Hierarchical task analysis as a systems mapping tool in complex health care environments: emergency department response to chemical, biological, radiological, and nuclear events

The emergency department (ED) is at the forefront of the chemical, biological, radiological, and nuclear (CBRN) response. This study adopted a multilevel systems approach using the human factors/ergonomics (HFE) method of hierarchical task analysis (HTA) with document analyses of CBRN plans to represent work-as-Imagined. Work-as-imagined was compared with data from semistructured interviews using prompt cards for CBRN scenarios (n = 57) representing work-as-done. The aim was to provide methodological evidence for the use of HTA with an empirical synthesis of the ED in response to CBRN events. HTA was the preferred systems mapping tool because it aligns with a systems thinking approach, allows multiple-level comparisons, highlights variability, and has an established usability track record. This study demonstrates the usability of HTA in the context of the ED responding to a CBRN event. The findings for core CBRN concepts included (1) liaise and communicate, (2) isolate and contain, and (3) personal protective equipment.