Tools
EMS System Regionalization
Introduction
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 (in-hospital components, outpatient clinics, public health). EMS services vary in capabilities, with some providers able to provide basic life support and others able to provide advanced life support (ALS) or air medical services.[1] Patients sometimes require definitive care unavailable at the closest hospital, so EMS systems need to be regionalized.[2] This means that patients are transported to hospitals best equipped to care for their specific needs, even if it is not the local hospital in the ambulance's jurisdiction. Regionalization can help to improve patient outcomes, avoid delays in care, and help reduce overall resource utilization by avoiding secondary transports.[3][4][5][6][7][8][9][10][11]
Regionalization of emergency medical care has become the standard of care in recent years. Studies have shown improved patient outcomes and reduced costs due to this policy. However, the success of a regionalized system requires constant quality assurance from all stakeholders and the EMS medical director. The system must focus on every aspect of the patient's journey through the acute unscheduled care system, constantly identify any barriers that need to be improved, and update processes as new outcome data becomes available. EMS medical directors play a crucial role by ensuring that the system meets the needs of the patients in their region while educating other healthcare stakeholders on the importance of regionalization, which healthcare organizations or individual providers may not fully understand. For example, local hospital administrators often have financial pressure to keep patients in the local community within their hospitals. EMS operations may want all units to go to the closest hospital to decrease turnaround times. Therefore, the EMS medical director must help different providers interface effectively and ensure the medical needs of the patient arriving by ambulance are the primary focus.
Issues of Concern
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Issues of Concern
Categorization and Designation
An effective regionalized prehospital system requires the categorization and designation of hospitals. Categorization is the process of classifying hospitals based on accepted standards, while designation is the process of formally selecting hospitals to receive patients who need specialized care. Professional bodies often set categorization, while governmental agencies usually set designation.
The need for categorization and designation arose from recognizing that not every hospital could possess every medical service. A patient with a time-sensitive diagnosis such as severe trauma requires specialty services such as trauma surgery and blood transfusions without delay.[12][13][14][15] Categorization and designation help to ensure that patients are transported to the most appropriate hospital with verified capabilities to treat their medical condition.
One challenge associated with categorization and designation is the need for explicit authority to designate hospitals. Without such authority, physicians, hospitals, or other special interest groups may impede the designation process. For example, bypassed institutions not designated for certain conditions may suffer adverse economic effects and be at odds with the regionalization process.[16][17][18] Federal funding for EMS systems has been unreliable, resulting in a lack of consistent funding for designation programs and patchwork solutions that vary by state and, in some cases, by municipality.[19][20][21][22] Lack of explicit authority to designate could also result in antitrust liability, as designations can inadvertently create a monopoly if only one center can meet the thresholds set.[23]
Another challenge is the need for clear criteria for categorization and subsequent designation. The American College of Surgeons releases criteria for level 1 and 2 trauma centers. There are no clear criteria for what may count as a pediatric emergency department.[24] Without clear categorization criteria, hospitals may self-designate themselves as having capabilities that may not be congruent with the needs of the time-sensitive illness and lead to patients receiving suboptimal care. Despite these challenges, categorization and designation are essential components of EMS systems worth maintaining so patients receive the care they need in the right place without delay.
Outcomes in Regionalized Systems
Time-critical emergencies require immediate medical attention and definitive care. The prehospital system has effectively regionalized three major time-critical crises: severe trauma, acute ischemic stroke, and ST-Elevation Myocardial Infarction (STEMI). Early identification and treatment are critical for improving a patient's outcome. Future directions could include pediatric center designations, return of spontaneous circulation after cardiac arrest, and sepsis designations.
Time to blood products and operative interventions are critical for trauma management. Trauma systems typically include a network of hospitals designated as trauma centers and an EMS system designed to bring patients who meet field trauma triage criteria to them. Research has shown that patients treated at trauma centers have better outcomes than those treated outside.[25][26][27][28] For example, one study found an overall reduction in preventable mortality in patients treated within a trauma system was approximately 50%. Trauma systems provide a framework for communication and coordination between different interfacing parts of the health system to decrease delays and barriers to definitive management.
