Intestinal anastomotic healing models during experimental colitis

Background Anastomotic leakage represents a major complication following resections in colorectal surgery. Among others, intestinal inflammation such as in inflammatory bowel disease is a significant risk factor for disturbed anastomotic healing. Despite technical advancements and several decades of focused research, the underlying mechanisms remain incompletely understood. Animal experiments will remain the backbone of this research in the near future. Here, instructions on a standardized and reproducible murine model of preoperative colitis and colorectal anastomosis formation are provided to amplify research on anastomotic healing during inflammatory disease. Methods We demonstrate the combination of experimental colitis and colorectal anastomosis formation in a mouse model. The model allows for monitoring of anastomotic healing during inflammatory disease through functional outcomes, clinical scores, and endoscopy and histopathological examination, as well as molecular analysis. Discussion Postoperative weight loss is used as a parameter to monitor general recovery. Functional stability can be measured by recording bursting pressure and location. Anastomotic healing can be evaluated macroscopically from the luminal side by endoscopic scoring and from the extraluminal side by assessing adhesion and abscess formation or presence of dehiscence. Histologic examination allows for detailed evaluation of the healing process. Conclusion The murine model presented in this paper combines adjustable levels of experimental colitis with a standardized method for colorectal anastomosis formation. Extensive options for sample analysis and evaluation of clinical outcomes allow for detailed research of the mechanisms behind defective anastomotic healing.

Assessment of risk tendency of coal bursting pressure in deep outburst seam based on fuzzy evaluation method

In order to analysis the mechanism of coal bursting pressures of deep coal seams, and take effective methods to identify, monitor and control coal bursting pressure, this study takes 21101 working face of No. 2 Coal seam in Dongpang Coal Mine as an example, risk identification was carried out for the harmful factors of coal bursting pressure in coal seam 21101 in Dongpang Coal Mine, and each influencing factor was classified. The hierarchical structure model of the influencing factors of coal bursting pressure in coal seam protruding deep in Dongpang Coal Mine was established in combination with expert opinions, and the weight of each level index was calculated by MATLAB software. The results show that the 21101 working face of No. 2 coal seam in Dongpang Coal Mine has strong impact risk, and the main risk factors include geological structure, impact resistance of coal and rock, mining stress, inducing factors, emphasis degree of impact risk. According to the hierarchical structure model of the influencing factors, the corresponding safety measures are put forward to prevent the damage caused by coal bursting pressure in advance and ensure the high quality and safe production in the mine. The qualitative and quantitative methods are used to make the evaluation process more reasonable and scientific.

Effect of three different needle holders on gastrointestinal anastomosis construction time and bursting pressure in equine jejunal segments

Background Equine small intestinal resection and anastomosis is a procedure where optimizing speed, without compromising integrity, is advantageous. There are a range of different needle holders available, but little is published on the impact surgical instrumentation has on surgical technique in veterinary medicine. The objectives of this study were to investigate if the needle holder type influences the anastomosis construction time, the anastomosis bursting pressure and whether the bursting pressure is influenced by the anastomosis construction time. Single layer end-to-end jejunojejunal anastomoses were performed on jejunal segments harvested from equine cadavers. These segments were randomly allocated to four groups. Three groups based on the needle holder type that was used: 16.5 cm Frimand (Group 1), 16 cm Mayo-Hegar (Group 2) or 20.5 cm Mayo-Hegar (Group 3) needle holders. One (Group 4) as control without anastomoses. Anastomosis construction time was recorded. Bursting pressure was determined by pumping green coloured fluid progressively into the lumen whilst recording intraluminal pressures. Maximum pressure reached prior to failure was recorded as bursting pressure. Construction times and bursting pressures were compared between needle holder, and the correlation between bursting pressure and construction time was estimated. Results Construction times were not statistically different between groups (P = 0.784). Segments from Group 2 and Group 3 burst at a statistically significantly lower pressure than those from Group 4; P = 0.031 and P = 0.001 respectively. Group 4 and Group 1 were not different (P = 0.125). The mean bursting pressure was highest in Group 4 (189 ± 61.9 mmHg), followed by Group 1 (166 ± 31 mmHg) and Group 2 (156 ± 42 mmHg), with Group 3 (139 ± 34 mmHg) having the lowest mean bursting pressure. Anastomosis construction time and bursting pressure were not correlated (P = 0.792). Conclusions The tested needle holders had a significant effect on bursting pressure, but not on anastomosis construction time. In an experimental setting, the Frimand needle holder produced anastomoses with higher bursting pressures. Further studies are required to determine clinical implications.

