Organization of emergency medical assistance
Emergency medical assistance is the first aid that is given to victims of accidents (casualties) or of the acute effects of diseases.
The basis of emergency medical assistance is the "chain of rescue": this system is based on the collaboration of different actors. The most advanced cares can only be performed by physicians and surgeons with the appropriate environment (medical imaging, biochemistry analysis laboratory, emergency room, operating room), but the acute event often happens outside the hospital (prehospital cares): at home, in the street, at work, in a public building...
The other actors involved are:
- the first witness of the event, who will call for help and possibly provide first aid (see also Emergency action principles);
- the medical regulation service that will receive the call and provide advice, and decide the action required;
- the general practitioner that will come and see the person, in case the situation is not too urgent and the person is in a safe environment;
- the ambulance that will take the casualty from its location to the hospital, when necessary.

# The responsibility of the national State
In the countries which signed the United Nations Charter, the organization of an emergency medical assistance is the duty of the States: the Universal Declaration of Human Rights says:
- art. 3: Everyone has the right to life, liberty and security of person.
- art. 22: Everyone, as a member of society, has the right to social security and is entitled to realization, through national effort and international co-operation and in accordance with the organization and resources of each State, of the economic, social and cultural rights indispensable for his dignity and the free development of his personality.
- art. 25:
Everyone has the right to a standard of living adequate for the health and well-being of himself and of his family, including food, clothing, housing and medical care and necessary social services, and the right to security in the event of unemployment, sickness, disability, widowhood, old age or other lack of livelihood in circumstances beyond his control.
Motherhood and childhood are entitled to special care and assistance. All children, whether born in or out of wedlock, shall enjoy the same social protection.
- Everyone has the right to a standard of living adequate for the health and well-being of himself and of his family, including food, clothing, housing and medical care and necessary social services, and the right to security in the event of unemployment, sickness, disability, widowhood, old age or other lack of livelihood in circumstances beyond his control.
- Motherhood and childhood are entitled to special care and assistance. All children, whether born in or out of wedlock, shall enjoy the same social protection.
The responsibility of the State was first introduced in the French law in 1789, with the Declaration of the Rights of Man and of the Citizen:
- art. 2:  The aim of all political association is the preservation of the natural and imprescriptible rights of man. These rights are liberty, property, security, and resistance to oppression.

# Prerequisites
The emergency medical assistance can be provided only when the non-emergency situations are already treated. This means that the country must have
- a network of physicians (general practitioners) and nurses that take care of the everyday health: preventive medicine (increasing public awareness, information, vaccination campaigns);
- a network of hospitals that take care of health problems requiring more advanced competence or technical support;
- emergency rooms that are buffers between acute situations and the other hospital services.
When these conditions are fulfilled, then the country must provide:
- an educational system able to educate the personnel (physicians, nurses, ambulance staff) in emergency medicine and the specificities of the prehospital care system (or possibly convention with other countries for this education);
- people specialised in rescue in specific situations (with appropriate education and equipment), e.g. vehicle extrication in case of road accidents, diver rescue, etc.
- an efficient communication network that allow one to call for help (i.e. telephone network) and tactical organization of the prehospital care network (i.e. radio communication);
- transportation infrastructure (roads, heliports) that allow casualty transportation and patient evacuation;
- public information to the organization of the public health.