Stroke networks are a newer concept, but they have shown promise for improving the quality of care for stroke patients. They are evolving in the age of endovascular thrombectomy for large vessel occlusions.[29][30][31] Stroke networks have been shown to reduce mortality and improve functional outcomes for patients taken to primary and comprehensive stroke centers.[32][33]
Endovascular therapy, available at comprehensive stroke centers, must be offered in the first 24 hours. There is emerging evidence suggesting earlier endovascular intervention may lead to better outcomes. Patient outcomes from bypass of primary to comprehensive stroke centers are actively being studied.[34][35][36][37] One research group is the OPUS-REACH consortium, which consists of nine health systems to study and optimize prehospital care systems for large vessel occlusions. Besides regionalization, EMS systems also optimize stroke care delivery by teaching EMS providers to identify stroke patients and initiate pre-alert notifications to activate stroke teams. All this decreases the time to fibrinolysis and endovascular therapy if appropriate and available. EMS providers use many scales, 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.
STEMI regionalization has shown significant mortality benefits and has been widely adopted.[38][39][40][41] For example, the Reperfusion of Acute MI in North Carolina Emergency Departments (RACE) effort has organized the entire state of North Carolina into a system that allows for a high level of coordinated STEMI treatment to decrease time to coronary reperfusion. Unlike trauma patients with high injury severity scores who are unlikely to self-transport and benefit from being transported by EMS to a regional trauma center, 50% of patients with STEMI continue to self-transport to receiving facilities. This results in STEMI patients often presenting to centers incapable of cardiac catheterization and increasing morbidity and mortality for these patients. Public education efforts have not been successful in changing this statistic. More work is needed to reduce the number of patients who self-transport to inappropriate treatment facilities. Unlike stroke, a clinical diagnosis, STEMI diagnosis requires a prehospital EKG, which complicates regionalization efforts. Many rural areas do not have ready access to ALS, which impedes STEMI recognition and results in improper destination choices for patients arriving by ambulance.
Diversion and Bypass
Diversion is when a receiving facility may decline to allow transport by EMS. There are several reasons why a hospital might need to divert ambulances. For example, if the hospital is overcrowded or the staff is overwhelmed, they may not be able to adequately care for any more patients.[42][43][44][45][46][47] Hospitals, in conjunction with the EMS medical director, need to have clear and strict criteria for diversion. This ensures that the decision to divert is made fairly and consistently and is not a permanent solution to systemic problems within the hospital. The criteria must also be in place to prevent individuals from arbitrarily diverting ambulance patients. Diversion can prolong the prehospital phase of the encounter and result in worse patient care.
In some cases, diverting ambulances for a subcategory of patients may be necessary. For example, suppose a STEMI center has many active patients waiting to receive care in the cardiac catheterization lab. In that case, they may go on STEMI divert because the next STEMI patient may not receive timely care and would be better served elsewhere. However, the hospital would be able to accept other types of patients. Regardless, ambulance diversion results in longer transport times and delays patient care delivery. Second, it can lead to patients being transported to facilities not equipped to treat their condition. Third, it can be confusing for EMS providers not used to practicing in the new prehospital system and patients who may be forced to go to unfamiliar institutions without records. For these reasons, some EMS systems have abandoned ambulance diversion. Massachusetts abandoned ambulance diversion in 2009 and found no changes in monthly ED volume, elopement, or patient length-of-stay.[48]
Bypass is a process in which EMS providers transport patients directly to the most appropriate facility for their condition, even if that facility is not the closest one. This can help patients receive the care they need as quickly as possible. Otherwise, patients may arrive in a facility not equipped to treat their condition, which could result in additional resources mobilized for an interfacility transfer and duplicative testing in multiple health systems. STEMI patients who go to the closest facility without cardiac catheterization capabilities for stabilization have an average of 79 minutes added to the patient's care and increased mortality.[8] EMS systems must have clear and consistent guidelines for specific disease processes to implement bypass. They also need to have the cooperation of all hospitals in the region.
