Fig. 1
From: A generic method for evaluating crowding in the emergency department
Conceptual models for the patient flow through the ED. a A simplified “black box” model of the patient flow to and from the ED depending only on time of arrival and departure. b By utilising surrogate-markers queues representing patients waiting on start of examination (Q1, waiting on triage), evaluation by a doctor (Q2, waiting on first TOKS), completion of examination/treatment in the ED (Q3, waiting on last TOKS) and leaving the ED (Q4) were proposed. All but a few patients in the ED would follow this flow in that exact order. Abbreviations: arr, arrivals; tri, triage; to1 first TOKS; tol, last TOKS; dep, departure, Q, queue