Assessing the Appropriateness of Helicopter Emergency Medical Services for Non- Traumatic Emergencies in Kochi prefecture, Japan

Assessing the Appropriateness of Helicopter Emergency Medical Services for Non- Traumatic Emergencies in Kochi prefecture, Japan | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Assessing the Appropriateness of Helicopter Emergency Medical Services for Non- Traumatic Emergencies in Kochi prefecture, Japan Shohei Matsubara, Ken-ei Sada, Masataka Kudo, Sho Sasaki, Atsushi Morizane, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7261381/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Although the effectiveness of helicopter emergency medical services (HEMS) in trauma care is well documented, assessment of the appropriateness of HEMS requests, especially in non-traumatic cases, remain limited. This study aimed to describe HEMS dispatches in non-trauma emergencies and evaluate undertriage and overtriage based on clinical necessity and transport time. Methods We conducted a retrospective cohort study in the western Kochi Prefecture, Japan, from 2017 to 2021. Adults (≥ 18 years) with moderate to severe non-traumatic conditions requiring emergency transport during HEMS operating hours were included. HEMS necessity was classified as “absolute” (treatment unavailable at the local hospital) or “relative” (critical condition with potential benefit from shorter transport time). Undertriage and overtriage were determined by comparing the actual HEMS dispatch requests with these criteria. Results Of the 2,312 patients analyzed, 63 had HEMS requests. Among the 2249 ground EMS dispatches, 248 cases met HEMS necessity criteria—two met absolute and 246 met relative necessity criteria—resulting in an undertriage rate of 11.0%. Of the 63 HEMS requests, 56 did not meet necessary criteria, yielding an overtriage rate of 88.9%. One-third involved ineligible conditions and the rest were unnecessary because of the longer transport time. Conclusions In non-traumatic emergencies, total transport time may be a better criterion for HEMS dispatch than diagnosis or severity alone. Revising dispatch protocols to include transport efficiency and regional contexts may help reduce inappropriate HEMS use. helicopter emergency medical service under-triage over-triage non-traumatic emergency Figures Figure 1 Figure 2 Introduction Helicopter emergency medical services (HEMS) are costly, specialized resources intended for patients with severe trauma or time-critical emergencies 1 . Accurate mission selection and proper on-scene triage are essential to ensure that air transport is used only when necessary. A 2021 joint position statement outlined three primary criteria for HEMS activation 2 (1) when advanced or specialty care is unavailable locally, (2) when rapid transportation to definitive care is necessary for time-sensitive interventions, and (3) when geographic, weather or logistical barriers impede timely via ground transport. These criteria aim to reduce mortality and morbidity from undertriage and avoid excessive costs from overtriage. HEMS reduces transport time 3 – 5 and improves trauma outcomes 6 – 11 . However, its benefits in non-traumatic emergencies are less clear. Some studies found no survival difference between HEMS and ground EMS (GEMS) in non-trauma cases 3 , 12 – 13 , while others reported longer time to treatment in HEMS 12 , 13 . This may reflect that possible interventions (e.g., transfusions, chest tubes) are more applicable in trauma, while fewer critical interventions are needed or possible in non-trauma cases. Furthermore, dispatch guidelines for non-trauma are inconsistent and remote severity is challenging. One trauma study reported a of 4.3% undertriage rate 14 , defined as canceled HEMS dispatch ultimate needed. To accurately estimate the true undertriage, data on patients without HEMS request are also essential. Overtriage in trauma cases has ranged from 17–54% 14–16 , often based on HEMS dispatch cancellation. Only one study has examined overtriaged in nontraumatic cases, reporting a rate of 13.1% 1 . However, overtriage rate in nontraumatic remains underexplored. This study focuses exclusively on non-trauma patients and aims to describe real-world HEMS dispatch conditions. It also evaluates undertriage and overtriage using combined dispatch and hospital data from both HEMS and ground EMS. Methods Study Design and Setting This retrospective cohort study was conducted in the Hata region of Kochi Prefecture, Japan, using data collected from fire department GEMS dispatch records, HEMS dispatch records, and medical records of the hospital to which the patient was transported. The Hata region spans an 1,238 square kilometers, has a population of approximately 80,000, and is located approximately 100 km from Kochi City, the prefecture’s main urban center. The Hata region is designated by the Japanese Ministry of Health, Labour and Welfare as a medically underserved area (hekichi iryo chiiki) . This designation is based on several key indicators of rurality: a low physician-to-population ratio (1.5 physicians per 1,000 residents), low population densities (less than 50 persons/km² in most municipalities), and a high aging rate (over 40% of residents aged ≥ 65 years). In Japan, when an injury or illness occurs and emergency transport is required, the first contact is made with the fire department. Upon receiving the call, the fire department dispatches an ambulance and simultaneously assesses the need for HEMS, a decision initially made by fire department paramedics. If HEMS dispatch is deemed necessary, they contact the base hospital of HEMS to determine whether dispatch is possible. Kochi Prefecture has one helicopter with one emergency department physician and one nurse on board. A primary request for HEMS dispatch refers to a request made simultaneously with an initial emergency call. By contrast, a secondary request is made after the emergency crew arrives at the location and engages with the patient. We divided the region of interest in this study into eight areas, including one main local core hospital, four local core hospitals, and seven fire departments (Fig. 1 ). The HEMS base hospital is located in Kochi City, Japan. Kochi City hosts four hospitals that serve as primary HEMS receiving facilities, including a HEMS base hospital. Participants We included patients who required emergency transport requests to the fire department between January 1, 2017, and December 31, 2021, based on fire department dispatch records. The eligibility criteria for this study were as follows: (1) aged 18 years or older, (2) transported to a local core hospital or tertiary emergency medical center in Kochi City, (3) presenting with moderate to severe non-traumatic emergencies, and (4) transported during HEMS operational hours (8:30 AM to 6:30 PM), weather and daylight permitting. Patient severity was confirmed using dispatch records. The exclusion criteria were as follows: (1) cancellation of transport request, (2) cardiopulmonary arrest at the time of transport, and (3) terminal stage conditions. Additionally, patients whose transport requests originated in Areas G and H were excluded due to the very low number of trauma-related HEMS transports from these areas, which made it impossible to estimate transport times. Variables Data collected from fire department and HEMS dispatch records included the following: patient sex and age, chief complaint, address of transport request, requests for HEMS dispatch (including primary and secondary requests), and transportation time to the hospital. After matching the patient age, sex, date, and time of transport with the fire department dispatch records, HEMS dispatch records, and medical records from the receiving hospital, additional data were collected from hospital records. These data included vital signs upon arrival at the hospital and final diagnoses. Final diagnoses were based on the disease names listed in the International Classification of Diseases, 11th edition (ICD-11). Primary Outcome The primary outcome was the necessity for HEMS dispatch. In this study, we define the following two levels of necessity for HEMS dispatch: •Absolute necessity: Stanford type A aortic dissection requiring treatment at a facility beyond the capabilities of a main local core hospital, for which HEMS dispatch is considered essential regardless of transport time. •Relative necessity: Shorter transport time via HEMS compared to that with GEMS with 1) a condition where early initiation of