Mosse, Charles Alexander; (2000) Devices to Assist the Insertion of Colonoscopes. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The thesis starts by describing the colon and the history and workings of the endoscope. It then suggests that the fundamental problem when inserting a colonoscope is that as one flexible tube (the colonoscope) is pushed along another poorly supported flexible tube (the colon), it tends to catch and push and form loops. The literature concerning devices for overcoming this problem is reviewed and the first phase of the thesis ends with an investigation of the forces applied by clinicians to the colonoscope during routine clinical procedures. The body of the thesis describes the following four novel devices intended to minimise this fundamental problem.1) Water is pumped through an array of backward facing nozzles mounted onto the endoscope tip. As water accelerates through the nozzles, the reaction force propels the endoscope. The forces and pressures are analysed theoretically and compared with experimental results. Prototypes, some incorporating atomisers to 'blunt' the jets, are described and results are presented from live pigs and models using excised porcine colon. 2) A "crawler" has two suction feet that can be moved together or apart using concertina bellows or a Bowden cable. To take a step, one foot advances while the other grips the colon wall with suction, then the suction is switched over, so that the first foot grips whilst the other advances. Results with model colons are presented. 3) Electrodes placed at the tapering end of a lozenge shaped piece of acrylic stimulate the bowel to contract, squeezing the taper forward, which in turn brings the electrodes into contact with new tissues. In vivo results are presented. 4) A disposable sleeve with a lubricious hydrogel coating is attached to the endoscope to minimize friction. Results from bench tests are presented. The thesis ends with some concluding comments and suggestions for future work.

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