Novel bionics developments in gastroenterology: fecobionics assessment of lower GI tract function.

Biomechatronics (bionics) is an applied science that is interdisciplinary between biology and engineering (mechanical, electrical and electronics engineering). Biomechatronics covers a wide area and is probably best known in development of prosthetic limbs, vision aids, robotics and neuroscience. Although the gastrointestinal tract is difficult to study, it is particularly suited for a bionics approach as demonstrated by recent developments. Ingestible capsules that travel the tract and record physiological variables have been used in the clinic. Other examples include sacral nerve stimulators that seek to restore normal anorectal function. Recently, we developed a simulated stool termed fecobionics. It has the shape of normal stool and records a variety of parameters including pressures, bending (anorectal angle) and shape changes during colonic transit and defecation, i.e. it integrates several current tests. Fecobionics has been used to study defecation patterns in large animals as well as in humans (normal subjects and patient groups including patients with symptoms of obstructed defecation and fecal incontinence). Recently, it was applied in a canine colon model where it revealed patterns consistent with shallow waves originating from slow waves generated by the interstitial cells of Cajal. Furthermore, novel analysis such as the rear-front pressure (preload-afterload) diagram and quantification of defecation indices have been developed that enable mechanistic insight. This paper reviews the fecobionics technology and outlines perspectives for future applications.

Fecobionics assessment of the effect of position on defecatory efficacy in normal subjects.

BACKGROUND: Defecation is a complex process and up to 25% of the population suffer from symptoms of defecatory dysfunction. For functional testing, diagnostics, and therapy of anorectal disorders, it is important to know the optimal defecation position. is The aim of this study was to evaluate defecation pressure patterns in side lying, seated and squatting defecation positions in normal subjects using a simulated stool device called Fecobionics. METHODS: The Fecobionics expulsion parameters were assessed in an interventional study design conducted from May 29 to December 9 2019. Subjects were invited to participate in the study through advertisement at The Chinese University of Hong Kong. The Fecobionics device consisted of a core containing pressure sensors at the front (caudal end) and rear (cranial end) and a polyester-urethane bag spanning most of the core length which also contained sensors. The Fecobionics bag was distended to 50 ml in the rectum of normal subjects (no present and past symptoms of defecatory disorders, no prior abdominal surgery, medication or chronic diseases). Studies were done in side lying (left lateral recumbent position), seated (hip flexed 90°) and squatting position (hip flexed 25°). Pressure endpoints including the rear-front pressure diagram and defecation indices were compared between positions. RESULTS: Twelve subjects (6 females/6 males, mean age 26.3 ± 2.6 [19.0-48.0] years) were included and underwent the planned procedures. The resting anal pressure for side lying and seated positions were 33.1 ± 4.1 cmH2O and 37.1 ± 4.0 cmH2O (p > 0.3). The anal squeeze pressure for side lying and seated positions were 98.4 ± 6.9 cmH2O and 142.3 ± 16.4 cmH2O (p < 0.05). The expulsion duration for the side lying, seated and squatting positions were 108.9 ± 8.3 s, 15.0 ± 2.1 s and 16.1 ± 2.9 s, respectively (p < 0.01 between lying and the two other positions). The maximum evacuation pressure for seated and squatting were 130.1 ± 12.4 cmH2O and 134.0 ± 11.1 cmH2O (p > 0.5). Rear-front pressure diagrams and distensibility indices demonstrated distinct differences in pressure patterns between the side lying position group and the other positions. CONCLUSIONS: The delay in expelling the Fecobionics device in the lying position was associated with dyssynergic pressure patterns on the device. Quantitative differences were not found between the seated and squatting position. Trial Registration http://www.clinicaltrials.gov Identifier: NCT03317938.

Propagation speed of sound assessment in the layers of the guinea-pig esophagus in vitro by means of acoustic microscopy.

The study's purpose was to evaluate the propagation speed of sound in the tissue layers of the esophagus at various mechanical loadings. Scanning laser acoustics microscopy was applied for the estimation of the propagation speed in the mucosa-submucosa and muscle layers of guinea-pig esophagus in vitro (n = 26). The propagation speed in the esophagus was determined in the no-load state with all external forces removed, and in the distended and zero-stress states. The zero-stress state was obtained by cutting the esophageal rings radially. The propagation speed in the no-load state differed significantly (p < 0.001) between the muscle layer (median 1740, quartiles 1735-1746 m/s) and the mucosa (1607, 1605-1609 m/s). In the distended state the propagation speed in the muscle layer decreased significantly (p < 0.001) to 1673 (1666-1681) m/s while it did not change significantly in mucosa (1602, 1600-1607 m/s). When compared to the no-load state, the propagation speed in the zero-stress state in the muscle layers decreased to 1624 (1615-1636) m/s (p < 0.001) and in mucosa to 1584 (1566-1603) m/s (p < 0.001). In conclusion, the esophagus is a composite structure with heterogeneous propagation speed characteristics. Furthermore, the mechanical loading state must be considered in esophageal ultrasound studies.

In vivo assessment of luminal cross-sectional areas and circumferential tension-strain relations of the porcine aorta.

UNLABELLED: The objectives were to measure the pressure--cross-sectional area relations and intrinsic stiffness of the porcine aorta in vivo. METHODS: Measurements were made in 12 pigs, weight 30, 50 or 75 kg, proximal and distal to the bifurcation of the renal arteries, using an electrical impedance system which was located inside a balloon mounted on a catheter. Vessel cross-sectional area (CSA) was assessed by measuring impedance of the fluid inside the balloon during distension. RESULTS: In vitro testing demonstrated the accuracy and reproducibility of impedance planimetry. In vivo steady-state CSA values showed non-linear relationship with rising distension pressures. Mean CSA values rose with increasing weight of the pigs. the suprarenal aorta was larger than the infrarenal only in 75 kg pigs (p < 0.05). At three measurements the within-subject variation was 0.89% and the between-subject variation 99.11%. Nitroglycerine infusion produced only minor, insignificant CSA increase, indicating negligible tone in the abdominal aorta. All segments showed circumferential wall strain-tension relations with exponential behaviour uninfluenced by weight class or site in the aorta. CONCLUSION: Information of vascular mechanics in vivo is obtainable by catheterization of the abdominal aorta.

[The clientele of physiotherapists in private practice]. / Privatpraktiserende fysioterapeuters klientel.

The aim of the study was to describe sociomedical characteristics of physiotherapy patients. A material of 466 patients answered questions about personal and social data and their disease. Women were significantly more frequent in the material than men (p less than 0.001). The following groups were underrepresented compared to the background population calculated by X2: 1) boys 0-9 years, 2) girls 0-19 years, 3) women more than 80 years old, 4) officials, 5) unskilled workers and 6) unemployed. The following groups were overrepresented: 1) women 30-39 years, 2) women 60-79 years, 3) pensioners and persons receiving public assistance and 4) students. More than half of the symptoms were located to the head-neck or back-thorax-loin. The cause was most often primarily somatic (46%), while 25% had an occupational genesis.