# Levels of care and progressive response
Not all situations require the same level of care. Basically, the situations can be sorted into three categories:
- non-urgent situations, relative emergencies;
- urgent situation that requires rapid transportation to the emergency room;
- urgent situation that requires advanced medical care before transportation.
These categories are not so clearly separated, and depend not only on the medical condition of the casualty, but also on the organization of the health system and on the social impact. For example, a deceased person is not a medical emergency (there is no care to perform), but in some societies, it is a social emergency (the people would not understand nothing is being done) especially in the case of a child's death; and it is not obvious to decide whether the person is dead or can be saved through advanced care (e.g. case of cardiac arrest and of cardiopulmonary resuscitation). In general, pain is usually not a life-threatening situation, but the situation is often unbearable from the point of view of the casualty.
Two things must thus be considered:
- the perceived emergency, and
- the "real" emergency.
The distinction requires assessment; assessment by the witness who calls (importance of first aid education) and remote assessment by the dispatcher (medical regulation).
The confidence in the emergency assistance system warrants the efficiency of the system; otherwise, the probable reaction would be to drive the casualty to the closest hospital, making the flow of patients impossible to manage (emergency rooms overcrowded with non-urgent cases, patients arriving at inadequate hospitals), and possibly worsening the health of the casualty (transportation without care). This confidence can be reached only by providing the appropriate response to all situations, even the non-urgent ones.
It is thus necessary to provide a progressive response, according to the situation:
- medical advice by phone (in France, 28% of the phone calls to the medical emergency service   samu  end with just an advice)
- sending a general practitioner (22% of the responses in France)
- sending an ambulance for non-medical transportation: first responder level (France: 26%)
- sending an ambulance for advanced care transportation (paramedics, or emergency physician).
A rescue team can be sent in parallel to the ambulance. Depending on the country/region, there are variations in the above levels.
Considering the efficiency:
- the first responders have a low level of education, it is thus possible to educate a lot of professionals and to have a dense networking of the territory; the rapidity of the first response is the main factor in case of acute situations, it must usually be performed within the first five minutes after the event (removing the casualty from the hostile environment, stop the external bleeding, performing Heimlich maneuver, placing the casualty in recovery position or perform cardiopulmonary resuscitation and automated external defibrillation)
- the paramedics usually have a three-year education; they can stabilize the patient (especially secure the airway and blood circulation, and use drugs), following protocols
- the emergency physicians usually have more than eight years of education; they are thus few, but they have the possibility to adapt the care to the situation, even when it is not within the protocols
It is important to have enough paramedics and/or prehospital emergency physicians, but not too many, not only because of the cost (they are logically more paid than the first responders), but also to keep them efficient: according to USA Today, the efficiency decreases when the number of paramedics increases. This is probably due to two phenomena:
- the paramedics are involved in all situations including situations that are not medical emergencies (nobody would take the risk not to "use" a paramedic who is available, in case the situation would be more complicated than first assessed); thus, they do not practice their specific competences as often;
- it is more difficult to organize the regular training;
The paramedics thus lack both training and everyday practice.

# Prehospital care strategies
The essential decision in prehospital care is whether the patient should be immediately taken to the hospital, or advanced care resources are taken to the patient where they lie.  The "scoop and run" approach is exemplified by the MEDEVAC aeromedical evacuation helicopter, where the "stay and play" is exemplified by the French SMUR emergency mobile resuscitation unit.

## Scoop and run (Scoop and shoot, Load and Go)
The strategy developed for prehospital care in North America is called Scoop and Run.  It is based on the Golden Hour theory, i.e., that a victim's best chance for survival is in an operating room, with the goal of having the patient in surgery within an hour of the traumatic event. This appears to be true in cases of internal bleeding, especially penetrating trauma such as gunshot or stab wounds. Thus, minimal time is spent providing prehospital care ("ABCs", i.e. ensure airway, breathing and circulation; external bleeding control; spine immobilization; endotracheal intubation) and the victim is transported as fast as possible to a trauma center.
This philosophy is aptly summarized by the following quotation from  "The Rules of EMS": "Trauma is treated with diesel first." The aim in "Scoop and Run" treatment is generally to transport the patient within ten minutes of arrival, hence the birth of the phrase, "the platinum ten minutes" (in addition to the "golden hour"), now commonly used in EMT training programs. The "Scoop and Run" is a method developed to deal with trauma, rather than strictly medical situations (e.g. cardiac or respiratory emergencies).

