Use of Emergency Medical Services for Pediatric Interfacility Transports

Interfacility transports (IFTs), defined as the transport of a patient from one health care facility to another,^1,2 are performed for a variety of indications in children, including a need for a higher-level and/or specialized care, caregiver preference, and resource availability.^3,4 As an important component of existing regional health care systems,⁵ pediatric IFTs have become increasingly more common.⁶ Most children requiring acute emergency and inpatient care present to emergency departments (EDs) in the closest proximity.⁷ Most EDs care for low volumes of children, with fewer encounters of higher-acuity children or those in need of specialty care.^8–10 This has led to an increased reliance on pediatric facilities, increased limitation in the capabilities of general EDs in the care of children, and greater regionalization of care.^6,11–15 This regionalization may lead to changes in the use of IFTs.^{11,13,16–19} 

As primary presentations and the resultant medical care within pediatrics change along an age spectrum, executing the transfer of a pediatric patient represents unique challenges for air and ground emergency medical services (EMS) agencies, including the need for pediatric equipment, education, and training on pediatric physiology and treatment and subsequent robust case review and quality improvement. Previous studies on pediatric IFTs have been limited by their shorter study periods,^19–21 regional nature,^{3,17,18,21,22} or primary focus on the standardization of IFT processes.^16,23–28 

In this study, we aimed to identify if there has been a change in the number and types of pediatric IFTs across a nationally representative sample of EMS agencies to better understand the changing needs for IFTs across EMS agencies in the United States. As there may be age-based differences in the use of IFTs over time,^11,17 we further aimed to identify potential differences in IFT characteristics across age groups to better understand changing needs for education and training, along with medication and equipment needs, among EMS agencies.

We performed a retrospective cross-sectional study using EMS encounters from 2018 to 2023 in the National EMS Information System (NEMSIS) data set. NEMSIS is a federally funded EMS registry that contains encounter-specific data on demographics, dispatch, assessment, interventions, and disposition that is entered by EMS clinicians for prehospital encounters.²⁹ NEMSIS contains EMS encounters from for-profit, nonprofit, and government-sponsored EMS agencies. The performance of the study was classified as nonhuman subjects research by our institutional review board.

We included all pediatric (<18 years) EMS encounters from 2018 to 2023. Although the NEMSIS database has consistently grown over the study period, we limited the present analysis to agencies that contributed over the entire 6-year period, using a masked agency identifier provided by NEMSIS. This was done to ensure a consistent denominator to evaluate for trends in pediatric IFTs over time. From encounters arising from these agencies, we excluded patients without a documented age or an age listed as 0 days (which may potentially represent an erroneous dispatch entry), boat transports, nontransports, assists, canceled, scheduled transports, patients classified as dead on arrival, and standbys (Figure 1).

We identified IFTs as encounters having a relevant complaint reported by dispatch as “Transfer/Interfacility/Palliative Care” or type of service requested listed as “Interfacility Transport.” This term is intended to describe encounters in which patients are transferred from one health care facility to another. We extracted demographic, transport, and dispatch data; clinical impressions; assessments; and interventions performed in IFT encounters. Demographics included age, sex, census region, and referring hospital urbanicity (as urban, suburban, rural, and wilderness). We categorized age as neonate (birth to 27 days), infant (28 days to <13 months), toddler (≥13 months to <2 years), early child (≥2 years to <6 years), middle child (≥6 years to <12 years), and adolescent (≥12 years to <18 years).³⁰ Transport modes included fixed wing, helicopter, and ground. The level of care was classified as basic life support, advanced life support (ALS), and critical care. Primary impressions were classified from the International Classification of Disease, Tenth Revision (ICD-10) codes used within NEMSIS using the Diagnosis Grouping System (DGS). The DGS classifies common pediatric ED ICD-10 diagnosis codes into 21 major groups.³¹ Applicable procedures extracted for these impressions included supplemental oxygen, basic airway management, advanced airway management, and physical restraints. Basic airway management includes airway suction, bag-valve-mask ventilation, assisted ventilation for an intubated patient, carbon dioxide monitoring, the performance of the Heimlich maneuver, placement of a nasal or oral airway, and manual opening of the airway. Advanced airway management included the provision of continuous positive airway pressure, bilevel positive airway pressure, endotracheal intubation, and supraglottic airway placement.

