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Mass Causality and Triage

April 12, 2022 - read ≈ 10 min



Sangki Oak, MD MPH.

Department of Surgery, Brigham & Women's Hospital, Boston MA. Former US Navy combat medic.


Geoffrey A Anderson, MD MPH.

Department of Surgery, Brigham & Women’s Hospital, Boston MA. Maj USAFR, CCATT



As medical providers, our job is to heal the sick and wounded, and often, to try to save lives. In this pursuit we often will pour immense time and resources to give the individual under our care the best chance they have to survive. We want everyone to live. But when there are many patients, this is not always possible. In situations where the number of patients exceeds the local resources, i.e. a mass casualty, there is a limited amount of supplies, personnel, and time that have to be rationed amongst the patients. And as the number of patients to be treated increases, that allocation becomes more and more critical. It also becomes more likely that people will die. The goal at that point is to save as many as possible. While our instinct is to treat the absolute sickest first, as they are seen as the most urgent, the priority in a mass casualty is to treat the sickest that are most likely to survive with timely intervention. The purpose of triage is thus to sort patients into categories of survival probability and acuity in order to determine priority of treatment. Therefore, those that have a low chance of survival must be bypassed for those that are more likely to survive with appropriate care. While this may be difficult, it is important to realize that we are not treating one patient but many at the same time and focusing on the one sickest may result in the death of several other patients that could have survived. It is therefore vital that patients in a mass casualty are appropriately and continually triaged so that the appropriate care is provided to those that have the best chance to benefit. Save as many as we can.


One of the most important things in triage is proper preparation. A mass casualty event is chaos. The goal is to make it controlled chaos. This requires everyone clearly understanding their job and actions in the event as well as having the proper basic equipment in hand. All personnel involved should receive training and practice specific to mass casualty events and triage, so they are ready when multiple patients arrive at the medical facility. 

Receiving area

While not required, ideally there is a large receiving area where all the patients arriving for a mass casualty can be initially sorted and processed. This may be outside in front of the medical facility or a large room near an entrance separate from existing waiting patients. In order to minimize confusion, a one-way flow through the receiving area should be maintained. What is most important is that the location is known to all personnel so that arriving patients can be directed to this area, triaged methodically, and then sent for the appropriate treatment. 


Some of these patients may arrive with an obvious life-threatening injury (i.e., massive bleeding, airway obstruction, tension pneumothorax) that requires a quick but essential intervention during the triage process to assist in their survival. It is critical to have equipment close at hand and ready such as tourniquets, gauze for wound packing, oral/nasal airways, surgical airway kits, and decompression needles. These can be centrally located at the receiving area or carried in a bag by medical personnel responding to the mass casualty event. 

In addition, a method for being able to quickly mark and identify the triage category of a patient is important. There are commercial triage tags available but other simpler methods such as using colored tape or ribbon or using a marker to place the first letter of the category on the patient, can be equally effective. Just ensure that the method is standardized and well-known (e.g. colored tape corresponding to category placed on left shoulder or first-letter of category placed with marker on forehead). 


During a mass casualty, there are several jobs that must be performed simultaneously to ensure appropriate triage and treatment. The most important role is the triage coordinator who is ideally the most experienced medical personnel available. The coordinator will conduct the initial sorting, oversee individual assessments, and make the final determination of priority of treatment. Coordinators should avoid providing individual treatment of patients until at least the initial triage is complete, if at all possible, so that more urgent patients are not missed. The temptation for this experienced medical provider to get deeply involved in patient care must be resisted or the triage system can quickly break down. Other healthcare providers may be tasked with conducting the individual assessments and providing any necessary life-saving interventions. Other staff can assist in directing and transporting patients to their appropriate locations. It is vital that these personnel clearly and continuously communicate with each other to provide updates in patient status and disposition.


As mentioned above, the primary goal of triage during a mass casualty is to save as many lives as possible. To achieve this goal, patients are sorted by their injuries to maximize the potential to save lives with limited resources. Those that are severely injured but expected to survive with appropriate interventions are prioritized first while those that are unlikely to survive despite maximum intervention may be delayed. The patients being triaged can be divided into five categories with corresponding color coding: immediate (red), delayed (yellow), minimal (green), expectant (gray), or dead (black).