## Stay and play
The stay and play strategy was designed in France with the SMUR (Service Mobile d'Urgence de Reanimation, emergency mobile resuscitation unit) and SAMU (Service d'Aide Medicale d'Urgence), as it was noted that an unacceptable number of patients were dying during transport. The French thus developed a strategy based on maximum care before transportation.  Prehospital medical care is provided by a medical doctor MD, a nurse and an ambulance technician, with almost all the equipment and drugs that can be found in an emergency department.  The priority here is the stabilization of the patient prior to transport, including intravenous drip to raise the blood pressure (one of the causes of death during transportation is the drop in pressure, which decreases perfusion of the brain and heart; see shock). The German EMS is very similar to the French system.
In case of a severe myocardial infarction (or heart attack), all care is performed on-site (including the possibility of thrombolysis), and the victim is transported only if the heart starts again or the patient is declared dead. Defibrillation is performed by a firefighter rescue team with an automated external defibrillator if they arrive before the medical team. Note that this example is one of the few "real" stay and play approaches performed in France; in most cases, the treatment by the physician is fast and the patient is transported to the hospital within the golden hour.
In the United States, the stay and play strategy is used for non-emergency patients. In most areas, patients with life-threatening emergencies, including severe myocardial infarctions, are treated as load and go patients with all care being done enroute to a hospital. It is done this way in the United States because many hospitals do not provide catheterization treatment for heart attack patients. Patients often use the EMS system for medical problems which are not considered emergencies. Patients complaining of simple problems, such as superficial lacerations which do not require sutures, are treated as stay and play patients. The injury will most likely be treated on scene by bandaging it. Even if transport to the hospital is found to be unnecessary by the EMS providers, it is at the patient's discretion.
In some places in the United States, non-traumatic cardiac arrest patients are treated as stay and play patients. The reason for this is that most of the interventions performed on an arrest patient are ones that paramedics are authorized to do. Bringing the patient to the hospital may do little good. Often paramedics will begin resuscitation efforts (CPR) and give two or more rounds of defibrillation and/or cardiac arrest drugs prior to transporting the patient to an emergency department.

## Load and play
The "Load and play" strategy is moving the patient from the scene and into the ambulance and performing most care while still parked at the scene. This is often done for non-critical patients especially when the transport time is short. The patient is assessed, vital signs are taken, and IVs or any other necessary interventions are performed. The patient interview may or may not be performed while parked. The reason for this is sometimes there is not enough time to do a complete assessment and perform interventions while enroute to the hospital. Another reason is to take the patient out of an environment that is either hostile or not conducive to good patient care, such as in the case of a rape, domestic dispute or bad weather.

## Play and run
Both the scoop and run and the stay and play strategies have their advantages and drawbacks.  The synthesis of these two opposite strategies has led recently to a new concept: the play and run.  The time that cannot be reduced (e.g. while extracting a victim trapped in a car) is used to perform medical care.  The treatment aim is no longer to recover a "normal" blood pressure, but a minimal blood pressure, using not only intravenous drip but also vasocompressing drugs and antishock pants (to compress the legs and push the blood into the rest of the body).   The aim is to reduce the risk of death due to transportation trauma while respecting the golden hour.  The problem with play and run lies in the difficulty of successfully starting IV therapy while in a moving vehicle and controlling the volume of IV fluids given to the patient. Too little fluid will cause inadequate circulation and heart failure, while too much fluid will cause excessive loss of oxygen-bearing blood.

# Organization in different countries

## In France
- 112 (general)
- 18 (firefighters)
- 15 (medical emergencies)
- firefighters (all absolute emergencies, all interventions in the dangerous environments and on the street)
- private ambulance companies (relative emergencies in buildings)
- general practitioners have a duty (few days a month), and can be called to visit the patient at home even by night and on week-end (they are called directly by the patient, or by the samu), in case of relative emergencies that do not require transportations this situation was contested by the physicians who made a strike in 2002
- Smur
- firefighter physicians (medecins sapeurs-pompiers, MSP, usually general practitionners who have a voluntary activity in the fire department) in some countryside areas
- Service specialized in emergency care (SAU): all emergencies, specialized services (incl. surgery, cardiology and neurology)
- Proximity units (Upatou): most common emergency (medical cares, small surgery)

## In the United States of America
- Level I trauma centers: all emergencies; also prevention, rehabilitation, and usually university teaching hospitals (traumatology research)
- Level II trauma centers: all emergencies, but without the teaching dimension
- Level III trauma centers: most common emergencies including small surgery (especially orthopedic surgery)
- Level IV trauma centers: patient assessment, emergencies that do not require advanced care

# Notes
-  Paramedics not always the saviors of cardiac-arrest patients, Robert Davis, USA Today, March 1, 2005