EMS, Mass Casualty Response

Article Author:
Evan Avraham Alpert
Article Editor:
Melissa Kohn
1/7/2019 11:56:24 AM
PubMed Link:
EMS, Mass Casualty Response


Unfortunately, over the past 20 years, mass casualty incidents (MCIs) have occurred worldwide. These include mass casualty terrorist attacks such as on September 11, 2001, natural disasters such as the earthquake that devastated Haiti in 2010, and nuclear disasters such as in Fukushima in 2011. In such MCIs, emergency medical services (EMS) provide a vital role in triaging, stabilizing, and transporting victims to definitive care. Communication with other organizations involved in disaster response is essential and may involve the military, fire department, police department, search, and rescue units, as well as the country's or jurisdiction's health ministry.

Issues of Concern


The safety of the EMS responder to the scene of a mass casualty incident (MCI) is the top priority. Emergency Medical Services (EMS) receive training in S-C-ABC, safety first, catastrophic hemorrhage treatment, and then the ABCs (airway, breathing, and circulation). Responders to a chemical, biological, radiological, or nuclear (CBRN) attack need to have necessary personal protective equipment (PPE).  If the response is to a terrorist bomb attack, one needs to consider the possibility of a secondary detonation of an explosive device or an additional suicide bomber. It is often necessary to wait until bomb disposal experts verify that the scene is safe. In a mass shooting incident, if the perpetrator is not neutralized, one must not approach the scene unless having received training in tactical medicine with appropriate protective gear. One must also be wary of building collapse as well as inhalation injuries after a fire.[1]

Clinical Significance

EMS Field Triage

EMS mass casualty response starts with field triage such as one of the following[2][3]:

  • START (Simple Triage and Rapid Treatment- ability to obey commands, respiratory rate, and radial pulse or capillary refill)
  • SALT (Sort, Assess, Life-Saving Interventions, Treatment, and/or Transport)
  • Triage Sieve and Sort (using respiratory rate and either capillary refill or heart rate)
  • CareFlight Triage (ability to obey commands, the presence of respirations, and being able to palpate a radial pulse) will need to be implemented

These field triage systems may be incorporated with geographic triage- bringing patients of the same triage level to one area.

Triage systems traditionally use colored tags to identify more easily patients for future routing. Red indicates someone who has an immediate, life-threatening injury; yellow means a serious injury that can tolerate delay, and green is for the walking wounded. Any deceased or expectant patients are assigned a black triage tag. It is noteworthy that often in mass casualty incidents triage tags did not get used. This was frequently due to the inability to find the tags and to the practice of scoop and run in which the tags were not necessary. Often, the walking wounded may find ways to get to the hospital on their own and may arrive first, with severe casualties soon following. Hours later victims experiencing stress and anxiety may begin to arrive on their own.

If any MCI, whether it is a CBRN or terrorist attack, the area of care is divided into the hot zone, warm zone, and cold zone. The hot zone is the location where the incident occurred, and in a CBRN event, where there is direct contamination.  The warm zone is where there can be contamination secondary to people leaving the hot zone but also being where triage and decontamination can take place. The cold zone is where casualty care can occur, and depending on the scenario it may be the location of the casualty clearing station. The EMS provider should have a high clinical suspicion that a conventional bomb blast may also involve a CBRN event. One should be aware of similar toxidrome symptoms on multiple victims or unusual odors. However, there is often a “silent gap” whereby it is not clear to EMS that there has been a CBRN attack or if there is suspicion then it is often not clear as to the specific agent.[4]

Usually, biological, radiological or nuclear exposures are not immediately life-threatening, so the goal is to remove the victim from the hot zone as soon as possible. On the other hand, chemical exposures such as to nerve agents may be immediately life-threatening. Work in the hot zone for the EMS provider may be challenging due to the need to wear personal protective equipment (PPE). The PPE for a chemical MCI ranges from Level A which consists of a chemically resistant suit and full-face self-contained breathing apparatus to Level D which consists of overalls and no respiratory protection. Responders to a biologic event may need a protective gown, gloves, and an N95 respirator. For a radiological disaster, personal protection includes masks, eye protection, gowns, gloves, and boots. As should be apparent, the heavier the protective clothing, the more challenging it will be to the EMS provider to operate.[5]

