The Development And Analytical Performance Of A Polymer Membrane Electrode-based P - Carbon Dioxide Catheter (ammonia, Sensor(s), In-vivo,coated-wire Electrode(s)).

The partial pressure of carbon dioxide (pCO(,2)) in blood is an important indicator of respiratory and metabolic function. For this reason, a continuous pCO(,2) monitor would be a useful tool to supplement conventional blood gas analysis. To this end, the development and analytical performance of a pCO(,2) sensor suitable for such monitoring is described in this thesis. Chaper I describes the common methods for analyzing blood gases and presents a thorough review of the methods that have been developed for the continuous analysis of these components. The second chapter explains the response mechanism of polymer membrane electrodes since their function is key to the operation of the gas sensors described in the remaining chapters. In Chaper III, the first gas sensor design is described and evaluated. The experiments demonstrated the feasibility of these devices for NH(,3) and CO(,2) gas sensing. Coated-substrate pH electrodes were also used as internal sensing elements as described in Chapter IV. The stability of these electrodes was not sufficient to warrant further study in this area. Chaper V reports the fabrication of the tubular pH electrodes which are essential to the final pCO(,2) sensor design. There is also a detailed explanation of the problems associated with the development of this new design. The final pCO(,2) catheter is described in Chapter VI as well as its performance in vitro and in vivo. Chapter VII summarizes the results of this research and speculates on future developments. Once assembled, this flexible catheter has an outer diameter of only 1.1 mm. When filled with an appropriate reference solution and internal electrolyte, they respond rapidly ((LESSTHEQ)80 sec for t(,0.95)) and reproducibly to pCO(,2) changes in a range exceeding that of normal physiological levels (15-150 torr) with nearly Nernstian behavior (54-61 mV/decade change in pCO(,2)). Continuous pCO(,2) values obtained with the new sensor during 6 hr in vitro blood pump studies correlate well with conventional blood-gas instruments. Preliminary results for sensors implanted intravascularly in dogs demonstrate their suitability for continuous in vivo monitoring of pCO(,2).Ph.D.Analytical chemistryPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/127882/2/8612594.pd