Automatic Control of Oxygen Concentration to Premature Neonates
Robert Farrenkopf, PhD
October 9, 2002
Abstract
This subject is considered using a recently developed computer simulation that involves models of all of the system elements, namely the controller, the oxygen mixing valve, the pulse oximeter, and a filter for smoothing the oximeter's output and rejecting its occasional signal dropouts. But the heart of the simulation is the inclusion of a model for the neonate's pulmonary system, derived, for the most part, from the impressive work of Professor Fleur T. Tehrani. It involves a few empirical relationships, and appeals to fundamental laws of physics regarding mass balance of oxygen and carbon dioxide in the lungs, brain, and body tissue. Use of this simulation provides a design methodology for selecting a controller and filter configuration that is compatible with the premature neonate, and to do this without having to deal with the obstacles and risks involved in using live subjects. A multitude of parameters define the neonate pulmonary model, and these can be varied in order to test the design's robustness and limitations to a broad neonate population. Particular focus addresses the detrimental effects of an imperfect pulse oximeter, and a set of alarm situations is defined that call for the intervention of a medical professional.Robert Farrenkopf, PhD
October 9, 2002
Abstract
This report describes the simulation and its use, and considers a particular controller and filter design that appears to work well for the neonate model described. Typical oxygen saturation (Sao2) vs. time results are presented for a variety of situations, such as what happens when the desired Sao2 is changed from one level to another, or what takes place when the baby experiences
