Emergency departments (EDs) in the United States provide a critical service for patients in need of urgent, often life-saving medical care. Additionally, the role of the ED has evolved from providing primarily life-saving treatment to providing urgent unscheduled care to patients unable to gain access to their primary care providers, to providing care to Medicaid beneficiaries, and to providing care to patients without insurance. These factors contribute to crowding in the ED. Timeliness of care in the ED is a matter of patient safety.

In 2010, the Pennsylvania Patient Safety Authority published an article that delineated the patient’s ED stay into the following phases:

• Phase I: patient arrival in the ED up to diagnostic evaluation
• Phase II: diagnostic evaluation through disposition decision
• Phase III: after disposition decision through departure from the ED

The Figure depicts each phase, including components and potential hazards to patient safety.

Figure. Emergency Department Flow Phases