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Journal of the Mechanical Behavior of... Mar 2019Colonoscopy is a commonly-performed procedure to diagnose pathology of the large intestine. Perforation of the colon is a rare but feared complication. It is currently...
INTRODUCTION
Colonoscopy is a commonly-performed procedure to diagnose pathology of the large intestine. Perforation of the colon is a rare but feared complication. It is currently unclear how much force is actually required to cause such injury nor how this is altered in certain diseases. Our aim was to analyze the forces required to perforate the colon in experiments using porcine tissues.
METHODS
Using 3D printing technology, models of two commercially available colonoscope heads were printed under three configurations: straight (I), 90°- bent (L) and fully bent (U). Samples of porcine colon were assessed with the models and configurations under perpendicular and angular load application and these data compared to the maximum force typically exerted by experienced colonoscopists.
RESULTS
The force required for perforation was significantly lower for the I compared to the L of the larger colonoscope head configuration under angular loading (14.1 vs. 46.5 N). Similar differences were found for linear stiffness when loaded (I vs. L small when loaded perpendicular: 0.8 vs. 2.4 N/mm, I vs. L large when loaded angled 0.7 vs. 2.1 N/mm). The mode and site of failure varied significantly between the scopes, with delamination of the mucosa/submucosa below the sample (96%) for the I, blunt mucosa/submucosa/muscularis failure adjacent to the loading site (77%) for the L, and failure of all colon layers lateral to the loading site (59%) for the U configuration, respectively. Perpendicular and angulated loading resulted in similar load-deformation values. Maximum forces typically exerted by colonoscopists averaged 13.9-27.9 N, depending on the colonoscope model and head configuration.
DISCUSSION
The force required for colon perforation varies depending on the type mode of loading and is likely lower than the force an experienced colonoscopist would exert in daily practice. There is a real risk of perforation, especially when the end of the scope is advancing directly into the colonic wall. The given experimental setup allowed to obtain reliable data of the colon in a standardized scenario, forming the basis for further experiments.
Topics: Animals; Biomechanical Phenomena; Colon; Colonoscopy; Intestinal Perforation; Mechanical Phenomena; Swine
PubMed: 30579111
DOI: 10.1016/j.jmbbm.2018.11.024 -
Discovery Medicine May 2019Ulcerative colitis is a life-long, chronic, relapsing and remitting inflammatory disease of the large intestine with an unpredictable course characterized by... (Review)
Review
Ulcerative colitis is a life-long, chronic, relapsing and remitting inflammatory disease of the large intestine with an unpredictable course characterized by debilitating gastrointestinal symptoms accompanied by healthcare and emotional burdens that reduce the quality of life and the ability to work, attend school, and be productive. Ulcerative colitis affects millions of people worldwide and is now considered a global disease. Although some form of primary immune abnormality is thought to underlie this illness, extensive laboratory research conducted since the mid-20th century has largely failed to definitively establish a primary antecedent immune abnormality in individuals with ulcerative colitis or their family members. An alternative approach employing a systems pathogenesis analysis has implicated a causal role for colonocyte-generated hydrogen peroxide in the pathogenesis of this illness. Significantly elevated levels of hydrogen peroxide in non-inflamed colonic mucosa have been demonstrated in individuals with ulcerative colitis, implying a build-up prior to the onset of inflammation and supporting a causal role for colonocyte hydrogen peroxide in the development of this disease. Hydrogen peroxide's unique properties of cell membrane permeability, long life, potent oxidizing potential, and the ability to attract white blood cells combine to promote oxidative disintegration of colonic epithelial tight junctional proteins while attracting white blood cells into the colonic epithelium, both of which lead to colonic inflammation and eventual ulcerative colitis.
Topics: Colitis, Ulcerative; Colon; Female; Humans; Intestinal Mucosa; Male; Tight Junction Proteins
PubMed: 31361982
DOI: No ID Found -
Veterinary Journal (London, England :... Aug 2018Enteropathy associated with sand accumulation in the large colon of horses has been reported worldwide. Intestinal sand accumulations are commonly treated medically, but...