treatment provides significant benefits or 2) critical vital signs upon arrival at hospital (systolic blood pressure < 90 mmHg, mean arterial pressure < 65 mmHg, or oxygen saturation < 90%). Relative necessity was assessed for the following diseases, identified based on criterion 1), such as: cerebral infarction, intracerebral hemorrhage, seizures and epilepsy, subarachnoid hemorrhage, superior mesenteric artery dissection, Stanford type B aortic dissection, heart failure, myocardial infarction, unstable angina, pulmonary embolism, acute limb arterial occlusion, post-ventricular fibrillation resuscitation, ventricular tachycardia, post-endoscopic mucosal resection colonic bleeding, sigmoid colon volvulus, sigmoid colon axial volvulus, duodenal bleeding, duodenal perforation, duodenal varices, acute cholangitis, gastric and duodenal ulcers, anastomotic bleeding, colonic perforation, small bowel perforation, acute abdominal syndrome, gastric ulcer perforation, gastric varices, esophageal varices, strangulated inguinal hernia, cholecystitis, cholangitis, necrotizing fasciitis, bacterial meningitis, pyelonephritis, spontaneous bacterial peritonitis, cholecystitis, sepsis, bacteremia, and anaphylactic shock. The classification of necessity was determined retrospectively by two board-certified emergency physicians based on final diagnoses and clinical data, with disagreements resolved by consensus. To facilitate comparison with actual transport times, we estimated the ambulance transport time from each area to the main local core hospital using GEMS or HEMS and tertiary emergency medical centers using HEMS. The estimated transport time was the average transport time calculated using trauma cases from the same database. Statistical methods Descriptive statistics for the enrolled patients were presented as mean and standard deviation (SD) for continuous variables and as n (%) for categorical variables. First, the patient characteristics and final diagnoses were summarized. Final diagnoses associated with more than 100 patients were classified using specific disease names, whereas those associated with fewer than 100 patients were grouped into broader disease categories based on the ICD-11 classification system. Subsequently, the undertriage and overtriage rates were calculated using the following formulas: Undertriage rate = number of patients requiring HEMS dispatch/number of patients who were managed with GEMS (those without primary request for HEMS) Overtriage rate = number of patients who did not require HEMS dispatch (patients who should have been managed using GEMS) / number of patients with a primary request for HEMS Statistical significance was defined as p < .05. All statistical analyses were performed using Stata software (version 17.0; StataCorp, College Station, TX, USA). Results Participants Of the 23,327 ambulance requests made during the study period, 3,201 met the inclusion criteria. After excluding 889 patients based on the exclusion criteria, 2,312 patients were enrolled in this study (Fig. 2 ). Among them, 63 had primary HEMS requests, 23 secondary HEMS, and 2,228 GEMS. The patient characteristics are presented in Table 1 . Table 1 Patient characteristics. Total (n = 2312) Primary request for HEMS dispatch (n = 63) Secondary request for HEMS dispatch (n = 21) Request for GEMS dispatch (n = 2228) Age, mean (SD), years 77.4 (13.2) 74.5 (14.9) 71.7 (16.6) 77.6 (13.1) Female, n (%) 1028/2312 (44.5) 22/63 (34.9) 8/21 (38.1) 998/2228 (44.8) Low blood pressure, n (%) 133/2093 (6.4) 2/62 (3.2) 1/21 (4.7) 130/2010 (6.5) Hypoxemia, n (%) 66/1995 (3.3) 1/59 (1.7) 0/18 (0) 65/1918 (3.4) Severe disease, n (%) 1077/2312 (46.5) 41/63 (65.1) 16/21 (76.2) 1020/2228 (45.8) Low blood pressure: systolic blood pressure < 90 mmHg or mean arterial pressure < 65 mmHg Hypoxemia: SpO2 < 90% at a hospital GEMS, ground emergency medical service; HEMS, helicopter emergency medical service. SD, standard deviation The mean age was 77.4 years (SD], 13.2), with 1,028 females (44.5%). Shock vitals were seen in 133 (6.4%) and hypoxemia in 66 (3.3%). Most primary HEMS requests were from Area C (23), B (17), and A (11). Of the 21 secondary HEMS requests, most were also from Area C (8) and Area B (7), while no requests were made from Areas E and F. In contrast, among GEMS requests, Area E had the highest number (720), followed by Area C (557) and D (526); the lowest was in Area F (151). The final diagnoses of the enrolled patients are summarized below. The top five diagnoses were cerebral infarction (14.4%), bacterial pneumonia (10.8%), intracerebral hemorrhage (5.7%), acute pyelonephritis (5.5%), and heart failure (4.6%). Among patients with primary dispatch HEMS, the most frequent diagnosis were cerebral infarction (22.2%), myocardial infarction (11.1%), intracerebral hemorrhage (7.9%), bacterial pneumonia (6.3%), and acute cholangitis (4.8%). In secondary HEMS cases, cerebral infarction (628.6%), epilepsy (23.8%), intracerebral hemorrhage (14.3%), and myocardial infarction (9.5%) were most common. For GEMS patients, the leading diagnoses were cerebral infarction (14.1%), bacterial pneumonia (11.0%), and pyelonephritis (5.6%). The most frequent diagnostic categories were diseases of the digestive system (12.5%) and circulatory system diseases excluding cerebral infarction, intracerebral hemorrhage, and heart failure (11.5%). Other notable categories included nervous system diseases (4.3%), respiratory diseases excluding bacterial pneumonia (3.8%), and ear or mastoid diseases (3.7%). Less frequent were endocrine/metabolic diseases excluding dehydration (3.0%), external causes such as injury or poisoning (2.4%), neoplasms (2.0%), and musculoskeletal or connective tissue diseases (2.0%). Rare diagnoses included skin diseases (0.9%), genitourinary diseases excluding pyelonephritis (0.9%), mental or neurodevelopmental disorders (0.6%), blood-related diseases (0.5%), and undiagnosed cases (0.1%). Necessity for helicopter emergency medical service requests Two patients met the absolute and 253 met the relative necessity criteria for HEMS dispatch. The estimated transport times using GEMS and HEMS from each area to the hospital were as follows: Area A (GEMS 70 min, HEMS 78 min), Area B (GEMS 58 min, HEMS 60 min), Area C (GEMS 47 min, HEMS 65 min), Area D (GEMS 76 min, HEMS 70 min), Area E (GEMS 38 min, HEMS 89 min), and Area F (GEMS 67 min, HEMS 119 min). Only in Area D was HEMS faster. A total of 1,075 patients who had diseases were subject to relative necessity. The breakdown of the final diagnosis of patients with HEMS dispatch necessity was as follows: cerebral infraction (334, 31.0%); intracerebral hemorrhage (132, 12.3%); acute pyelonephritis (126, 11.7%); heart failure (107, 10.0%); diseases of the digestive system (154, 14.3%); diseases of the circulatory system other than cerebral infraction; intracerebral hemorrhage; heart failure (125, 11.6%); diseases of the nervous system (84, 7.8%); certain infectious or parasitic diseases (5, 0.5%); injury, poisoning, or certain other consequences of external causes (4, 0.4%); and symptoms, signs, or clinical findings, not elsewhere classified (1, 0.1%). Among patients with relative HEMS necessity, HEMS offered shorter transport time in 253 cases, including 33 with critical vital signs. Appropriateness of HEMS dispatch Among 63 primary HEMS requests, seven were deemed appropriate. Similarly, of the 2249 primary GEMS requests, 2,001 were deemed appropriate for GEMS dispatch (Table 2 ). Table 2 Distribution of primary dispatch and necessity for HEMS. Primary request for HEMS dispatch + - Necessity for HEMS + 7 248 - 56 2001 HEMS, helicopter emergency medical service. Of the 2249 primary GEMS requests, 248 patients were deemed to require HEMS dispatch (two patients had absolute necessity and 246 patients had relative necessity), resulting in an under-triage rate of 11.0%. Because the expected transport time was shorter with HEMS than with GEMS alone in Area D, all undertriaged patients were from Area D. The undertriaged patients had cerebral infarction (60, 24.2%), heart failure (33, 13.3%), intracerebral hemorrhage (26, 10.5%), and other conditions (Table 3 ). Table 3 Final diagnosis of the patients judged as undertriage. Disease name Number (%) of patients Specific diseases Cerebral infraction 60 (24.2) Heart failure 33 (13.3) Intracerebral hemorrhage 26 (10.5) Acute pyelonephritis 21 (8.5) Bacterial pneumonia 5 (2.0) Dehydration 3 (1.2) Disease categories Other diseases of the circulatory system other than cerebral