Browsing by Author "Urzua Urzua, Jorge"

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    A fuzzy logic based model computes cardiac output from the radial arterial pressure waveform
    (IEEE, 1994) Urzua Urzua, Jorge; Guarini Hermann, Marcelo Walter; Cipriano, Aldo; Matus Acuña, Marcelo Enrique; Lee, J.; Salinas, C.; Olmedo Hidalgo, Juan Carlos; Lema F., Guillermo; Canessa, Roberto
    An interactive scheme for the development of a fuzzy logic based model has been implemented and applied to build a model that is able to determine cardiac output from radial arterial pressure. It was built using as input radial pressure waveforms from patients in whom cardiac output was simultaneously measured by thermodilution. The scheme was programmed in C language in an Apollo workstation under Unix. Input variables were area under the curve, ratio between systolic and diastolic pressure, and pulse frequency. To determine fuzzy sets and membership functions the authors used 149 pressure waveforms. To test the model, the authors used 6 waveforms not used in building the model. Correlation between predicted cardiac output with measured flow was 0.98.<>
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    A model of internal control may improve the response time of an automatic arterial pressure controller
    (IEEE, 2000) Urzua Urzua, Jorge; Sauma Santis, Enzo Enrique; Cipriano, Aldo; Guarini Hermann, Marcelo Walter
    A simplified model for the arterial pressure control system was implemented on a personal computer using Matlab Simulink(R). Model responses to variations of systemic vascular resistance were comparable to those predicted by physiology. Computer simulation suggested that including this model of the internal pressure control system within the design of an external controller would achieve better arterial pressure control and faster response than previous systems.