Coordination of hemodynamic monitoring and control performance

Date of Completion

January 1993


Engineering, Biomedical|Health Sciences, Nursing|Psychology, Physiological




In intensive care units, clinicians must observe various physiological monitoring systems and make adjustments in treatment quickly to prevent medical crises. Current displays provide little assistance to clinicians in either selecting relevant information or coordinating treatment with clinical problems. This thesis used a hemodynamic monitoring and control task to compare design strategies derived from cognitive and ecological psychology. A traditional "strip-chart" display was compared with an integrated balloon display and an ecological potentials display. The traditional "strip-chart" showed target and danger values for three pressures and cardiac output as five independent graphs. The integrated balloon display showed the biological constraints on pressure and flow in an object-like display. The ecological potentials display immersed pressures and flows (symptoms) in the etiology space to show the relationships of symptoms to causes. Dynamic simulations of common clinical problems were generated by a computer model of Guyton (1980) and presented in an interactive computer environment. Critical care nurses, nursing students, and non-nurses observed changes in pressures and flow corresponding to certain disease states and corrected those states using simulated drugs. It was hypothesized that speed and accuracy of treatment coordination with the traditional strip-chart display would be increasingly improved by the integrated balloon display and further enhanced by the ecological potentials display. In general, this order held for both novices and experts and was a significant main effect in the analysis of variance. The results of the five experiments showed that treatment coordination was significantly faster and more accurate with the integrated balloon display than with the traditional strip-chart display, and still further improved with the ecological potentials display. The results suggest that, when a display explicitly makes available relevant lawful constraints or relationships, the number of degrees of freedom that must be cognitively managed by the user will be reduced. When the observables of the display are scaled to the controllables so that the kind and number of things to be controlled match the kind and number of controls available and are at the scale required by the task goal and operator's intentions, the degrees of freedom are further reduced. ^