Effect of input variables uncertainty in free tube hydroforming process

Tube hydroforming (THF) is a plastic forming process that uses tubes with an initial circular cross section, in which pressurized fluid and axial feeds are applied for producing parts with various cross-sectional shapes. Despite of the complexity of THF process, a great progress in the automotive and aerospace industry has been made due to its advantages, such as, consolidation and weight reduction over conventional stamped and welded parts. The analysis of THF process is typically based on deterministic approaches, excluding scattering effects that influence the process reliability. Thus, robust design of tube hydroforming aims to vanish noise factors effects on process responses by considering the influence of process parameters variability. If this fluctuation is not monitored, then the fluctuation of the hydroformed parts quality may contribute to high scrap rates. In this work, the influence of variability in the THF material and process parameters (e.g. yield stress, strength coefficient, strain hardening exponent, plastic anisotropy, initial tube thickness and bulged length) on the bursting pressure is analyzed resorting to a response surface model. The statistically significant variables, which mostly influence the free bulge hydroforming process, are identified through an analysis of variance. Assuming that the input parameters variability follows the normal distribution, the probability distribution of the bursting pressure is evaluated by involving random process variables into the built response surface model. It was shown that the initial tube thickness is the most statistically significant variable, whereas the strain hardening exponent is the least statistically significant variable.

An insight to tympanic membrane perforation pressure through morphometry: A cadaver study

Introduction: A cadaveric experimental investigation aimed to show the rupture pressure of the tympanic membrane (TM) for otologists to evaluate its tensile strength. Methods: Twenty adult ears in 10 fresh frozen whole cadaveric heads (four males, six females) mean age 72.8 (SD 13.8) years (range 40–86) were studied. The tensile strength of the TM was evaluated with bursting pressure of the membrane. The dimensions of the membranes and perforations were measured with digital imaging software. Results: The mean bursting pressure of the TM was 97.71 (SD 36.20) kPa. The mean area, vertical and horizontal diameters of the TM were 57.46 (16.23) mm2, 9.54 (1.27) mm, 7.99 (1.08) mm respectively. The mean area, length and width of the perforations were 0.55 (0.25) mm2, 1.37 (0.50) mm, and 0.52 (0.22) mm, respectively. Comparisons of TM dimension, bursting pressure, and perforation size by laterality and gender showed no significant differences. The bursting pressure did not correlate (positively or negatively) with the TM or perforation sizes. Conclusions: The TM can rupture during activities such as freediving or scuba diving, potentially leading to serious problems including brain injuries. Studying such events via cadaveric studies and data from case studies is of fundamental importance. The minimum experimental bursting pressures might better be taken into consideration rather than average values as the danger threshold for prevention of TM damage (and complications thereof) by barotrauma.

Ileocolonic Healing After Extended Small Bowel Resection in Mice: NOD2 Deficiency Impairs Anastomotic Healing and Postoperative Outcome

Background Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) mutations are a genetic risk factor for Crohn disease. Ileocecal resection is the most often performed surgery in Crohn disease. We investigated the effect of Nod2 knockout (KO) status on anastomotic healing after extended ileocecal resection (ICR) in mice. Methods Male C57BL6/J wild-type and Nod2 KO mice underwent an 11 cm resection of the terminal ileum including the cecum. An end-to-end jejuno-colostomy was performed. Animals were killed after 5 days investigating bursting pressure, hydroxyproline content, and expression of matrix metabolism genes, key cytokines, and histology of the anastomosis. Results Mortality was higher in the Nod2 KO group but not because of local or septic complications. Bursting pressure was significantly reduced in the Nod2 KO mice (32.5 vs 78.0 mmHg, P < 0.0024), whereas hydroxyprolin content was equal. The amount of granulation tissue at the anastomosis was similar but more unstructured in the Nod2 KO mice. Gene expression measured by real-time polymerase chain reaction showed significantly increased expression for Collagen 1alpha and for collagen degradation as measured by matrix metalloproteinase-2, -9, and -13 in the Nod2 KO mice. Gelatinase activity from anastomotic tissue was enhanced by Nod2 status. Gene expression of arginase I, tumor necrosis factor-α, and transforming growth factor-ß but not inducible nitric oxide synthase were also increased at the anastomosis in the Nod2 KO mice compared with the control mice. Conclusions We found that Nod2 deficiency results in significantly reduced bursting pressure after ileocecal resection. This effect is mediated via an increased matrix turnover. Patients with genetic NOD2 variations may be prone to anastomotic failure after bowel resection.

