Pressure within the esophagus arises from two mechanisms: intrabolus pressure, which is a hydrodynamic phenomenon, and esophageal occlusion pressure, which is a contact phenomenon. Current esophageal manometers are sensitive to both hydrodynamic and contact pressures and cannot distinguish between the two measurements in the absence of other information. It has been shown that measurement of intrabolus pressure is a clinically relevant parameter in esophageal manometry. There is no single device available that can obtain this measurement directly. This work presents a novel fibre optic-based flexible catheter for high resolution manometry with sensing pods that can be selectively sensitized to either hydrodynamic pressure alone, or contact and hydrodynamic pressure, offering sensing schemes not possible with existing high resolution manometers. The catheter is designed to be used with a time division multiplexing interrogation technique, yielding a system capable of exceeding the 36-sensor count limit of current solid state manometers. The device consists of rigid sensing pods connected by flexible tubing with in-fiber Bragg gratings acting as sensing elements within each of the pods. Absent in each sensing pod are rigid anchor points, representing a novel departure from comparable designs and resulting in increased sensitivity and decoupling from axial loading. Device functionality is demonstrated through bench top trials. A pressure sensitivity of 1.8 pm/mmHg and axial sensitivity of 11 mmHg/N of applied load is demonstrated. Crosstalk between individual sensors is characterized and a compensation scheme is developed and validated. Temperature response is demonstrated to be linear such that its confounding can be corrected for procedurally. Sensing schemes afforded by this design may yield clinically relevant parameters not achievable by any single existing device. / Graduate

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Die vorliegende Arbeit umfasst die Entwicklung einer neuartigen Drucksonde, welche die faseroptischen Sensortypen Fabry-Pérot-Interferometer und Faser-Bragg-Gitter als Hybridsensor kombiniert und minimalinvasiv im Gefäßsystem oder Hohlorganen platziert werden soll. Die simultane Auswertung aller Sensoren ermöglicht die Erfassung des räumlich und zeitlich verteilten Druckes. Die diagnostische Relevanz der Hybridsonde zur Analyse von Stenosen wird an den Krankheitsbildern der koronaren Herzkrankheit und der lumbalen Spinalkanalstenose aufgezeigt. Anhand von experimentellen in vitro Untersuchungen sowie eines in vivo Tierversuches wird die Leistungsfähigkeit der Hybridsonde zur verteilten Druckmessung evaluiert sowie das Potential der Neuentwicklung in der medizinischen Diagnostik bestätigt. Ausgehend von den gewonnen klinischen Daten wird eine Entwicklungsperspektive für ein Medizinprodukt zur minimalinvasiven Diagnostik aufgezeigt.:Abkürzungs- und Formelzeichenverzeichnis ix Vorwort 1 1. Einleitung 3 2. Medizinische Grundlagen 9 3. Technische und physikalische Grundlagen 23 4. Referenzdrucksensor 47 5. Faseroptische Hybridsonde 85 6. In vivo Tierversuch 115 7. Erkenntnisgewinn 135 8. Zusammenfassung und Ausblick 143 Anhang 147 Literaturverzeichnis 159 Abbildungsverzeichnis 175 Tabellenverzeichnis 179 Thesen 181 / This thesis presents the development of a novel pressure probe combining a fiber optic Fabry-Pérot-Interferometer and Fiber Bragg Gratings as a hybrid probe. The application is minimally invasive manometry of the vascular system as well as hollow organs. The simultaneous evaluation of several pressure reading points enables the detection of spatially and temporally distributed pressure. The diagnostic relevance of the hybrid probe for the analysis of stenoses severity is demonstrated at the application for coronary heart disease and lumbar spinal stenosis. By means of experimental in vitro investigations as well as an in vivo animal trial the hybrid probe's performance for distributed pressure sensing is assessed. Furthermore, this confirms the potential of the new development for medical diagnostics. Based on the clinical data obtained, a development perspective for a medical device for minimally invasive diagnostics is presented.:Abkürzungs- und Formelzeichenverzeichnis ix Vorwort 1 1. Einleitung 3 2. Medizinische Grundlagen 9 3. Technische und physikalische Grundlagen 23 4. Referenzdrucksensor 47 5. Faseroptische Hybridsonde 85 6. In vivo Tierversuch 115 7. Erkenntnisgewinn 135 8. Zusammenfassung und Ausblick 143 Anhang 147 Literaturverzeichnis 159 Abbildungsverzeichnis 175 Tabellenverzeichnis 179 Thesen 181