title: Automatic control of isolated organ perfusion.
abstract: If provided with adequate physiological conditions explanted hearts may continue to operate in the regular beating mode. This property offers the opportunity to substitute extensive animal experiments by investigations on the isolated organs. At the same time it enables the development of an alternative method for the transport of donor hearts for transplantation. Experimental setups for both applications are described in this paper. The focus is laid on the optimisation of handling and effectiveness of these setups by means of automatic control. The method for investigating the controlled system ("plant") for blood gas exchange, and especially the determination of the transfer function for the partial pressure of oxygen are described. The plant was triggered with stepwise changes on the gas side at several operating points. A first order lag element with time delay was chosen as approximation of every transfer function. The parameter 'time delay', 'gain of the plant' and 'time constant' were analysed as to the dependency on blood flow rate, gas flow rate and partial pressure of oxygen at the blood outlet of the oxygenator. As a result an equation was found to calculate the time delay from gas flow rate and blood flow rate. Correlation of gain and time constant with parameters of the plant were obtained, too. The data is used for the design of a controller, adapting to the different operating points of the plant.
authors.affiliation: Department of Biomedical Engineering, Medical Faculty, University Centre of Medical Engineering, Ruhr-University Bochum, Germany. prenger@biomed.rub.de
authors.forename: A
authors.initials: A
authors.lastname: Prenger-Berninghoff
authors.forename: M
authors.initials: M
authors.lastname: Hexamer
authors.forename: U
authors.initials: U
authors.lastname: Schütt
authors.forename: H
authors.initials: H
authors.lastname: Knobl
authors.forename: R
authors.initials: R
authors.lastname: Körfer
authors.forename: J
authors.initials: J
authors.lastname: Werner
mesh_terms: D000465:Algorithms; D000826:Animal Testing Alternatives; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D003199:Computer Systems; D016027:Heart Transplantation / Q000295:instrumentation*; D006801:Humans; D007260:Infusion Pumps; D009924:Organ Culture Techniques / Q000295:instrumentation*; D009926:Organ Preservation / Q000295:instrumentation*; D010100:Oxygen / Q000097:blood*; D010107:Oxygenators, Membrane; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013552:Swine
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen