The Principle of Classification and Labeling

Color labeling is used in triage systems to categorize and prioritize injured people. In color labeling, according to the severity of the injury, individuals are assigned different colors, including white, green, yellow, red, and black, through which patients are placed in specific classes based on anatomical, physiological, functional, and vital signs. In this categorization, injured people who are able to walk and have very mild injuries are placed in the green group (out-patient treatment); injured people suffering from moderate injuries whose treatment can be delayed for two to 12 hours are placed in the yellow group (delayed treatment); injured individuals suffering from serious and severe injuries that require rescue measures and, if left untreated, will die within two hours, are placed in the red group (immediate treatment); and finally, injured people without spontaneous breathing and still cannot breathe after opening the airway are classified in the black group (dead).^{Reference Iserson and Moskop3,Reference Moskop and Iserson4,Reference Bazyar, Farrokhi and Khankeh11,Reference O’Meara, Porter and Greaves31}

Triage models have two main approaches including algorithmic and number-based. In the former approach, the injured person is evaluated by each criterion and placed in a particular class accordingly, and if the examined criterion is normal, the next criterion of the model will be evaluated. The main color labels of the triage model are red, yellow, green, and black. In Simple Triage and Rapid Treatment/Transport (START); Sort, Assess, Life-saving intervention, Treatment/Transport (SALT); Modified START (MSTART); SMART; CareFlight; Amberg –Schwandorf Algorithm for Primary Triage (ASAV); Modified Physiological Triage Tool (MPTT); Sieve; Move, Assess, Sort, Send (MASS); Tactical; JumpSTART; and Pediatric Triage Tape triage systems, color labeling is done using green, yellow, red, and black colors. In the Mass-Gathering Triage system, individuals are categorized into four groups: resuscitation, urgent, minor, and self-help.^{Reference Jenkins, McCarthy and Sauer2,Reference Vassallo, Beavis, Smith and Wallis8,Reference Cone, Serra and Kurland20,Reference Cannon, Roitman, Ranse and Morphet28,Reference Lerner, Schwartz, Coule, Weinstein, Cone and Hunt35,Reference Coule and Horner42–Reference Wolf, Bigalke, Graf, Birkholz and Dittmar44} In the Homeboush triage system, in addition to the four colors, injured people who have a pulse but lack breathing (in the dying state) will be labeled through a white color code. These patients will be given medical services if medical facilities are available. Patients labeled with this color have more severe injures compared with those categorized as the red group, and on the other hand, since they still have signs of life, they are not to be placed in the black group. In this model, other codes such as ALPHA (equivalent to red), BRAVO (equivalent to yellow), CHARLIE (equivalent to green), DELTA (equivalent to white), and ECHO (equivalent to black) are used.^{Reference Nordberg, Lethvall and Castrén30} In the Burn Triage systems, the Consciousness, External profuse bleeding, Shock, Insufficiency of respiration, Rupture of bones, Another pathology (CESIRA) Protocol; the Spanish Prehospital Advanced Triage Method (META) Triage; and the Medical Triage Protocol, the classification of the injured individuals is done using three colors: green, yellow, and red. In other words, especially in the CESIRA model, since the definitive diagnosis of death is only determined by the physician and is out of the responsibility of the technician, the black color does not exist in these models, and all the injured people with the black color conditions will be placed in the red group.^{Reference González, Delgado and Alvarez34,Reference Lerner, Schwartz, Coule, Weinstein, Cone and Hunt35,Reference Dyer, Regev, Burnett, Festa and Cloyd37} In five-level triage systems, including Canadian, Manchester, Australian, and Emergency Severity Index (ESI) triage systems, injured people are ranked from Level 1 to Level 5 rather than color-labeled. In ESI, patients are leveled according to severity of injuries and diagnostic resources. Initially, the triage expert analyzes only the patient’s severity level and, if the patient does not have a high ESI level (ie, Level 1 or Level 2), then the nurse will evaluate the potential diagnostic and therapeutic resources needed for the patient, and ultimately the patient will be ranked at Level 3, Level 4, or Level 5. Level 1 is associated with the patients with unstable vital signs, Level 2 is related to the patients with persistent vital signs, Level 3 and Level 4 are associated with the patients requiring para-clinic and radiologic measures, and Level 5 is specified for the injured people needing out-patient treatments.^{Reference Durani, Brecher, Walmsley, Attia and Loiselle45–Reference Bottrill, Joseph and Carwardine47} Although the ESI is the most commonly used method for routine triage, this method is based both on acuity and resource needs, and could theoretically be used in MCI situations to prioritize patients for placement in the hospital.⁴⁸

