Usability Study of the User-Interface of Intensive Care Ventilators Based on User Test and Eye-Tracking Signals

BACKGROUND The aim of this study was to evaluate the ergonomics of the user-interface for 3 intensive care ventilators, and identify usability problems leading to user errors. MATERIAL AND METHODS Sixteen respiratory therapists were recruited to perform 6 specific user-interface operational tasks on ventilators. Data (task completion time, pupil diameter, average slope of pupil diameter change, and subjective evaluation) were collected through objective measurement, questionnaires, and an eye-tracking instrument. RESULTS For task completion time, there were significant differences among ventilators in recognition tasks of ventilator mode and settings (P<0.05), modification of ventilator modes and recognizing (P<0.05) and changing alarm settings (P<0.05). A mean of 15±2 task failures was observed for each ventilator. For the change of pupil diameter, a significant difference was observed between ventilators (except task 2, P<0.05). For average slope of pupil diameter change, a significant difference was also observed between ventilators (except task 2, P<0.05). The Servo I showed a better correlation between task completion time and pupil diameter change. The subjective evaluation results were clear: Evital 4 received worst scores in terms of friendliness of user-interface, information display and safety (respectively, P<0.05). CONCLUSIONS The present study provided valuable evidence to indicate the ergonomic of ventilators now used in China. With the result of this study, we can infer that the Evital 4 were poorly ergonomic designed. Furthermore, the study also demonstrated that eye-tracking can be a promising tool to evaluate the ergonomics of the user-interface.