Stapler-less burst pressure in an ex vivo human gastric tissue: a randomized controlled trial

Stapler-less laparoscopic sleeve gastrectomy (LSG) is emerging as a new potential affordable cost-effective alternative procedure. However, no pre-clinical data are currently available on human tissue. We aimed to evaluate whether traditionally suturing without the use of surgical stapling may produce a comparable bursting pressure on human gastric tissue. A prospective cohort of consecutive patients undergoing LSG was divided in two groups to compare a barbed extra-mucosal running suture (stapler-less) versus a standard stapler line. A burst pressure test was applied to the gastric specimen employing high-resolution manometric catheter. Type, location and features of the leak were described. We enrolled a total of 40 obese patients, 20 patients for each group. Median burst pressures of the stapler-less group resulted statistically significant increased (p < 0.0001) than the one in standard stapler group. In all cases, leak occurred along the surgical closure site independently from the used technique (group 1 vs 2; p = N.S.), more often at the proximal stomach (p < 0.05). In human ex vivo model, traditional surgical suture (i.e. running hand-sewn) produced an effective temporary closure, with superior resistance to increasing volume and pressure. How this may impact on clinical LSG outcomes needs further evaluations and was not the object of this study.

Effect of Three Different Needle Holders on Gastrointestinal Anastomosis Construction Time and Bursting Pressure in Equine Jejunal Segments

Background: Equine small intestinal resection and anastomosis is a procedure where optimizing speed, without compromising integrity, is advantageous. There is a range of different needle holders available, but little is published on their impact on surgical technique in veterinary medicine. The objectives of this study were to investigate if the needle holder type influences the anastomosis construction time, and the anastomosis quality (estimated by bursting pressure), and whether the bursting pressure is influenced by the anastomosis construction time. Single layer end-to-end jejunojejunal anastomoses were performed on jejunal segments harvested from equine cadavers. These segments were randomly allocated to four groups. Three groups based on the needle holder type that was used: 16.5 cm Frimand (Group 1), 16 cm Mayo-Hegar (Group 2) or 20.5 cm Mayo-Hegar (Group 3) needle holders. One (Group 4) as control without anastomoses. Anastomosis construction time was recorded. Bursting pressure was determined by pumping green coloured fluid progressively into the lumen whilst recording intraluminal pressures. Maximum pressure reached prior to failure was recorded as bursting pressure. Construction times and bursting pressures were compared between needle holder, and the correlation between bursting pressure and construction time was estimated.Results: Construction times were not statistically different between groups. Yet, the mean construction time was shortest in Group 2 followed by Group 3, with Group 1 having the longest mean construction time but showing most consistency. Segments from Group 2 and Group 3 burst at a statistically significantly lower pressure than those from Group 4. Group 4 and Group 1 were not different. The mean bursting pressure was highest in Group 4, followed by Group 1 and Group 2, with Group 3 having the lowest mean bursting pressure. Anastomosis construction time and bursting pressure were not correlated.Conclusions: The tested needle holders had a significant effect on bursting pressure, but not on anastomosis construction time. The Frimand needle holder shows promise to be superior for anastomoses in a clinical setting. However, future studies need to confirm these findings.

Multilayered Human Skeletal Muscle Myoblast Sheets Promote the Healing Process After Colonic Anastomosis in Rats

Colorectal anastomotic leakage is one of the most feared and fatal complications of colorectal surgery. To date, no external coating material that can prevent anastomotic leakage has been developed. As myoblasts possess anti-inflammatory capacity and improve wound healing, we developed a multilayered human skeletal muscle myoblast (HSMM) sheet by periodic exposure to supraphysiological hydrostatic pressure during repeated cell seeding. We assessed whether the application of an HSMM sheet can promote the healing process after colonic anastomosis. Partial colectomy and insufficient suturing were employed to create a high-risk colo-colonic anastomosis model in 60 nude rats. Rats were divided into a control group ( n = 30) and an HSMM sheet group ( n = 30). Macroscopic findings, anastomotic bursting pressure, and histology at the colonic anastomotic site were evaluated on postoperative day (POD) 3, 5, 7, 14, and 28. The application of an HSMM sheet significantly suppressed abscess formation at the anastomotic site compared to the control group on POD3 and 5. The anastomotic bursting pressure in the HSMM sheet group was higher than that in the control group on POD3 and 5. Inflammatory cell infiltration in the HSMM sheet group was significantly suppressed compared to that in the control group throughout the time course. Collagen deposition in the HSMM sheet group on POD3 was significantly abundant compared to that in the control group. Regeneration of the mucosa at the colonic anastomotic site was promoted in the HSMM sheet group compared to that in the control group on POD14 and 28. Immunohistochemical analysis demonstrated that surviving cells in the HSMM sheet gradually decreased with postoperative time and none were detected on POD14. These results suggest that the application of a multilayered HSMM sheet may prevent postoperative colonic anastomotic leakage.