infraction, intracerebral hemorrhage, and heart failure 34 (13.7) Others 12(4.81) Diseases of the digestive system 36 (14.5) Diseases of the nervous system 20 (8.1) Of the 63 primary HEMS requests, 56 were judged not to require HEMS dispatch, resulting in an overtriage rate of 88.9%. Among these 56 overtriaged patients, 19 had no conditions, warranting even the relative necessity for HEMS requests. The final diagnosis of these 19 patients were as follows: bacterial pneumonia (4, 21.1%), hypokalemia (2, 10.5%), chronic subdural hematoma (1, 5.3%), acute subdural hematoma (1, 5.3%), aortic valve stenosis (1, 5.3%), hepatic hydrothorax (1, 5.3%), viral upper respiratory tract infection (1, 5.3%), influenza (1, 5.3%), oral cavity cancer (1, 5.3%), ureteral stones (1, 5.3%), hypoglycemia (1, 5.3%), heat stroke (1, 5.3%), carbon monoxide poisoning (1, 5.3%), and asphyxiation (1, 5.3%). Primary HEMS requests for nine patients were canceled after contact with the emergency crew. Despite the relative necessity for HEMS requests based on their condition, the final diagnoses of the 37 patients judged to be overtriaged based on estimated transport time were as follows: cerebral infarction (13, 35.1%), myocardial infarction (6, 16.2%), intracerebral hemorrhage (5, 13.5%), and the other conditions (Table 4 ). Table 4 Final diagnosis of the patients judged as overtriage. Disease name Number (%) of patients Specific diseases Cerebral infraction 13 (23.2) Intracerebral hemorrhage 5 (8.9) Bacterial pneumonia 4 (7.1) Acute pyelonephritis 1(1.8) Disease categories Other diseases of the circulatory system other than cerebral infraction, intracerebral hemorrhage, and heart failure 13 (23.2) Diseases of the digestive system 4 (7.1) Other diseases of the respiratory system 3 (5.4) Other endocrine, nutritional or metabolic diseases 3 (5.4) Diseases of the nervous system 2 (3.7) Symptoms, signs or clinical findings, not elsewhere classified 2 (3.7) Other diseases of the genitourinary system 2 (3.7) Injury, poising or certain other consequences of external causes 2 (3.7) Neoplasms 1 (1.8) Diseases of the ear or mastoid process 1 (1.8) By area, overtriaged cases were: Area A (11, 19.6%), B (17, 30.4%), C (23, 41.1%), D (1, 1.8%), E (3, 5.4%), F (1, 1.8%). Discussion This study evaluated undertriage and overtriage in primary HEMS requests for non-traumatic emergencies. Cerebral infarction was the most frequent diagnosis, followed by bacterial pneumonia and cerebral hemorrhage. Only two patients met absolute HEMS necessity, while 253 met relative necessity. The undertriage rate was 11.0%, all involving relative necessity cases where GEMS transport was longer. The overtriage rate was 88.9%, with one-third involving conditions not meeting even relative necessity, and the rest unnecessary due to longer HEMS transport times. Total transport time appears to be the most critical factor in HEMS decisions for non-trauma cases. The American College of Surgeons (ACS) recommends an undertriage threshold of ≤ 5% for trauma 17 . However, no such standard exists for non-trauma. Unlike trauma, where on-site interventions significantly affect outcomes, non-trauma cases rarely benefit from such care. Thus, reaching a facility capable of providing definitive treatment quickly is crucial. In this study, all undertriaged patients were in Area D, the only region where HEMS had a time advantage, suggesting that location-based time differences are essential for minimizing undertriage. To improve the overtriage rate, it is essential to consider the request location. Currently, no established benchmark exists for overtriage in non-traumatic emergencies involving HEMS. The ACS guidelines recommend an overtriage rate of 25–35% for traumatic emergencies 17 . Previous studies reported HEMS dispatch cancellation rates–a form of overtriage ranging from 17–54% 14–16 , which is much lower than the rate observed in our study. It is well established that reducing transport time improves prognosis not only in surgical emergencies but also in medical conditions such as stroke, myocardial infarction, bacterial meningitis, and sepsis 18 – 21 . In non-traumatic emergencies, dispatch criteria often rely on subjective symptoms, such as severe pain (e.g., headache, chest pain, or abdominal pain), making triage heavily dependent on the judgment of emergency responders. In fact, 34% of patients in the present study were in a condition that did not necessitate a HEMS request. Furthermore, many of the remaining overtriaged patients did not benefit from the transport time advantage typically associated with HEMS. These findings suggest that the current triage system may over-rely on subjective symptoms rather than objective transport benefits. Therefore, at least in the setting of this study, where a primary local core hospital is capable of managing most nontraumatic conditions, HEMS requests should be based on the total transport time rather than on the type or severity of the condition. Our study has several strengths. First, while most previous studies assessing HEMS triage evaluated only HEMS dispatch cases 1 , 15 , 22 – 24 , thus making it impossible to assess the undertriage rate, our study integrated both GEMS and HEMS dispatch data to evaluate both undertriage and overtriage. Second, previous studies typically assessed the necessity of HEMS dispatch based on final diagnoses, severity, and duration of hospitalization in traumatic emergencies 1 , 14 , 25 , 26 . However, in our present study on non-traumatic emergencies, transport time was also considered a crucial factor in determining necessity. Our study has some limitations. First, we divided the target region into multiple areas to estimate the transport time. However, the transport time was not uniform across the entire study area. It is essential to consider the specific location of each patient's request when determining the necessity of HEMS. Second, we estimated transport time using data from traumatic emergency cases. The absolute transport time may differ between traumatic and non-traumatic cases. However, because both HEMS and GEMS were used for the estimation, this difference is unlikely to have significantly affected the results. Lastly, this study was conducted in a rural and medically underserved area characterized by geographic isolation, low population density, and limited access to emergency care. While the findings may not be generalizable to all rural settings, they are likely applicable to similarly remote regions with limited medical resources. In conclusion, the transport time to a hospital capable of providing appropriate care may need to be prioritized over the type or severity of the condition for HEMS requests in non-traumatic emergencies. Declarations Ethics approval and consent to participate: This study was conducted in accordance with the Declaration of Helsinki and the Ethical Guidelines for Medical and Health Research Involving Human Subjects in Japan. Ethical approval was obtained from the Ethics Committee (No. 2022-101). All patient data were anonymized and de-identified prior to analysis. In line with the Ethical Guidelines for Medical and Health Research Involving Human Subjects in Japan, the requirement for written informed consent was waived owing to the retrospective nature of the study, in which participant consent was implied through an opt-out approach. Consent for publication: Not applicable. Availability of data and materials: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests: K.S. received a speaker’s honorarium from Glaxo Smith Kline K.K., but these financial interactions were unconnected to the present study. The other authors declare that they have no competing interests. Funding: The authors received no financial support for this article's research, authorship, or publication. Authors’ contributions: MK and SS contributed to the study design. HO, KK, YS, and KT contributed to data collection. All authors read and approved the final manuscript. Acknowledgments: We sincerely appreciate the cooperation of the Hata Western Firefighting Association, the Hata Central Firefighting Association, the Tosashimizu Fire Department, Kochi Prefectural Hata Kenmin Hospital, Oida Hospital, Shimanto City Hospital, Otsuki Hospital, Inan Hospital, and Kochi Health Sciences Center in facilitating data collection for this study. Their invaluable support made this research possible. References Petrie DA, Tallon JM, Crowell W, Cain E, Martell P, McManus D. Medically appropriate use of helicopter EMS: the mission acceptance/triage process. Air Med J. 2007;26(1):50–4. Lyng JW, Braithwaite S, Abraham H, et al. