Evaluation of basic life support interventions for foreign body airway obstructions: A population-based cohort study.

AIM: To quantify the associations of foreign body airway obstruction (FBAO) basic life support (BLS) interventions with FBAO relief and survival to discharge. METHODS: We identified prehospital FBAO patient encounters in Alberta, Canada between Jan 1, 2018 and Dec 31,2021 using the provincial emergency medical services' medical records, deterministically linked to hospital data. Two physicians reviewed encounters to determine cases and extract data. Multivariable logistic regression determined the adjusted odds ratio of FBAO relief (primary outcome) and survival to discharge for the exposure of BLS interventions (abdominal thrusts [AT], chest compressions/thrusts [CC], or combinations) relative to back blows [BB]. Intervention-associated injuries were identified using International Classification of Diseases codes, followed by health records review. RESULTS: We identified 3,677 patient encounters, including 709 FBAOs requiring intervention. Bystanders performed the initial BLS intervention in 488 cases (77.4%). Bystanders and paramedics did not relieve the FBAO in 151 (23.5%) and 11 (16.7%) cases, respectively. FBAOs not relieved before paramedic arrival had a higher proportion of deaths (n = 4[0.4%] versus n = 92[42.4%], p < 0.001). AT and CC were associated with decreased odds of FBAO relief relative to BB (adjusted odds ratio [aOR] 0.49 [95%CI 0.30-0.80] and 0.14 [95%CI 0.07-0.28], respectively). CC were associated with decreased odds of survival to discharge (aOR 0.04 [95%CI 0.01-0.32]). AT, CC, and BB were implicated in intervention-associated injuries in four, nine, and zero cases, respectively. CONCLUSIONS: Back blows are associated with improved outcomes compared to abdominal thrusts and chest compressions. These data can inform prospective studies aimed at improving response to choking emergencies.

Exploring paramedic care for First Nations in Alberta: a qualitative study.

BACKGROUND: Prior work has shown that a greater proportion of First Nations patients than non-First Nations patients arrive by ambulance to emergency departments in Alberta. The objective of this study was to understand First Nations perspectives on transitions in care involving paramedics, and paramedic perspectives on serving First Nations communities. METHODS: Participants for this participatory qualitative study were selected by means of purposive sampling through author networks, established relationships and knowledge of the Alberta paramedicine system. First Nations research team members engaged First Nations community organizations to identify and invite First Nations participants. Four sharing circles were held virtually in July 2021 via Zoom by the Alberta First Nations Information Governance Centre. We analyzed the data from the sharing circles using a Western thematic approach. The data were reviewed by Indigenous researchers. RESULTS: Forty-four participants attended the 4 sharing circles (8-14 participants per circle), which ranged from 68 to 88 minutes long. We identified 3 major themes: racism, system barriers and solutions. First Nations participants described being stereotyped as misusing paramedic systems and substance using, which led to racial discrimination by paramedics and emergency department staff. Discrimination and lack of options to return home after care sometimes led First Nations patients to avoid paramedic care, and lack of alternative care options drove patients to access paramedic care. First Nations providers described facing racism from colleagues and completing additional work to act as cultural mentors to non-First Nations providers. Paramedics expressed moral distress when called on to handle issues outside their scope of practice and when they observed discrimination that interfered with patient care. Proposed solutions included First Nations self-determination in paramedic service design, cultural training and education for paramedics, and new paramedicine service models. INTERPRETATION: First Nations people face discrimination and systemic barriers when accessing paramedicine. Potential solutions include the integration of paramedics in expanded health care roles that incorporate First Nations perspectives and address local priorities, and First Nations should lead in the design of and priority setting for paramedic services in their communities.

Changes in presentation, presenting severity and disposition among patients accessing emergency services during the first months of the COVID-19 pandemic in Calgary, Alberta: a descriptive study.

