Preliminary Study of a Novel Puborectalis-Like Artificial Anal Sphincter

Perception of defecation intent: applied methods and technology trends

The aging population has led to a widening gap between the supply and demand for defecation care. To address this issue, the development of defecation care devices is the most direct and effective solution. Pre-defecation care devices offer a more personalized and comfortable alternative to the conventional post-defecation care devices currently available on the market. Furthermore, they facilitate greater patient involvement in the care process. Real-time monitoring and accurate identification of defecation intention are key technologies in the development of pre-defecation nursing devices. Automatic and accurate online monitoring of defecation intention can provide accurate early warning information for differentiated defecation assistance and cleansing care, effectively reducing nursing workload and improving patients' quality of life. However, there are relatively few studies on real-time monitoring and accurate identification of defecation intention. This review summarizes the existing defecation intention sensing technologies and their monitoring principles and research status, and explores the potential development direction of defecation intention sensing systems by comparing the characteristics and application conditions of various sensing technologies, which provides a direction for perception strategies for future defecation intention monitoring and early warning research.

Problems with repairing gut sphincters malfunctions

Correcting a gut sphincter malfunction is a difficult problem. Because each sphincter has two opposite functions, that of closure and opening, repairing one there is a risk of damaging the other. Indeed, widening a narrow sphincter, such as lower esophageal sphincter (LES) and anal sphincter, may cause gastroesophageal reflux and fecal incontinence, respectively, whereas narrowing a wide sphincter, may cause a difficult transit. All the corrective treatments for difficult or retrograde transit concerning LES and anal sphincter with their unwanted consequences have been analyzed and discussed. To overcome the drawbacks of sphincter surgical repairs, researchers have devised devices capable of closing and opening the gut lumen, named artificial sphincters (ASs). Their function is based on various mechanisms, e.g., hydraulic, magnetic, mechanical etc, operating through many complicated components, such as plastic cuffs, balloons, micropumps, micromotors, connecting tubes and wires, electromechanical clamps, rechargeable batteries, magnetic devices, elastic bands, etc. Unfortunately, these structures may facilitate the onset of infections and induce a local fibrotic reaction, which may cause device malfunctioning, whereas the compression of the gut wall to occlude the lumen may give rise to ischemia with erosions and other lesions. Some ASs are already being used in clinical practice, despite their considerable limits, while others are still at the research stage. In view of the adverse events of the ASs mentioned above, we considered applying bioengineering methods to analyze and resolve biomechanical and biological interaction problems with the aim to conceive and build efficient and safe biomimetic ASs.

Artificial sphincters: An overview from existing devices to novel technologies

Artificial sphincters (ASs) are used to replace the function of the biological sphincters in case of severe urinary and fecal incontinence (UI and FI), and gastroesophageal reflux disease (GERD). The design of ASs is established on different mechanisms, e.g., magnetic forces or hydraulic pressure, with the final goal to achieve a implantable and durable AS. In clinical practice, the implantation of in-commerce AS is considered a reasonable solution, despite the sub-optimal clinical outcomes. The failure of these surgeries is due to the malfunction of the devices (between 46 and 51%) or the side effects on the biological tissues (more than 38%), such as infection and atrophy. Concentrating on this latter characteristic, particular attention has been given to the interaction between the biological tissues and AS, pointing out the closing mechanism around the duct and the effect on the tissues. To analyze this aspect, an overview of existing commercial/ready-on-market ASs for GERD, UI, and FI, together with the clinical outcomes available from the in-commerce AS, is given. Moreover, this invited review discusses ongoing developments and future research pathways for creating novel ASs. The application of engineering principles and design concepts to medicine enhances the quality of healthcare and improves patient outcomes. In this context, computational methods represent an innovative solution in the design of ASs, proving data on the occlusive force and pressure necessary to guarantee occlusion and avoid tissue damage, considering the coupling between different device sizes and individual variability.

Design and evaluation of perception reconstruction with sensor system for artificial anal sphincter based on vector similarity

BACKGROUND

Artificial organs are playing an increasingly important role in medical field. Artificial anal sphincter, as an example, is a widely used medical device for fecal incontinence. Though it could help patients maintain continence, the issue of perception reconstruction is still unsolved, which means that patients cannot control defecation as desired.

METHODS

In this paper, a novel sensor system based on vector similarity has been analyzed and evaluated. The sensor system is a self-packaged strain gauge sensor with a small size 14.5mm x 6mm, especially for medical device implanted in body to reconstruct perception function. In order to overcome the disadvantages of single threshold judgment, a more accurate and reliable judgment standard for content pressure detection in rectum is developed by using vector similarity method. Therefore, in the novel sensor system, standard multi-parameters are comprehensive considered. Furthermore, weight-optimization of sensors are investigated since each sensor has played a different role in detection. Finally, sensor calibration, in vitro and in vivo experiments are established.

RESULTS

In sensor calibration, the result R² > 0.99 presents the strain gauge pressure sensor has a good linearity. After that, a series of in vitro experiments have been conducted. The optimized sensor system shows a high accuracy rate in perception reconstruction, which is 87.5% on early warning and 95% on the alarm. In the following in vivo experiments. The results indicate that the average accuracy of the proposed perception reconstruction module has increased by 17.7%, compared with that without optimized sensor system.