Special Considerations Affecting Regionalization
When EMS systems were originally designed, care delivery was done in series. For example, an ambulance would respond to a 911 call, followed by assessment, treatment, and transport. When the patient arrives at the emergency department, the evaluation is often repeated, and appropriate consultants or notifications are made. Simultaneous processing is a newer approach involving concurrent medical system activation. This can be done by authorizing field personnel to activate specific teams or procedures, such as stroke teams or cardiac catheterization labs, to mobilize resources before the patient arrives at the receiving hospital. This can decrease the door-to-needle time for strokes and door-to-balloon time for STEMIs. Simultaneous processing decreases the time elapsed from symptom onset to definitive care. In the future, simultaneous processing will likely become even more critical as new technologies are developed. For example, drones could deliver medications to patients in the field while EMS is en route and notify nearby receiving centers of a potential patient.[49]
Funding is a crucial factor in the operation of both EMS and health systems. Different types of care are reimbursed differently, which can lead to competition between hospitals for specific designations. For example, trauma care is not as well-reimbursed as cardiac care, so some hospitals may choose to focus on cardiac care while hollowing out trauma care. Reimbursement incentives thus unintentionally affect the availability of services at ambulance-receiving centers. Facilities may also inappropriately self-designate to receive high-reimbursing disease processes. EMS agencies must also be reasonably reimbursed for their work, especially when using nuanced medical decision-making to transport patients to farther away facilities. Longer transport times lead to increased costs. Payers should adjust their reimbursement standards, often flat fee reimbursements, to accommodate the advances and reinforce the medical benefits of regionalization.
Clinical Significance
Regionalization is a never-ending process that requires continuous quality improvement and re-evaluation. For example, prehospital stroke systems evolve as endovascular therapy becomes the standard of care for large vessel occlusions. Clear protocols regarding diversion, bypass, and specialty receiving center criteria must be developed so no one entity (EMS or facility) feels marginalized and medical care is not arbitrary. 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 employ simultaneous processing to decrease time to definitive care by allowing for EMS-initiated prenotification.
Conversely, EMS medical directors must ensure their providers appropriately identify time-sensitive diseases, such as stroke and STEMI cardiac catheterization candidates. EMS medical directors are positioned to gain an understanding of the viewpoints of all stakeholders and ensure that the system is impartial and acting in the patient's best interest. These concepts will help to ensure that regionalized EMS systems are effective and fair and improve outcomes of ambulance-arrived patients through proper destination choices.
References
Hackey RB. The politics of trauma system development. The Journal of trauma. 1995 Dec:39(6):1045-53 [PubMed PMID: 7500391]
Luft HS. Regionalization of medical care. American journal of public health. 1985 Feb:75(2):125-6 [PubMed PMID: 3966613]