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7261381","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":502048386,"identity":"09ef58fc-0416-402a-b283-783f1b842c8a","order_by":0,"name":"Shohei Matsubara","email":"","orcid":"","institution":"Kochi University","correspondingAuthor":false,"prefix":"","firstName":"Shohei","middleName":"","lastName":"Matsubara","suffix":""},{"id":502048387,"identity":"0cc90c64-82fe-459b-8367-fbe533d9181c","order_by":1,"name":"Ken-ei Sada","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0UlEQVRIiWNgGAWjYHACA8aGigQGBgnGBqjAAWK0nCFZS2MbSAuxrpJvP7zx48x5aXL8s5sbmHkY7OQZGM/it8bgTFqx5MZtOcYSdw6CtCQbNjCcS8CvhSHHQPLhtorEDRKJ7b95GJiBys8Y4HdY/xvjnw/ngLWAbKknrIXhRo6Z5MaGHJiWw4S1GNx4VmY541iascSNxAbGOQbHDdsI+UW+P3nzzZ6aZDn+GekPGN5UVMvzSxAIMXRLGRjYJM6QogMM+HtI1jIKRsEoGAXDGwAAiodFi4OdiTwAAAAASUVORK5CYII=","orcid":"","institution":"Kochi University","correspondingAuthor":true,"prefix":"","firstName":"Ken-ei","middleName":"","lastName":"Sada","suffix":""},{"id":502048388,"identity":"a6889bfb-964f-4162-a334-2a50b9e578c8","order_by":2,"name":"Masataka Kudo","email":"","orcid":"","institution":"Kochi University","correspondingAuthor":false,"prefix":"","firstName":"Masataka","middleName":"","lastName":"Kudo","suffix":""},{"id":502048389,"identity":"a25b2df0-1072-4792-a976-12b4ad9bc87e","order_by":3,"name":"Sho Sasaki","email":"","orcid":"","institution":"Iwase Satellite for Teaching And Research (STAR), Fukushima Medical University","correspondingAuthor":false,"prefix":"","firstName":"Sho","middleName":"","lastName":"Sasaki","suffix":""},{"id":502048390,"identity":"acc18dfc-f8b5-4c2e-80d8-42c9881f36db","order_by":4,"name":"Atsushi Morizane","email":"","orcid":"","institution":"Kochi Health Sciences Center","correspondingAuthor":false,"prefix":"","firstName":"Atsushi","middleName":"","lastName":"Morizane","suffix":""},{"id":502048391,"identity":"80537c44-745a-4c7b-be47-ac70a1445aa1","order_by":5,"name":"Koshi Kajihara","email":"","orcid":"","institution":"Hata Western Fire Department Union","correspondingAuthor":false,"prefix":"","firstName":"Koshi","middleName":"","lastName":"Kajihara","suffix":""},{"id":502048392,"identity":"a7a09b13-95ec-48a6-8253-35c018f808a4","order_by":6,"name":"Hidenao Okubo","email":"","orcid":"","institution":"Otsuki Hospital","correspondingAuthor":false,"prefix":"","firstName":"Hidenao","middleName":"","lastName":"Okubo","suffix":""},{"id":502048393,"identity":"09afaf2c-66b1-4f3c-bf31-4c3d215c46e4","order_by":7,"name":"Kosuke Hamagawa","email":"","orcid":"","institution":"Shimanto City Hospital","correspondingAuthor":false,"prefix":"","firstName":"Kosuke","middleName":"","lastName":"Hamagawa","suffix":""},{"id":502048394,"identity":"c054aac4-6fa1-4042-b4da-5eae79a91981","order_by":8,"name":"Toshimi Mizobuchi","email":"","orcid":"","institution":"Inan Hospital","correspondingAuthor":false,"prefix":"","firstName":"Toshimi","middleName":"","lastName":"Mizobuchi","suffix":""},{"id":502048395,"identity":"bb6fb61e-13a2-4f3e-93eb-835d418cb1a4","order_by":9,"name":"Toshikazu Yabe","email":"","orcid":"","institution":"Kochi Prefectural Hata Kenmin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Toshikazu","middleName":"","lastName":"Yabe","suffix":""},{"id":502048396,"identity":"14682226-f431-4c62-839b-05cca6ba9305","order_by":10,"name":"Yuichi Saisaka","email":"","orcid":"","institution":"Kochi Health Sciences Center","correspondingAuthor":false,"prefix":"","firstName":"Yuichi","middleName":"","lastName":"Saisaka","suffix":""},{"id":502048397,"identity":"e7aaad6b-e16f-4fd9-8fda-4855da6b6b69","order_by":11,"name":"Kimiaki Tanaka","email":"","orcid":"","institution":"Oida Hospital","correspondingAuthor":false,"prefix":"","firstName":"Kimiaki","middleName":"","lastName":"Tanaka","suffix":""},{"id":502048398,"identity":"4cd8eddc-5b80-4b2f-bc6a-7b2d2776cf0a","order_by":12,"name":"Narufumi Suganuma","email":"","orcid":"","institution":"Kochi University","correspondingAuthor":false,"prefix":"","firstName":"Narufumi","middleName":"","lastName":"Suganuma","suffix":""}],"badges":[],"createdAt":"2025-07-31 10:53:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7261381/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7261381/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":89630529,"identity":"da8cb4c4-b186-4c82-959a-e79e16e4c147","added_by":"auto","created_at":"2025-08-22 06:39:13","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":334342,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA map of the target region.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7261381/v1/66e61ca121e0eff67db0af4c.jpg"},{"id":89630512,"identity":"deaa7d40-5ec9-4d03-8ef9-e8df0e6c92dd","added_by":"auto","created_at":"2025-08-22 06:39:11","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":260562,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlowchart showing all missions and the inclusion of patients.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCPA, cardiopulmonary arrest; EMS, emergency medical service; GEMS, ground emergency medical service; HEMS, helicopter emergency medical service.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7261381/v1/2149be5f1882b2973f20bb35.jpg"},{"id":90066761,"identity":"52fd86fc-2000-45ac-8556-ca467c0e846b","added_by":"auto","created_at":"2025-08-28 05:39:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1208337,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7261381/v1/78bd9a76-5925-4225-81fa-14f5a0b9fbfc.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assessing the Appropriateness of Helicopter Emergency Medical Services for Non- Traumatic Emergencies in Kochi prefecture, Japan","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHelicopter emergency medical services (HEMS) are costly, specialized resources intended for patients with severe trauma or time-critical emergencies\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Accurate mission selection and proper on-scene triage are essential to ensure that air transport is used only when necessary. A 2021 joint position statement outlined three primary criteria for HEMS activation \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e (1) when advanced or specialty care is unavailable locally, (2) when rapid transportation to definitive care is necessary for time-sensitive interventions, and (3) when geographic, weather or logistical barriers impede timely via ground transport. These criteria aim to reduce mortality and morbidity from undertriage and avoid excessive costs from overtriage.\u003c/p\u003e\u003cp\u003eHEMS reduces transport time \u003csup\u003e\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e and improves trauma outcomes \u003csup\u003e\u003cspan additionalcitationids=\"CR7 CR8 CR9 CR10\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. However, its benefits in non-traumatic emergencies are less clear. Some studies found no survival difference between HEMS and ground EMS (GEMS) in non-trauma cases \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, while others reported longer time to treatment in HEMS \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e,\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. This may reflect that possible interventions (e.g., transfusions, chest tubes) are more applicable in trauma, while fewer critical interventions are needed or possible in non-trauma cases. Furthermore, dispatch guidelines for non-trauma are inconsistent and remote severity is challenging.\u003c/p\u003e\u003cp\u003eOne trauma study reported a of 4.3% undertriage rate \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, defined as canceled HEMS dispatch ultimate needed. To accurately estimate the true undertriage, data on patients without HEMS request are also essential. Overtriage in trauma cases has ranged from 17\u0026ndash;54% \u003csup\u003e14\u0026ndash;16\u003c/sup\u003e, often based on HEMS dispatch cancellation. Only one study has examined overtriaged in nontraumatic cases, reporting a rate of 13.1% \u003csup\u003e1\u003c/sup\u003e. However, overtriage rate in nontraumatic remains underexplored.\u003c/p\u003e\u003cp\u003eThis study focuses exclusively on non-trauma patients and aims to describe real-world HEMS dispatch conditions. It also evaluates undertriage and overtriage using combined dispatch and hospital data from both HEMS and ground EMS.