CONCLUSIONS

All of these have proven that the novel perception reconstruction module with sensor system based on vector similarity is more acceptable and reliable.

Design, Improvement and Evaluation of a Novel in Situ Implanted Bionic Artificial Anal Sphincter

Artificial anal sphincter has gradually become an emerging means of treating anal incontinence. However, most of the systems cannot be implanted in the human body for a long time due to insufficient reliability. Therefore, this paper has designed and improved a novel bionic artificial anal sphincter (BAAS). In order to make it work reliably for a long time, we first optimized and improved key parts to increase their strength. Given the humid working environment in the body, we optimized the design of the waterproof pressure sensor and carried out experimental research on the sealing of the circuit board and the overall sealing. When evaluating the improved system, I used simulation to analyze the structural strength and motion characteristics of the BAAS and used underwater experiments to simulate the human environment to evaluate the waterproofness of the system. The results showed that the strength of the key joint increased by 49.4%, the average clamping time and opening time of the prosthesis were 14.5s and 13.4s, respectively, and the angular velocity of the pendulum rod approaching the intestine was about 4.5°/s, which was in line with the normal defecation process of the human body. The performance is stable and reliable in the 20-day underwater body fluid simulation experiment. BAAS basically meets the application needs of long-term implantation in the treatment of fecal incontinence.

Diagnosis analysis of rectal function through using ensemble empirical mode decomposition-deep belief networks algorithm

The rectal motility function can reflect a person's rectal health status. To diagnose the rectal motility function after artificial anal sphincter implantation, this paper proposes a rectal function diagnosis model based on ensemble empirical mode decomposition-deep belief networks (EEMD-DBNs). Because of the rectal pressure signals that are unstable and subjected to noise interferences, an EEMD framework based on EMD, which can reduce the effect of signal modal mixing, is proposed. EMD and EEMD were used to decompose the analog signal, respectively, and it was found that EEMD can significantly reduce the effect of mode aliasing. During the rectal pressure signal decomposition experiment, by analyzing the intrinsic mode functions generated by the signals from normal people and diseased patients, the rectal signals at these two different conditions can be well distinguished. Additionally, the DBN was introduced to perform deep learning to extract the multi-dimensional features of rectal signals and then output the classification results via using the top-level classifier, which can overcome the difficulties in extracting the rectal signal features. The results showed that, following the principle of balancing the diagnosis accuracy and model running speed, the best diagnosis performance was achieved when three restricted Boltzmann machines and five layers of DBN model were set, with the diagnosis rate of 85%. The diagnostic model used in this study can distinguish the signals between normal and abnormal rectal functions with accurate performance, thus providing the technical support for the recovery of the rectal motility function of artificial anal sphincter implanters.

An artificial anal sphincter based on a novel clamping mechanism: Design, analysis, and testing

An artificial anal sphincter is a device to help patients with fecal incontinence rebuild the ability to control the excrement through the anus. In this article, an artificial anal sphincter based on a novel clamping mechanism (AASNCM) is proposed to improve the safety and reliability. The AASNCM, which is powered by a transcutaneous energy transfer system, consists of a novel clamping mechanism, a receiving coil and a control unit. According to design requirements, the novel clamping mechanism model was established. After that, its kinematics and dynamics were analyzed. The results of force tests on the prototype AASNCM show that the maximum values of clamping force and expanding force are 15.859 and 31.029 N, respectively. Comparing the experimental results with theoretical analysis, a good match can be concluded. Finally, in vitro experiments were conducted, and have verified the safety and reliability of the proposed AASNCM.

Modelling on mutual inductance of wireless power transfer for capsule endoscopy

Wireless capsule endoscopy (WCE) is noninvasive, painless, and riskless on detection for gastrointestinal disease. It attracts increasing attention. Wireless power transfer (WPT) technology is utilized to supply power for WCE. Receiving coil (RC) of WPT is capsulated into WCE. Its position and direction change all through gastrointestinal tract. Transmitting coil (TC) is worn by the patient. So the mutual inductance varies all the time. It should be studied to ensure sufficient receiving power. However, existing analytical methods do not reach satisfactory accuracy. They can only solve simple cases with positional misalignment. Numerical simulation models are time-consuming. Furthermore, an entirely new simulation must be repeated when any change in alignment occurs. Thus, based on geometry and misalignment of RC and TC, a model for mutual inductance is proposed. Compared with analytical methods, it is applicable to not only circular and rectangular RC, but also the elliptic, with directional misalignment. It costs below 0.1% of computational time of the simulation for the same accuracy. Moreover, any change in misalignment is easily handled by a simple change of parameter in the model. It reaches a tradeoff between computational accuracy and time. Receiving power is evaluated rapidly and accurately with proposed model.