While the goal is also to evacuate these victims as quickly as possible, some life-saving interventions may need to be given even in the hot zone especially if this involves a bomb blast. This should follow the C-ABC protocol. This may include massive hemorrhage control with tourniquets, airway management with bag-valve-mask ventilation, needle application for pneumothorax, and administration of the initial dose of an antidote. Some systems have developed the mnemonic MARCH (Massive hemorrhage control, Airway, and Antidote, Respiratory protection and oxygen, Circulation management, Head- CNS evaluation). As one moves into the warm zone where triage and decontamination occur, more advanced care is possible. It is worth noting that some systems advocate the decontamination of all toxicological mass casualty victims at the hospital. The EMS provider while in protective gear can undress the victim in the ambulance and then proper decontamination can be done at the hospital.[6]

Transport of victims

There are different theories as to how to best transfer patients from the disaster site to local hospitals. In the traditional method rescue, triage, and basic emergency care take place at the disaster site. Subsequent to this, all of the ambulances take patients directly to area hospitals.

In the sequential/conveyance method, rescue and emergency care take place at the disaster site. Patients are then taken by ambulance to a Mobile Emergency Medical Center (MEMC). At the MEMC, patients with minor injuries can receive rapid treatment and discharge. More severely injured patients can under stabilization procedures before being taken to the hospital. Some contend that this is a theoretically more regulated system for ambulance transportation. It is similar to care in rural areas where severely injured patients are stabilized in a level 3 emergency department before transfer to a level 1 trauma center. Another advantage over the traditional method is that the suggestion of hospital destination comes from physicians and this may lead to decreases in hospital overcrowding.

The location of the MEMC can is obtainable from the internet or cellphone-based mapping apps which uses artificial intelligence to help determine the fastest routes. The limitation to this is that in a real catastrophe, many roads may be unpassable, and the internet or cellular network out of commission. The MEMC is ideally designated in advance. However, in real life, the location itself may be affected by the disaster.[7]

It is worth noting that in a fast-onset disaster such as a terrorist attack in a large city, helicopter evacuation is limited as in large urban areas there is a limited room for landing zones as well as a limited number of victims for whom initial evacuation is possible.[8]

The evacuation of patients itself must occur with the utmost of care. As a result of the earthquake that hit Fukushima, there was morbidity from the transportation itself. Bedridden patients were laid on seats with some falling and suffering from injuries, patients with severe illnesses such as end-stage renal disease or stroke died during transportation, other patients died of hypothermia or dehydration during the transport.[9]

Additional Aid

In actual disasters, mutual aid between different jurisdictions, states or countries will be necessary. Additionally, international agencies, such as the International Committee of the Red Cross are attempting to take the lead in coordinating aid in a CBRN type event.[10]

Risk to health care workers

Depending on the type of disaster, the EMS provider may become injured or ill. The Chernobyl nuclear accident involved 600,000 liquidators who were involved in the cleanup. The average absorbed dose of radiation was between 5 and 9 cGy. There was an increase in leukemia, thyroid cancer.

There were an estimated 90,000 workers and responders to the 9/11 attack on the Twin Towers. Rescue workers suffered both physical and mental health effects. Periodic health assessments should include pulmonary function tests, chest x-rays, routine blood tests, and a urinalysis. Mental health screening may also be necessary to identify post-traumatic stress disorder, suicidality, or drug abuse.

Rescue workers who responded to the Fukushima nuclear accident in March 2011 underwent medical surveillance that included (based on radiation exposure) cancer screening, eye examinations for cataracts, and thyroid tests.

Some advocate issuing electronic GPS based ID cards for all responders so that their location during the disaster is recordable. This may help regarding assessing the amount of radiation or chemical exposure.[11]


EMS response to an MCI is usually very challenging. There will be large numbers of victims who will need triage, stabilization, and evacuation. In the event of a CBRN attack, heavy protective gear may be necessary. One must always prioritize the safety of oneself. In certain circumstances, there may be future health effects on the EMS worker.


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