| BackgroundFecal incontinence is a disease with serious hazard to people's health and can be defined as the discharge of solid or liquid stool without self-control, which continues at least one month. The incidence of fecal incontinence is high in the elderly, women, and frail people. The causes of fecal incontinence include the loss of function of anal sphincter and nerve related to defecation. Multiple reasons, such as surgery, obstetric injury, trauma, rectal prolapse, inflammatory diseases, congenital anal deformity, neurological diseases, can lead to fecal incontinence. Fecal incontinence make patients lose the ability to work and seriously affect the physical and mental health if it can not be cured in a longterm.In order to restore anal normal function of the effective control of incontinence, many scholars over the years have made many explorations such as biofeedback training, pelvic floor muscle strengthening treatment, electrical stimulation of sacral nerve and reconstruction of autologous tissue of the anal sphincter. But up to now fecal incontinence has not been improved ideally through the application of those methods listed above. For those who suffered from complete fecal incontinence, the treatment by the prosthesis implanted in body may be the only option. Application of artificial anal sphincter by Christiansen in 1989 to control fecal incontinence opened up a new pathway for the treatment of fecal incontinence. After that, many experimental studies on artificial anal sphincter such as the Acticon (?) Neosphincter anal sphincter in United States, Prosthetic Anal Sphincter in the United Kingdom, Shape Memory Alloy based Artificial Anal Sphincter in Japan, Remote-Controlled based Artificial Bowel Sphincter in Germany, to control defecation, have been undergone.Up to now, fecal incontinence has been controlled to some extent by using artificial anal sphincter and it has relieve the patients from suffering from not being able to control bowel movements. However, the present various types of artificial anal sphincter are only able to make the stool accumulate in the intestine and work only as a manual device. The receptors on normal bowel can perceive stool and distinguish the different states of intestinal contents and the nerve impulses can be transmitted to the primary and advanced perception and defecation center. Therefore, the lack of receptors on artificial anal sphincter function leads to make the patients unble to perceive whether there are contents in intestinal lumen and the states of intestinal contents, thus the patient is unable to ascertain the actual situation of the intestinal tract, and can not take the initiative to make the decision to defecate.Ultrasound is mechanical oscillation in elastic mediums in two forms:horizontal oscillation (shear wave) and longitudinal oscillations (longitudinal wave). The longitudinal wave is used more in the practical application. Longitudinal wave beam can be targeted disseminated as its energy is much larger than the same general sound waves, thus it has strong penetrating power. Various substances have different acoustic impedance characteristics on the ultrasound, which reflects the ability of the material to transmit ultrasound, the higher the acoustic impedance, the more conductive to the propagation of ultrasound. Generally saying, the sequence of acoustic impedance of material is solid, liquid, followed by gas the minimum. There are gas, solid and liquid within intestine. Different attenuation would occur when the ultrasound pass through different intestinal contents, and ultrasonic sensors can convert the the ultrasonic signal received into defferent voltage signals.For these reasons, modern ultrasonic detection, microelectronic processing and communication technology were utilized so as to develop a system of" Intelligent Intestinal Contents Sensory Nerve" and lay the foundation for smart artificial anal sphincter.Methods and materials1. Study on preparation of ultrasonic detection system1.1 A digital multimeter was connected to the output of the amplifying circuit of ultrasonic bubble detection instrument of MLU02-212 type. And the digital multimeter range was adjusted to 2 voltages.1.2 A similar ring supporter was designed to fix the two modified ultrasonic transducers, making the planes of the ultrasonic transducers parallel to each other, with the emmitting center in the oposite direction of receiving center.1.3 The transducers merged into the saline were divided into three groups: completely submerged group, semi-submerged group, and the out of saline group.1.4 The data of the three states in the digital multimeter