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eStudy Design and Setting\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThis retrospective cohort study was conducted in the Hata region of Kochi Prefecture, Japan, using data collected from fire department GEMS dispatch records, HEMS dispatch records, and medical records of the hospital to which the patient was transported. The Hata region spans an 1,238 square kilometers, has a population of approximately 80,000, and is located approximately 100 km from Kochi City, the prefecture\u0026rsquo;s main urban center. The Hata region is designated by the Japanese Ministry of Health, Labour and Welfare as a \u003cem\u003emedically underserved area (hekichi iryo chiiki)\u003c/em\u003e. This designation is based on several key indicators of rurality: a low physician-to-population ratio (1.5 physicians per 1,000 residents), low population densities (less than 50 persons/km\u0026sup2; in most municipalities), and a high aging rate (over 40% of residents aged\u0026thinsp;\u0026ge;\u0026thinsp;65 years). In Japan, when an injury or illness occurs and emergency transport is required, the first contact is made with the fire department. Upon receiving the call, the fire department dispatches an ambulance and simultaneously assesses the need for HEMS, a decision initially made by fire department paramedics. If HEMS dispatch is deemed necessary, they contact the base hospital of HEMS to determine whether dispatch is possible. Kochi Prefecture has one helicopter with one emergency department physician and one nurse on board. A primary request for HEMS dispatch refers to a request made simultaneously with an initial emergency call. By contrast, a secondary request is made after the emergency crew arrives at the location and engages with the patient.\u003c/p\u003e\u003cp\u003e We divided the region of interest in this study into eight areas, including one main local core hospital, four local core hospitals, and seven fire departments (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The HEMS base hospital is located in Kochi City, Japan. Kochi City hosts four hospitals that serve as primary HEMS receiving facilities, including a HEMS base hospital.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eParticipants\u003c/em\u003e\u003c/p\u003e\u003cp\u003eWe included patients who required emergency transport requests to the fire department between January 1, 2017, and December 31, 2021, based on fire department dispatch records. The eligibility criteria for this study were as follows: (1) aged 18 years or older, (2) transported to a local core hospital or tertiary emergency medical center in Kochi City, (3) presenting with moderate to severe non-traumatic emergencies, and (4) transported during HEMS operational hours (8:30 AM to 6:30 PM), weather and daylight permitting. Patient severity was confirmed using dispatch records. The exclusion criteria were as follows: (1) cancellation of transport request, (2) cardiopulmonary arrest at the time of transport, and (3) terminal stage conditions. Additionally, patients whose transport requests originated in Areas G and H were excluded due to the very low number of trauma-related HEMS transports from these areas, which made it impossible to estimate transport times.\u003c/p\u003e\u003cp\u003e\u003cem\u003eVariables\u003c/em\u003e\u003c/p\u003e\u003cp\u003eData collected from fire department and HEMS dispatch records included the following: patient sex and age, chief complaint, address of transport request, requests for HEMS dispatch (including primary and secondary requests), and transportation time to the hospital. After matching the patient age, sex, date, and time of transport with the fire department dispatch records, HEMS dispatch records, and medical records from the receiving hospital, additional data were collected from hospital records. These data included vital signs upon arrival at the hospital and final diagnoses. Final diagnoses were based on the disease names listed in the International Classification of Diseases, 11th edition (ICD-11).\u003c/p\u003e\u003cp\u003e\u003cem\u003ePrimary Outcome\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThe primary outcome was the necessity for HEMS dispatch. In this study, we define the following two levels of necessity for HEMS dispatch:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u0026bull;Absolute necessity: Stanford type A aortic dissection requiring treatment at a facility beyond the capabilities of a main local core hospital, for which HEMS dispatch is considered essential regardless of transport time.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u0026bull;Relative necessity: Shorter transport time via HEMS compared to that with GEMS with 1) a condition where early initiation of treatment provides significant benefits or 2) critical vital signs upon arrival at hospital (systolic blood pressure\u0026thinsp;\u0026lt;\u0026thinsp;90 mmHg, mean arterial pressure\u0026thinsp;\u0026lt;\u0026thinsp;65 mmHg, or oxygen saturation\u0026thinsp;\u0026lt;\u0026thinsp;90%). Relative necessity was assessed for the following diseases, identified based on criterion 1), such as: cerebral infarction, intracerebral hemorrhage, seizures and epilepsy, subarachnoid hemorrhage, superior mesenteric artery dissection, Stanford type B aortic dissection, heart failure, myocardial infarction, unstable angina, pulmonary embolism, acute limb arterial occlusion, post-ventricular fibrillation resuscitation, ventricular tachycardia, post-endoscopic mucosal resection colonic bleeding, sigmoid colon volvulus, sigmoid colon axial volvulus, duodenal bleeding, duodenal perforation, duodenal varices, acute cholangitis, gastric and duodenal ulcers, anastomotic bleeding, colonic perforation, small bowel perforation, acute abdominal syndrome, gastric ulcer perforation, gastric varices, esophageal varices, strangulated inguinal hernia, cholecystitis, cholangitis, necrotizing fasciitis, bacterial meningitis, pyelonephritis, spontaneous bacterial peritonitis, cholecystitis, sepsis, bacteremia, and anaphylactic shock.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThe classification of necessity was determined retrospectively by two board-certified emergency physicians based on final diagnoses and clinical data, with disagreements resolved by consensus.\u003c/p\u003e\u003cp\u003eTo facilitate comparison with actual transport times, we estimated the ambulance transport time from each area to the main local core hospital using GEMS or HEMS and tertiary emergency medical centers using HEMS. The estimated transport time was the average transport time calculated using trauma cases from the same database.\u003c/p\u003e\u003cp\u003e\u003cem\u003eStatistical methods\u003c/em\u003e\u003c/p\u003e\u003cp\u003eDescriptive statistics for the enrolled patients were presented as mean and standard deviation (SD) for continuous variables and as n (%) for categorical variables.\u003c/p\u003e\u003cp\u003eFirst, the patient characteristics and final diagnoses were summarized. Final diagnoses associated with more than 100 patients were classified using specific disease names, whereas those associated with fewer than 100 patients were grouped into broader disease categories based on the ICD-11 classification system. Subsequently, the undertriage and overtriage rates were calculated using the following formulas:\u003c/p\u003e\u003cp\u003eUndertriage rate\u0026thinsp;=\u0026thinsp;number of patients requiring HEMS dispatch/number of patients who were managed with GEMS (those without primary request for HEMS)\u003c/p\u003e\u003cp\u003eOvertriage rate\u0026thinsp;=\u0026thinsp;number of patients who did not require HEMS dispatch (patients who should have been managed using GEMS) / number of patients with a primary request for HEMS\u003c/p\u003e\u003cp\u003eStatistical significance was defined as \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;.05. All statistical analyses were performed using Stata software (version 17.0; StataCorp, College Station, TX, USA).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cem\u003eParticipants\u003c/em\u003e\u003c/p\u003e\u003cp\u003eOf the 23,327 ambulance requests made during the study period, 3,201 met the inclusion criteria. After excluding 889 patients based on the exclusion criteria, 2,312 patients were enrolled in this study (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Among them, 63 had primary HEMS requests, 23 secondary HEMS, and 2,228 GEMS. The patient characteristics are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePatient characteristics.