Triage Categories
ImmediateNeeds immediate medical intervention to preserve life or limbUncontrolled massive bleedingMinutes
DelayedWill require urgent definitive medical intervention but is currently stableControlled major bleedingHours
Minimal“Walking wounded” with minor injuriesCuts, abrasionsDays
ExpectantMinimal or no chance for survival despite maximum medical interventionExposed brain matterNA
DeadNo breathing and no pulseNA

Steps of Triage

There are several steps involved to efficiently and safely triage wounded patients into these categories. These steps are as follows: scene safety, sort, life-saving interventions, assess, and treatment. While these are described as “steps”, depending on available personnel, certain steps may occur simultaneously. For instance, obvious life-saving interventions might be provided while walking wounded are sorted to another location. As mentioned above, good coordination, communication, and practice is required to ensure the process occurs smoothly and efficiently.

Figure 1: Triage Flowchart


The first step of triage is scene safety. While it is necessary to treat the wounded, it is equally important to ensure there are no further casualties generated during the evaluation and treatment of patients. In modern warfare, many weapons of mass destruction are used to kill and disable. Patients may arrive with unexploded ordnance, such as an RPG missile that has caused injury but have not detonated or be contaminated with chemical weapons. When treating both friendly and enemy soldiers, weapons such as grenades or blasting caps may be on their persons. It is important to identify and manage these hazards prior to bringing these patients into the vicinity of other patients and medical workers. While outside the scope of this manual, explosives and other weapons should be removed and taken to a safe location while any patients exposed to chemical/biological/radioactive weapons should be appropriately decontaminated prior to evaluation and treatment. Ideally, dedicated security personnel are available to screen incoming patients during a mass casualty for hazards and properly manage them as needed.


The next step of triage is to perform a global sort of all the patients presenting from the mass casualty. This is a quick process to first divide the wounded into three priorities:

Priority 1: Lies still or with obvious life threat

Priority 2: Waves or purposeful movement

Priority 3: Can walk

The coordinator will loudly ask the wounded that all patients who can walk should move to a designated location. These patients are Priority 3 and will be assessed last. The coordinator will then ask the remaining patients to wave. Those that wave or make some purposeful movements are classified as Priority 2 and informed that they will be seen soon. The remaining patients are those that are lying still or have obvious life-threatening injuries and are categorized as Priority 1. These are the first patients seen for any life-saving interventions and individual assessments. Once priority 1 patients have been assessed into their appropriate triage category, priority 2 patients are assessed and then priority 3.

Life Saving Interventions

The first step in assessing an individual is to identify any obvious life threats and to provide immediate initial intervention. These life threats are major uncontrolled bleeding, airway compromise, and tension pneumothorax. The interventions are initial immediate actions that can be performed in less than a minute such as tourniquets, airway adjuncts, and needle decompression. In the event of chemical weapons, such as nerve gas, auto-injector antidotes may need to be provided at this point.

Life-Saving Interventions
Major bleedingTourniquet/wound packing
Airway compromiseAirway adjunct/surgical airway
Tension pneumothoraxNeedle decompression
Chemical weaponAuto-injector antidote


Once any needed initial life-saving interventions are performed, an individual assessment is performed on the patient. If after any initial interventions the patient is not breathing, the patient is classified as Dead. If the patient has injuries that are incompatible with life, such as exposed brain matter, or injuries with low likelihood of survival despite maximum treatment given available resources, then the patient is classified as Expectant. If after any initial interventions the patient still has uncontrolled hemorrhage, remains in respiratory distress, has no peripheral pulse, or does not obey commands, the patient is classified as Immediate. If the patient requires definitive medical care (i.e. surgical management) but is currently stable then they are classified as Delayed. All remaining patients with minor injuries are classified as Minimal.


After a patient is classified into a triage category, then the appropriate treatment can be provided in the order determined by triage priority. While a patient categorized as immediate may need to be taken directly to the OR due to their injuries, if at all possible, it may be beneficial to delay initiating surgical care until the initial triage is complete. This ensures that patients with more urgent surgical priorities are not subsequently identified and delayed. This is particularly important for facilities with limited resources such as only one surgeon/OR. For more stable patients, this is also when a more thorough assessment of the patient is made with appropriate history and physical evaluation followed by treatment. 


It is important to keep in mind that triage is a continual process. Ideally, triage begins at the point of injury and continues until all patients have been thoroughly evaluated and treated. An initially Immediate patient may become Delayed after an appropriate intervention. Conversely, an initially Minimal patient could become Immediate due to a missed critical wound. Remember, that triage is a quick initial sorting process and important injuries could be overlooked on that first pass. Therefore, patients waiting to be formally evaluated and treated must be continually reassessed and triage category adjusted as needed as their condition changes. Once all Immediate, Delayed, and Minimal patients have been fully evaluated and treated, Expectant and Dead patients can also be more thoroughly evaluated for prognosis and, if determined to be appropriate, possible interventions depending on patient survivability and available resources.

Stay strong. Save lives.

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