Design and evaluation of puborectalis-like artificial anal sphincter that replicates rectal perception

While fecal incontinence (FI) is not fatal, it can dramatically decrease the patient's quality of life. An artificial anal sphincter (AAS) is an implantable device that treats FI by replacing a diseased or damaged anal sphincter, thus allowing the patient's continence to be maintained. Here, we report a novel implantable puborectalis-like artificial anal sphincter (PAAS) that replicates rectal perception and has a low risk of ischemia necrosis. Using the pressure sensors embedded in the PAAS, the relationship between the mass of feces and the pressure was determined, and a feces mass estimation model was developed based on in vitro studies. Rectal perception is provided through the real-time monitoring of rectal feces, and the feeling of defecation is quantified based on a comparison between the feces mass and a preset threshold mass. In vivo studies were performed for validation, and the accuracy of the model was determined to be as high as 90%. The performance of the PAAS in the real-time monitoring of rectal feces and its in vivo biocompatibility were also evaluated. The device should further the functionality of existing AAS systems while improving their biosafety and thus expand the applicability of implantable AAS systems in the treatment of FI.

Inhibition of hyperplasia during the implantation of the puborectalis-like artificial anal sphincter

OBJECTIVES

This study aims to extend the implantation lifetime of the puborectalis-like artificial anal sphincter by inhibiting the occurrence of hyperplasia following the implantation process.

METHOD

A new transmission structure was designed inside the puborectalis-like artificial anal sphincter to generate an adequate torque to maintain the feces, even if hyperplasia developed around the prosthetic sphincter. An outer shell was added to the prosthetic sphincter to decelerate the occurrence of hyperplasia on the outer shell side. Medical titanium alloy was tested to replace the nylon-12 prosthetic sphincter, while polyetheretherketone was used for the construction of the power supply unit in the puborectalis-like artificial anal sphincter system instead of nylon-12. In vivo experiments were conducted to evaluate all the methods presented in this study with 10 Pa Ma piglets, 1 domestic pig, and 1 beagle dog during the past 2 years.

RESULTS

Compared with the previous prosthetic sphincter that was equipped with a fixed-axle gear transmission, the new transmission structure is equipped with a planet-gear train managed to generate a prosthetic sphincter output with a 53% larger torque but with the same size and type of motor as that used previously and increase the implantation lifetime by 56%. After the replacement of the nylon-12, the new prosthetic sphincter made of medical titanium alloy succeeded in extending the implanted lifetime by 83%. In addition, the lifetime was increased by 143%, when an outer shell was added to the prosthetic sphincter. Polyetheretherketone significantly decreased the growth rate of hyperplasia around the power supply unit by 44% after the replacement of the power supply unit material. After the combination of all the improvements, the longest implantation lifetime of the puborectalis-like artificial anal sphincter during the in vivo experiments was 7 months and 10 days, which reflected an improvement of 249%.

CONCLUSION

All methods posted in this study were evaluated to be effective to prolong the implantation lifetime of the puborectalis-like artificial anal sphincter. Among the methods proposed, the most effective was the addition of the outer shell to the puborectalis-like artificial anal sphincter. The least effective method was the improvement of the transmission structure. Medical titanium alloy and polyetheretherketone were good replacements for nylon-12 that managed to extend the implantation lifetime and yield a moderate improvement.

Research of improved fast independent component analysis algorithm in rectal diagnosis signal preprocessing

With the maturity of artificial organ technology, the use of artificial anal sphincters was proposed to help patients who suffered anal incontinence for various causes reconstruct rectal perception, monitor rectal pressure and diagnose rectal lesion. Aimed at the lack of signal pretreatment in the artificial anal sphincter system, we find a way to solve it, that is, the multi-dimensional reconstruction of the intestinal one-dimensional pressure signal sequence by using phase space reconstruction, and the separation of the reconstructed signal by using the improved fast independent component analysis algorithm. We did some relevant experiments, further extracted the features of the isolated rectal signal, and used back propagation neural network to diagnose the rectal lesions. Experiments show that the method can pretreat the rectal signal, and further analyze the separated signal to diagnose of rectal function. The improved fast independent component analysis algorithm has few iterations, fast convergence, short run time, low requirements on initial weights and good diagnosis. This study lays a foundation for the diagnosis of rectal function by using artificial anal sphincters.

Artificial Organs 2017: A Year in Review

In this Editor's Review, articles published in 2017 are organized by category and summarized. We provide a brief reflection of the research and progress in artificial organs intended to advance and better human life while providing insight for continued application of these technologies and methods. Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level." Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ Replacement, Recovery, and Regeneration from all over the world. Peer-reviewed Special Issues this year included contributions from the 12th International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion edited by Dr. Akif Undar, Artificial Oxygen Carriers edited by Drs. Akira Kawaguchi and Jan Simoni, the 24th Congress of the International Society for Mechanical Circulatory Support edited by Dr. Toru Masuzawa, Challenges in the Field of Biomedical Devices: A Multidisciplinary Perspective edited by Dr. Vincenzo Piemonte and colleagues and Functional Electrical Stimulation edited by Dr. Winfried Mayr and colleagues. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers the quality expected from such a journal could not be possible. We also express our special thanks to our Publisher, John Wiley & Sons for their expert attention and support in the production and marketing of Artificial Organs. We look forward to reporting further advances in the coming years.