Emergency Medical Services (EMS)

Author: Matthew Chinn, MD, Medical College of Wisconsin
Editor: Jonathan Fisher, MD, MPH, Maricopa Medical Center


  • Introduce the concept of Emergency Medical Services.
  • Discuss the integration of EMS into the healthcare system.
  • Discuss the levels of care.
  • Review the factors that influence transport decisions.


Emergency Medical Services (EMS) is a broad term encompassing the many parts that are involved in the prehospital care and transportation of patients.  Often serving as the initial point of contact for patients with the healthcare system, The EMS system encompass from all phases of prehospital care including call answering at dispatch centers, prehospital care field care, and transport and delivery of patients to hospitals.  EMS also incorporates planning, prevention and public health from preparation for large scale events like concerts and marathons to public access defibrillator programs.

Historically in the United States, the importance and training of EMS personnel began formally beginning in the 1950s with the American College of Surgeons (ACS) developing the first training program for ambulance attendants.  The National Academy of Sciences and National Research Council’s (NAS/NRC) Accidental Death and Disability: The Neglected Disease of Modern Society, published in 1966, was the first paper to readily recognize the important role of prehospital care and is considered one of the landmark  papers. This served as the stimulus for  federal funding and the birth of modern EMS.

Levels of Care

The differentiation of levels of transport, practitioner skill sets, and certification has been a debate amongst the EMS community for some time. The Emergency Medical Services Systems Act of 1973 served as the catalyst to the development of the Department of Transportation’s National Standard Curricula. This was the first attempt to establish standards of training for EMS personnel. In 1996, the National Highway Traffic Safety Administration (NHTSA) and the Health Resources and Services Administration (HRSA) published the EMS Agenda for the Future which attempted to create a common vision for the future of EMS.  The National EMS Scope of Practice Model defines, by name and by function, the levels of out of hospital EMS providers based upon the National EMS Core Content. These levels were defined by a standard minimum level of knowledge and skills into Emergency Medical Responder (EMR), Emergency Medical Technician (EMT), Advanced Emergency Medical Technician (AEMT), and paramedic. This formal guideline served to provide some standardization of what previously had been levels of skill determined by curricula. In addition to these levels, an emphasis was placed on using a single, national, certification agency. Currently, the most recognized agency is the National Registry of EMTs (NREMT). This agency’s initial certification process is used in the licensing process of prehospital personnel in 47 states currently and follows the National EMS Scope of Practice Model. However, states are not required to use this protocol and some states still use home-grown tests and licensure procedures. The state licensing process grants the governmental permission of a prehospital provider to practice at their specific skill level.

From EMR to paramedic, there is a progression in both the foundation of knowledge and skills.

Skills and Knowledge Continuum

EMT Progression

Emergency Medical Responder (EMR) also known as First Responder (FR)

Trained in the most basic first aid skills including basic airway maneuvers, CPR, and AED usage.

Emergency Medical Technician (EMT)

These providers have the ability to perform some more advanced skills including more advanced airway maneuvers, including PPV, and basic medication administration, along with all the skills of an EMR.

Representative EMT Skills

  1. Airway
    1. OPA and NPA insertion
    2. BVM
  2. Medications
    1. Assist with patient prescribed medications
    2. Administration of over-the-counter medications with medical oversight
  3. Procedures
    1. Basic Splinting

Advanced Emergency Medical Technician (AEMT)

The AEMT builds on all the skills of the EMT with the major addition of IV initiation and advanced airways.

Representative AEMT Skills

All skills from previous levels of training

  1. Airway
    1. Supraglottic Airways
  2. Medications
    1. Glucagon, dextrose, opioid antagonists, fluids
  3. Procedures
    1. IV placement


Paramedics have the highest level of training, and are able to perform more even more advanced skills including electrical pacing, cardiac monitoring and interpretation, advanced medication administration, surgical airways, and other advanced procedures.

Representative Paramedic Skills

All skills from previous training levels

  1. Airway
    1. Endotracheal intubation
    2. Surgical airway management
    3. Needle thoracostomy
  2. Medications
    1. All available medications available under protocols
  3. Procedures
    1. Cardioversion, manual defibrillation, and transcutaneous pacing

Despite the attempts at a national scope of practice, there still exists local and state variability in the scope of practice between states of providers.

Basic Life Support versus Advanced Life Support (BLS vs. ALS)

The staffing configuration of an ambulance determines the designation, and thus, the level of care of the unit.  Basic Life Support (BLS) generally represents a unit staffed by at minimum one EMT and one EMR.  Advanced Life Support (ALS) usually represents a unit staffed by at least one paramedic.  There is no consensus on the most efficient model with regards to level of prehospital care with evidence suggesting improved outcomes for certain disease processes with different levels of care.  It would seem that the highest level of care being ALS would provide the best outcomes, but that data is by no means definitive and much controversy still exists regarding that.

Community Paramedicine/Mobile Integrated Healthcare

Community Paramedicine or Mobile Integrated Healthcare is new and evolving delivery system using EMS providers outside of traditional roles. Initiatives include alternative treatment destinations for patients who may not require an Emergency Department or delivery of preventative or follow up care.