Among all EMS transports, we assessed the proportion characterized as IFTs. We described the demographics, impressions, vital signs, and procedures of IFTs by age group. To evaluate changes in IFT use over time, we first visualized the number of encounters per month, overall, and by age group. We modeled the change in IFT over time using an Autoregressive Integrated Moving Average (ARIMA) model. Compared with segmented regression models, ARIMA models address autocorrelation, referring to the resemblance between a time series and its delayed versions over consecutive time periods, and seasonality, characterized by consistent and predictable variations in a time series that happen at certain fixed intervals. We used an automated ARIMA algorithm to identify nonseasonal and seasonal p (autoregressive), d (differencing), and q (moving average) parameters. Our outcome of interest was the number of IFTs, with each month considered as the unit of analysis. As an external regressor, we incorporated a slope variable (represented as a dummy variable, which increased by 1 unit per month) to model linear trends present in the time series data explicitly and a variable to mark the onset of the COVID-19 pandemic in the United States in March 2020 (which on visual inspection of the data, and based on prior work,^32,33 was associated with a steep decrease in EMS encounters). We expressed our results as the unit change in IFTs occurring per month in the adjusted model, with 95% CIs. We repeated this analysis within each of the study age groups. We additionally evaluated for changes among the most common DGS groups. As a post hoc analysis to further evaluate the role of regionalization in study findings, we assessed for changes in the use of critical care/specialty IFTs over time. Analyses were performed using the astsa (v2.0) and forecast (v8.21) packages in R (version 4.3.2; R Foundation for Statistical Computing).

There were 256 577 805 patient encounters available through the NEMSIS data set during the study period 2018 to 2023. After applying exclusions, we included 4 333 424 pediatric encounters, of which 937 122 (21.6%) represented IFTs encountered by 2711 EMS agencies. Of these 2711 agencies, most (2692, 99.2%) also provided care to adult and/or children for purposes other than IFTs. Among IFTs, there was a slight male predominance (50.3%), and the median age was 9 years (IQR 1–14 years). Most children were transferred from urban settings (80.3%), with the largest proportion of IFTs occurring in the Western Census Region (35.8%). Demographics of the sample are provided in Table 1.

Overall, half (52.8%) of the total IFTs were ALS responses, with lower proportions of basic life support (27.1%) and critical care (20.2%) responses (Table 2). ALS responses made up most responses across all individual age groups except for neonates, for whom most responses had a critical care team (50.2%). Most transports were via ground-based services. Younger children were more frequently transported by air compared with older children (as high as 17.7% of IFTs among neonates).

Among the neonate, infant, toddler, and early childhood groups, respiratory diseases were most common, accounting for 24.0% to 32.8% of EMS impressions. Psychiatric/behavioral/substance use conditions was the most common impression among adolescents (28.5%). Among the studied interventions (Table 3), respiratory interventions were most applied for younger children. Most applications of restraints were for adolescents (69.0% of all restraint uses).

Visual inspection demonstrated an overall rise in IFTs over time, with a decrease during the COVID-19 pandemic (Figure 2), The ARIMA model demonstrated an increase in IFTs of 168 encounters per month (95% CI, 106–230) from 2018 to 2023 (Table 4), representing an increase of 2014 per year. The COVID-19 pandemic period resulted in a negative step change in overall IFTs by 4050 encounters (95% CI, −5994.2 to −2105.2). When stratified by age, there was a positive trend in IFT encounters per month among the neonate, toddler, early childhood, and middle childhood age groups. There was no significant trend observed in the infant and adolescent age groups. In an analysis performed by impression, we identified an increase in IFTs with psychiatric/behavioral/substance use conditions, systemic states (including conditions such as fever, viral illnesses, and acute [eg, malaise and fatigue] and chronic systemic conditions [eg, congenital malformations]), gastrointestinal diseases, and trauma (Table 5). In a post hoc analysis evaluating the use of specialty transport teams, there was no significant increase in linear trend (15.6 IFTs per month; 95% CI, −25.1 to 55.6).

We used a multiyear, nationally representative data set to evaluate pediatric IFTs by age and over time. In a model adjusted for the onset of the COVID-19 pandemic, we identified a rise in pediatric IFTs by 168 encounters per month between 2018 and 2023. Trends in impression type and intervention differed among age groups and EMS impressions. The significant increase in IFTs over time and notable differences among age groups, along with previously described increasing regionalization,^6,11,13 have implications for improving pediatric readiness in general EDs and training initiatives for EMS clinicians carrying out IFTs.

