The design of a fibre Bragg grating based manometry catheter for in-vivo diagnostics in the human colon is presented. The design is based on a device initially developed for use in the oesophagus, but in this instance, longer sensing lengths and increased flexibility were required to facilitate colonoscopic placement of the device and to allow access to the convoluted regions of this complex organ. The catheter design adopted allows the number of sensing regions to be increased to cover extended lengths of the colon whilst maintaining high flexibility and the close axial spacing necessary to accurately record pertinent features of peristalsis. Catheters with 72 sensing regions with an axial spacing of 1 cm have been assembled and used in-vivo to record peristaltic contractions in the human colon over a 24hr period. The close axial spacing of the pressure sensors has, for the first time, identified the complex nature of propagating sequences in both antegrade (towards the anus) and retrograde (away from the anus) directions in the colon. The potential to miss propagating sequences at wider sensor spacings is discussed and the resultant need for close axial spacing of sensors is proposed.

Fiber optic catheters for the diagnosis of gastrointestinal motility disorders are demonstrated in-vitro and in-vivo. Single element catheters have been verified against existing solid state catheters and a multi-element catheter has been demonstrated for localized and full esophageal monitoring. The multi-element catheter consists of a series of closely spaced pressure sensors that pick up the peristaltic wave traveling along the gastrointestinal (GI) tract. The sensors are spaced on a 10 mm pitch allowing a full interpolated image of intraluminal pressure to be generated. Details are given of in-vivo trials of a 32-element catheter in the human oesophagus and the suitability of similar catheters for clinical evaluation in other regions of the human digestive tract is discussed. The fiber optic catheter is significantly smaller and more flexible than similar commercially available devices making intubation easier and improving patient tolerance during diagnostic procedures.

Graduated compression bandaging of the lower limbs is the primary therapy for venous leg ulcers with its efficacy believed to be predominantly dependent on the amount and the distribution of the compressive pressure applied. There has been on-going demand for an ideal sensor to facilitate in-vivo monitoring of the sub-bandage pressure. Several methods and devices have been reported but each has its limitations, such as bulkiness, low tolerance to movement, susceptible to thermal noise and single point sensing. An optical fiber force sensor is demonstrated, consisting of two arrays of fiber Bragg grating (FBG) entwined in a double helix form and packaged with contact-force sensitivity. This sensor array has inherent temperature immunity and is capable of real-time, distributed sensing of sub-bandage pressure. The calibration results of the sensor array, as well as the validation human trial results, are presented.

Background Manometry is commonly used for diagnosis of esophageal and anorectal motility disorders. In the colon, manometry is a useful tool, but clinical application remains uncertain. This uncertainty is partly based upon the belief that manometry cannot reliably detect non-occluding colonic contractions and, therefore, cannot identify reliable markers of dysmotility. This study tests the ability of manometry to record pressure signals in response to non-lumen-occluding changes in diameter, at different rates of wall movement and with content of different viscosities. Methods A numerical model was built to investigate pressure changes caused by localized, non-lumen-occluding reductions in diameter, similar to those caused by contraction of the gut wall. A mechanical model, consisting of a sealed pressure vessel which could produce localized reductions in luminal diameter, was used to validate the model using luminal segments formed from; i) natural latex; and ii) sections of rabbit proximal colon. Fluids with viscosities ranging from 1mPa.s to 6800mPa.s and luminal contraction rates over the range 5 – 20 mmHg/s were studied. Key Results Manometry recorded non-occluding reductions in diameter, provided that they occurred with sufficiently viscous content. The measured signal was linearly dependent on the rate of reduction in luminal diameter and also increased with increasing viscosity of content (R2= 0.62 and 0.96 for 880 and 1760 mPa.s respectively). Conclusions & Inferences Manometry reliably registers non-occluding contractions in the presence of viscous content, and is therefore a viable tool for measuring colonic motility. Interpretation of colonic manometric data, and definitions based on manometric results, must consider the viscosity of luminal content.