Research On The Artificial Sphincter System Based On Rectal Sensation Function Rebuilding

Anal incontinence is a common disease in clinic, which means natural analsphincter loses the control ability for defecation of fecal and gases. It is likely tocause a variety of complications, and the incidence is higher in elderly patients,critically ill patients, and paraplegic patients. It doesn’t only bring great suffering tothe patient, but also increases difficulties to nursing work. Under the tendency ofaging population, fecal incontinence has been addressed as a matter of urgency inmedical and nursing field. The development of related therapeutic means andtechnology has a vital practical significance to improve patients’ life quality and topromote social civilization.There are several traditional therapy treatments for anal incontinence. However,these treatments have some drawbacks and might even lead to severe complications.As the development of modern technology, people have asked for more requirementson health and quality of the life, so traditional treatments cannot meet patients’requirement. Artificial anal sphincter has opened up a new way for treatment of analincontinence. Lots of related research work aiming at the bionic mechanism, controlmanner and power supply of artificial anal sphincter have been studied by domesticand foreign scholars, while the current research work involving rectal sensationfunction rebuilding has no significant progress. So it is imperative to solve theproblem of how to rebuild rectal sensation function, and use interdisciplinary field ofmodern information processing technology, material technology and biomedicine, todesign an artificial anal sphincter system completely suitable to be implanted inhuman body.Based on the research background of National Natural Science Fund of China,the dissertation takes artificial anal sphincter as research object and focuses on therelated theory and method research of rectal sensation rebuilding. Related approachaiming at feature vector selection and pattern recognition optimizing is explored, andan integrated experimental platform of rectal sensation function rebuilding isestablished to verify its feasibility and effectiveness. The dissertation can besummarized to three main parts, which are implementation of artificial anal sphinctersystem, theory approach of rectal sensation function rebuilding and the third part includes the establish of intestinal simulations experimental platform and the theoryverify. The research work is mainly reflected as follows:(1) The dissertation introduces the basis physiological sense and the generalsituation of anal incontinence, then states the general treatment for anal incontinenceand related domestic and foreign research present situation. In view of existingproblem of traditional therapy treatment, the rectal sensation function model is built.According to the structure feature of human nature anal and colorectum, thedissertation proposes the conception of an artificial anal sphincter system based onbiological feedback control.(2) The bionics realization of artificial anal sphincter system is discussed. Usingengineering technology, the dissertation studies the nature anal sphincter musclegroup in physiology based on anal sphincter rebuilding theory, approach anddefecation control mechanism to simulate the basis function of anal sphincter musclegroup. The artificial anal sphincter system that consists of executive mechanism,wireless communication module and transcutaneous energy transmission module isproposed. The research and implementation structure of the artificial anal sphinctersystem are based on modeling and low-power consumption requirement.(3) Feature extraction algorithm of rectal pressure contraction signal is studied.The dissertation firstly studies the problem of existing feature extraction method. Inview of the non-stationary and nonlinear characteristics of rectal pressure signal,feature extraction method based on wavelet packet decomposition subspace timedomain feature and subspace frequency domain feature is proposed. In order to findthe optimal feature set from the original feature set for a higher classify accuracy andprecise, the dissertation proposes rectal pressure signal optimal wavelet packet basisfeature extraction method based on Fisher distance and optimal wavelet packet basisextraction method based on DB (Davis-Bouldin, DB) index. And the effectiveness ofthe two feature extraction methods has been verified based on PNN (ProbabilisticNeural Network, PNN) model.(4) The classify algorithm of rectal pressure contraction signal is studied. Bothof the classification based on PNN and the classification based on SVM are appliedfor the classification forecasting of rectal pressure contraction signal. Meanwhile,PSO (Particle Swarm Optimizer, PSO) algorithm is used to optimize SVMparameters, and classification forecasting is applied for the collected rectal pressure signal feature vectors. At last, contrast analysis of prediction accuracy using the threedifferent methods is studied to verify the proposed classification methods’effectiveness and superiority.(5) An experimental platform prototype of the artificial anal sphincter systembased on biological feedback is developed and human nature intestinal simulationexperiment is carried out. With the guidance of the above theory and methods, a lotof experimental data is obtained through the human nature intestinal simulationenvironment. Experimental results verify the basic function of artificial analsphincter and effectiveness of the rectal sensation function rebuilding model. Basedon the assessment result, it is possible to improve the artificial anal sphincter systemand provide theoretical basis and technical support for AI patients in clinic treatment.