BACKGROUND: The COVID-19 pandemic has resulted in unique pressures on the emergency services system. This study describes changes in the presentation, presenting severity and disposition of patients accessing emergency services in Calgary, Alberta, during the first wave of the pandemic. METHODS: In this descriptive study, we constructed a population cohort of all patients who accessed emergency services by calling emergency medical services (EMS) (ambulance service that provides prehospital treatment and transport to medical facilities) or presenting directly to an emergency department (4 adult and 1 pediatric) or 2 urgent care centres in Calgary during the exposure period (December 2019 to June 2020) compared to 2 historical control periods (December to June, 2017-2018 and 2018-2019) combined. Outcomes included frequency of presentation, system flow indicators, patient severity, disposition and mortality. We used a locally estimated scatterplot smoothing function to visualize trends. We described differences at the maximum and minimum point of the exposure period compared to the control period. RESULTS: A total of 1 127 014 patient encounters were included. Compared to the control period, there was a 61% increase in the number of patients accessing EMS and a 35% decrease in the number of those presenting to an adult emergency department or urgent care centre in the COVID-19 period. The proportion of EMS calls for the highest-priority patients remained stable, whereas the proportion of patients presenting to an emergency department or urgent care centre with the highest-priority triage classification increased transiently by 0.9 percentage points (increase of 89%). A smaller proportion of patients were transported by EMS (decrease of 21%), and a greater proportion of emergency department patients were admitted to hospital (increase of 25%). After the first case was reported, the mortality rate among EMS patients increased by 265% (3.4 v. 12.4 per 1000 patient encounters). INTERPRETATION: The first wave of the COVID-19 pandemic was associated with substantial changes in the frequency and disposition of patients accessing emergency services. Further research examining the mechanism of these observations is important for mitigating the impact of future pandemics.

A qualitative study to identify factors that influence patients' decisions to call Emergency Medical Services for syncope.

BACKGROUND: Protocols that support paramedics to assess, treat and refer low-risk syncope (fainting) may allow for ED transport of only high-risk patients. The development and uptake of such protocols is limited by a dearth of information about factors patients consider when deciding to seek EMS care following syncope. OBJECTIVE: We explored decision-making processes of individuals with syncope regarding whether (or not) to call EMS after fainting as a starting point in the development of prehospital risk-stratification protocols for syncope. METHODS: Twenty-five Canadian adults (aged 18-65 years) with a history of ≥ 1 syncopal episode were recruited. Individual semi-structured interviews were conducted, recorded, and transcribed. Straussian grounded theory methods were used to identify common themes and a core (overarching) category. RESULTS: Four themes were identified: (a) previous experiences with the healthcare system (e.g., feeling dismissed), (b) individual patient factors (e.g., age, medical history), (c) attitudes and beliefs (e.g., burdening the health care system, syncope is "not serious"), and (d) contextual factors (e.g., influence of important others, symptom severity). Perceived judgement, including judgement from EMS and negative self-evaluations, was identified as the core category that influenced patients' decisions to seek care. CONCLUSION: We theorize that, while patients consider many factors in deciding to contact EMS for syncope, previous experiences of feeling judged and unfavorable beliefs about syncope may interfere with patients' receptiveness to traditional EMS protocols for syncope. The findings highlight potential patient needs that program developers may wish to consider in the development of prehospital protocols to improve care and satisfaction among patients with syncope.

RéSUMé: CONTEXTE: Les protocoles qui aident les ambulanciers paramédicaux à évaluer, traiter et orienter les patients à faible risque de syncope (évanouissement) peuvent permettre le transport de patients à haut risque seulement. L'élaboration et l'adoption de tels protocoles sont limitées par un manque d'information sur les facteurs dont les patients tiennent compte lorsqu'ils décident de demander des soins médicaux après une syncope. OBJECTIF: Nous avons exploré les processus décisionnels des personnes en syncope concernant l'appel (ou non) à EMS après un évanouissement comme point de départ dans l'élaboration de protocoles de stratification des risques préhospitaliers en cas de syncope. MéTHODES: Vingt-cinq adultes canadiens (âgés de 18 à 65 ans) ayant des antécédents d'épisode syncopal ≥ 1 ont été recrutés. Des entretiens individuels semi-structurés ont été menés, enregistrés et transcrits. Des méthodes de théorie straussienne ont été utilisées pour identifier les thèmes communs et une catégorie de base (globale). RéSULTATS: Quatre thèmes ont été identifiés: (a) expériences antérieures avec le système de soins de santé (par exemple, Se sentir rejeté), (b) facteurs individuels du patient (par exemple, âge, antécédents médicaux), (c) attitudes et croyances (par exemple, fardeau pour le système de soins de santé, la syncope n'est "pas grave"), et (d) facteurs contextuels (c.par exemple, influence d'autres personnes importantes, gravité des symptômes). Le jugement perçu, y compris le jugement du SME et les auto-évaluations négatives, a été identifié comme la catégorie principale qui a influencé les décisions des patients de se faire soigner. CONCLUSION: Nous théorisons que, bien que les patients tiennent compte de nombreux facteurs lorsqu'ils décident de communiquer avec le AMU pour une syncope, les expériences antérieures de se sentir jugé et les croyances défavorables au sujet de la syncope peuvent nuire à la réceptivité des patients aux protocoles traditionnels de EMS pour la syncope. Les résultats mettent en évidence les besoins potentiels des patients que les concepteurs de programmes pourraient vouloir prendre en compte dans l'élaboration de protocoles préhospitaliers pour améliorer les soins et la satisfaction des patients atteints de syncope.

