How does the Emergency Department triage patients?

Fall 2019

The triage system determines the how quickly patients are seen depending on how severe their illness is.

Triage is a sorting process for patients coming to the emergency department. The triage nurse, who receives additional triage training, assesses the severity of a patient’s symptoms using a standard set of guidelines called the Canadian Triage and Acuity Scale (CTAS).

CTAS was first introduced in the early 1960s and is used in emergency departments across Canada:

  • Level 1 – Resuscitation
  • Level 2 – Emergent
  • Level 3 – Urgent
  • Level 4 – Less Urgent
  • Level 5 – Non-urgent


Patients who are assessed at CTAS-1, in need of resuscitation, are seen immediately on arrival. Examples of CTAS-2 or emergent might include conditions such as chest pain, broken bones, and kidney stones.

CTAS-3 patients might be those with, for example, low back pain or abdominal pain. However, if either is severe the patients would be triaged to a CTAS-2.

Patients who are CTAS-4, less urgent, or CTAS-5, non-urgent, might have a longer wait time because they have less severe symptoms. Examples include viral upper respiratory tract infections such as the common cold, stitch removal and medication renewals.

“Wait times fluctuate throughout the 24-hour day depending on a number of factors. At LHSC, our entire health-care team strives to provide timely, high quality and compassionate care to all of our patients and families,” says Dr. Christie MacDonald, Interim Chair/Chief, Emergency Medicine, LHSC.

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