. There is one RWH base (Cody, Wyoming) that can reach a Level II trauma center (Billings, Montana) within the 60-minute parameters, but this RWH does not add trauma access to any region of Montana beyond what the RWHs in Billings already provide. The current study was focused solely on examining the adequacy of Montana-based RWH EMS in facilitating trauma access for Montana residents.
Conclusions
Access to timely trauma care is essential in preventing mortality after injury. Study findings show significant trauma access disparities in Montana, particularly among the American Indian population.
Disclosures: Ms. Spilman received compensation for her work as a medical writing and research consultant.
Funding: This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.
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