Strategy to Identify Paramedic Transported Sepsis Cases in an Emergency Department Administrative Database.

Background: To evaluate a new strategy for identifying sepsis in Emergency Department (ED) patients that combines administrative diagnosis codes with clinical information from the point of first contact. Methods: This study linked clinical data from adult patients transported by a provincial Emergency Medical Services (EMS) system to ED and inpatient administrative databases. Sepsis cases were identified by searching ED databases for diagnosis codes consistent with infection and organ dysfunction. Organ dysfunction was further assessed using a partial Sequential Organ Failure Assessment (SOFA) score derived from EMS clinical information. Reliability was evaluated by comparing patients' ED diagnosis codes (ICD-10CA) to their inpatient diagnosis codes; criterion validity by comparing cases classified by the new strategy to an existing inpatient administrative algorithm; and construct validity by assessing for clinical characteristics typically associated with sepsis (e.g., mortality). Results: A total of 43,297 patients were included. ED infection codes were more reliable for classifying patients with infection than using ED sepsis codes alone (proportion of agreement with inpatient codes 79% vs. 74%; p-value < 0.001). The novel strategy requiring the presence of an infection code and either an organ dysfunction code or 2 or more SOFA points from EMS clinical information identified 1,379 more ED patients as having sepsis than the inpatient algorithm. These patients had high mortality supporting construct validity. Conclusions: Incorporation of a broader range of diagnostic codes and linking to an electronic database to obtain initial clinical information for the assessment of organ dysfunction improves reliability, criterion, and construct validity for identifying sepsis in ED patients.

Community paramedic point of care testing: validity and usability of two commercially available devices.

BACKGROUND: Community Paramedics (CPs) require access to timely blood analysis in the field to guide treatment and transport decisions. Point of care testing (POCT), as opposed to laboratory analysis, may offer a solution, but limited research exists on CP POCT. The purpose of this study was to compare the validity of two devices (Abbott i-STAT® and Alere epoc®) by CPs in the community. METHODS: In a CP programme responding to 6000 annual patient care events, a split sample validation of POCT against traditional laboratory analysis for seven analytes (sodium, potassium, chloride, creatinine, hemoglobin, hematocrit, and glucose) was conducted on a consecutive sample of patients. The difference of proportion of discrepant results between POCT and laboratory was compared using a two sample proportion test. Usability was analysed by survey of CP experience, a linear mixed effects model of Systems Usability Scale (SUS) adjusted for CP clinical and POCT experience, an expert heuristic evaluation of devices, a review of device-logged errors, and coded observations of POCT use during quality control testing. RESULTS: Of 1649 episodes of care screened for enrollment, 174 required a blood draw, with 108 episodes (62.1%) enrolled from 73 participants. Participants had a mean age of 58.7 years (SD16.3); 49% were female. In 4 of 646 (0.6%) comparisons, POCT reported a critical value but the laboratory did not; with no statistically significant (p = 0.323) difference between i-STAT® (0.9%;95%CI:0.0,1.9%) compared with epoc® (0.3%;95%CI:0.0,0.9%). There were no instances of the laboratory reporting a critical value when POCT did not. In 88 of 1046 (8.4%) comparisons the a priori defined acceptable difference between POCT and the laboratory was exceeded; occurring more often in epoc® (10.7%;95%CI:8.1,13.3%) compared with i-STAT® (6.1%;95%CI:4.1,8.2%)(p = 0.007). Eighteen of 19 CP surveys were returned, with 11/18 (61.1%) preferring i-STAT® over epoc®. The i-STAT® had a higher mean SUS score (higher usability) compared with epoc® (84.0/100 vs. 59.6/100; p = 0.011). There were no statistically significant differences in device logged errors between i-STAT® and epoc® (p = 0.063). CONCLUSIONS: CP programmes can expect clinically valid results from POCT. Device usability assessments should be considered with any local implementation as the two POCT systems have different strengths.

