Date of Award

Spring 1963

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

First Advisor

Horgan, James D.

Second Advisor

Lange, R. L.

Third Advisor

Moeller, Arthur C.

Abstract

The purpose of this research is to present a digital computer model of the respiratory system, and to show the application in which a clinical experiment in carbon dioxide inhalation has been successfully simulated. Previous to the time of this research, simulation studies were published by Grodins et al and extended by Defares et al. There were no completely satisfactory results, because of the failure to model short time dynamic phenomena, such as Cheyne-Stokes respiration. The simulation of Horgan and Lang, on the other hand, has successfully modeled Cheyne-Stokes phenomena, but has not been applied to the simulation of the longer transients involved in CO2 inhalation. Such work is carried out in this thesis. A review of the definition of a feedback control system is presented to show that the respiratory system can be considered as a nonlinear feedback control system. Pertinent physiological quantities are interpreted in terms of the corresponded control system quantities. In Grodins' model, the coefficients of the differential equation of the controlled quantity are independent of time. But in the author's model, the corresponded control quantities are dependent on time. In the controlling system, Grodins' model neglects all the time lag, where as the important time lags and mixing process are considered in the author's model. As a result, the initial slope of the on-transient resulting from CO2 inhalation is much steeper than that of Grodins' model. Furthermore, oscillation occurs in the author's model, but not in Grodins' model.

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