triage triage in medicine, triage (/ˈtriːɑːʒ, triˈɑːʒ/) is a process by which care providers such as medical professionals and those with first aid knowledge determine the order of priority for providing treatment to injured individuals and/or inform the rationing of limited supplies so that they go to those who can most benefit from it. triage is normally relied upon when there are more injured individuals than available care providers (known as a mass casualty incident), or when there are more injured individuals than supplies to treat them. clockwise from top-left:covid-19 triage tent outside of a swedish hospital9/11 triage station out side of the pentagon2010 pakistan floods triage station under a treekorean war triage station in modern south korea mass casualty drill at misawa air base cbrn triage drill at yokato air base the methodologies of triage vary by institution, locality, and country, but have the same universal underlying concepts. in most cases, the triage process places the most injured and most able to be helped as the first priority, with the most terminally injured the last priority (except in the case of reverse triage). triage systems vary dramatically based on a variety of factors, and can follow specific measurable metrics, like trauma scoring systems, or can be based on the medical opinion of the provider. triage is an imperfect practice, and can be largely subjective, especially when based on general opinion rather than a score. this is because triage needs to balance multiple and sometimes contradictory objectives simultaneously, most of them being fundamental to personhood: likelihood of death, efficacy of treatment, patients' remaining lifespan, ethics and religion. etymology and origin the term triage comes directly from french, where the term means to pick or to sort, it itself coming from the old french verb trier, meaning to separate, sort, shift, or select; with trier in turn came from late latin tritare, to grind. although the concept existed much earlier, at least as far back as the reign of maximillian i, it wasn't until the 1800's that the old french trier was used to describe the practice of triage. that year, baron dominique-jean larrey, the surgeon in chief of napoleon's imperial guard laid the groundwork for what would eventually become modern triage introducing the concept of "treat the wounded according to the observed gravity of their injuries and the urgency for medical care, regardless of their rank or nationality". history pre-modern history a page of the edwin smith papyrus the edwin smith papyrus the general concept was first described in a 17th-century bce egyptian document, the edwin smith papyrus. discovered in 1862, outside of modern day luxor, egypt, the edwin smith papyrus contains descriptions of the assessment and treatment of a multitude of medical conditions, and divides injuries into three categories: “a medical condition i can heal” "a medical condition i intend to fight with.” "a medical condition that cannot be healed.” the holy roman empire during the reign of emperor maximilian i, during wartime, a policy was implemented where soldiers where prioritized over all others in hospitals, and the sickest soldiers received treatment first. modern triage larrey's "flying ambulance" design. napoleonic triage modern triage grew out of the work of baron dominique-jean larrey and barron francois percy during the reign of napoleon. larrey in particular introduced the concept of a "flying ambulance" (flying in this case meaning rapidly moving) or in it's native french, ambulance volante. world war i triage continued to gain traction in france, and was utilized during world war i by french doctors treating the battlefield wounded at the aid stations behind the front. those responsible for the removal of the wounded from a battlefield or their care afterwards would divide the victims into three categories: those who are likely to live, regardless of what care they receive; those who are unlikely to live, regardless of what care they receive; those for whom immediate care may make a positive difference in outcome. as medical technology has advanced, so have modern approaches to triage, which are increasingly based on scientific models. the categorizations of the victims are frequently the result of triage scores based on specific physiological assessment findings. some models, such as the start model may be algorithm-based. as triage concepts become more sophisticated, and to improve patient safety and quality of care, several human-in-the-loop decision-support tools have been designed on top of triage systems to standardize and automate the triage process (e.g., ectas, nhs 111) in both hospitals and the field. moreover, the recent development of new machine learning methods offers the possibility to learn optimal triage policies from data and in time could replace or improve upon expert-crafted models.vital signs defining the color-coded triage. rr: respiratory rate; spo2: saturation of peripheral oxygen (pulse oximetry); hr: heart rate; gcs: glasgow coma score; tp: temperature. abnormal vital signs are strong predictors for intensive care unit admission and in-hospital mortality in adults triaged in the emergency department. concepts in triage simple triage simple triage is usually used in a scene of an accident or "mass-casualty incident" (mci), in order to sort patients into those who need critical attention and immediate transport to a secondary or tertiary care facility, those who require low-intensity care, those who are uninjured, and those who are deceased or will be so imminently. in the united states, this most commonly takes the form of the start triage model, in canada, the ctas model, and in australia the ats model. assessment often begins with asking anyone who can walk to walk to a designated area, labeling them the lowest priority, and assessing other patients from there. upon completion of the initial assessment by the care provider, which is based on the so called abcde approach, patients are generally labelled with there available information, including "patient’s name, gender, injuries, interventions, care-provider ids, casualty triage score, and an easily visible overall triage category". abcde assessment main article: abc (medicine) an abcde assessment (other variations include abc, abcd, abcdef, and many others, including those localized to non-english) is rapid patient assessment designed to check bodily function in order of importance. abcde assessment example letter term