Cales RH, Anderson PG, Heilig RW Jr. Utilization of medical care in Orange County: the effect of implementation of a regional trauma system. Annals of emergency medicine. 1985 Sep:14(9):853-8 [PubMed PMID: 4025982]
Shackford SR, Hollingworth-Fridlund P, Cooper GF, Eastman AB. The effect of regionalization upon the quality of trauma care as assessed by concurrent audit before and after institution of a trauma system: a preliminary report. The Journal of trauma. 1986 Sep:26(9):812-20 [PubMed PMID: 3746956]
Level 2 (mid-level) evidenceDeBritz JN, Pollak AN. The impact of trauma centre accreditation on patient outcome. Injury. 2006 Dec:37(12):1166-71 [PubMed PMID: 17098237]
Jurkovich GJ, Mock C. Systematic review of trauma system effectiveness based on registry comparisons. The Journal of trauma. 1999 Sep:47(3 Suppl):S46-55 [PubMed PMID: 10496611]
Level 2 (mid-level) evidenceNathens AB, Jurkovich GJ, Cummings P, Rivara FP, Maier RV. The effect of organized systems of trauma care on motor vehicle crash mortality. JAMA. 2000 Apr 19:283(15):1990-4 [PubMed PMID: 10789667]
Level 2 (mid-level) evidenceGross BW, Dauterman KW, Moran MG, Kotler TS, Schnugg SJ, Rostykus PS, Ross AM, Weaver WD. An approach to shorten time to infarct artery patency in patients with ST-segment elevation myocardial infarction. The American journal of cardiology. 2007 May 15:99(10):1360-3 [PubMed PMID: 17493460]
Level 2 (mid-level) evidenceLe May MR, Davies RF, Dionne R, Maloney J, Trickett J, So D, Ha A, Sherrard H, Glover C, Marquis JF, O'Brien ER, Stiell IG, Poirier P, Labinaz M. Comparison of early mortality of paramedic-diagnosed ST-segment elevation myocardial infarction with immediate transport to a designated primary percutaneous coronary intervention center to that of similar patients transported to the nearest hospital. The American journal of cardiology. 2006 Nov 15:98(10):1329-33 [PubMed PMID: 17134623]
Le May MR, So DY, Dionne R, Glover CA, Froeschl MP, Wells GA, Davies RF, Sherrard HL, Maloney J, Marquis JF, O'Brien ER, Trickett J, Poirier P, Ryan SC, Ha A, Joseph PG, Labinaz M. A citywide protocol for primary PCI in ST-segment elevation myocardial infarction. The New England journal of medicine. 2008 Jan 17:358(3):231-40. doi: 10.1056/NEJMoa073102. Epub [PubMed PMID: 18199862]
Jollis JG, Roettig ML, Aluko AO, Anstrom KJ, Applegate RJ, Babb JD, Berger PB, Bohle DJ, Fletcher SM, Garvey JL, Hathaway WR, Hoekstra JW, Kelly RV, Maddox WT Jr, Shiber JR, Valeri FS, Watling BA, Wilson BH, Granger CB, Reperfusion of Acute Myocardial Infarction in North Carolina Emergency Departments (RACE) Investigators. Implementation of a statewide system for coronary reperfusion for ST-segment elevation myocardial infarction. JAMA. 2007 Nov 28:298(20):2371-80 [PubMed PMID: 17982184]
Boyd DR, Cowley RA. Comprehensive regional trauma/emergency medical services (EMS) delivery systems: the United States experience. World journal of surgery. 1983 Jan:7(1):149-57 [PubMed PMID: 6837054]
Dakessian A, Bachir R, El Sayed MJ. Association Between Trauma Center Designation Levels and Survival of Patients With Motor Vehicular Transport Injuries in the United States. The Journal of emergency medicine. 2020 Mar:58(3):398-406. doi: 10.1016/j.jemermed.2019.12.029. Epub 2020 Feb 15 [PubMed PMID: 32070648]
Cudnik MT, Newgard CD, Sayre MR, Steinberg SM. Level I versus Level II trauma centers: an outcomes-based assessment. The Journal of trauma. 2009 May:66(5):1321-6. doi: 10.1097/TA.0b013e3181929e2b. Epub [PubMed PMID: 19430234]
