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Abstract
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.