A prehospital treat-and-release protocol for supraventricular tachycardia.

OBJECTIVE: Paroxysmal supraventricular tachycardia (SVT) is a common dysrhythmia treated in the prehospital setting. Emergency medical service (EMS) agencies typically require patients treated for SVT to be transported to the hospital. This retrospective cohort study evaluated the impact, paramedic adherence, and patient re-presentation rates of a treat-and-release (T+R) protocol for uncomplicated SVT. METHODS: Data were linked from the Alberta Health Services EMS electronic patient care record (EPCR) database for the City of Calgary to the Regional Emergency Department Information System (REDIS). All SVT patients treated by EMS between September 1, 2010, and September 30, 2012, were identified. Databases were queried to identify re-presentations to EMS or an emergency department (ED) within 72 hours of T+R. RESULTS: There were 229 confirmed SVT patient encounters, including 75 T+R events. Of these 75 T+R events, 10 (13%, 95% confidence interval [CI] [7.4, 23]) led to an EMS re-presentation within 72 hours, and 4 (5%, 95% CI [2.1, 13]) led to an ED. All re-presentations were attributed to a single individual. After excluding 15 records that were incomplete due to limitations in the EPCR platform, 43 of 60 (72%) T+R encounters met all protocol criteria for T+R. CONCLUSION: The T+R protocol evaluated in this study applied to a significant proportion of patients presenting to EMS with SVT. Risk of re-presentation following T+R was low, and paramedic protocol adherence was reasonable. T+R appears to be a viable option for uncomplicated SVT in the prehospital setting.

Sustainable emergency medical service systems: how much energy do we need?

OBJECTIVE: Modern emergency medical service (EMS) systems are vulnerable to both rising energy prices and potential energy shortages. Ensuring the sustainability of EMS systems requires an empirical understanding of the total energy requirements of EMS operations. This study was undertaken to determine the life cycle energy requirements of US EMS systems. METHODS: Input-output-based energy requirement multipliers for the US economy were applied to the annual budgets for a random sample of 19 metropolitan or county-wide EMS systems. Calculated per capita energy requirements of the EMS systems were used to estimate nationwide EMS energy requirements, and the leading energy sinks of the EMS supply chain were determined. RESULTS: Total US EMS-related energy requirements are estimated at 30 to 60 petajoules (10(15) J) annually. Direct ("scope 1") energy consumption, primarily in the form of vehicle fuels but also in the form of natural gas and heating oil, accounts for 49% of all EMS-related energy requirements. The energy supply chain-including system electricity consumption ("scope 2") as well as the upstream ("scope 3") energy required to generate and distribute liquid fuels and natural gas-accounts for 18% of EMS energy requirements. Scope 3 energy consumption in the materials supply chain accounts for 33% of EMS energy requirements. Vehicle purchases, leases, maintenance, and repair are the most energy-intense components of the non-energy EMS supply chain (23%), followed by medical supplies and equipment (21%). CONCLUSION: Although less energy intense than other aspects of the US healthcare system, ground EMS systems require substantial amounts of energy each year.

The Canadian National EMS Research Agenda: a mixed methods consensus study.

INTRODUCTION: Research is essential for the development of evidence-based emergency medical services (EMS) systems of care. When resources are scarce and gaps in evidence are large, a national agenda may inform the growth of EMS research in Canada. This mixed methods consensus study explores current barriers and existing strengths within Canadian EMS research, provides recommendations, and suggests EMS topics for future study. METHODS: Purposeful sampling was employed to invite EMS research stakeholders from various roles across the country. Study phases consisted of 1) baseline interviews of a subsample, 2) roundtable discussion, and 3) an online Delphi survey, in which participants scored each statement for importance. Consensus was defined a priori and met if 80% scored a statement as "important" or "very important." RESULTS: Fifty-three stakeholders participated, representing researchers (37.7%), EMS administrators (24.6%), clinicians/providers (20.7%), and educators (17.0%). Participation rates were as follows: interviews, 13 of 13 (100%); roundtable, 47 of 53 (89%); survey round 1, 50 of 53 (94%); survey round 2, 47 of 53 (89%); and survey round 3, 40 of 53 (75%). A total of 141 statements were identified as important: 20 barriers, 54 strengths/opportunities, 31 recommendations, and 36 suggested topics for future research. Like statements were synthesized, resulting in barriers (n  =  10), strengths/opportunities (n  =  24), and recommendations (n  =  19), which were categorized as time, opportunities, and funding; education and mentorship; culture of research and collaboration; structure, process, and outcome of research; EMS and paramedic practice; and the future of the EMS Research Agenda. CONCLUSION: Consensus-based key messages from this agenda should be considered when designing, funding, and publishing EMS research and will advance EMS research locally, regionally, and nationally.