Models of EMS Systems

The delivery systems and integration of EMS are highly variable.  There are many different components and facets to EMS systems.

Most EMS systems designs include the some or all of the following services:

Prevention and public educationTriageMedical first responseEMS responsePrearrival instructions
Assessment and treatmentEmergency and Inter-facility medical transportationEvent coverageDisaster servicesCritical care transport
Air medical transportHazardous materials response and medical supportTactical response medical supportCommunity paramedicine

The delivery systems vary widely based on several factors, some of which include: geography, population density, politics, and financing.  Common delivery systems are fire-based EMS, municipal EMS, and private EMS.  Fire-based EMS takes advantage of the already present required staffing of communities with 24/7 fire services.  Many departments utilize the same personnel as both fire and EMS providers with cross-training.  This can often result in significant cost savings for the local government by utilizing existing personnel.  Municipal EMS allows providers employed by the local government to focus on and provide only EMS to an entire area, often a county or city.  This system, with its EMS focus, requires a significant financial commitment from the government as a recognized “third service,” outside of police and fire.  Private EMS delivery models utilize private companies to deliver prehospital services to the community.  Often this involves contractual agreements between local governments and private companies to respond to and provide emergency medical services in the community.  These companies can often provide a financially viable option for some areas.

Additionally, EMS provides the umbrella for interfacility and specialized transport services, such as air medical, pediatric, and critical care specialties, tactical EMS, and the burgeoning community paramedicine sector.

911, Dispatch, And Public Safety Answering Points

When an emergency occurs, people call 911to get help. 911 is the universal emergency number to access police, fire or medical services in a crisis..  These call answering centers play a vital role in the EMS system and are know as primary public safety access points.  The call taker or dispatchers are often highly trained specialist who try to identify the emergency and send the proper resources whether they be police, fire, rescue, or medical.  In the event of medical emergencies, a call may be answered by a one person and then transferred to an emergency medical dispatch specialist who can better identify the needs and more importantly provide pre-arrival instructions such as CPR.   Dispatcher assisted CPR has been shown to improve survival in cardiac arrest.

Field Care 

Prehospital medicine has a distinct and growing science.   The initiation of traditional hospital based treatments in the field has improved the care of many patients.  Innovations such as prehospital BIPAP/CPAP has decreased the need for intubation.  The evidence for other interventions like intubation and cervical spinal immobilization are controversial.   There are two general schools of treatment paradigms in EMS often characterized by “stay and play’ versus “scoop and run.”   It is unclear which approach is better and it may depend on the underlying condition.

Transport Destination

The decision of where to transport a patient is a complex one.  One of the factors influencing that decision has been the regionalization of emergency care.  Specifically, regionalization refers to the formation of a coordinated system of care across a geographical area.  The most prominent example of this is the regionalization of trauma care.  Certain centers are designated based on the resources available and ability to care for trauma patients.  Level 1 Trauma centers are highest level.  It has been proposed that this both has a positive effect of patient outcomes and serves as a way to reduce costs for the healthcare system. Regionalization has been well documented to have a significant effect on morbidity and mortality in trauma care. EMS systems may decide to bypass facilities to transport a specific patient to a more appropriate hospital based on their designation.  This is based on the concept that transport to the closest, most appropriate facility will have the best outcome for the patient.  Local EMS policy often dictates transport destination based on these principles. This regionalization theory has been extrapolated to both STEMI and stroke with some evidence of improved outcomes.

Prehospital DNR/MOLST/POLST, and Termination of Resuscitation 

Another unique aspect of EMS is end of life care in the prehospital setting.  Under most circumstances EMS is required to resuscitate patients.  Situations where CPR and other measures can be withheld either fall into the category of obvious death such as rigor mortis or where there are specific documents that dictate patient wishes.   There are often legal documents such a state Do Not Resuscitate Form or Medical or Physician Order for Life Sustaining Treatment form.  These forms must be present and have clear instructions for EMS to follow.   Many systems also allow for EMS provider to terminate resuscitation after a reasonable unsuccessful attempt.


EMS is the umbrella term to describe all the working parts that make of prehospital medicine.  It is incorporated into almost all aspects of healthcare and continues to be an important part of the medical field.  The field is ever evolving and changing to reflect a more evidenced based approach to medical care and a desire of a national standard for providers.  Nonetheless, it is a crucial part of the delivery of healthcare to the population at large and the safety net for many.


  1. American Trauma Society. “Trauma Center Levels Explained.” American Trauma Society, n.d. Web. 13 Jan. 2016.
  2. Cone, David C., Jane H. Brice, Theodore R. Delbridge, and J. Brent Myers. Emergency Medical Services: Clinical Practice and Systems Oversight. 2nd ed. 2015. Print.
  3. United States Department of Transportation, National Highway Traffic Safety Administration & United States Department of Health & Human Services Public Health Services, Health Resources & Services
  4. Administration (2000) Emergency Medical Services Agenda for the Future: A Systems Approach.
  5. United States Department of Transportation, National Highway Traffic Safety Administration & United States Department of Health & Human Services Public Health Services, Health Resources & Services
  6. Administration (2007) EMS Scope of Practice Model.