A Component-Based Framework for Comparing Emergency Department Flow Models Across Health Systems: A Critical Narrative Review.

Emergency departments use named flow models to address crowding, yet the same label may describe very different selection rules, staffing, authority, space, and access to diagnostics. The objective of this article is to compare model components and identify conditions governing cross-system transfer. PubMed, CINAHL, and Scopus were searched for reports published from 2000 through August 3, 2026. Of 1,271 unique records, 188 reports were sought, 135 assessed, and 120 included. Across six model families, five recurring mechanisms were identified: demand segmentation, front-loaded assessment, parallel task completion, spatial substitution, and redistribution of professional authority. Their effects varied with staffing, operating conditions, diagnostic access, and downstream congestion. These findings informed the seven-domain MODEL-ED framework. Managers and other leaders should transfer components rather than model names, match each configuration to the local constraint, and evaluate safety, equity, experience, workload, and sustainability alongside speed.