The Emergency Severity Index (ESI) is a tool for use in emergency department (ED) triage. The ESI triage algorithm yields rapid, reproducible, and clinically relevant stratification of patients into five groups, from level 1 (most urgent) to level 5 (least urgent). The ESI provides a method for categorizing ED patients by both acuity and resource needs.

Emergency physicians Richard Wuerz and David Eitel developed the original ESI concept in 1998. After pilot testing of the ESI yielded promising results, they brought together a number of emergency professionals interested in triage and the further refinement of the algorithm. The ESI Triage Group included emergency nursing and medical clinicians, managers, educators, and researchers. The ESI was initially implemented in two university teaching hospitals in 1999, and then refined and implemented in five additional hospitals in 2000. The tool was refined further based on feedback from the seven sites. Several research studies have been conducted to evaluate the reliability, validity, and ease of use of the ESI. Since the publication of the first edition of this handbook, research has led to a further refinement in the algorithm. ESI Version 4 is presented in this handbook. The key difference between ESI Version 3 and ESI Version 4 is the expansion of ESI level 1 criteria and refinement of the pediatric fever criteria. Supporting research is presented in Chapter 2 of this handbook. Research on the ESI continues and may lead to future revisions of the tool.

A conceptual version of the algorithm is presented in Chapters 2 and 3, followed by the actual algorithm in Chapters 3 and beyond. One of the ESI Triage Group's primary goals was to publish a handbook to assist emergency nurses and physicians with implementation of the ESI. The group agreed that this was crucial to preserving the reliability and validity of the tool. A draft of this handbook was in progress in 2000, when Dr. Wuerz died suddenly and unexpectedly. The remaining group members were committed to the value of ESI and carrying out Dr. Wuerz's vision for a scientifically sound tool that offers emergency departments a standardized approach to patient categorization at triage. The group completed the first edition of The Emergency Severity Index (ESI) Implementation Handbook in 2002. We once again dedicate this handbook to our leader, collaborator, and friend, Dr. Richard Wuerz.

This book is intended to be a complete resource for ESI implementation. Emergency department educators, clinicians, and managers can use this practical guide to develop and conduct an ESI educational program, implement the algorithm, and design an ongoing quality improvement program. The book includes background information on the evolution of ED triage, other triage acuity scales, how the ESI was developed, and research reports on the ESI and other triage scales. Next, we present a chapter on each aspect of the ESI in detail: an overview, identifying high-risk patients, predicting resources, and using vital signs. The book also includes chapters on ESI implementation and quality monitoring. Chapters 9 and 10 provide the reader with practice and competency cases. The algorithm and notes may be reproduced to provide to ED triage nurses. The handbook can be used alone or in conjunction with the training DVD titled Emergency Severity Index, Version 4: Everything You Need to Know, also produced by the Agency for Healthcare Research and Quality (AHRQ).

The ESI represents a major change in the way triage is practiced; implementation of the ESI requires a serious commitment from education, management, and clinical staff. Successful implementation of this system is accomplished by committing significant resources during training and implementation. Like any major change, it is necessary to monitor triage staff's use of the ESI and provide ongoing feedback and clarification over time. The ESI Triage Group believes that all this hard work is worth the effort. The benefits of a successful ESI implementation are myriad: improvements in ED operations, support for research and surveillance, and a standardized metric for benchmarking.

This handbook is intended only as a guide to using the ESI system for categorizing patients at triage. Nurses who participate in an ESI educational program are expected to be experienced triage nurses, or have attended a separate, comprehensive triage educational program.

This handbook is not a comprehensive triage educational program. The ESI educational materials in this handbook are best used in conjunction with a triage educational program such as the Emergency Nurses Association's Making the Right Decision: A Triage Curriculum®. Triage nurses also need education in institution-specific triage policies and protocols. For example, hospitals may develop policies regarding which types of patients can be triaged to fast-track. Triage protocols may also be developed, such as giving acetaminophen for fever, or ordering ankle films for patients who meet specified criteria.

Copyright Notice

The Emergency Severity Index Version 4 Triage Algorithm (the "Algorithm") is the intellectual property of The ESI Triage Research Team, LLC (the "Author"). The Author has applied for copyright with the United States Copyright Office. The Algorithm is the sole and exclusive property of the Author, and the Agency for Healthcare Research and Quality has a license to use and disseminate the two works derived from this algorithm: the training two-DVD set (Emergency Severity Index Version 4: Everything You Need to Know) and the implementation handbook (Emergency Severity Index Version 4: Implementation Handbook). The Author hereby assures physicians and nurses that use of the Algorithm as explained in these two works by health care professionals or physicians and nurses in their practices is permitted. Each professional user of these two works is granted a royalty-free, non-exclusive, non-transferable license to use the Algorithm in accordance with the guidance in these two works.

The Algorithm may not be changed in any way by any user. The algorithm and the contents of the DVD set and implementation handbook may be incorporated into additional training materials developed by a user, on the condition that no fee is charged by the user for the Algorithm, the contents of these two works, or the additional training materials.

The Algorithm has been rigorously tested and found to be both reliable and valid, as described in the research references included in these two works. However, the Author and the Agency for Healthcare Research and Quality require that the implementation and use of the Algorithm be conducted and completed in accordance with the contents of these two works using the professional judgement of authorized physicians or nurses and staff directed and supervised by them. Each health care professional who decides to use this algorithm for emergency triage purposes does so on the basis of that health care provider's professional judgment with respect to the particular patient that the provider is caring for. The Author and the Agency for Healthcare Research and Quality disclaim any and all liability for adverse consequences or for damages that may arise out of or be related to the professional use of the Algorithm by others, including, but not limited to, indirect, special, incidental, exemplary, or consequential damages, as further set forth below.

Note: The Author and the Agency for Healthcare Research and Quality have made a good faith effort to take all reasonable measures to make these two works accurate, up-to-date, and free of material errors in accord with clinical standards accepted at the time of publication. Users of these two works are encouraged to use the contents for improvement of the delivery of emergency health care. Any practice described in these two works should be applied by health care practitioners in accordance with professional judgment and standards of care used in regard to the unique circumstances that may apply in each situation they encounter. The Author and the Agency for Healthcare Research and Quality cannot be responsible for any adverse consequences arising from the independent application by individual professionals of the materials in these two works to particular circumstances encountered in their practices.

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