Enteropathy associated with sand accumulation in the large colon of horses has been reported worldwide. Intestinal sand accumulations are commonly treated medically, but randomised controlled clinical trials on horses are scarce. This prospective study evaluated the efficacy of an enterally administered combination of psyllium and magnesium sulphate (MgSO) for the removal of large colonic sand accumulations in horses without clinical signs of acute colic. The two groups comprised 20 untreated control horses and 20 horses treated with 1g/kg bodyweight (bwt) of psyllium and 1g/kg bwt of MgSO administered by nasogastric intubation once daily for 4 days. Both groups had no access to soil during the study period. The amounts of accumulated sand were evaluated radiographically before and after treatment. Significantly more treated horses cleared their sand accumulations than horses in the control group. This clearance was determined by observing the estimated quantity by area of sand remaining in the large colon (P<0.001) and by comparing the numbers of successfully treated horses (P=0.004) between the two groups after 4days of treatment. However, there were unexplained individual variations in the clearance of sand accumulation.
Topics: Animals; Cathartics; Colic; Colon; Horse Diseases; Horses; Intestinal Obstruction; Magnesium Sulfate; Prospective Studies; Psyllium; Silicon Dioxide
PubMed: 30103912
DOI: 10.1016/j.tvjl.2018.06.005 -
Neurourology and Urodynamics Mar 2012Normal functioning of the urinary bladder and the distal gut is an essential part of daily physiological activity coordinated by the peripheral and central nervous... (Review)
Review
Normal functioning of the urinary bladder and the distal gut is an essential part of daily physiological activity coordinated by the peripheral and central nervous systems. Pathological changes in one of these organs may induce the development of cross-organ sensitization in the pelvis and underlie clinical co-morbidity of genitourinary and GI dysfunctions. Experimental human and animal data suggest that the bladder and distal colon interact under both normal and pathological conditions, however, the directions of these interactions can change dramatically depending on the nature and duration of the applied stimuli. This review article aimed to summarize the clinical data on colon-bladder cross-reflexes in healthy individuals, as well as in patients with co-morbid disorders. It also discusses currently used animal models, experimental approaches, and suggested mechanisms of colon-bladder cross-talk. Additionally, it provides an overview of the potential pharmacological targets to develop treatment options for patients with co-morbid disorders. Presented work resulted from the discussion of colon/bladder interactions during "Think Tank 9" presentations at the International Consultation on Incontinence Research Society meeting held in Bristol, UK, 2011.
Topics: Animals; Colon; Colonic Diseases; Comorbidity; Disease Models, Animal; Evidence-Based Medicine; Humans; Reflex; Urinary Bladder; Urinary Bladder Diseases
PubMed: 22378593
DOI: 10.1002/nau.21228 -
The British Journal of Surgery Nov 1992Despite the volume of research on human colonic dysfunction, little is known about colonic function in health. This has stemmed partly from the difficulty in obtaining... (Review)
Review
Despite the volume of research on human colonic dysfunction, little is known about colonic function in health. This has stemmed partly from the difficulty in obtaining access to the organ. Two approaches have been used: studies on patients with stomas, and intestinal intubation techniques. The colonoscope has also recently been used to gain access. All these methods have limitations and results must be interpreted with caution. The accepted roles of the colon include the conservation of water and electrolytes and the controlled evacuation of faeces. Recent research has demonstrated its importance as a metabolic organ with an influence on overall metabolism, an effect that may in large part be attributed to the activity of colonic microflora. Evidence demonstrating that the defunctioned colon behaves differently from the functioning colon in the same individual has implications for a proper understanding of the organ, as practically all previous in vivo studies have been conducted in cleansed or defunctioned human colon.