Our findings provide rich information on the use of pediatric IFTs from a nationally representative EMS data set. Respiratory diseases prevailed in the younger age groups, and psychiatric/behavioral/substance use conditions was the single most common impression among adolescents. These differences in primary impressions paralleled the differences in interventions among age groups according to the predominating impression, including increased respiratory interventions in younger children and restraint use in adolescents. Our findings expand on a prior statewide study that identified the most common conditions requiring IFT among children were asthma (13.5%), epilepsy (8.5%), and diabetes mellitus (6.6%).¹¹ Similarly, a review of IFTs for critically ill children identified that respiratory diagnoses were the most common clinical problem requiring transport, followed by nervous system injuries.³⁴ 

We also demonstrate important trends in the use of IFTs over time. Even accounting for a substantial decrease in EMS responses related to the COVID-19 pandemic,³⁵ there was a rise in pediatric IFTs over time. There were increases across all studied impressions, with the highest rise among systemic states, followed by respiratory diseases and psychiatric/behavioral/substance use conditions. More specifically, the largest rate of rise for respiratory conditions was in the fall/winter of 2022, likely related to the large national increase in respiratory syncytial virus, influenza virus, and COVID-19.³⁶ The rise in IFTs for mental health and substance use–related reports corroborates with a rise in these presentations within EDs reported over the last decade, especially among adolescents, which was further exacerbated by the COVID-19 pandemic.^35,37–40 

We postulate that the overall increase in EMS IFTs may be due to the background changes in pediatric regionalization, particularly as the number of EMS agencies studied in the present analysis contributed to NEMSIS over the entire study period. Numerous studies have suggested that regionalization of care for children has increased,^{11–13,18,41} with governing bodies such as the American Academy of Pediatrics, National Academy of Medicine, and Society of Critical Care Medicine being supportive of regionalization to optimize patient outcomes and promote efficiency in resource use.^9,15 Further literature has suggested that an increasing amount of care for children has become concentrated at pediatric centers, which can be related to closure of pediatric units owing to lower reimbursement rates, decreased staffing, and limited bed availability.^13,18 This has resulted in a decrease in the provision of definitive care at general hospitals,^13,18 although children frequently seek care at these facilities.^42–44 Consequently, hospitals’ capability to provide definitive care, even for common pediatric conditions, has declined.¹³ The downstream effect is reflected in the increasing numbers of IFTs nationally, disproportionate to adults.¹⁸ 

IFTs have risks, which include transportation hazards, potential for clinical deterioration, and fewer staff during transport, with a potentially more limited scope of practice.^2,44–47 IFTs are also resource intensive, result in care delays, and can cause work-related job and financial strain to families.⁴⁸ Prior work has shown that between 28% and 55% of pediatric IFTs result in discharge from receiving facilities soon after transport with minimal to no interventions, suggesting that these may be avoidable.^{19,21,48–53} More specifically, the diagnoses that required advanced interventions less than 10% of the time included cough, febrile seizures, croup, and allergic reactions.¹⁹ As respiratory disease is the most common primary impression in IFTs among young children, there exists a potential for a significant decrease in the number of unnecessary IFTs within this patient population.

Given the continued rise in IFTs demonstrated in this study, several systemic interventions may facilitate a safe reduction in unnecessary IFTs.⁵⁴ Interventions suggested in prior work include enhancing telemedicine systems,^21,55,56 developing specific quality improvement plans including clinical care guidelines, and ensuring appropriate equipment availability.⁵⁷ Addressing these challenges is particularly important as most EMS agencies in this study performed IFT alongside other EMS services, such as scene encounters, leading to challenges in allocating resources between these varying needs. Additional research is needed to assess the public health and institutional barriers to pediatric readiness^43,58 and the indications for transfer on a national scale to best provide universal access to safe, reliable pediatric ED care and IFTs as regionalization increases.

Our study findings are subject to limitations. We used retrospective data, which may be subject to errors in classification. We cannot verify the accuracy of the information collected on patients, and we are also limited to the data that are available in NEMSIS, which may be subject to reporting bias and other limitations of large data sets. Details regarding the nature of the referring facility, or patient outcomes following hospital transport in NEMSIS, is lacking. As NEMSIS has an increasing number of agencies that contribute data annually, we attempted to mitigate this limitation by only incorporating agencies that contributed during all the study years.

In this evaluation of 2711 EMS agencies, we found an increase in pediatric IFTs by 168 encounters per month nationally between 2018 and 2023. The most common impressions among younger children requiring IFTs were for respiratory conditions. Among adolescents, psychiatric/behavioral/substance use conditions occurred most frequently. Further research into pediatric readiness of general EDs, institutional barriers, and the use of alternative resources such as telemedicine is needed. Greater investments in outreach efforts for pediatric training and educational initiatives in general EDs, such as standardized clinical care guidelines, hands-on simulation training, and provisioning of a formalized curriculum, may decrease unnecessary IFTs.⁵⁹