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;2312)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePrimary request\u003c/p\u003e\u003cp\u003efor HEMS dispatch\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;63)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSecondary request\u003c/p\u003e\u003cp\u003efor HEMS dispatch\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;21)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRequest for GEMS dispatch\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;2228)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge, mean (SD), years\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e77.4\u003c/p\u003e\u003cp\u003e(13.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e74.5\u003c/p\u003e\u003cp\u003e(14.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e71.7\u003c/p\u003e\u003cp\u003e(16.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e77.6\u003c/p\u003e\u003cp\u003e(13.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFemale,\u003c/p\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1028/2312\u003c/p\u003e\u003cp\u003e(44.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22/63\u003c/p\u003e\u003cp\u003e(34.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8/21\u003c/p\u003e\u003cp\u003e(38.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e998/2228\u003c/p\u003e\u003cp\u003e(44.8)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLow blood pressure, n (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e133/2093\u003c/p\u003e\u003cp\u003e(6.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2/62\u003c/p\u003e\u003cp\u003e(3.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1/21\u003c/p\u003e\u003cp\u003e(4.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e130/2010\u003c/p\u003e\u003cp\u003e(6.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypoxemia, n (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e66/1995\u003c/p\u003e\u003cp\u003e(3.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1/59\u003c/p\u003e\u003cp\u003e(1.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0/18\u003c/p\u003e\u003cp\u003e(0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e65/1918\u003c/p\u003e\u003cp\u003e(3.4)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSevere disease, n (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1077/2312\u003c/p\u003e\u003cp\u003e(46.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41/63\u003c/p\u003e\u003cp\u003e(65.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16/21\u003c/p\u003e\u003cp\u003e(76.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1020/2228\u003c/p\u003e\u003cp\u003e(45.8)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eLow blood pressure: systolic blood pressure\u0026thinsp;\u0026lt;\u0026thinsp;90 mmHg or mean arterial pressure\u0026thinsp;\u0026lt;\u0026thinsp;65 mmHg\u003c/p\u003e\u003cp\u003eHypoxemia: SpO2\u0026thinsp;\u0026lt;\u0026thinsp;90% at a hospital\u003c/p\u003e\u003cp\u003eGEMS, ground emergency medical service; HEMS, helicopter emergency medical service.\u003c/p\u003e\u003cp\u003eSD, standard deviation\u003c/p\u003e\u003cp\u003eThe mean age was 77.4 years (SD], 13.2), with 1,028 females (44.5%). Shock vitals were seen in 133 (6.4%) and hypoxemia in 66 (3.3%). Most primary HEMS requests were from Area C (23), B (17), and A (11). Of the 21 secondary HEMS requests, most were also from Area C (8) and Area B (7), while no requests were made from Areas E and F. In contrast, among GEMS requests, Area E had the highest number (720), followed by Area C (557) and D (526); the lowest was in Area F (151).\u003c/p\u003e\u003cp\u003eThe final diagnoses of the enrolled patients are summarized below. The top five diagnoses were cerebral infarction (14.4%), bacterial pneumonia (10.8%), intracerebral hemorrhage (5.7%), acute pyelonephritis (5.5%), and heart failure (4.6%). Among patients with primary dispatch HEMS, the most frequent diagnosis were cerebral infarction (22.2%), myocardial infarction (11.1%), intracerebral hemorrhage (7.9%), bacterial pneumonia (6.3%), and acute cholangitis (4.8%). In secondary HEMS cases, cerebral infarction (628.6%), epilepsy (23.8%), intracerebral hemorrhage (14.3%), and myocardial infarction (9.5%) were most common. For GEMS patients, the leading diagnoses were cerebral infarction (14.1%), bacterial pneumonia (11.0%), and pyelonephritis (5.6%).\u003c/p\u003e\u003cp\u003eThe most frequent diagnostic categories were diseases of the digestive system (12.5%) and circulatory system diseases excluding cerebral infarction, intracerebral hemorrhage, and heart failure (11.5%). Other notable categories included nervous system diseases (4.3%), respiratory diseases excluding bacterial pneumonia (3.8%), and ear or mastoid diseases (3.7%). Less frequent were endocrine/metabolic diseases excluding dehydration (3.0%), external causes such as injury or poisoning (2.4%), neoplasms (2.0%), and musculoskeletal or connective tissue diseases (2.0%). Rare diagnoses included skin diseases (0.9%), genitourinary diseases excluding pyelonephritis (0.9%), mental or neurodevelopmental disorders (0.6%), blood-related diseases (0.5%), and undiagnosed cases (0.1%).\u003c/p\u003e\u003cp\u003e\u003cem\u003eNecessity for helicopter emergency medical service requests\u003c/em\u003e\u003c/p\u003e\u003cp\u003eTwo patients met the absolute and 253 met the relative necessity criteria for HEMS dispatch. The estimated transport times using GEMS and HEMS from each area to the hospital were as follows: Area A (GEMS 70 min, HEMS 78 min), Area B (GEMS 58 min, HEMS 60 min), Area C (GEMS 47 min, HEMS 65 min), Area D (GEMS 76 min, HEMS 70 min), Area E (GEMS 38 min, HEMS 89 min), and Area F (GEMS 67 min, HEMS 119 min). Only in Area D was HEMS faster. A total of 1,075 patients who had diseases were subject to relative necessity. The breakdown of the final diagnosis of patients with HEMS dispatch necessity was as follows: cerebral infraction (334, 31.0%); intracerebral hemorrhage (132, 12.3%); acute pyelonephritis (126, 11.7%); heart failure (107, 10.0%); diseases of the digestive system (154, 14.3%); diseases of the circulatory system other than cerebral infraction; intracerebral hemorrhage; heart failure (125, 11.6%); diseases of the nervous system (84, 7.8%); certain infectious or parasitic diseases (5, 0.5%); injury, poisoning, or certain other consequences of external causes (4, 0.4%); and symptoms, signs, or clinical findings, not elsewhere classified (1, 0.1%). Among patients with relative HEMS necessity, HEMS offered shorter transport time in 253 cases, including 33 with critical vital signs.\u003c/p\u003e\u003cp\u003e\u003cem\u003eAppropriateness of HEMS dispatch\u003c/em\u003e\u003c/p\u003e\u003cp\u003eAmong 63 primary HEMS requests, seven were deemed appropriate. Similarly, of the 2249 primary GEMS requests, 2,001 were deemed appropriate for GEMS dispatch (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDistribution of primary dispatch and necessity for HEMS.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c2\" namest=\"c1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003ePrimary request for\u003c/p\u003e\u003cp\u003eHEMS dispatch\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eNecessity for HEMS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e248\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eHEMS, helicopter emergency medical service.\u003c/p\u003e\u003cp\u003eOf the 2249 primary GEMS requests, 248 patients were deemed to require HEMS dispatch (two patients had absolute necessity and 246 patients had relative necessity), resulting in an under-triage rate of 11.0%. Because the expected transport time was shorter with HEMS than with GEMS alone in Area D, all undertriaged patients were from Area D. The undertriaged patients had cerebral infarction (60, 24.2%), heart failure (33, 13.3%), intracerebral hemorrhage (26, 10.5%), and other conditions (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFinal diagnosis of the patients judged as undertriage.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDisease name\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNumber (%) of patients\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecific diseases\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCerebral infraction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e60 (24.2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHeart failure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e33 (13.3)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIntracerebral hemorrhage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e26 (10.