Introduction: Cognitive aids, such as a guideline for the management of severe local anaesthetic (LA) toxicity, are tools designed to help users complete a task. Human factors experts recommend the use of simulation to iteratively test and re-design these tools. The purpose of this study was to apply human factors engineering principles to the testing and iterative re-design of three existing cognitive aids used for the management of severe LA toxicity and to use these data to develop a 'new' cognitive aid.
Methods: Twenty anaesthetist-anaesthetic assistant pairs were randomised into four groups. Each of the first three groups received one of three different existing cognitive aids during a standardised simulated LA toxicity crisis. Postsimulation semistructured interviews were conducted to identify features beneficial and detrimental to the format and usability of the aid. Synthesis of the interview data with established checklist design recommendations resulted in a prototype aid, which was subjected to further testing and re-design by the fourth group (five more pairs) under the same conditions thus creating the final iteration of the new aid.
Results: Features of the new aid included a single-stream flowchart structure, single-sided, large-font design with colour contrast, simplified instructions and no need for calculations. This simplified tool contains only the information users reported as essential for the immediate crisis management.
Conclusions: Utilisation of formative usability testing and simulation-based user-centred design resulted in a visually very different cognitive aid and reinforces the importance of designing aids in the context in which they are to be used. Simplified tools may be more appropriate for use in emergencies but more detailed guidelines may be necessary for training, education and development of local standard operating procedures. Iterative simulation-based testing and re-design is likely to be of assistance when developing aids for other crises, and to eliminate design failure as a confounder when investigating the relationship between use of cognitive aids and performance.
Keywords: cognitive aid; human factors engineering; local anaesthetic toxicity; simulation; useability testing.
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