The introduction of new medical devices (technologies) into complex systems usually includes usability evaluation (formative and summative) using Human Factors (Engineering) methods. This paper outlines the use of Hierarchical Task Analysis (HTA) to not only look at usability but also consider implementation in a complex system. Firstly, the macro system is mapped as a process model for a complex field exercise (simulation) for prehospital care following a chemical incident; and secondly the individual human-medical device interface is analyzed. This allows the two outputs to be integrated by combining the macro systems modelling and micro product interactions. It provides an example of using HTA to support implementation of new devices and technologies in complex healthcare systems
