Comparison of four different display designs of a novel anaesthetic monitoring system, the 'integrated monitor of anaesthesia (IMA)'.

Background: A novel monitoring system (integrated monitor of anaesthesia, IMA) which integrates three components of general anaesthesia on one single display was developed. The focus of this study was to evaluate the performance and user-friendliness of four different display designs.
Methods: Four interface displays of the IMA were developed, including one numerical, one numerical and graphical (mixed numerical-graphical), one only graphical, and one an advanced two-dimensional graphical display. Each of the four displays was evaluated in a random order by 10 staff anaesthetists and 10 residents/fellows using a set of five scenarios. Scenarios involved one or more abnormal variables that participants had to verbally phrase. For each interface test, reaction time, response accuracy, and NASA-Task Load Index were measured and compared.
Results: The numerical, graphical, and advanced-graphical interfaces yielded similar median reaction times, respectively, 7.99 s (5.15-10.79), 8.21 s (6.20-11.88), and 9.43 s (6.19-13.3). Reaction times were significantly shorter (P<0.006) with the mixed numerical-graphical interface: 6.26 s (4.52-8.32). The correct response rate was significantly lower in the graphical interface. The three others presented no statistical difference when compared among each other. The mixed numerical-graphical interface yielded a significantly lower NASA-TLX than the numerical and the advanced-graphical interfaces (19/100 vs 34/100, P<0.003).
Conclusions: A mixed numerical-graphical display design appears to present the best results in terms of user reaction times, response accuracy, and performance index when detecting abnormal critical events.