Ergonomic evaluation of an ecological interface and a profilogram display for hemodynamic monitoring

Objective. Comprehensive monitoring of the patient state and subsequent dec ision making is an essential part of the task of an anaesthetist. The physi cians' decision making process is based upon a concept of partly abstract p hysiologic parameters such as depth of anaesthesia or contractility. This c oncept is derived from the measured parameters given on todays' trend displ ays in addition to context information available for the anaesthetist. We i nvestigated two alternative approaches of display design for hemodynamic mo nitoring: 1) integrated displays based on ecological interface design, and 2) profilogram displays based on intelligent alarms. Method. To evaluate di fferences in decision making, the two displays and a trend display were com pared in an experimental set-up with computer simulated vital parameter cur ves. From a start state with random parameter deviations from the ideal sta te, subjects had to achieve the ideal circulatory performance as fast as po ssible by manipulating vasomotor tone, heart rate, blood volume and contrac tility. To analyse subjects' decision making process, eye-tracking, event-l ogging, and the method of think aloud protocols were used. Twenty anaesthes iologists performed 113 experiments (approximately 2 with each display). Re sults. The anaesthetists failed to achieve the task in 37% using the trend display, in 19% using the profilogram display, and in 13% using the ecologi cal interface. Hence, a safer task solution was possible with the ecologica l interface and the profilogram display but at the expense of various perfo rmance parameters such as higher trial time, more interactions with the sim ulated system, and more frequent eye movements. In contrast to the trend di splay and the profilogram display, where anaesthetists were mainly focussed on controlling the left atrial pressure, such an behaviour was less observ ed with the ecological interface. Conclusion.Our results have shown that su bjects came to more effective solutions with the traditional trend display. The main reason for this result may be their years of experience with this kind of display type. Regarding safe and goal-intended decision finding, t he results are encouraging for further experiments with redesigned ecologic al displays. But these displays ought to have smoother changes with respect to the traditional trend displays. Furthermore, new experiments have to be performed under real or fairly real (e.g. together with an anaesthesia sim ulator) conditions to underline the positive results for ecological interfa ces.