Tools
EMS System Regionalization
Introduction
In the United States, the emergency medical services (EMS) system is a network of healthcare resources that delivers acute unscheduled care to patients outside of a hospital. The system closely interfaces with the rest of the healthcare infrastructure, including in-hospital components, outpatient clinics, and public health. These services vary in capabilities, with some healthcare providers able to offer basic life support and others able to offer advanced life support or air medical services.[1] A key characteristic of EMS is regionalization, ensuring that patients are transported to hospitals that are best capable of treating their medical needs,[2] even if it is not the local hospital in the ambulance's jurisdiction. Regionalization of care refers to organizing healthcare delivery so that high-acuity or specialized patients are directed to facilities with the appropriate resources, often within a geographical network. The most common reasons for bypassing local hospitals include transport to specialized hospitals hosting designated stroke centers, trauma centers, ST-elevation myocardial infarction (STEMI) centers, and burn centers, among others.
Regionalization of emergency medical care has become the standard of care in recent years, supported by evidence showing improved patient outcomes, reduced overall resource utilization, and reduced costs.[3][4] However, the success of a regionalized system requires constant quality assurance from all stakeholders, including the EMS medical director. EMS physicians play a crucial role in ensuring that the system meets the needs of patients in their region while educating other healthcare providers on the importance of regionalization. For example, hospital administrators may prioritize retaining patients within their facilities to support operational sustainability, and EMS operations may favor shorter transports to improve unit availability and response times.[5][6][7] Therefore, the EMS medical director must help different stakeholders interface effectively and ensure that the medical needs of the ambulance-arrived patient are the primary focus.
An effective regionalized prehospital system separates hospitals into different levels based on their ability to treat specific emergencies. This process involves 2 key steps—categorization and designation of hospitals. Categorization is the process of classifying hospitals based on their capabilities, whereas designation is the process of formally selecting hospitals to receive patients who need specific, specialized care. Professional bodies often set categorization, whereas governmental agencies typically set designation.
The need for categorization and designation emerged from the understanding that not every hospital can be equipped to manage the full spectrum of medical emergencies, particularly those requiring highly specialized resources and personnel. For example, a patient with a time-sensitive condition, such as severe trauma, requires specialty services for hemorrhage control and blood transfusions without delay.[8][9][10][11] Categorization and designation help to ensure that patients are transported to the most appropriate hospital with verified capabilities to treat their medical condition.
Issues of Concern
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Issues of Concern
Categorization and Designation
One challenge associated with categorization and designation is the need for explicit authority to designate hospitals. Without such authority, clinicians, hospitals, or other special interest groups may impede the designation process. Federal support for EMS systems in the United States has been inconsistent, resulting in unreliable funding for designation programs, which has led to a patchwork of solutions that vary by state and, in some cases, by municipality.[12][13][14][13] Lack of explicit authority to designate can also result in antitrust liability, as designations can inadvertently create a monopoly if only one center can meet the thresholds set.[15]
Another challenge is the need for clear criteria for categorization and designation. The American College of Surgeons provides criteria for level 1 and 2 trauma centers. Meanwhile, there are no clear criteria for what qualifies as a pediatric emergency department.[16] In the absence of standardized criteria, hospitals may overestimate their capabilities, which may lead to mismatches between a facility's resources and the needs of patients with specific, time-sensitive conditions. Despite these challenges, categorization and designation remain essential components of EMS, ensuring patients receive the proper care in the right place without delay.
Outcomes in Regionalized Systems
The prehospital system has effectively regionalized 3 major time-critical disease processes—severe trauma, acute ischemic stroke, and STEMI. Early identification and treatment are critical for improving patient outcomes. Future directions include pediatric center designations, cardiac arrest receiving centers, and sepsis designations.
Severe trauma: Time to surgical intervention for hemorrhage control is critical for trauma management, and regionalization of trauma care has greatly improved survival. Trauma systems typically include a network of designated trauma centers and an EMS system that directs patients meeting field trauma triage criteria to these specialized hospitals. Research has shown that patients treated at trauma centers have better outcomes compared to those treated elsewhere.[11][17][18][19][20][21] For example, one study found that patients treated within a trauma system had a reduced preventable mortality from 30% to 16% [4] compared to those who did not receive regionalized trauma care. Another study found that adding a second helicopter, which reduced transport times and allowed for effective regionalization into a county-wide trauma system on Long Island, improved mortality by 5%.[22] Trauma systems provide a framework for communication and coordination between different parts of the health system to decrease delays and barriers to emergency surgery and other definitive management.