Level 2 (mid-level) evidenceDiRusso S, Holly C, Kamath R, Cuff S, Sullivan T, Scharf H, Tully T, Nealon P, Savino JA. Preparation and achievement of American College of Surgeons level I trauma verification raises hospital performance and improves patient outcome. The Journal of trauma. 2001 Aug:51(2):294-9; discussion 299-300 [PubMed PMID: 11493787]
Friedman HR, Holmes GM. Rural Medicare beneficiaries are increasingly likely to be admitted to urban hospitals. Health services research. 2022 Oct:57(5):1029-1034. doi: 10.1111/1475-6773.14017. Epub 2022 Jul 13 [PubMed PMID: 35773787]
Sanders SR, Erickson LD, Call VR, McKnight ML, Hedges DW. Rural health care bypass behavior: how community and spatial characteristics affect primary health care selection. The Journal of rural health : official journal of the American Rural Health Association and the National Rural Health Care Association. 2015 Spring:31(2):146-56. doi: 10.1111/jrh.12093. Epub 2014 Sep 12 [PubMed PMID: 25219792]
Greenwood-Ericksen M, Kamdar N, Lin P, George N, Myaskovsky L, Crandall C, Mohr NM, Kocher KE. Association of Rural and Critical Access Hospital Status With Patient Outcomes After Emergency Department Visits Among Medicare Beneficiaries. JAMA network open. 2021 Nov 1:4(11):e2134980. doi: 10.1001/jamanetworkopen.2021.34980. Epub 2021 Nov 1 [PubMed PMID: 34797370]
Shah MN. The formation of the emergency medical services system. American journal of public health. 2006 Mar:96(3):414-23 [PubMed PMID: 16449600]
Pozner CN, Zane R, Nelson SJ, Levine M. International EMS systems: The United States: past, present, and future. Resuscitation. 2004 Mar:60(3):239-44 [PubMed PMID: 15050754]
Boyd DR. The conceptual development of EMS systems in the United States, Part I. Emergency medical services. 1982 Jan-Feb:11(1):19-23 [PubMed PMID: 10298361]
Boyd DR. The conceptual development of EMS systems in the Unites States, Part II. Emergency medical services. 1982 Mar-Apr:11(2):26, 28-30, 32-3 passim [PubMed PMID: 10298550]
Young CJ. Emergency! Says who?: analysis of the legal issues concerning managed care and emergency medical services. The Journal of contemporary health law and policy. 1997 Spring:13(2):553-79 [PubMed PMID: 9212530]
Fuchs S. The Origins and Evolution of Emergency Medical Services for Children. Pediatric annals. 2021 Apr:50(4):e150-e154. doi: 10.3928/19382359-20210316-01. Epub 2021 Apr 1 [PubMed PMID: 34039172]
Nguyen JK, Sanghavi P. Comparison of survival outcomes among older adults with major trauma after trauma center versus non-trauma center care in the United States. Health services research. 2023 Aug:58(4):817-827. doi: 10.1111/1475-6773.14148. Epub 2023 Mar 9 [PubMed PMID: 36829289]
Jarman MP, Jin G, Weissman JS, Ash AS, Tjia J, Salim A, Haider A, Cooper Z. Association of Trauma Center Designation With Postdischarge Survival Among Older Adults With Injuries. JAMA network open. 2022 Mar 1:5(3):e222448. doi: 10.1001/jamanetworkopen.2022.2448. Epub 2022 Mar 1 [PubMed PMID: 35294541]
van Rein EAJ, van der Sluijs R, Houwert RM, Gunning AC, Lichtveld RA, Leenen LPH, van Heijl M. Effectiveness of prehospital trauma triage systems in selecting severely injured patients: Is comparative analysis possible? The American journal of emergency medicine. 2018 Jun:36(6):1060-1069. doi: 10.1016/j.ajem.2018.01.055. Epub 2018 Feb 1 [PubMed PMID: 29395772]
Level 2 (mid-level) evidenceGarwe T, Cowan LD, Neas B, Cathey T, Danford BC, Greenawalt P. Survival benefit of transfer to tertiary trauma centers for major trauma patients initially presenting to nontertiary trauma centers. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine. 2010 Nov:17(11):1223-32. doi: 10.1111/j.1553-2712.2010.00918.x. Epub [PubMed PMID: 21175521]