In the number-based approach used in triage systems, numbers are used for the classification of the injured people. Accordingly, after the assessment of each criterion, a certain number is specified and after evaluating all the criteria, ultimately, a total number is given to the injured person. Based on this final score, the injured person will be placed in a particular class according to specific colors. Among the triage systems in which the classification of injured people is based on scoring and numbers, included are: Sacco Triage Method (STM); Triage Early Warning Score (TEWS); Sort; and Circulation, Respirations, Abdomen, Motor, Speech (CRAMS) triage systems. In the Sort and CRAMS models, the injured people are categorized in green, yellow, and red groups based on the obtained scores. In the STM model, injured people are categorized in four groups of green, yellow, red, and black. The first group includes injured people with a score of zero to four, is equal to the last black group in the START triage (dead or waiting group), and their survival probability is less than 35%. The second group consists of the injured individuals with a score of five to eight who are likely to survive with interventions. The third group has a score of nine to 12, with the survival probability of more than 90%. In the TEWS model, the injured people are classified in five classes including red (seven or more than 17), orange (five to six), yellow (three to four), green (score zero to two), and blue. The blue color in this model is equal to black color (or dead).^{Reference Bazyar, Pourvakhshoori, Khankeh, Farrokhi, Delshad and Rajabi15,Reference Sacco, Navin, Fiedler, Waddell, Long and Buckman38,Reference Tian, Fang, Xiao, Li and Li39,Reference Abbasi Dolat Abadi, Hosseini, Atighechian, Pour-Sheikhian and Delkhosh49,Reference Kelen, Kraus and McCarthy50}

The Principle of Runtime

Since time is critical to the survival of the injured patients who need immediate action, the duration of the triage is of particular importance in the classification of the injured individuals. Furthermore, the shorter the time period, the shorter the number of injured patients, and the faster the delivery of medical services will be. However, along with the short duration of triage, triage accuracy is also important. In other words, if the accuracy of the triage is decreased by reducing the duration of the triage, the classification of the injured people will be problematic, and subsequently, the provision of services is not done according to the need of the injured people. The duration of triage in divergent systems is different, but usually this is a short time and less than 60 seconds. In the previous studies conducted so far, the average duration of triage has been reported to be approximately 30 to 60 seconds in START, 60 seconds in MSTART, 34.5 seconds in ASAV, 15 seconds in Care Flight, and 15 to 25 seconds in JumpSTART triage systems.^{Reference Frykberg5,Reference Kahn, Schultz and Miller19,Reference Cannon, Roitman, Ranse and Morphet28,Reference O’Meara, Porter and Greaves31,Reference Wolf, Bigalke, Graf, Birkholz and Dittmar44}

Principle of Accuracy

Another important factor in conducting triage is the correctness or accuracy of the triage systems. The correctness or accuracy of the triage system indicates the correct classification of the injured people, according to the severity of the injury, to receive medical services. So that if an injured person is placed in the wrong category, it can lead to waste of resources or disrupt the access to the services required to maintain his or her life. In order to estimate the correctness and accuracy of the triage systems, several factors including sensitivity, specificity, positive/negative predictive value, and over-triage/under-triage are used. The sensitivity and specificity indicators show the correct classification of the injured person and the predictive value indicates the power of the triage method in the correct classification of these individuals. Over-triage and under-triage mistakenly place the injured people in the higher and lower groups, respectively, compared to their real level of severity. Accordingly, if the sensitivity and specificity levels of the triage system are not optimal, injured people will fall into wrong groups causing an increase in the over-triage or under-triage of the patients. If over-triage has occurred for a patient, he or she will be provided with a service that is not needed (or at least currently is not required), which causes a waste of time and resources. On the contrary, if under-triage has occurred for an injured person, he or she will be provided with a service which is lower than the person’s real needs and can endanger the life of the individual. As a result, in triage systems, attempts are made to reduce the amount of over-triage and under-triage by meeting the triage criteria and principles in the classification of the injured people. Although according to the previous studies, the over-triage and under-triage rates of up to 50% and five percent, respectively, are plausible, it is more ideal when the accuracy rate of the triage systems is closer to 100% and the amount of over-triage and especially under-triage is closer to zero.^{Reference Vassallo, Beavis, Smith and Wallis8,Reference Bhalla, Frey, Rider, Nord and Hegerhorst18–Reference Cone, Serra and Kurland20,Reference Kariman, Joorabian, Shahrami, Alimohammadi, Noori and Safari24,Reference Wolf, Bigalke, Graf, Birkholz and Dittmar44,Reference Challen and Walter51}