Acute ischemic stroke: Stroke networks are a promising approach to improving care for patients who have had a stroke. The development of these networks has accelerated in the era of endovascular thrombectomy for large vessel occlusions.[23][24][25] Stroke networks have been shown to reduce mortality and improve functional outcomes by directing patients to primary and comprehensive stroke centers.[26][27][28]
Endovascular therapy, available at comprehensive stroke centers, should be administered in the first 24 hours, with emerging evidence suggesting that earlier endovascular intervention may lead to better outcomes, specifically in large vessel occlusions.[29] Compared to patients who have had an ischemic stroke, those who have had a hemorrhagic stroke have not experienced the same benefit. The RACE-CAT trial found worse outcomes and more complications in patients who have had a hemorrhagic stroke bypassed to distant centers, suggesting that these patients may benefit from initial care at the nearest stroke center.[30] Current guidelines recommend transporting all suspected patients who have had a stroke to specialized stroke centers, as historical data show that approximately 90% of strokes are ischemic in nature.[31]
In conjunction with regionalization, EMS systems also optimize stroke care by training healthcare providers to identify patients who have had a stroke and simultaneously activating stroke teams, which decreases the time to fibrinolysis and endovascular therapy. This ability to simultaneously activate hospital resources themselves, such as the stroke team, can shorten time to definitive treatment by obviating the wait for an in-hospital emergency physician assessment. To aid pre-arrival activation, EMS providers use many stroke identification tools, including the Cincinnati Prehospital Stroke Scale or Los Angeles Motor Scale, to screen for acute stroke and the Rapid Arterial Occlusion Evaluation Scale for large vessel occlusions. A new paradigm in prehospital stroke care is the use of mobile stroke units, which are specialized ambulances equipped with imaging and stroke treatment capabilities that can enable rapid diagnosis and on-scene initiation of thrombolytic therapy. However, how these units integrate into existing regionalized stroke care models and their cost-effectiveness in the prehospital setting remain to be determined.[32][33]
ST-elevation myocardial infarction: STEMI regionalization has shown significant mortality benefits and has been widely adopted.[34][35] For example, the Mission: Lifeline Accelerator-2 study has established that an organized care model between EMS systems and hospitals is associated with significantly reduced time to reperfusion in patients experiencing acute myocardial infarction.[36]
A key challenge in STEMI regionalization is patient self-transport. Unlike trauma patients with severe injuries—who are unlikely to self-transport and benefit from being transported by EMS to a regional trauma center—50% of patients who have had a STEMI self-transport to emergency departments. Many of these facilities lack cardiac catheterization capabilities, leading to delays in reperfusion and increased morbidity and mortality. Currently, public education efforts from the American Heart Association recommend activating EMS for patients experiencing chest pain.[37]
STEMI regionalization also faces logistical barriers. Unlike stroke, a clinical diagnosis that is typically capable at the basic life support level, a STEMI diagnosis requires an electrocardiogram (ECG), complicating regionalization efforts. In medically underserved areas lacking prehospital advanced life support providers with ECG capabilities, STEMI recognition may be hindered and can result in improper destination choices for patients arriving by ambulance. Basic life support ECG acquisition offers a solution by enabling basic life support providers to capture and transmit ECGs to clinicians, who can then guide transport to facilities capable of coronary reperfusion.[38]
Emerging Regionalization Models
Cardiac arrest receiving centers are specialized centers equipped to provide immediate and long-term care for patients who have experienced a non-traumatic cardiac arrest, often utilizing interventions such as therapeutic hypothermia and cardiac catheterization. A 2014 study in Arizona demonstrated improved outcomes following the implementation of a statewide EMS protocol that permitted bypass of local hospitals in favor of these specialized centers.[39] Similarly, a 2019 study conducted in northern Appalachia reported better outcomes for patients transported directly by EMS or via interfacility transfer to cardiac arrest receiving centers.[40] However, a 2024 international systematic review found a very low certainty of evidence supporting improved outcomes with the implementation of specialized cardiac arrest receiving centers, with the sole randomized control trial in the review showing no benefit.[41][42]
Sepsis is another condition that may benefit from regionalization. Although severe sepsis does not require advanced technology or procedural interventions, it may necessitate intensive care that is best equipped at specialized centers.[43] Studies have found improved outcomes in high-volume centers when caring for patients with sepsis.[44][45] However, further research is needed to evaluate the efficacy of formal sepsis regionalization before widespread adoption. For example, Ofama et al reported worse outcomes at higher capability hospitals. However, this may reflect de facto regionalization, where more severely ill patients are preferentially transported to these centers, leading to higher observed rates of morbidity and mortality, and confounding the true impact of sepsis regionalization.[46]
Extracorporeal cardiopulmonary resuscitation is an emerging method for treating cardiac arrest that is beginning to become regionalized among certain EMS systems. Extracorporeal cardiopulmonary resuscitation is a resuscitation technique that uses extracorporeal membrane oxygenation, which is a machine that takes over the function of the cardiopulmonary system by pumping and oxygenating the blood supply externally. The ARREST trial showed improved survival compared to standard Advanced Cardiac Life Support (ACLS). Although the trial included only 30 patients, it was halted early due to ethical concerns arising from strong evidence of the efficacy of extracorporeal cardiopulmonary resuscitation.[47] In contrast, another study was stopped early for futility after finding no significant improvement in 180-day neurologically favorable survival. Notably, this study used much broader inclusion criteria.[48] Although concerns about the cost of extracorporeal cardiopulmonary resuscitation remain, regionalization data suggest that extracorporeal cardiopulmonary resuscitation can lead to improved outcomes compared to ACLS in a carefully selected group of patients who have had a cardiac arrest and has been successfully adopted in several systems.[49]
Approximately 20% of all visits to emergency departments in the United States are by children.[50] Unlike adult regionalization care models, such as trauma or STEMI, there is limited formal categorization for pediatric emergency care. The pediatric readiness score is a close analogue to formal categorizations used in adult care, offering a comprehensive evaluation of a hospital's capacity to care for children and is associated with improved pediatric outcomes.[51] A challenge with regionalization of pediatric emergency care is that children overwhelmingly arrive at the hospital via private transportation.[52] Because children are physically easier to transport, parents often instinctively drive them to the closest hospital instead of calling EMS, which may interfere with the regionalized system of care.