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAcute pyelonephritis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e21 (8.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBacterial pneumonia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e5 (2.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDehydration\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3 (1.2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDisease categories\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOther diseases of the circulatory system other than cerebral infraction, intracerebral hemorrhage, and heart failure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e34 (13.7)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOthers\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e12(4.81)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDiseases of the digestive system\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e36 (14.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDiseases of the nervous system\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e20 (8.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eOf the 63 primary HEMS requests, 56 were judged not to require HEMS dispatch, resulting in an overtriage rate of 88.9%. Among these 56 overtriaged patients, 19 had no conditions, warranting even the relative necessity for HEMS requests. The final diagnosis of these 19 patients were as follows: bacterial pneumonia (4, 21.1%), hypokalemia (2, 10.5%), chronic subdural hematoma (1, 5.3%), acute subdural hematoma (1, 5.3%), aortic valve stenosis (1, 5.3%), hepatic hydrothorax (1, 5.3%), viral upper respiratory tract infection (1, 5.3%), influenza (1, 5.3%), oral cavity cancer (1, 5.3%), ureteral stones (1, 5.3%), hypoglycemia (1, 5.3%), heat stroke (1, 5.3%), carbon monoxide poisoning (1, 5.3%), and asphyxiation (1, 5.3%). Primary HEMS requests for nine patients were canceled after contact with the emergency crew. Despite the relative necessity for HEMS requests based on their condition, the final diagnoses of the 37 patients judged to be overtriaged based on estimated transport time were as follows: cerebral infarction (13, 35.1%), myocardial infarction (6, 16.2%), intracerebral hemorrhage (5, 13.5%), and the other conditions (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFinal diagnosis of the patients judged as overtriage.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDisease name\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNumber (%) of patients\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecific diseases\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCerebral infraction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e13 (23.2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIntracerebral hemorrhage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e5 (8.9)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBacterial pneumonia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4 (7.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAcute pyelonephritis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1(1.8)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDisease categories\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOther diseases of the circulatory system other than cerebral infraction, intracerebral hemorrhage, and heart failure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e13 (23.2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDiseases of the digestive system\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4 (7.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOther diseases of the respiratory system\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3 (5.4)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOther endocrine, nutritional or metabolic diseases\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3 (5.4)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDiseases of the nervous system\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2 (3.7)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSymptoms, signs or clinical findings, not elsewhere classified\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2 (3.7)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOther diseases of the genitourinary system\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2 (3.7)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInjury, poising or certain other consequences of external causes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2 (3.7)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNeoplasms\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1 (1.8)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDiseases of the ear or mastoid process\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1 (1.8)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eBy area, overtriaged cases were: Area A (11, 19.6%), B (17, 30.4%), C (23, 41.1%), D (1, 1.8%), E (3, 5.4%), F (1, 1.8%).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study evaluated undertriage and overtriage in primary HEMS requests for non-traumatic emergencies. Cerebral infarction was the most frequent diagnosis, followed by bacterial pneumonia and cerebral hemorrhage. Only two patients met absolute HEMS necessity, while 253 met relative necessity. The undertriage rate was 11.0%, all involving relative necessity cases where GEMS transport was longer. The overtriage rate was 88.9%, with one-third involving conditions not meeting even relative necessity, and the rest unnecessary due to longer HEMS transport times.\u003c/p\u003e\u003cp\u003eTotal transport time appears to be the most critical factor in HEMS decisions for non-trauma cases. The American College of Surgeons (ACS) recommends an undertriage threshold of \u0026le;\u0026thinsp;5% for trauma\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. However, no such standard exists for non-trauma. Unlike trauma, where on-site interventions significantly affect outcomes, non-trauma cases rarely benefit from such care. Thus, reaching a facility capable of providing definitive treatment quickly is crucial. In this study, all undertriaged patients were in Area D, the only region where HEMS had a time advantage, suggesting that location-based time differences are essential for minimizing undertriage.\u003c/p\u003e\u003cp\u003eTo improve the overtriage rate, it is essential to consider the request location. Currently, no established benchmark exists for overtriage in non-traumatic emergencies involving HEMS. The ACS guidelines recommend an overtriage rate of 25\u0026ndash;35% for traumatic emergencies \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Previous studies reported HEMS dispatch cancellation rates\u0026ndash;a form of overtriage ranging from 17\u0026ndash;54% \u003csup\u003e14\u0026ndash;16\u003c/sup\u003e, which is much lower than the rate observed in our study. It is well established that reducing transport time improves prognosis not only in surgical emergencies but also in medical conditions such as stroke, myocardial infarction, bacterial meningitis, and sepsis \u003csup\u003e\u003cspan additionalcitationids=\"CR19 CR20\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. In non-traumatic emergencies, dispatch criteria often rely on subjective symptoms, such as severe pain (e.g., headache, chest pain, or abdominal pain), making triage heavily dependent on the judgment of emergency responders. In fact, 34% of patients in the present study were in a condition that did not necessitate a HEMS request. Furthermore, many of the remaining overtriaged patients did not benefit from the transport time advantage typically associated with HEMS. These findings suggest that the current triage system may over-rely on subjective symptoms rather than objective transport benefits. Therefore, at least in the setting of this study, where a primary local core hospital is capable of managing most nontraumatic conditions, HEMS requests should be based on the total transport time rather than on the type or severity of the condition.