| BackgroundFaecal incontinence is the involuntary loss of liquid or solid stool and continued for more than one month. The main clinical manifestations of FI is inability to control bowel movements or leaking stool which is one of the common diseases of anorectal surgery. Studies have shown that the incidence of faecal incontinence in adults was5%to10%, with1%to2%experiencing significant impact on daily activities. There is a higher incidence of fecal incontinence in the elderly, women, and frail people. It becomes more common with advancing age and disability. Faecal incontinence is a social or hygienic problem which has a major negative impact on physical and psychological health and lifestyle, many sufferers feel that is particularly embarrassing and socially unacceptable, and do not seek professional treatment.There are multiple reasons could lead to fecal incontinence, including obstetric or other trauma, or a congenital abnormality of one or both of the anal sphincters or the pelvic floor muscles; neurological disease or injury causing sensory or motor impairment to the continence mechanism; local anorectal pathology; rectal loading and subsequent "overflow" leakage in frail or immobile individuals; and physical or mental disabilities affecting toilet habits. With the increase of fecal incontinence incidence, the study on fecal incontinence is gradually increasing and many treatments were applied to treat fecal incontinence, such as biofeedback training, pelvic floor muscle strengthening treatment, electrical stimulation of sacral nerve and reconstruction of autologous tissue of the anal sphincter. These treatments received a certain effects on incomplete fecal incontinence, but the fully fecal incontinence, such as the rectum low tumor that the anal sphincter and peripheral nerve were completely damaged is lack of effective treatment methods. Successful application of artificial urinary sphincter in the treatment of urinary incontinence provides a new strategy for the treatment of fecal incontinence. The application of artificial anal sphincter has made some patients regain the ability to control defecation. However, the existing artificial anal sphincter still have some limitations, such as lack of perception and feedback, hypoxic ischemic complications caused by the oppression of the artificial anal sphincter, complicated implant surgery, and inconvenient to use that limit the promotion and application of artificial anal sphincter.Objective:For these reasons, according to the defects of the existing artificial anus and the human body defecation principle, we use biomedical engineering technology to look forward to developing a highly integrated in situ intelligent artificial anal sphincter system and lay the foundation for the development and application of the artificial anus. And the situ intelligent artificial anal sphincter system has the function of perception and feedback, can effectively control stool outflow, convenient to use, with good biocompatibility.Method1. Development of biofeedback artificial anal sphincter perceptual system1.1Study on the manufacture of the artificial anal sphincter pressure acquisition cuffThe artificial anal sphincter pressure acquisition cuff was made base on the Artificial Anal Sphincter and rectal physiology, put the soft silicone membrane tube into the rigid polyethylene pipe, then reflex both ends of the silicone tube, cover and stick on both ends of polyethylene pipe to form a closed set of capsule. An aqueduct was lead from the outer wall of the cuff which connected with the cavity of cuff.1.2Determine the relationship of pressure between the intestinal and acquisition cuffConnecting the pressure sensors, pressure acquisition cuff and syringe with three-way pipe, then connecting the pressure sensors to PCLAB-UE biomedical signal acquisition and processing system. Twenty healthy New Zealand rabbits were used to test its feasibility, and the experiments were performed on the distal part of proximal colon of the rabbits. The pressure of colon and pressure acquisition cuff were measured after injecting four states simulation intestinal contents of gas, liquid, semi-fluid, solid into the colon respectively, and the relationship between the volume of the four states of intestinal contents and the intestinal pressure and the cuff pressure was analyzed.1.3Statistical analysisRecord the pressure of the experimental bowel and pressure acquisition cuff while injecting four different types of simulated intestinal contents, and all data was analyzed and tested with SPSS13.0statistical software, and analysis the correlation of the pressure between the experimental bowel and pressure acquisition cuff respectively.1.4Study on the establishment of the pressure acquisition and feedback systemMake use of pressure sensor to collect the real-time pressure of acquisition bowel, and the pressure signals were converted to electrical signals and send to the central control system which comparison of intestinal real-time pressure and preset threshold pressure. When the pressure reach to the threshold the central control system drive buzzer alarm to remind patients to defecate.2. Study on the manufacture of artificial anal sphincter system 2.1Manufacture of artificial anal sphincter cuffWe designed cylindrical and L-shaped with pressure sensor artificial anal sphincter. The inner wall of artificial anal sphincter was made by soft silicone membrane and the outer wall was made by cylindrical and L-shaped rigid polyethylene pipe. An aqueduct was lead from the outer wall of the cuff which connected with the cavity of cuff.2.2Determine the relationship of pressure between the artificial anal sphincter and bowel when it leakageConnecting the pressure sensor, artificial anal sphincter cuff and syringe with three-way pipe, then connecting the pressure sensor to PCLAB-UE biomedical signal acquisition and processing system. Twenty healthy New Zealand rabbits were used to test and compare the two artificial anal sphincters’ bowel-restrained function, and