meaning a airway checking for airway obstruction b breathing checking if the patient is breathing and if the breathing is normal c circulation checking to see if the heart rate and capillary refill time is normal d disability checking the patients alertness, awareness, and response to painful stimuli e exposure checking the patient for trauma, bleeding, temperature, and other skin signs tags main article: triage tag many triage systems use triage tags with specific formats emergency triage (e/t) lights – particularly useful at night or under adverse conditions a triage tag is a premade label placed on each patient that serves to accomplish several objectives: identify the patient. bear record of assessment findings. identify the priority of the patient's need for medical treatment and transport from the emergency scene. track the patients' progress through the triage process. identify additional hazards such as contamination. triage tags take a variety of forms. some countries use a nationally standardized triage tag, while in other countries commercially available triage tags are used, which vary by jurisdictional choice. in some cases, international organazations also have standardized tags, as is the case with nato. the most commonly used commercial systems include the mettag, the smarttag, e/t light and the cruciform systems. more advanced tagging systems incorporate special markers to indicate whether or not patients have been contaminated by hazardous materials, and also tear off strips for tracking the movement of patients through the process. advanced triage in advanced triage, those with advanced training, such as doctors, nurses and paramedics make further care determinations based on more in-depth assessments, and may make use of advanced diagnostics like ct scans. this can also be a form of secondary triage, where the evaluation occurs at a secondary location like a hospital, or after the arrival of more qualified care providers. reverse triage there are a three primary concepts referred to as reverse triage. the first is concerned with the discharge of patients from hospital often to prepare for an incoming mass casualty. the second concept of reverse triage is utilized for certain conditions such as lightning injuries, where those appearing to be dead may be treated ahead of other patients, as they can typically be resuscitated successfully. the third is the concept of treating the least injured, often to return them to functional capability. this approach originated in the military, where returning combatants to the theatre of war may lead to overall victory (and survivability). undertriage and overtriage undertriage is underestimating the severity of an illness or injury. an example of this would be categorizing a priority 1 (immediate) patient as a priority 2 (delayed) or priority 3 (minimal). the rate of undertriage generally varies by the location of the triage, with a 2014 review of triage practices in emergency rooms finding that in-hospital undertriaging occurred 34% of the time in the united states, while reviews of pre-hospital triage finding undertriage rates of 14%. overtriage is the overestimating of the severity of an illness or injury. an example of this would be categorizing a priority 3 (minimal) patient as a priority 2 (delayed) or priority 1 (immediate). acceptable overtriage rates have been typically up to 50% in an effort to avoid undertriage. some studies suggest that overtriage is less likely to occur when triaging is performed by hospital medical teams, rather than paramedics or emts. telephone triage in telephone triage, care providers like nurses assess symptoms and medical history, and make a care recommendation over the phone. a review of available literature found that these services provide accurate and safe information about 90% of the time. palliative care in triage, palliative care takes on a wider applicability, as some conditions which may be survivable outside of extreme circumstances become unsurvivable due to the nature of a mass casualty incident. for these patients, as well as those who are deemed to be unsavable, palliative care can mean the difference of a painful death, and a relatively peaceful one. during the covid-19 pandemic issues of palliative care in triage became more obvious as some countries were forced to deny care to large groups of individuals due to lack of supplies and ventilators. evacuation in the field, evacuation of all casualties is the ultimate goal, so that the site of the incident can ultimately be cleared, if necessary investigated, and eventually rendered safe. additional considerations must be made to avoid overwhelming local resources, and in some extreme cases, this can mean evacuating some patients to other countries. alternative care facilities alternative care facilities are places that are set up for the care of large numbers of patients, or are places that could be so set up. examples include schools, sports stadiums, and large camps that can be prepared and used for the care, feeding, and holding of large numbers of victims of a mass casualty or other type of event. such improvised facilities are generally developed in cooperation with the local hospital, which sees them as a strategy for creating surge capacity. while hospitals remain the preferred destination for all patients, during a mass casualty event such improvised facilities may be required in order to divert low-acuity patients away from hospitals in order to prevent the hospitals becoming overwhelmed. specific triage systems and methods a triage sign at a mexican emergency department indicating the waiting time for patients based on the severity of their conditionmost simply, the general purpose of triage is to sort patients by level of acuity to inform care decisions; so that the most people possible can be saved. although a multitude of systems, color codes, codewords, and categories exist to help direct it, in all cases, triage follows the same basic process. in all systems, patients are first assessed for injuries, then, they are categorized based on the severity of those injuries. although the number of categories differs from system to system, all have at least three in common; high severity, low severity, and deceased. some systems involve features like scoring systems, such as the revised trauma score, the injury severity score, and the trauma and injury severity score, the latter of which has been shown to be most effective at determining outcome. s.t.a.r.t. model main article: simple triage