\u003c/p\u003e\u003cp\u003eOur study has several strengths. First, while most previous studies assessing HEMS triage evaluated only HEMS dispatch cases \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e, thus making it impossible to assess the undertriage rate, our study integrated both GEMS and HEMS dispatch data to evaluate both undertriage and overtriage. Second, previous studies typically assessed the necessity of HEMS dispatch based on final diagnoses, severity, and duration of hospitalization in traumatic emergencies \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. However, in our present study on non-traumatic emergencies, transport time was also considered a crucial factor in determining necessity.\u003c/p\u003e\u003cp\u003eOur study has some limitations. First, we divided the target region into multiple areas to estimate the transport time. However, the transport time was not uniform across the entire study area. It is essential to consider the specific location of each patient's request when determining the necessity of HEMS. Second, we estimated transport time using data from traumatic emergency cases. The absolute transport time may differ between traumatic and non-traumatic cases. However, because both HEMS and GEMS were used for the estimation, this difference is unlikely to have significantly affected the results. Lastly, this study was conducted in a rural and medically underserved area characterized by geographic isolation, low population density, and limited access to emergency care. While the findings may not be generalizable to all rural settings, they are likely applicable to similarly remote regions with limited medical resources.\u003c/p\u003e\u003cp\u003eIn conclusion, the transport time to a hospital capable of providing appropriate care may need to be prioritized over the type or severity of the condition for HEMS requests in non-traumatic emergencies.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cem\u003eEthics approval and consent to participate:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the Declaration of Helsinki and the Ethical Guidelines for Medical and Health Research Involving Human Subjects in Japan. Ethical approval was obtained from the Ethics Committee (No. 2022-101). All patient data were anonymized and de-identified prior to analysis. In line with the Ethical Guidelines for Medical and Health Research Involving Human Subjects in Japan, the requirement for written informed consent was waived owing to the retrospective nature of the study, in which participant consent was implied through an opt-out approach.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConsent for publication:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAvailability of data and materials:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCompeting interests:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eK.S. received a speaker\u0026rsquo;s honorarium from Glaxo Smith Kline K.K., but these financial interactions were unconnected to the present study. The other authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFunding:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors received no financial support for this article\u0026apos;s research, authorship, or publication.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAuthors\u0026rsquo; contributions:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eMK and SS contributed to the study design. HO, KK, YS, and KT contributed to data collection.\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAcknowledgments:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe sincerely appreciate the cooperation of the Hata Western Firefighting Association, the Hata Central Firefighting Association, the Tosashimizu Fire Department, Kochi Prefectural Hata Kenmin Hospital, Oida Hospital, Shimanto City Hospital, Otsuki Hospital, Inan Hospital, and Kochi Health Sciences Center in facilitating data collection for this study. Their invaluable support made this research possible.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003ePetrie DA, Tallon JM, Crowell W, Cain E, Martell P, McManus D. Medically appropriate use of helicopter EMS: the mission acceptance/triage process. 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Crit Care Med. 2006;34(6):1589\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMart\u0026iacute;n-Cerezuela M, Aseginolaza-Lizarazu M, Boronat-Garc\u0026iacute;a P, et al. Severe community-acquired Streptococcus pneumoniae bacterial meningitis: clinical and prognostic picture from the intensive care unit. Crit Care. 2023;27(1):72.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAlstrup K, Petersen JAK, Sollid S, Johnsen SP, Rogn\u0026aring;s L. Mortality and hospitalisation in the Danish Helicopter Emergency Medical Service (HEMS) population from 2014 to 2018: a national population-based study of HEMS triage. BMJ Open. 2020;10(8):e038718.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYamada N, Kitagawa Y, Yoshida T, Nachi S, Okada H, Ogura S. Validity and risk factor analysis for helicopter emergency medical services in Japan: a pilot study. BMC Emerg Med. 2021;21(1):87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSaviluoto A, Bj\u0026ouml;rkman J, Olkinuora A, et al. The first seven years of nationally organized helicopter emergency medical services in Finland - the data from quality registry. Scand J Trauma Resusc Emerg Med. 2020;28(1):46.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAgeron FX, Debaty G, Savary D, et al. Association of helicopter transportation and improved mortality for patients with major trauma in the northern French Alps trauma system: an observational study based on the TRENAU registry. Scand J Trauma Resusc Emerg Med. 2020;28(1):35.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGordon K, Swain A, Thirkell C, Bailey M, Greenberg D. The Wellington Life Flight Helicopter Emergency Medical Service (HEMS): a retrospective audit against new Ministry of Health criteria. N Z Med J. 2014;127(1402):30\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"helicopter emergency medical service, under-triage, over-triage, non-traumatic emergency","lastPublishedDoi":"10.21203/rs.3.rs-7261381/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7261381/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eAlthough the effectiveness of helicopter emergency medical services (HEMS) in trauma care is well documented, assessment of the appropriateness of HEMS requests, especially in non-traumatic cases, remain limited. This study aimed to describe HEMS dispatches in non-trauma emergencies and evaluate undertriage and overtriage based on clinical necessity and transport time.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe conducted a retrospective cohort study in the western Kochi Prefecture, Japan, from 2017 to 2021. Adults (\u0026ge;\u0026thinsp;18 years) with moderate to severe non-traumatic conditions requiring emergency transport during HEMS operating hours were included. HEMS necessity was classified as \u0026ldquo;absolute\u0026rdquo; (treatment unavailable at the local hospital) or \u0026ldquo;relative\u0026rdquo; (critical condition with potential benefit from shorter transport time). Undertriage and overtriage were determined by comparing the actual HEMS dispatch requests with these criteria.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eOf the 2,312 patients analyzed, 63 had HEMS requests. Among the 2249 ground EMS dispatches, 248 cases met HEMS necessity criteria\u0026mdash;two met absolute and 246 met relative necessity criteria\u0026mdash;resulting in an undertriage rate of 11.0%. Of the 63 HEMS requests, 56 did not meet necessary criteria, yielding an overtriage rate of 88.9%. One-third involved ineligible conditions and the rest were unnecessary because of the longer transport time.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eIn non-traumatic emergencies, total transport time may be a better criterion for HEMS dispatch than diagnosis or severity alone. Revising dispatch protocols to include transport efficiency and regional contexts may help reduce inappropriate HEMS use.\u003c/p\u003e","manuscriptTitle":"Assessing the Appropriateness of Helicopter Emergency Medical Services for Non- Traumatic Emergencies in Kochi prefecture, Japan","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-22 06:38:35","doi":"10.21203/rs.3.rs-7261381/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3eac6ea7-47db-45cd-bcd6-2fe1356de246","owner":[],"postedDate":"August 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-08-28T05:23:15+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-22 06:38:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7261381","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7261381","identity":"rs-7261381","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}