Topics: Colon; Humans
PubMed: 1467882
DOI: 10.1002/bjs.1800791106 -
Scandinavian Journal of... 1984Blood flow and its intramural distribution in the large and small intestines 'at rest' appear to be quite similar, but there are some obvious differences in the... (Review)
Review
Blood flow and its intramural distribution in the large and small intestines 'at rest' appear to be quite similar, but there are some obvious differences in the regulation of the circulation in these two viscera. Autoregulation of blood flow is well developed in most regions of the gut, with the exception of the colon in which total blood flow varies greatly with arterial blood pressure. However, the colonic autoregulatory capacity can be improved by increasing the metabolic demand of the tissue, e.g. by intra-luminal placement of nutrients. Metabolic and myogenic factors seem to be mutually responsible for autoregulatory behaviour in the large intestine. Functional vasodilatation occurs in the large intestine in response to increased metabolism, a reaction which can be evoked for instance by intra-luminal placement of volatile fatty acids. Mechanical stimulation of the mucosa in the proximal colon also elicits a local hyperaemic response which is postulated to be mediated via an intrinsic nervous reflex possibly releasing 5-HT. In the distal colon and the rectum mechanical stimulation evokes a more wide-spread hyperaemia which is reported to be the result of a pelvo -pelvic reflex with vasoactive intestinal polypeptide (VIP) as a possible mediator. Activation of the sympatho-adrenal system causes constriction of the large intestinal resistance and capacitance vessels. Reflex increase in sympathetic activity, as in exercise or haemorrhage, causes a redistribution of flow and a mobilization of blood from the large intestine to other tissues, thereby, in stress situations, promoting the circulation in more vital organs such as the heart and brain. The most distal part of the large intestine, in particular the rectum, seems to have a unique extrinsic vasodilator control via the parasympathetic pelvic nerves. Activation of these nerves elicits a very pronounced and well maintained vasodilator response in the rectum but only a transient one in the distal colon. This neural vasodilator response is little affected by muscarinic blockade and, hence, largely non-cholinergic in nature. VIP is released from the colon and rectum during pelvic nerve stimulation, the rectal output being especially large and well correlated in time to the concomitant vasodilatation. The rectal vessels are very sensitive to VIP, and intra-arterial infusion of this peptide causes a vascular response which closely resembles that of pelvic nerve stimulation. Such evidence indicates that VIP might be the neurotransmitter responsible for the non-cholinergic vasodilatation in the most distal part of the large intestine.
Topics: Animals; Cats; Colon; Dogs; Humans; Intestinal Mucosa; Parasympathetic Nervous System; Pelvis; Rectum; Regional Blood Flow; Sympathetic Nervous System; Vasoactive Intestinal Peptide; Vasomotor System
PubMed: 6374876
DOI: No ID Found -
Gastrointestinal Endoscopy Dec 1998
Topics: Colon; Colonic Polyps; Humans; Hyperplasia
PubMed: 9852501
DOI: 10.1016/s0016-5107(98)70081-1 -
Equine Veterinary Journal Nov 2014Intraoperative assessment of colonic viability can be challenging and largely subjective. Objective methods are often impractical. Viability is related to...
REASON FOR PERFORMING STUDY
Intraoperative assessment of colonic viability can be challenging and largely subjective. Objective methods are often impractical. Viability is related to re-establishment of colonic perfusion; particularly microvascular perfusion. This study evaluated the utility of dark-field microscopy (DFM) of the colonic serosa as an objective method of assessing microperfusion.
OBJECTIVES
To measure microvascular perfusion indices (MPI) of the pelvic flexure serosa in horses with surgical colonic lesions and correlate these with macroperfusion indices (MaPI) and histomorphometry.
STUDY DESIGN
Prospective, clinical, case-control study.
METHODS
Control horses and horses with colonic volvulus (LCV), displacement, and/or simple obstruction undergoing surgery had DFM video loops performed on the pelvic flexure. Total vessel density, perfused vessel density, proportion of perfusion vessels and microvascular flow index were calculated from video analysis. Macroperfusion indices (arterial blood pressure and heart rate) were recorded. Histomorphometry was used to determine a mucosal injury score. Differences between lesions for MPI, MaPI and histomorphometry were compared using ANOVA or Kruskal-Wallis statistic. Spearman correlations between MPI with MaPI were performed. Linear regression was used to assess the relationship between MPI and histomorphometry. P<0.05 was significant.
RESULTS
Horses with LCV had lower perfused vessel density, proportion of microvascular perfusion vessels and flow index than horses with nonstrangulating obstructions and control horses. Macroperfusion indices were not correlated with MPI but MPI were correlated with histomorphometry.