the experiments were performed on the distal part of proximal colon of the rabbits. Put the experimental bowel into through the pressure acquisition cuff, and inject water into the artificial anal sphincter cuff to control the bowel leakage, and maintain the artificial anal sphincter cuff pressure at different levels. Then inject saline into the experimental bowel to simulate formation of stool, and record the pressure of the bowel when it leakage.2.3Statistical analysisRecord the pressure of two types of artificial anal sphincter cuff and that of the experimental bowel when it leakage and all data was analyzed and tested with SPSS13.0statistical software.2.4Study on the establishment of artificial anal sphincter pressure detection moduleConnecting the pressure sensor, artificial anal sphincter cuff and syringe with three-way pipe, the difference signal output from the pressure sensor was processed by the filtering, amplification and signal isolation conditioning circuit, and then lead to central processor A/D converter module to acquisition real-time sphincter pressure.2.5Study on establishment of pump control module of artificial anal sphincterThe pump control module of artificial anal sphincter consists of low-power micro gear pump and its drive circuit. The central processor of drive circuit can drive the pump forward, backward and shutdown so as to control the artificial anal sphincter expansion and contraction.3. Study on the establishment of situ intelligent artificial anal sphincter system and observation on its efficacy3.1Study on the establishment of LCD module, matrix keyboard module, central processor module, and alarm, keys and power modulesWe make use of LCD1602to establish LCD module to display the intestinal pressure and alarm information,4*4matrix keyboard and MM74C922keyboard scanning chip to establish matrix keyboard module to set the parameters, ARM-Cortex-M3chip to establish central processor module, and buzzer to establish alarm module.3.2Design and implementation of the each system module softwareAccording to the requirements of the system function, the system software was divided into four functional modules:bowel pressure A/D sampling module, pump control module, LCD module, keyboard input module. And the system software was compiled and debuged in the IAR compiler environment based on the C language.3.3Observation of the intelligent artificial anal sphincters’bowel-restrained functionSet the alarm threshold and the artificial anal sphincters’bowel-restrained pressure base on the pre-experiment. The physiological saline was injected into the bowel to simulate the formation of stool, and observe the bowel-restrained function of the intelligent artificial anal sphincters. Result1. Development of biofeedback colostomy sensing systemWe developed a biofeedback colostomy sensing system with pressure acquisition cuff, pressure sensor and its conditioning circuit. The results of the experiment showed that the pressure of colon and pressure-detection cuff was increased with the increasing of the volume of intestinal contents, the pressure and the volume was positively correlated within a certain range.[Gaseous intestinal contents (R2=0.981, P<0.001),Liquid intestinal contents (R2=0.981, P<0.001), Semi-fluid intestinal contents (R2=0.981, P<0.001), and Solid intestinal contents (R2=0.981, P<0.001)]。2. Study on the manufacture of artificial anal sphincterWe designed cylindrical and L-shaped with pressure sensor artificial anal sphincter. Twenty healthy New Zealand rabbits were used to test and compare the two artificial anal sphincters’ bowel-restrained function, and the experiments were performed on the distal part of proximal colon of the rabbits. The results of the experiment show that when the cylindrical and the L-shaped artificial anal sphincters’ bowel-restrained pressure reach to60mmHg, the leakage pressure of bowel under the control of the two anal sphincters are75.26±3.74mmHg and83.26±2.08mmHg.3. Study on the establishment of situ intelligent artificial anal sphincter system and observation on its efficacyWe established a situ intelligent artificial anal sphincter system, and the system was divided into four functional modules:bowel pressure A/D sampling module, pump control module, LCD module, keyboard input module. The function of the intelligent artificial anal sphincter system was assessed in vitro and in vivo in New Zealand rabbits. The pressure of the feedback cuff was positively correlated with the pressure and the volume of the bowel within a certain range, the pressure feedback system able to reflect the change of the intra-intestinal pressure effectively. And the L-style artificial anal sphincter is available for the control of fecal incontinence under the control of chip microcomputer.Conclusion1. Development of biofeedback colostomy sensing systemAccording to experiment, the bio-feedback artificial anal sphincter perceptual system could effectively reflect the change of intestinal pressure and the volume of intestinal contents, and maybe a effective strategy to address the awareness and feedback problem of artificial anal sphincter, so as to lay the basis for the research of intelligent bio-feedback artificial anal sphincter.2. Study on the manufacture of artificial anal sphincterAccording to experiment, the two artificial anal sphincters are available for the control of fecal incontinence, and the L-shaped artificial anal sphincter is better than cylindrical artificial anal sphincter. It is concluded that with pressure feedback function and ergonomically designed artificial anal sphincter could provide a new reference to solve the complication because of the oppression.3. Study on the establishment of situ intelligent artificial anal sphincter system and observation on its efficacyThe results indicated that the IAAS could efficiently maintain continence and reflect the change of the intra-intestinal pressure, and lay a basis for the research of intelligent artificial anal sphincter. |
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