Level 2 (mid-level) evidenceMolyneux A, Kerr R, Stratton I, Sandercock P, Clarke M, Shrimpton J, Holman R, International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet (London, England). 2002 Oct 26:360(9342):1267-74 [PubMed PMID: 12414200]
Level 1 (high-level) evidenceBerman MF, Solomon RA, Mayer SA, Johnston SC, Yung PP. Impact of hospital-related factors on outcome after treatment of cerebral aneurysms. Stroke. 2003 Sep:34(9):2200-7 [PubMed PMID: 12907814]
National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. The New England journal of medicine. 1995 Dec 14:333(24):1581-7 [PubMed PMID: 7477192]
Level 1 (high-level) evidenceHacke W, Donnan G, Fieschi C, Kaste M, von Kummer R, Broderick JP, Brott T, Frankel M, Grotta JC, Haley EC Jr, Kwiatkowski T, Levine SR, Lewandowski C, Lu M, Lyden P, Marler JR, Patel S, Tilley BC, Albers G, Bluhmki E, Wilhelm M, Hamilton S, ATLANTIS Trials Investigators, ECASS Trials Investigators, NINDS rt-PA Study Group Investigators. Association of outcome with early stroke treatment: pooled analysis of ATLANTIS, ECASS, and NINDS rt-PA stroke trials. Lancet (London, England). 2004 Mar 6:363(9411):768-74 [PubMed PMID: 15016487]
Level 1 (high-level) evidenceKatzan IL, Furlan AJ, Lloyd LE, Frank JI, Harper DL, Hinchey JA, Hammel JP, Qu A, Sila CA. Use of tissue-type plasminogen activator for acute ischemic stroke: the Cleveland area experience. JAMA. 2000 Mar 1:283(9):1151-8 [PubMed PMID: 10703777]
Katzan IL, Hammer MD, Furlan AJ, Hixson ED, Nadzam DM, Cleveland Clinic Health System Stroke Quality Improvement Team. Quality improvement and tissue-type plasminogen activator for acute ischemic stroke: a Cleveland update. Stroke. 2003 Mar:34(3):799-800 [PubMed PMID: 12624312]
Level 2 (mid-level) evidenceSchwamm LH, Pancioli A, Acker JE 3rd, Goldstein LB, Zorowitz RD, Shephard TJ, Moyer P, Gorman M, Johnston SC, Duncan PW, Gorelick P, Frank J, Stranne SK, Smith R, Federspiel W, Horton KB, Magnis E, Adams RJ, American Stroke Association's Task Force on the Development of Stroke Systems. Recommendations for the establishment of stroke systems of care: recommendations from the American Stroke Association's Task Force on the Development of Stroke Systems. Stroke. 2005 Mar:36(3):690-703 [PubMed PMID: 15689577]
Level 1 (high-level) evidenceRymer MM, Thurtchley D, Summers D, America Brain and Stroke Institute Stroke Team. Expanded modes of tissue plasminogen activator delivery in a comprehensive stroke center increases regional acute stroke interventions. Stroke. 2003 Jun:34(6):e58-60 [PubMed PMID: 12730555]
Jauch EC, Saver JL, Adams HP Jr, Bruno A, Connors JJ, Demaerschalk BM, Khatri P, McMullan PW Jr, Qureshi AI, Rosenfield K, Scott PA, Summers DR, Wang DZ, Wintermark M, Yonas H, American Heart Association Stroke Council, Council on Cardiovascular Nursing, Council on Peripheral Vascular Disease, Council on Clinical Cardiology. Guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2013 Mar:44(3):870-947. doi: 10.1161/STR.0b013e318284056a. Epub 2013 Jan 31 [PubMed PMID: 23370205]
Glickman SW, Lytle BL, Ou FS, Mears G, O'Brien S, Cairns CB, Garvey JL, Bohle DJ, Peterson ED, Jollis JG, Granger CB. Care processes associated with quicker door-in-door-out times for patients with ST-elevation-myocardial infarction requiring transfer: results from a statewide regionalization program. Circulation. Cardiovascular quality and outcomes. 2011 Jul:4(4):382-8. doi: 10.1161/CIRCOUTCOMES.110.959643. Epub 2011 Jun 28 [PubMed PMID: 21712523]