Developing a Canadian emergency medical services research agenda: a baseline study of stakeholder opinions.

PURPOSE: This study forms the first phase in the development of the Canadian National EMS Research Agenda. The purpose was to understand the current state of emergency medical services (EMS) research through the barriers and opportunities perceived by key stakeholders in the Canadian system and to identify the recommendations this group had for moving forward. METHODS: This qualitative study was conducted in the spring of 2011 using one-on-one semistructured telephone interviews. Purposeful sampling was used to recruit a cross section of EMS research stakeholders, representing a breadth of geographic regions and roles. Data were collected until thematic saturation was reached. A constant comparative approach was used to develop a basic coding framework and identify emerging themes. RESULTS: Twenty stakeholders were invited to participate, and saturation was reached after 13 interviews. Thematic saturation was used to ensure that the findings were grounded in the data. Four major themes were identified: 1) the need for additional research education within EMS; 2) the importance of creating an infrastructure to support pan-Canadian research collaboration; 3) addressing the complexities of involving EMS providers in research; and 4) considerations for a national research agenda. CONCLUSION: This hypothesis-generating study reveals key areas regarding EMS research in Canada and through the guidance it provides is a first step in the development of a comprehensive national research agenda. Our intention is to collate the identified themes with the results of a larger roundtable discussion and Delphi survey and, in doing so, guide development of a Canadian national EMS research agenda.

A validation of ground ambulance pre-hospital times modeled using geographic information systems.

BACKGROUND: Evaluating geographic access to health services often requires determining the patient travel time to a specified service. For urgent care, many research studies have modeled patient pre-hospital time by ground emergency medical services (EMS) using geographic information systems (GIS). The purpose of this study was to determine if the modeling assumptions proposed through prior United States (US) studies are valid in a non-US context, and to use the resulting information to provide revised recommendations for modeling travel time using GIS in the absence of actual EMS trip data. METHODS: The study sample contained all emergency adult patient trips within the Calgary area for 2006. Each record included four components of pre-hospital time (activation, response, on-scene and transport interval). The actual activation and on-scene intervals were compared with those used in published models. The transport interval was calculated within GIS using the Network Analyst extension of Esri ArcGIS 10.0 and the response interval was derived using previously established methods. These GIS derived transport and response intervals were compared with the actual times using descriptive methods. We used the information acquired through the analysis of the EMS trip data to create an updated model that could be used to estimate travel time in the absence of actual EMS trip records. RESULTS: There were 29,765 complete EMS records for scene locations inside the city and 529 outside. The actual median on-scene intervals were longer than the average previously reported by 7-8 minutes. Actual EMS pre-hospital times across our study area were significantly higher than the estimated times modeled using GIS and the original travel time assumptions. Our updated model, although still underestimating the total pre-hospital time, more accurately represents the true pre-hospital time in our study area. CONCLUSIONS: The widespread use of generalized EMS pre-hospital time assumptions based on US data may not be appropriate in a non-US context. The preference for researchers should be to use actual EMS trip records from the proposed research study area. In the absence of EMS trip data researchers should determine which modeling assumptions more accurately reflect the EMS protocols across their study area.

Emergency medical services response time and mortality in an urban setting.

