Emergency Severity Index (ESI): A Triage Tool for Emergency ...

Chapter 4. ESI Levels 3-5 and Expected
Resource Needs
Traditionally, comprehensive triage has been the
dominant model for triage acuity assignment in U.S.
emergency departments (Gilboy, 2010; Gilboy,
Travers, & Wuerz, 1999). Triage acuity rating systems
have been based solely on the acuity of the patient,
determined through the nurse's assessment of vital
signs, subjective and objective information, past
medical history, allergies, and medications. Such
systems require the nurse to assign an acuity level
by making a judgment about how sick the patient is
and how long the patient can wait to be seen by a
provider.
The ESI triage system uses a novel approach that
includes not only the nurse’s judgments about who
should be seen first, but also, for less acute patients
(those at ESI levels 3 through 5), calling on the
nurse to add predictions of the resources that are
likely to be used to make a disposition for the
patient.
This chapter includes background information on
the inclusion of resource predictions in the ESI and
a description of what constitutes a resource.
Examples are given of patients rated ESI levels 3 to 5
and the resources that each patient is predicted to
need.
Estimation of resource needs begins only after it has
been determined that the patient does not meet ESI
level 1 or 2 criteria. The nurse then predicts the
number of resources a patient will need in order for
a disposition to be reached. When Wuerz and Eitel
created the ESI triage system, they included resource
utilization to provide additional data and allow a
more accurate triage decision. They believed that an
experienced emergency department (ED) triage
nurse would be able to predict the nature and
number of tests, therapeutic interventions, and
consultations that a patient would need during
his/her ED stay. Studies of ESI implementation and
validation have verified 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 were able to predict
how many ESI-defined resources the ED patients
required 70 percent of the time. That is, experienced
triage nurses can reasonably predict at triage how
many resources patients will require to reach ED
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disposition; more importantly, they can discriminate
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 4-1), the nurse
decides which patients meet criteria for ESI levels 1
Figure 4-1. ESI Triage Algorithm, v. 4
©ESI Triage Research Team, 2004. Reproduced with
permission.