Beyond the already well-established regionalization models in the United States, such as trauma and stroke systems, there are many new and emerging regionalization models. Given current evidence showing improved morbidity and mortality in several presenting conditions, further research should be encouraged to explore the impact of regionalization in other clinical scenarios.
Special Considerations Affecting Regionalization
Diversion occurs when a receiving facility declines to accept transport by EMS, often due to overcrowding or an imbalance between available staff and patient demand.[53][54][55][56][54] Hospitals and EMS medical directors must establish clear and consistent criteria for diversion to ensure it is applied fairly and is not a permanent solution to systemic issues. Diversion can delay definitive care and result in worse patient care.[57] Additionally, it can create confusion for both EMS providers and patients, as providers must navigate unfamiliar systems while patients receive care at institutions where their prior medical records are unavailable. For these reasons, some EMS systems, such as Massachusetts in 2009, have abandoned ambulance diversion and found no changes in ED volume, elopement, or patient length-of-stay.[58]
Bypass is a process in which EMS transports patients directly to the most appropriate facility for their condition, even if that facility is farther away, and is the byproduct of effective regionalized care. This approach prevents delays caused by transport to a facility ill-equipped to treat their condition, which can result in additional resources mobilized for an interfacility transfer and duplicative testing in multiple health systems. Patients who have had a STEMI transported to facilities not equipped for cardiac catheterization experience an average 79-minute delay and increased mortality.[59] EMS systems must have clear and consistent guidelines for bypass with the cooperation of all regional hospitals. Proper guidelines may help to avoid confusion or resistance from receiving facilities, standardize EMS decision-making in the field, and ensure that all stakeholders understand and support the rationale behind bypass protocols.
Adequate funding is essential to the effective functioning of both EMS and health systems. Variations in reimbursement structures across different types of care can create financial incentives that drive competition among hospitals for specific designations. These reimbursement models may also inadvertently influence the availability of care at ambulance-receiving facilities. EMS agencies must also be fairly reimbursed, especially when transporting to distant specialty centers, as longer transport times raise operational costs and require additional expertise and training. Supporting regionalization and aligning with evidence-based care may require payers to better account for the actual value of transporting patients to the right level of care. Past regionalization efforts have often struggled with implementation, largely due to financial barriers.[49]
Although regionalization has proven to improve outcomes, healthcare systems must be wary of over-regionalization.[60][61][62] Emergency physicians are trained to stabilize all patient presentations, and community hospitals are capable of providing high-quality initial care for a broad range of emergencies. Regionalization of routine cases such as sepsis or cardiac arrest could increase financial burdens on the payer and strain EMS resources, perhaps without clear evidence of improved morbidity or mortality. In the absence of strong data demonstrating a clear benefit, such expansions can risk inefficiencies and should not yet be implemented until there is clear evidence.
Clinical Significance
Regionalization has demonstrated clear benefits in improving patient outcomes for several time-sensitive emergencies. However, its continued success depends on balanced implementation and evidence-based expansion. For example, prehospital stroke systems are evolving as endovascular therapy becomes the standard of care for large vessel occlusions. Clear protocols regarding diversion, bypass, and specialty receiving center criteria must be established to ensure fair and consistent care. The public must also understand the destination choices and why they may have to go to one facility over another. Prehospital care, especially for time-sensitive diseases, must also decrease time to definitive care by not only bypassing the most appropriate destination but also having the ability for EMS-initiated prenotification and activation of in-hospital teams.
Conversely, EMS physicians must ensure healthcare providers correctly identify time-sensitive diseases, such as stroke, and patients who have had a STEMI who are candidates for cardiac catheterization. EMS medical directors play a key role in aligning EMS regionalization efforts with both system capabilities and patient needs, while helping to coordinate input from all stakeholders. These efforts help to ensure that regionalized EMS systems are both effective and fair, improving outcomes of ambulance-arrived patients through proper destination choices.
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Level 3 (low-level) evidence