Traditionally, triage systems have been based solely upon the acuity of the patient. Such systems require the nurse to assign an acuity level by making a judgment about how long the patient can wait to be seen by a provider. The Emergency Severity Index (ESI) triage system uses a novel approach to triage level assignment by including not only judgments about who should be seen first, but also for the less acute patients, adding predictions of the resources that are likely to be used to make a disposition for the patient.
This chapter includes background information on why resource predictions were included in the ESI and a description of what constitutes a resource. Also included are examples of patients rated ESI level 3 to 5 and the resources that each patient is predicted to need.
Historically, comprehensive triage has been the dominant model for triage acuity assignment in U.S. emergency departments (Emergency Nurses Association [ENA], 1997, p. 3-10; Gilboy, Travers & Wuerz, 1999). Triage systems have been based on the nurse's assessment of vital signs, subjective and objective information, past medical history, allergies, and medications to determine triage acuity.
Resource prediction is an integral part of the ESI for patients identified as ESI level 3, 4, or 5. It is important to understand that resource allocation does not have a role for patients of high acuity, e.g. ESI level 1 or 2. Resource prediction distinguishes the ESI from other triage systems that are based only on acuity.
When Drs. Wuerz and Eitel created the ESI triage system, they added resource utilization to provide additional data and allow a better, more accurate triage decision. They believed that an experienced emergency department (ED) triage nurse was able to predict the nature and number of tests, therapeutic interventions, and consultations that a patient would need during his/her ED stay. This has been verified in recent studies of ESI implementation and validation, which have shown that triage nurses are able to predict ED patients' resource needs (Eitel, Travers, Rosenau, Gilboy & Wuerz, 2003; Tanabe, Gimbel, Yarnold & Adams, 2004). One study was conducted at seven EDs representing varied regions of the country, urban and rural areas, and academic and community hospitals. Nurses using the ESI were able to predict how many resources the ED patients required 70 percent of the time. That is, ESI classification by experienced triage nurses reasonably predicts at triage how many resources patients will require to reach ED disposition, but, more importantly, discriminates at presentation low versus high resource intensity patients. This differentiation by resource requirements allows for much more effective streaming of patients at ED presentation into alternative operational pathways within the ED, that is, the parallel processing of patients. Research has also established that ESI triage levels correlate with important patient outcomes, including admission and mortality rates (Eitel, et al., 2003).
Again, it is important to note that resource prediction is only used for less acute patients. At decision points A and B on the ESI algorithm (Figure 5-1), the nurse decides which patients meet criteria for ESI levels 1 and 2 based only on patient acuity. However, at decision point C, the nurse assigns ESI levels 3 to 5 by assessing both acuity and predicted resource needs. Thus, the triage nurse only considers resources when the answers to decision points A and B are "no."
To identify ED patients' resource needs, the triage nurse must be generally familiar with emergency department standards of care, and, specifically, what constitutes prudent and customary emergency care. An easy way to think about this concept is to ask the question, "Given this patient's chief complaint, what resources are the emergency providers likely to utilize?"
The triage nurse uses information from the brief subjective and objective triage assessment, as well as past medical history, medications, age, and gender, to determine how many different resources will be needed for the ED provider to reach a disposition. For example, a healthy teenage patient with a simple leg laceration and no prior medical history would need only one resource: Suturing. On the other hand, an older adult with multiple chronic medical problems and no history of dizziness who presents with a head laceration from a fall will clearly need multiple resources: suturing, plus blood/urine tests, ECG, and x-rays or consultations with specialists. Accurate use of ESI triage is contingent on the nurses' ability to predict resources and as such is best performed by an experienced emergency nurse. In general, we believe that no matter what triage system is used, an experienced emergency nurse is needed to safely perform triage.
Guidelines for the categorization of resources in the ESI triage system are shown in Table 5-1. ESI levels 3, 4, and 5 are differentiated by the nurse's determination of how many resources are needed to make a patient disposition. On the basis of the triage nurse's predictions, patients who are expected to consume no resources are classified as level 5, those who are likely to require one resource are level 4, and those who are expected to need two or more resources are designated as ESI level 3. Patients who need two or more resources have been shown to have higher rates of hospital admission and mortality and longer lengths of stay in the ED (Eitel, et al., 2003; Tanabe, et al., 2004 Reliability and validity).
Though the list of resources in Table 5-1 is not exhaustive, it provides general guidance on the types of diagnostic tests, procedures, and therapeutic treatments that constitute a resource in the ESI system. Emergency nurses who use the ESI are cautioned not to become overly concerned about the definitions of individual resources.
It is important to remember that ESI requires the triage nurse to merely estimate resources that the patient will need while in the ED. The most common resources are listed in Table 5-1; however a comprehensive list of every possible ED resource is neither practical nor necessary. In fact, all that is really necessary for accurate ESI rating is to predict whether the patient will need no resources, one, or two or more resources. Once a triage nurse has identified two probable resources, there is no need to continue to estimate resources. The essence of the ESI resource component is to separate more complex (resource-intensive) patients from those with simpler problems. The interventions considered as resources for the purposes of ESI triage are those that indicate a level of assessment or procedure beyond an exam or brief interventions by ED staff and/or involve personnel outside of the ED. Resources that require significant ED staff time (such as intravenous medication administration or chest tube insertion) and those that require staff or resources outside the ED (such as x-rays by the radiology staff or surgical consults) increase the patient's ED length of stay and indicate that the patient's complexity, and, therefore, triage level is higher.
