Mass casualty incident

A mass casualty incident (often shortened to MCI) describes an event where emergency medical services are overwhelmed by the number and seriousness of injuries or illnesses. This can happen when many people are hurt at once, such as in a big accident or natural disaster. For example, if only a few medical workers are trying to help many severely injured people after a motor vehicle collision, it could be considered a mass casualty incident.

Anniston, Alabama, US, January 21, 2011: Healthcare workers triage simulated victims during an MCI drill at the Center for Domestic Preparedness.

People often think of large, dramatic events like building collapses, train and bus collisions, plane crashes, or earthquakes as mass casualty incidents. Well-known examples include the Oklahoma City bombing in 1995, the September 11 attacks in 2001, and the Boston Marathon bombing in 2013.

The most common causes of mass casualty incidents are terrorism, accidents involving many people moving together, fires, or natural disasters. In a multiple casualty incident, there are many injured people, but there are enough medical resources to help them all. A mass casualty incident happens when there simply aren’t enough resources to care for everyone who needs help, making it a very challenging situation for emergency responders.

Declaration

When a big emergency happens, the first person to arrive on the scene usually tells everyone that it is a mass casualty incident. Sometimes, the person answering emergency calls will also declare it, depending on what they hear from the emergency units. A senior officer or chief will formally declare the incident and take charge.

At first, the most experienced paramedic on the scene leads the response. As more help arrives, a senior officer or chief will take control, using an incident command system to organize everything. In the United States, this system is called the National Incident Management System (NIMS). The Federal Emergency Management Agency says that "NIMS provides the template for the management of incidents."

After the right teams arrive, they will carefully look at the scene using the M.E.T.H.A.N.E method to gather important details:

M Mass incident declared
E Exact location
T Type of incident
H Hazards present
A Access and egress
N Number of casualties and severity
E Emergency services required

Agencies and responders

There are many different groups that help during big emergencies where many people need care. These groups need special training to work together and support each other.

Emergency medical services (EMS)

Different people and teams help take care of those who are hurt. Some arrive in ambulances, while others might come from nearby areas. They help with checking who needs help the most, giving treatment, and taking people to hospitals.

Ambulance buses often respond to mass casualty incidents to help transport the large amount of patients

Fire and rescue

Firefighters and rescue workers help save people and put out fires. They might also give medical help if they are trained to do so. Near airports, special teams help if there is an accident far from the airport.

Public Safety

Police officers keep the area safe and make sure everyone follows the rules. Utility workers turn off power or water if needed to keep people safe. Emergency teams help get extra supplies and equipment. Trained volunteers and radio operators help with communication when normal systems stop working.

At night, firefighters will often utilize a Light and air unit to provide light to allow emergency responders to see properly

Specialized teams

Some teams are experts in certain types of rescues, like finding people in buildings or helping in places that are hard to reach. Other teams clean up dangerous materials to keep everyone safe.

Public services

Train and bus services might stop to keep people safe and help move those who are hurt. The media helps tell the public what is happening and keeps them away from the area. Organizations like the Red Cross help with medical care, food, and shelter.

HazMat specialists in Level II/B protection suits training to carry a patient out of an incident zone to be decontaminated.

Hospitals

Hospitals get ready to help many people at once. They call in more staff and get extra equipment ready. Some doctors might even go to the scene to help decide who needs to go to the hospital right away.

Trauma centers

Some hospitals are special trauma centers. They have different levels, from level 1, which can care for anyone all the way to recovery, to level 4, which helps quickly decide if someone needs to go to a bigger hospital.

Flow

When a big emergency happens and there are many people who need help, there is a special way to make sure everyone gets the care they need. This has three main steps: sorting people, giving treatment, and taking them to hospitals.

In an MCI drill aboard Naval Air Station Oceana, firefighter/EMT Greg Tetro breaks the rear glass of an automobile to rescue a trapped victim.

First, people arriving at the scene will sort everyone into groups based on how serious their injuries are. They use a simple method to decide who needs help right away and who can wait. They put people into four groups: those who need help immediately, those who can wait, those who can walk to a safer place, and, sadly, those who cannot be helped.

After sorting, people are taken to special areas to get treatment. Helpers move people to these areas, where they get care until they can be taken to a hospital. Finally, people are taken to hospitals in order of how urgent their needs are, with the most serious cases going first. Sometimes, if there aren’t enough ambulances, other vehicles like police cars or buses can be used to help transport people.

Definitive care

When many people get hurt at once, the care given right away is usually just to keep them safe until they can go to a hospital. This is called definitive care.

Sometimes, a special temporary place is set up to help people before they reach a hospital. This place is called an interim-care center. It can be in schools, community centers, or hotels. These centers have doctors, nurses, and helpers who make sure everyone gets the care they need and helps families stay together after a big problem happens.

A mass casualty event happens when hospitals get too many hurt people at once. During these times, hospitals might let some people who are okay go home and use more space and staff to help those who need it most. Some people who are hurt less might walk to the hospital on their own, which can make things even busier. Mass casualty events can happen during things like sickness spreading fast, chemical problems, big accidents, or natural disasters such as bad weather.

Demobilization

The end result of handling a mass casualty incident, when using the M.E.T.H.A.N.E. method, is called demobilization. This step is very important for the whole process. Planning for demobilization should start right from the beginning, when help is first called in. This helps prevent things from getting out of control. Having a clear plan also helps everyone know how long emergency services will need to stay in the area, and which places might be blocked off.

Sometimes, like during big events such as Hurricane Katrina, plans for demobilization are not made early enough. This can make the process take longer than needed. It also adds extra costs and makes it harder for local services to do their normal jobs while also managing the emergency.