Emergency Severity Index - ESI

The Emergency Severity Index is a five-level, emergency department triage program relied upon by nurses to assess patient acuity based on their presentation in the ED and the expected level of care the patient will require. ENA’s commitment to triage extends beyond ESI as it is actively involved in generating original research and developing new education to support improvements in triage and clinical decision-making.


ESI Training Courses

ENA offers online courses that help better identify patients who should be seen first while prioritizing the care of patients with less emergent conditions through engaging, interactive modules.

Triage and ESI


Research indicates the accuracy of nurse triage accuracy is at an alarmingly low rate of approximately 60 percent. Experience, time constraints, environmental conditions, interruptions and bias are some of the factors that lead to inaccurate triage.

To ensure every ED patient gets the right care at the right time, ENA is focused on supporting and guiding emergency nurses overcomes the challenges they face with triage.

Since 1998, ESI has been the leading triage resource relied upon by nearly every emergency nurse in the United States to assess patient acuity based on their presentation in the emergency department and the expected level of care they will require and is currently used by approximately 80 percent of U.S. hospitals.

“There is no dispute – being able to quickly and accurately triage every person who arrives in the emergency department sets the tone for delivering the best care possible to patients when they need us most.” - ENA President Ron Kraus, MSN, RN, EMT, CEN, ACNS-BC, TCRN

ENA's Commitment to You

ENA’s commitment to triage extends beyond ESI. It is actively involved in generating original research and developing new education to support improvements in triage and clinical decision making.

  • In 2019, ENA acquired the five-level ESI triage system with plans to align it with the association’s high-quality standards for educational and skill development resources.
  • ENA partnered with Silicon Valley-based Mednition to focus on research and the machine learning technology, KATE, to improve ESI triage accuracy.
  • ENA’s collaboration with Mednition is a major milestone in the association’s plan to update, enhance, and expand the use of ESI.
  • ENA has expanded ESI’s reach by working with hospital systems interested in providing their nurses with high-quality triage education and, in 2020, partnered with the Ministry of Health in Poland to bring triage training to nearly 1,400 nurses there.
  • In March 2021, ENA added CNE to the Adult/Pediatric training course (English and Spanish versions) and Pediatric Course. The addition of CNE brings even more value to these imperative training courses. And, taking into account the COVID-19 pandemic, ENA has maintained current course prices to provide emergency nurses with an exceptional value.

About KATE

Real-time AI notifies triage nurses to anomaliesKATE ESI in care that merit a second look. KATE combines clinical expertise and learnings informed by more than 10 billion data points to predict the acuity of emergency triage patients. KATE works within existing workflows and with any EHR.

Click here to get in touch with KATE.

Accredited Provider Logo

The Emergency Nurses Association is accredited as a provider of nursing continuing professional development by the American Nurses Credentialing Center’s Commission on Accreditation. Provider Unit No. P0232

The Emergency Nurses Association is approved by the California Board of Registered Nursing, Provider #2322.

FAQ and Resources

  • Click here to check out our ESI FAQ PDF
  • Click here to download the free ESI Handbook
  • Click here to purchase ESI pocket cards, badge cards and posters through our partner, Scrub Pocket
  • Click here for the latest ESI and triage education news
ENA University is here to meet emergency nurses professional development needs from orientation to advanced practice.