What is the Emergency Severity Index (ESI) triage?

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Last updated: March 24, 2025View editorial policy

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From the Guidelines

The Emergency Severity Index (ESI) triage is a 5-level system used in emergency departments to prioritize patients based on acuity and resource needs, with Level 1 being the most critical and Level 5 being non-urgent. This system is recommended by the Emergency Nurses Association and the American College of Emergency Physicians for use in busy EDs, as seen in the study by 1. The ESI triage system categorizes patients into different levels, including:

  • Level 1: patients requiring immediate life-saving interventions
  • Level 2: patients who need immediate assessment, such as stroke patients or unstable trauma patients
  • Level 3: patients who require multiple resources
  • Level 4: patients who require one resource
  • Level 5: patients with non-urgent conditions who require no resources

According to the study by 1, the ESI triage system puts all stroke patients in the Level 2 category, emphasizing the need for immediate assessment and care. The triage nurse plays a critical role in rapidly assessing patients and identifying those who require immediate attention, using specialized checklists and protocols to guide their decision-making. The goal of the ESI triage system is to efficiently allocate resources and ensure that the most critical patients receive care first, ultimately improving patient outcomes and departmental flow, as noted in the study by 1.

From the Research

Definition and Purpose of the Emergency Severity Index (ESI) Triage

  • The Emergency Severity Index (ESI) is a five-level triage acuity scale used to prioritize patients in emergency departments based on the severity of their condition and the need for immediate treatment 2, 3, 4, 5, 6.
  • The ESI levels range from 1 (highest acuity) to 5 (lowest acuity), with level 1 patients requiring immediate intervention and level 5 patients being the least urgent 2.

Key Components and Application of the ESI Triage

  • The ESI triage system takes into account various factors, including the patient's vital signs, chief complaint, and medical history, to determine the appropriate level of care 5.
  • The system is designed to be reliable and valid, with studies demonstrating high inter-rater agreement between emergency nurses and physicians in assigning ESI levels 3.
  • The ESI triage system is widely used in emergency departments, with various studies evaluating its effectiveness in different clinical settings 4, 6.

Evaluation and Refining of the ESI Triage

  • Research has focused on refining the ESI criteria to improve its accuracy and reliability, including the identification of level 2 patients who may require immediate intervention 2.
  • Studies have also investigated the use of web-based tools and clinical decision support systems to enhance the ESI triage process 4.
  • The ESI triage system has been evaluated in various clinical contexts, including the triage of anaphylaxis patients, with findings highlighting the importance of accurate triage in ensuring timely and effective treatment 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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