BACKGROUND: A common tenet in emergency medical services (EMS) is that faster response equates to better patient outcome, translated by some EMS operations into a goal of a response time of 8 minutes or less for advanced life support (ALS) units responding to life-threatening events. OBJECTIVE: To explore whether an 8-minute EMS response time was associated with mortality. METHODS: This was a one-year retrospective cohort study of adults with a life-threatening event as assessed at the time of the 9-1-1 call (Medical Priority Dispatch System Echo- or Delta-level event). The study setting was an urban all-ALS EMS system serving a population of approximately 1 million. Response time was defined as 9-1-1 call receipt to ALS unit arrival on scene, and outcome was defined as all-cause mortality at hospital discharge. Potential covariates included patient acuity, age, gender, and combined scene and transport interval time. Stratified analysis and logistic regression were used to assess the response time-mortality association. RESULTS: There were 7,760 unit responses that met the inclusion criteria; 1,865 (24%) were ≥8 minutes. The average patient age was 56.7 years (standard deviation = 21.5). For patients with a response time ≥8 minutes, 7.1% died, compared with 6.4% for patients with a response time ≤7 minutes 59 seconds (risk difference 0.7%; 95% confidence interval [CI]: -0.5%, 2.0%). The adjusted odds ratio of mortality for ≥8 minutes was 1.19 (95% CI: 0.97, 1.47). An exploratory analysis suggested there may be a small beneficial effect of response ≤7 minutes 59 seconds for those who survived to become an inpatient (adjusted odds ratio = 1.30; 95% CI: 1.00, 1.69). CONCLUSIONS: These results call into question the clinical effectiveness of a dichotomous 8-minute ALS response time on decreasing mortality for the majority of adult patients identified as having a life-threatening event at the time of the 9-1-1 call. However, this study does not suggest that rapid EMS response is undesirable or unimportant for certain patients. This analysis highlights the need for further research on who may benefit from rapid EMS response, whether these individuals can be identified at the time of the 9-1-1 call, and what the optimum response time is.

Methodology for the development of a Canadian national EMS research agenda.

BACKGROUND: Many health care disciplines use evidence-based decision making to improve patient care and system performance. While the amount and quality of emergency medical services (EMS) research in Canada has increased over the past two decades, there has not been a unified national plan to enable research, ensure efficient use of research resources, guide funding decisions and build capacity in EMS research. Other countries have used research agendas to identify barriers and opportunities in EMS research and define national research priorities. The objective of this project is to develop a national EMS research agenda for Canada that will: 1) explore what barriers to EMS research currently exist, 2) identify current strengths and opportunities that may be of benefit to advancing EMS research, 3) make recommendations to overcome barriers and capitalize on opportunities, and 4) identify national EMS research priorities. METHODS/DESIGN: Paramedics, educators, EMS managers, medical directors, researchers and other key stakeholders from across Canada will be purposefully recruited to participate in this mixed methods study, which consists of three phases: 1) qualitative interviews with a selection of the study participants, who will be asked about their experience and opinions about the four study objectives, 2) a facilitated roundtable discussion, in which all participants will explore and discuss the study objectives, and 3) an online Delphi consensus survey, in which all participants will be asked to score the importance of each topic discovered during the interviews and roundtable as they relate to the study objectives. Results will be analyzed to determine the level of consensus achieved for each topic. DISCUSSION: A mixed methods approach will be used to address the four study objectives. We anticipate that the keys to success will be: 1) ensuring a representative sample of EMS stakeholders, 2) fostering an open and collaborative roundtable discussion, and 3) adhering to a predefined approach to measure consensus on each topic. Steps have been taken in the methodology to address each of these a priori concerns.

Carbon footprinting of North American emergency medical services systems.

OBJECTIVES: This study was undertaken to characterize the carbon emissions from a broad sample of North American emergency medical services (EMS) agencies, and to begin the process of establishing voluntary EMS-related emission targets. METHODS: Fifteen diverse North American EMS systems with more than 550,000 combined annual responses and serving a population of 6.3 million reported their direct and purchased ("Tier 2") energy consumption for one year. We calculated total carbon dioxide equivalent (CO(2)e) emissions using Environmental Protection Agency, Energy Information Administration, and locality-specific emission conversion factors. We also calculated per-response and population-based emissions. We report descriptive summary data. RESULTS: Participants included government "third-service" (n = 4), public utility model (n = 1), private contractor (n = 6), and rural rescue squad (n = 4) systems. Call volumes ranged from 800 to 114,280 (median 20,093; interquartile range [IQR] 1,100-55,217). Emissions totaled 46,941,690 pounds of CO(2)e (21,289 metric tons); 75% of emissions were from diesel or gasoline. For systems providing complete Tier 2 data, median emissions per response were 80.7 (IQR 65.1-106.5) pounds of CO(2)e and median emissions per service-area resident were 7.8 (IQR 4.7-11.2) pounds of CO(2)e. Two systems reported aviation fuel consumption for air medical services, with emissions of 2,395 pounds of CO(2)e per flight, or 0.7 pounds of CO(2)e per service-area resident. CONCLUSION: EMS operations produce substantial carbon emissions, primarily from vehicle-related fuel consumption. The 75th percentiles from our data suggest 106.5 pounds of CO(2)e per unit response and/or 11.2 pounds of CO(2)e per service-area resident as preliminary maximum emission targets. Air medical services can anticipate higher per-flight but lower population-based emissions.