There is no single type of triage system used by all EDs in the United States. Three types of triage systems have been described in the literature. The simplest triage system is called traffic director. ^{17. and 26.} In this type of system a nonclinical person is stationed at the ED entrance to greet patients upon presentation. Based on his or her initial impression, this nonclinical person decides if the patient should go to the waiting room or go to an open ED bed. Another system used by EDs with a lower volume of visits is called spot-check triage. For these departments it is not cost-effective to staff triage with a registered nurse (RN) 24 hours a day. Instead, the RN is notified when a patient presents. The RN does a quick look or brief assessment and then assigns a triage acuity. ^{17. and 26.}

Comprehensive triage, the most advanced system, is performed by an RN and is the system recommended by the Emergency Nurses Association (ENA). ¹⁷ ENA’s Standards of Emergency Nursing Practice state: “The ED RN triages every patient and determines priority of care based on physical, developmental, and psychosocial needs as well as factors influencing flow through the emergency care system.”¹⁰ Based on this assessment, the RN will assign an acuity rating. There are many advantages to comprehensive triage, as follows:

The ENA recommends that the triage encounter take no more than 2 to 5 minutes. ³¹ Travers²⁷ found that this was met only 22% of the time and the time frame was extended with patient age. The average time spent on comprehensive triage of the pediatric patient was 7 minutes. ¹⁸

Many EDs are using comprehensive triage, but some are struggling with how to manage the rapid influx of patients at various points in the day. Patients are waiting an unacceptably long period of time from entry into the ED (time of arrival) to actual triage time. Some EDs have addressed this issue by choosing to use a greeter as the first contact with ambulatory patients. Their role is to greet the patient, document time of arrival, and keep a list of the patients waiting for triage. Other EDs ask the patient or family member to write their name and reason for the visit on a list or card. The triage nurse uses this initial information from the greeter or from a list to determine the order in which patients are triaged. However, this system is not perfect and delays in care can occur. Delay may be due to the patient giving a vague description of why he or she came to the ED or the patient putting an incorrect label on his or her problem. For example, a patient tells the greeter, “I have a migraine,” when he or she is in fact having a stroke. To prevent this potential problem, some hospitals have adopted a two-tiered triage process or system.

Based on an “across-the-room assessment,” brief interview, and focused examination, the triage nurse assigns an acuity rating. Historically a three-level acuity rating system has been used by most EDs. ¹³ The three levels are emergent, urgent, and nonurgent (Table 7-1). In an effort to better sort incoming patients, some hospitals added a fourth level to relieve the number of patients who were assigned to the middle or urgent level.

A number of published research studies demonstrate the poor interrater reliability of the three-level triage acuity rating system. 16.^{29. and 30.} Interrater reliability is the level of agreement or consistency among users of the system. As triage has evolved, there has been an increasing recognition that high interrater reliability is a necessary characteristic of an effective triage acuity rating system.

With the publication of research questioning the reliability of a three-level acuity rating system and concerns about ED crowding, the American College of Emergency Physicians (ACEP) and the ENA convened a five-level triage task force to review the evidence on five-level triage scales. The following statement was developed by the task force and approved by the boards of directors of both ENA and ACEP:

ACEP and ENA believe that quality of patient care would benefit from implementing a standardized emergency department (ED) triage scale and acuity categorization process. Based on expert consensus of currently available evidence, ACEP and ENA support the adoption of a reliable, valid five-level triage scale. ¹⁴

As a result of this effort the Five-Level Triage Task Force recommended the use of either the Canadian Triage and Acuity Scale (CTAS) or the Emergency Severity Index (ESI). ¹⁵

The CTAS, which is based on the Australasian Triage Scale, was developed by a group of Canadian emergency physicians working with the National Emergency Nurses Association (Canada). ^{2. and 3.} All Canadian EDs use this five-level acuity rating system. The system mandates that every patient presenting for care should be at least visually assessed within 10 minutes of presentation. For each triage level there is a list of presenting complaints or conditions. The ED RN assigns acuity based on chief complaint and a focused subjective and objective assessment. CTAS identifies time to physician for each triage level but recognizes that meeting this time objective 100% of the time is not realistic. Accordingly, fractile response time, or the percentage of patient visits for a given triage level in which the patient should be seen within the CTAS time frame, is identified. ³ Reassessment times are identified for each of the five triage levels. Training materials are available from the Canadian Association of Emergency Physicians, http://www.caep.ca.

Two ED physicians, Richard Wuerz and David Eitel, developed the original concept for the Emergency Severity Index (ESI). Working with a group of emergency physicians and nurses, they made further refinements to the original algorithm based on research. The ESI is a five-level triage scale that categorizes patients initially by acuity and then by expected resource consumption (Figure 7-1). The algorithm is straightforward to use and allows for the rapid sorting of patients into one of five categories. Research has demonstrated that it is a valid and reliable system. Training materials that include the implementation handbook and training DVD are available free of charge from the Agency for Healthcare Research and Quality, http://www.ahrq.gov/research/esi, or call 1-800-358-9295.17. ^{23.24. and 30.}

The triage process is the rapid collection of relevant subjective and objective data in order for the triage nurse to assign an accurate acuity rating. It should be brief and occur soon after the patient arrives in the ED. The triage process begins with an across-the-room assessment. The triage nurse uses his or her sense of sight, hearing, and smell to gather vital information (Table 7-2) and form a general impression of the patient’s health status. ^{11.12. and 13.} Occasionally the patient is so ill or injured that the nurse will recognize the patient needs to be seen immediately. At that point the triage process is over, and the patient is taken directly to the treatment area. This occurs in a small number of patients, and usually the triage process continues.

In a two-tiered triage system the first nurse is performing an across-the-room assessment, as well as determining the patient’s chief complaint. Based on this information, the first triage nurse decides whether this patient needs to be taken directly to the patient care area or is stable enough to go to step two of the triage process.