| Digestive system diseases are commonly and frequently encountered diseases clinically,and the functional gastrointestinal disorders(FGIDs)account for a considerable proportion in digestive disease clinic.In the medical field,most doctors focus on gastrointestinal organic diseases,but the study of FGIDs receives little attention.The main reason for this situation is that only part of gastrointestinal physiological parameters could be acquired by interventional detection equipment under abnormal physiological state and these data have a low credibility.Until recently,people have not been able to fully understand motion characteristics and regularity of the gastrointestinal tract,and there have not been any effective ways to evaluate function of the gastrointestinal tract.Although the problem of acquiring gastrointestinal physiological parameters under normal physiological state has been solved with the appearing of micro electronic capsule,yet the working time of most micro electronic capsule products is too short for some subjects to finish the whole gastrointestinal tract examination.Under the supports of the Advanced Study of Manned Space Project(010203),the National Natural Science Foundation of China(31170968)and the Program of Shanghai Science and Technology Commission(09DZ1907400),a multi-parameter gastrointestinal inspection system has been developed,which can obtain multiple physiological parameters of human gastrointestinal tract under the normal physiological state.In this system,design of micro electronic capsule is based on Application Specific Integrated Circuit(ASIC),of which independent intellectual property rights are owned by us.The stability and reliability of the micro electronic capsule system have been improved,and the power consumption of the system has been reduced by using this ASIC chip as well.On this basis,the research on motility function of gastrointestinal tract has been carried out.We have analyzed motion characteristics of gastrointestinal peristalsis pressure signal,and a method for evaluating the motion state of gastrointestinal tract has also been proposed.This study tries to further the research on acquiring gastrointestinal tract physiological parameters under normal physiological state,denoising physiological signals,analyzing different gastrointestinal diseases,and evaluating assessment method of the motility state of gastrointestinal tract.The main content and contribution of this dissertation can be summarized as the following aspects:A multi-parameter noninvasive gastrointestinal tract inspection system is developed,which consists of one micro electronic capsule,one portable data recorder and one data processing workstation.Based on the characteristics of gastrointestinal physiological signals,an ASIC chip with independent intellectual property rights has been developed.This chip integrates analog switch,signal amplifier,analog-to-digital converter,clock system,reference voltage source and some other functional modules.Not only is the power consumption of micro electronic capsule system reduced,but the reliability of the system is improved as well by applying the ASIC chip.In order to improve the stability of the pressure sensor integrated into the micro electronic capsule,the structure of the pressure sensor module has been optimized,and simulation result and test result confirm that the optimized structure is effective for enhancing the stability of the pressure sensor module.The denoise and signal extraction methods for gastrointestinal physiological parameter have been researched.After analyzing the pressure signal of gastrointestinal tract,a method of dividing the pressure signal has been proposed.According to the characteristics of pressure signal in gastrointestinal tract,denoise method based on wavelet analysis has been studied.Compared with the traditional filter,wavelet denoise can better eliminate noise from physiological signal.By utilizing wavelet multiscale analysis,the peristalsis signal of the gastrointestinal tract could be extracted.The peristalsis signal can reflect systolic and diastolic state of gastrointestinal tract.The motility of the human digestive system possesses some characteristics of nonlinear systems,so nonlinear systematic analysis method has been applied to analyze the human gastrointestinal physiological signals.In this paper,the differences of colonic peristalsis pressure signal between healthy subjects and patients with gastrointestinal dysfunction have been analyzed and explained from the perspective of system complexity.Many calculations,such as box dimension,multi-fractal spectrum,approximate entropy,C0 complexity and L-Z complexity,are used to calculate the complexity of colonic peristalsis pressure signal.According to the results,the applicability of different algorithms for the colonic peristalsis pressure signal is analyzed.The L-Z complexity of different subjects' colorectal pressure signal have been calculated and the discrepancy has also been analyzed.The clustering method has been studied based on characteristic parameters of colonic peristalsis pressure signal.Characteristic parameters which reflect the motility state of the gastrointestinal tract are extracted;then the characteristic parameters are clustered by using fuzzy C-means clustering algorithm.In order to avoid the fuzzy Cmeans clustering algorithm falling into a local optimal solution,ant colony clustering algorithm with the global searching ability is used to calculate the clustering center of sample data.The clustering center acquired from ant colony clustering algorithm will be used as the initial cluster center of fuzzy C-means clustering algorithm,then a new clustering center could be obtained by iterating.Based on this method,the characteristic parameters of colonic peristalsis pressure signal which come from healthy subjects and patients with slow transit constipation are used for clustering.Clustering results show that the same type of subjects can be clustered into one class.In addition,the complexity of gastrointestinal peristalsis pressure signal is used for clustering.Colorectal movement characteristics of different types of subjects have been studied by clustering.This method not only can evaluate the gastrointestinal tract status of the subjects,but also can distinguish various types of functional constipation.The method proposed in this dissertation has an important significance for the clinical diagnosis of functional constipation.Although this dissertation presents some criteria for gastrointestinal tract motility state,these methods should be further verified by more sample data.Finally,the work of this dissertation and research results are summarized,and further research work is also discussed. |
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