Modeling of Arterial Baroceptor Feedback in a Hydromec Cardiovascular Pulse Duplicator System
ARMSTRONG LAB BROOKS AFB TX AEROSPACE MEDICINE DIRECTORATE
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We have developed a hydro-mechanical cardiovascular pulse duplicator system CPDS for modeling the systemic arterial system. The CPDS has the ability to reproduce physiologically equivalent aortic pressures and flows and has been used to test and evaluate electrical analog arterial models of the systemic circulation. Feedback from a flow probe from measuring flow through a simulated aorta has been developed for regulating cardiac output by controlling heart rate andor stroke volume. The output from a pressure sensor adjacent to the flow probe provides the opportunity to regulate heart rate using pressure feedback. The primary objective of the proposed research was to test the hypothesis that a physiologically equivalent arterial-cardiac baroreflex feedback mechanism can be accurately modeled by integrating a pressure sensor into the existing CPDS. A secondary objective was to cross-validate the mechanical feedback model by comparing heart rate responses during tilt tests with those of existing physiologic experimental data. Because of significant cracks and leaks in various plexiglas parts of the original Ormec CPDS, a number of parts had to be refabricated. All of the parts subjected to the most stress were refabricated from aluminum and anodized for protection against corrosion. Aluminized parts included both walls of the atrium and inlet hose connection, and all inlet and outlet hose connections to the Systemic Reservoir with their supporting parts. All other parts which included the walls surrounding the mitral valve test section required fabrication from plexiglas in order to provide a clear view of the valve in the test section. All hardware fabrication has been and have been completed completed by the fabrication shop at Brooks AFB.