Principle Values in Triage

Such values as “human life” are important in triage. Indeed, the priority in performing triage is to help those people whose lives are at a high risk. Accordingly, these injured people who are placed in the red group (first priority) and require rescue actions will receive the available resources and facilities earlier than other groups. Another value is “human health,” which states that although the triage gives the highest priority to patients at higher risk of death, it also cares for the health of the injured people with less immediate needs and does not neglect them. As another value, “efficient use of resources,” which was explained above, is based on the management and categorization of needs in response to resource and service constraints. It is worth mentioning that “fairness” is another value, which seeks to ensure that no action is taken contrary to the accepted standards and principles of justice in triage.^{Reference Culley and Svendsen26}

Principles Not Considered in Triage

The principles which are neither considered nor observed in triage include “autonomy,”^{Reference Wuerz, Milne, Eitel, Travers and Gilboy27,Reference Cannon, Roitman, Ranse and Morphet28} or self-determination, based on which the right to decide on the state of health and services is given to the patient, which does not matter in the triage and will not be considered. What is important in triage is saving that person, even if the patient’s satisfaction has not been obtained; another value is “fidelity,”^{Reference Wuerz, Milne, Eitel, Travers and Gilboy27} based on which the patient’s benefit is considered in every situation and the benefit of the people who need more help at the time of triage is preferred over the benefit of other patients; the last value which is not considered in triage is the “property ownership of resources,”^{Reference Culley and Svendsen26} which decides to provide transportation and service systems to the injured people. As they may interfere with the service provision process, the aforementioned values are often ignored in the triage process and are unimportant in MCIs.

Principles of Triage in Certain Situations

Triage systems are designed primarily for traumatic incidents and usually do not fit into CBRN incidents. Chemicals or hazardous substances can pose particular challenges to hospital personnel, including exposure to toxins or creating physiological effects on the personnel who take care of the casualties. Therefore, all hospitals need to design a system for triage in specific conditions and decontamination after the arrival of contaminated injured individuals.^{Reference Cone and Koenig40} Triage is performed in special conditions in three areas in the field:^{Reference Sidell, William and Dashiel52}

1. Hot Zone: In this area, rescue measures are taken to stabilize the conditions for the injured person, including opening the airway, controlling bleeding, and injections of antidotes. In this area, triage staff should wear appropriate personal protective equipment.

2. Warm Zone: The distance of this place is at least 300 feet from the hot zone. The fast triage is performed to categorize and prioritize the injured on a vital, immediate, and delayed basis. Here the decontamination of the injured individuals is done. Moreover, the wearing of appropriate personal protective equipment is necessary in this place. And,

3. Cold Zone: In this area, injured patients are again assessed for secondary injuries and receive the necessary health care services based on the severity of injuries.

Triage in Special Circumstances in the Hospital

As soon as the injured individuals arrive to a hospital in the dirty area, life-stabilizing measures, injections of the antidotes, and separation of the injured people in terms of walking ability/inability, as well as the need for the diagnosis of the contaminated injured people, will be done in this area. Contaminated clothes and accessories of the injured individuals will be taken out, and the triage personnel are required to wear appropriate personal protective equipment. In the warm region, decontamination is usually carried out with soap and water, and in the clean area, injured people are dried, covered with clean clothes, and again prioritized according to the triage protocol after the decontamination. Then they will be accepted and receive the necessary health care in the hospital, based on the priority type and color labels that they receive.