There are some common questions about what is considered an ESI resource. First, there is often a question about the number of blood or urine tests and x-rays that constitute a resource. In the ESI triage method, the triage nurse should count the number of different types of resources needed to determine the patient's disposition, not the number of individual tests:
Another resource frequently questioned is the application of a splint, which does not count as a resource. If a splint did count, patients with sprained ankles would be triaged as ESI level 3 (x-ray and splint application). While the application of a splint can certainly be resource intensive, it is important to remember the only purpose of resource prediction is to sort patients into distinct groups and help get the right patient to the right area of the ED. In many EDs, ESI level-3 patients are not appropriate for a fast track or urgent care area. Triage scores are not a measure of total nursing workload intensity.
Another common question about ESI resources relates to the fact that eye irrigation is also considered a resource. Patients with a chemical splash usually meet ESI level-2 criteria because of the high-risk nature of the splash, so eye irrigation is not a key factor in their ESI rating. However, if the eye problem was due to dust particles in the eye, the patient would not necessarily be high risk. In this type of patient, the eye irrigation would count as a resource and the patient would meet ESI level-4 criteria. The eye exam does not count as a resource because it is considered part of the physical exam.
Other common questions about resources are addressed in the Chapter 5 Frequently Asked Questions section of Appendix A.
Another frequent question posed by clinicians is related to the items listed as "not resources" in Table 5-1. The purpose of the list is to assist triage nurses with quick, accurate sorting of patients into five clinically distinct levels (Wuerz, Milne, Eitel, Travers & Gilboy, 2000). As such, items listed as not being resources include physical exams, point-of-care tests, and interventions that tend not to lead to increased length of stay in the ED or indicate a higher level of complexity. Since the standard of care is that all ED patients undergo a basic history and physical exam, an exam and even a pelvic exam does not constitute a resource for ESI classification. The beauty of the ESI is its simplicity; the true goal of the resource determination is to differentiate the more complicated patients needing two or more resources (level 3 or above) from those with simpler problems who are likely to need fewer than two resources (level 4 or 5). Emergency nurses should not try to complicate ESI by concentrating overly on resource definitions. Usually, a patient requires either no resources, one, or two or more resources.
Though resource consumption may vary by site, provider, and even individual patient, triage nurses are urged to make the ESI resource prediction by thinking about the common approaches to the most common presenting problems. Ideally, a patient presenting to any emergency department should consume the same general resources. For example, a provider seeing an 82-year-old nursing home resident who has an in-dwelling urinary catheter and a chief complaint of fever and cough will most likely order blood and urine tests and a chest x-ray. The triage nurse can accurately predict that the patient needs two or more resources and therefore classify the patient as ESI level 3.
There may be minor variations in operations at different EDs, but this will rarely affect the triage rating. For example, some departments do pregnancy tests in the ED (not a resource by ESI) and others send them to the lab (a resource by ESI). However, patients rarely have the pregnancy test as their only resource, so most of those patients tend to have two or more resources in addition to the pregnancy test. One ED practice variation that may result in different ESI levels for different sites is the evaluation of patients with an isolated complaint of sore throat. At some hospitals it is common practice to obtain throat cultures (one resource, ESI level 4), while at others it is not (no resources, ESI level 5).
Another example of different site practice variation is the use of the Ottowa Ankle Rules. These are validated rules used to determine the need for an x-ray of the ankle for patients that present with ankle injuries. Institutional adoption of these rules into practice varies. Institutions that use these rules at triage may obtain fewer x-rays when compared with institutions that do not routinely use these rules.
Temperature is an important assessment parameter for determining the number of resources for very young children. This subject will be covered in Chapter 6.
From a clinical standpoint, ESI level 4 and 5 patients can wait several hours to be seen by a provider. However, from a customer service standpoint, these patients are perhaps better served in a fast-track or urgent care setting. Mid-level practitioners with the appropriate skills mix and supervision could care for level-4 and 5 patients. The ESI provides yet another operational advantage, in that level-5 patients can sometimes be "worked in" for a quick exam and disposition by the provider, even if the department is at capacity. Often triage policies clearly state ESI level-4 or 5 patients can be triaged to an urgent care or fast-track area.
In summary, the ESI provides an innovative approach to ED triage with the inclusion of predictions about the number of resources needed to make a patient disposition. Consideration of resources is included in the triage level assignment for ESI level-3, 4, and 5 patients, while ESI level-1 and 2 decisions are based only on patient acuity. Examples of ESI level-3, 4, and 5 patients are shown in Table 5-2. Practical experience has demonstrated that resource estimation is very beneficial in helping sort the large number of patients with non-acute presentations.
Eitel DR, Brown C, Takayesu J. (in press). The business management life support course-BMLS®—for emergency department care delivery teams. York, PA: Author.
Eitel DR, Travers DA, Rosenau A, Gilboy N, Wuerz RC (2003). The emergency severity index version 2 is reliable and valid. Academic Emergency Medicine 10(10):1079-80.
Emergency Nurses Association (1997). Triage: Meeting the challenge. Park Ridge, IL: Author.
Gilboy N, Travers DA, Wuerz RC (1999). Reevaluating triage in the new millennium: A comprehensive look at the need for standardization and quality. Journal of Emergency Nursing 25(6):468-73.
Tanabe P, Gimbel R, Yarnold PR, Adams J (2004). The emergency severity index (v. 3) five level triage system scores predict ED resource consumption. Journal of Emergency Nursing 30:22-9.
Tanabe P, Gimbel R, Yarnold PR, Kyriacou DN, Adams J (2004). Reliability and validity of scores on the Emergency Severity Index version 3. Academic Emergency Medicine 11:59-65.
Wuerz R, Milne LW, Eitel DR, Travers D, Gilboy N (2000). Reliability and validity of a new five-level triage instrument. Academic Emergency Medicine 7(3):236-42.
Note: Appendix A of this handbook includes frequently asked questions and post-test assessment questions for Chapters 3 through 8. These sections can be incorporated into the ESI training course.