were recorded. Each state in water was measured 5 times and the mean values were caculated.1.5 The repeated measure analysis of variance was used tor analyzed the data of voltage in the three states to investigate whether there is significant difference among the three groups.2. Stuy on extracting signal of intestinal contents in different states by ultrasonic detection system.2.1 A first-order filter circuit) precision rectifier circuit and second-order filter circuit were manufactured next to the amplifier circuit of the ultrasonic detection system mentioned above. A wire was used to connect the end of the senond-order filter circuit to a digital multimeter.2.2 Ultrasonic detection system mentioned above was used to obtain voltage signal of solid, fluid, gas, and empty state of the intestine on proximal colon about 10 cm long in 20 New Zealand rabbits.2.3 Five measurement points were randomly selected for getting data of voltage on each bowel of each state and the mean values were calculated and recorded.2.4 The data of the voltage signal of the four states analyzed by repeated measure analysis of variance were used to determine whether there are significant differenc among the four groups.3.Study on the Intelligent Intestinal Contents Sensory Nerve3.1 An "Intelligent Intestinal Contents Sensory Nerve" was manufectured with ultrasonic transducers, ultrasonic transmitter circuit, ultrasonic receiving ciruit, amplifier circuit, two-order filter circuit* precision rectifier circuit, microcontroller, alarming circuit and two LED lights(red and green).3.2 The software system of "Intelligent Intestinal Contents Sensory Nerve" to determine different states was composed into a microcontroller of TMega8 type. Software thresholds for solid, fluid, gas, empty of intestinal contents are defined as follows:#define VGAS ((295*400+500)/1000)#define VSOLID ((461*400+500)/1000)#define VFLUID ((611*400+500)/1000)3.3 The LED light states were defined as follows,When U(voltage)< 295mV, red and green are on at the same time, which indicate gas contents; 295mV<U?461 mV, only red light on, the solid content indicated.461mV<U?610 mV only green light on, the fluid indicated; When U>611mV, the red and green are both off, the empty state.3.4 Twenty healthy New Zealand rabbits were used to test the system, the experiment was performed on the distal part of proximal colon of the rabbits. Five positions were randomly chosen on each segment of proximal colon as the measuring points, and the "Intelligent Intestinal Contents Sensory Nerve" was used to judge the solid, liquid, gas, and vacant status of the content inside the colon lumen.Results1. Study on preparation of ultrasonic detection system1.1 The difference among the the voltage signal of the three states were statistically significant (F-value=27900, P-value=0.000), and the voltage signal of the three states for multiple comparisons aslo had significant differences (P-values for pairwise comparison were all 0.000).1.2 Voltage of completely immersed state (1215.60±2.30)> semi-immersed state signal (795.34±14.34)> air signal (375.22±2.21).2. Stuy on extracting signal of intestinal contents in different states by ultrasonic detection system.2.1 There was significant difference among the voltage signals of the 4 conditions. (F-value=5476,P-value= 0.000). Multiple comparisons showed significant difference existed in any pair of the four conditions (P= 0.000).2.2 Empty status signal (660.34±7.05)>fluid status signal (510.33±10.38)> Solid Signal (402.10±18.06)> gas signal (258.29±4.78).3.Study on the Intelligent Intestinal Contents Sensory NerveThe number of the right judgment about the solid,liquid,gaseous,and vacant status of the contents were 96%,99%,100%,100% respectively.Conclusion1. An "Intelligent Intestinal Contents Sensory Nerve" has been produced based on the application of ultrasonic detection, modern microelectronic processing and communication technology for the first time, and using ultrasound to detect the information of different status of intestinal lumen may be an effective method.2. This "Intelligent Intestinal Contents Sensory Nerve"could be used to judge the feces whether or not exists and to distinguish various states of intestinal contents.3. The "Intelligent Intestinal Contents Sensory Nerve" may to some extent make up the common weakness of lack of perception of intestinal contents and to distinguish intestinal contents for all kinds of artificial anal sphincter currently exist and lay the theoretical and practical foundation for the further development of intelligent artificial anal sphincter. |
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