CONCLUSIONS
Dark-field microscopy is achievable in the operating room and can quantify MPI from the colonic serosa in different colonic lesions. Macroperfusion indices were not related with colonic MPI. Microvascular perfusion indices can predict the severity of histopathological change at the pelvic flexure. Derangements of MPI may be more useful indicators of colonic pathology and viability and offer a more objective assessment of intestinal injury than subjective methods. Further study is needed to determine the utility of DFM in predicting survival in horses with LCV.
Topics: Animals; Colon; Colonic Diseases; Female; Horse Diseases; Horses; Intestinal Mucosa; Male; Microscopy
PubMed: 24164428
DOI: 10.1111/evj.12202 -
The Journal of Trauma Jun 1984Of 56 patients with penetrating colon injuries over 6 years, 15% underwent exteriorized repair, 21% received a colostomy, and 64% were treated with primary repair. Of...
Of 56 patients with penetrating colon injuries over 6 years, 15% underwent exteriorized repair, 21% received a colostomy, and 64% were treated with primary repair. Of the eight exteriorized repairs, four required conversion to colostomies. In the entire group of 12 colostomies, there were two deaths, four abscesses, and one empyema. Thirty-six patients (64%) underwent primary repair. In this group there was one superficial wound infection, one empyema, but no intra-abdominal abscesses. Eighty per cent had associated injuries. All laparotomy incisions in the primary repair group except two were closed primarily. Large amounts of saline irrigant were used in all cases. All patients received broad spectrum antibiotics pre- and postoperatively. Primary repair of colon injuries can be done safely in many cases. Proper attention must be given to the associated injuries, the patient's general condition, and the time interval between injury and repair. We now find few indications for exteriorization of injured colons. Colostomies are done if our criteria for safe primary repair are not fulfilled.
Topics: Adolescent; Adult; Anti-Bacterial Agents; Colon; Colostomy; Humans; Laparotomy; Male; Premedication; Surgical Wound Infection; Therapeutic Irrigation; Time Factors; Wounds, Penetrating
PubMed: 6737525
DOI: 10.1097/00005373-198406000-00006 -
Journal of the American Veterinary... Apr 1997To determine the number of myenteric plexuses and neurons in the large colon of clinically normal horses and whether the number was decreased in the large colon of...
OBJECTIVE
To determine the number of myenteric plexuses and neurons in the large colon of clinically normal horses and whether the number was decreased in the large colon of horses with colon disease.
DESIGN
Prospective study.
SAMPLE POPULATION
Colon samples from 15 clinically normal horses and 31 horses with colon disease.
PROCEDURE
Samples were obtained, fixed, and stained with H&E. The number of myenteric plexuses and neurons and longitudinal muscle thickness were determined in each segment of colon for clinically normal horses. Counts for segments were compared with each other and with counts in the same segment from horses with colon disease.
RESULTS
Myenteric plexus and neuron densities and longitudinal muscle thickness in clinically normal horses were significantly greater in the pelvic flexure and left dorsal and transverse colons. Horses with chronic obstruction (> 24 hours' duration) or with previous obstruction had significantly lower neuron density in the pelvic flexure. Myenteric plexus density in horses with strangulating large colon torsion/volvulus was significantly less in the right ventral, right dorsal, and transverse colons, and neuron density in these horses was significantly less in all segments of colon, except the left ventral colon. Horses with colon strangulation that survived had significantly greater neuron density than horses with colon strangulation that died. Enteroglial cell numbers were increased in myenteric plexuses of horses with acute and chronic obstruction.
CLINICAL IMPLICATIONS
Myenteric plexus and neuron densities can be estimated by evaluating linear counts of H&E-stained colon samples. Enteroglial cells may increase in number in response to myenteric plexus inflammation, which may affect bowel function.
Topics: Animals; Colic; Colon; Colonic Diseases; Female; Horse Diseases; Horses; Intestinal Obstruction; Male; Myenteric Plexus; Neurons; Reference Values
PubMed: 9096722
DOI: No ID Found