Dauerman HL, Bates ER, Kontos MC, Li S, Garvey JL, Henry TD, Manoukian SV, Roe MT. Nationwide Analysis of Patients With ST-Segment-Elevation Myocardial Infarction Transferred for Primary Percutaneous Intervention: Findings From the American Heart Association Mission: Lifeline Program. Circulation. Cardiovascular interventions. 2015 May:8(5):. pii: e002450. doi: 10.1161/CIRCINTERVENTIONS.114.002450. Epub [PubMed PMID: 25901044]
Ting HH, Rihal CS, Gersh BJ, Haro LH, Bjerke CM, Lennon RJ, Lim CC, Bresnahan JF, Jaffe AS, Holmes DR, Bell MR. Regional systems of care to optimize timeliness of reperfusion therapy for ST-elevation myocardial infarction: the Mayo Clinic STEMI Protocol. Circulation. 2007 Aug 14:116(7):729-36 [PubMed PMID: 17673456]
Camp-Rogers T, Kurz MC, Brady WJ. Hospital-based strategies contributing to percutaneous coronary intervention time reduction in the patient with ST-segment elevation myocardiaI infarction: a review of the "system-of-care" approach. The American journal of emergency medicine. 2012 Mar:30(3):491-8. doi: 10.1016/j.ajem.2011.02.011. Epub 2011 Apr 22 [PubMed PMID: 21514087]
Cooney DR, Millin MG, Carter A, Lawner BJ, Nable JV, Wallus HJ. Ambulance diversion and emergency department offload delay: resource document for the National Association of EMS Physicians position statement. Prehospital emergency care. 2011 Oct-Dec:15(4):555-61. doi: 10.3109/10903127.2011.608871. Epub [PubMed PMID: 21870947]
Brennan JA, Allin DM, Calkins AM, Enguidanos ER, Heimbach LJ, Pruden JN Sr, Stilley DG. Guidelines for ambulance diversion. American College of Emergency Physicians. Annals of emergency medicine. 2000 Oct:36(4):376-7 [PubMed PMID: 11020687]
Level 1 (high-level) evidenceSchull MJ, Lazier K, Vermeulen M, Mawhinney S, Morrison LJ. Emergency department contributors to ambulance diversion: a quantitative analysis. Annals of emergency medicine. 2003 Apr:41(4):467-76 [PubMed PMID: 12658245]
. Ambulance Diversion. EMS Committee, American College of Emergency Physicians. Annals of emergency medicine. 1999 Jul:34(1):127 [PubMed PMID: 10409094]
Level 1 (high-level) evidenceMillin MG, Brown LH, Schwartz B. EMS provider determinations of necessity for transport and reimbursement for EMS response, medical care, and transport: combined resource document for the National Association of EMS Physicians position statements. Prehospital emergency care. 2011 Oct-Dec:15(4):562-9. doi: 10.3109/10903127.2011.598625. Epub 2011 Jul 28 [PubMed PMID: 21797787]
Olshaker JS, Rathlev NK. Emergency Department overcrowding and ambulance diversion: the impact and potential solutions of extended boarding of admitted patients in the Emergency Department. The Journal of emergency medicine. 2006 Apr:30(3):351-6 [PubMed PMID: 16677993]
Hsia RY, Asch SM, Weiss RE, Zingmond D, Liang LJ, Han W, McCreath H, Sun BC. California hospitals serving large minority populations were more likely than others to employ ambulance diversion. Health affairs (Project Hope). 2012 Aug:31(8):1767-76. doi: 10.1377/hlthaff.2011.1020. Epub [PubMed PMID: 22869655]
Level 2 (mid-level) evidenceJohnson AM, Cunningham CJ, Arnold E, Rosamond WD, Zègre-Hemsey JK. Impact of Using Drones in Emergency Medicine: What Does the Future Hold? Open access emergency medicine : OAEM. 2021:13():487-498. doi: 10.2147/OAEM.S247020. Epub 2021 Nov 16 [PubMed PMID: 34815722]