©ESI Triage Research Team, 2004. Reproduced with permission.

©ESI Triage Research Team, 2004. Reproduced with permission.

 ©ESI Triage Research Team, 2004. Reproduced with permission.

©ESI Triage Research Team, 2004. Reproduced with permission.

Appendix B. ESI Triage Algorithm, v. 4


The Emergency Severity Index (ESI) is a five-level emergency department (ED) triage algorithm that provides clinically relevant stratification of patients into five groups from 1 (most urgent) to 5 (least urgent) on the basis of acuity and resource needs.

The ESI version 4 algorithm is copyrighted and is the intellectual property of the ESI Triage Research Team, LLC. In order to maintain reliabilty and validity, it is important that the algorithm not be changed. 

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 the ESI Handbook, or the additional training materials in the DVDs.