Pancolonic spatiotemporal mapping reveals regional deficiencies in, and disorganization of colonic propagating pressure waves in severe constipation

An expert's guide to classical manometric patterns seen in high-resolution colonic manometry

INTRODUCTION

High-resolution colonic manometry is a research and diagnostic tool used to evaluate colonic motility. Used in health it helps us understand normal colonic motility and the colonic response to physiological stimuli such as meal, as well as chemical (laxatives) and mechanical (distension) stimuli. In pediatric and adult patients with suspected colonic disorders, it can help to understand the abnormal colonic motility associated with the condition.

AREA COVERED

High-resolution manometric catheters contain multiple closely spaced sensors that detect intraluminal pressure changes and contractile force, which can be interpreted as contractile activity. This activity forms several distinctive motor patterns that help in understanding normal colonic physiology and provide insights into the potential pathophysiology underlying colonic disorders such as constipation. After a PubMed search of colonic high-resolution manometry studies, this review provides an overview of the characterized motor patterns, when they occur, how they are initiated, their clinical relevance, and their role, if any, in guiding therapeutic interventions.

EXPERT OPINION

High-resolution colonic manometry has identified motor patterns that were missed or mislabeled by low-resolution recordings. How best to use this information to guide treatment remains to be determined.

Examining linaclotide for the treatment of chronic idiopathic constipation

INTRODUCTION

Chronic idiopathic constipation (CIC) is characterized by infrequent bowel movements and hard stools lasting for at least three months or longer. This disease affects 8-12% of the US population and 10-17% of the world population. Treatment and management involve identifying the primary cause, changing dietary habits, and adequate physical activity. Linaclotide is a guanylate cyclase-agonist acting locally in the luminal surface of the intestinal enterocyte leading to a signal transduction cascade, activation of the cystic fibrosis transmembrane conductance regulator (CFTR), thus increasing secretion of chloride and bicarbonate into the intestinal lumen with eventual increased intestinal fluid and faster transit time.

AREAS COVERED

We reviewed multiple studies and did a thorough literature review on CIC including its pathophysiology. Through this literature review, we were able to discuss and give the context and rationale for drug regimens indicated for CIC.

EXPERT OPINION

The era we live in right now is akin to nutrient-rich and fertilized soil as knowledge and resources are abundant. The opportunities and potential are endless. Constipation being more extensively studied, our understanding of medications and diseases broadens, leading to novel medications being discovered. Linaclotide is a pioneer in this aspect and can pave the way for future generations.

Functional Constipation and Obstructed Defecation

Constipation encompasses symptoms of decreased colonic motility or difficulty with the defecation process. As a broad definition, this can be inclusive of functional constipation (FC) or colonic inertia, obstructed defecation (OD), and irritable bowel syndrome-constipation type (IBS-CS). After excluding IBS-C, FC and OD diagnosis and management require a multidisciplinary approach often involving nutritionists, pelvic floor therapists, urogynecologists, and colon and rectal surgeons. Differentiating the presence or absence of each can direct therapy and prognosticate chances for improvement in this often complex combination of disorders.

Abnormal gastrointestinal motility is a major factor in explaining symptoms and a potential therapeutic target in patients with disorders of gut-brain interaction

The objective of this article is to review the evidence of abnormal gastrointestinal (GI) tract motor functions in the context of disorders of gut-brain interaction (DGBI). These include abnormalities of oesophageal motility, gastric emptying, gastric accommodation, colonic transit, colonic motility, colonic volume and rectal evacuation. For each section regarding GI motor dysfunction, the article describes the preferred methods and the documented motor dysfunctions in DGBI based on those methods. The predominantly non-invasive measurements of gut motility as well as therapeutic interventions directed to abnormalities of motility suggest that such measurements are to be considered in patients with DGBI not responding to first-line approaches to behavioural or empirical dietary or pharmacological treatment.

Overview of the Enteric Nervous System

Propulsion of contents in the gastrointestinal tract requires coordinated functions of the extrinsic nerves to the gut from the brain and spinal cord, as well as the neuromuscular apparatus within the gut. The latter includes excitatory and inhibitory neurons, pacemaker cells such as the interstitial cells of Cajal and fibroblast-like cells, and smooth muscle cells. Coordination between these extrinsic and enteric neurons results in propulsive functions which include peristaltic reflexes, migrating motor complexes in the small intestine which serve as the housekeeper propelling to the colon the residual content after digestion, and mass movements in the colon which lead to defecation.

Tissue distribution and abuse potential of prucalopride: findings from non-clinical and clinical studies

Background

Prucalopride is a selective serotonin type 4 (5-HT₄) receptor agonist indicated for treatment of chronic idiopathic constipation (CIC) in adults (2 mg orally, daily). 5-HT₄ receptors are present in the central nervous system; therefore, non-clinical and clinical assessments were performed to evaluate the tissue distribution and abuse potential of prucalopride.

Methods

In vitro receptor-ligand binding studies were performed to assess the affinity of prucalopride (≤1 mM) for peptide receptors, ion channels, monoamine neurotransmitters and 5-HT receptors. The tissue distribution of ¹⁴C-prucalopride (5 mg base-equivalent/kg) was investigated in rats. Behavioural assessments in mice, rats and dogs after treatment with single or repeated (up to 24 months) subcutaneous or oral doses of prucalopride (0.02-640 mg/kg across species) were performed. Treatment-emergent adverse events possibly indicative of abuse potential during prucalopride CIC clinical trials were evaluated.

Results

Prucalopride showed no appreciable affinity for the receptors and ion channels investigated; its affinity (at ≤100 μM) for other 5-HT receptors was 150-10,000 times lower than that for the 5-HT₄ receptor. In rats, <0.1% of the administered dose was found in the brain and concentrations were below the limit of detection within 24 hours. At supratherapeutic doses (≥20 mg/kg), mice and rats exhibited palpebral ptosis, and dogs exhibited salivation, eyelid tremors, decubitis, pedalling movements and sedation. All clinical treatment-emergent adverse events, possibly indicative of abuse potential, except dizziness, occurred in <1% of patients treated with prucalopride or placebo.

Conclusion

This series of non-clinical and clinical studies suggest low abuse potential for prucalopride.

Lactobacillus rhamnosus GG normalizes gut dysmotility induced by environmental pollutants via affecting serotonin level in zebrafish larvae

Intestinal peristalsis is essential for gastrointestinal function, which could maintain the appropriate progression and digestion of food and reduce bacterial aggregation through mixing function. Even though certain ingredients of foodstuff are known to increase or decrease intestinal peristalsis, the role of environmental pollutants on intestinal peristalsis is relatively unknown. Therefore, the effects of four typical environmental pollutants (oxytetracycline, arsenic, polychlorinated biphenyls and chlorpyrifos) on intestinal peristalsis in the zebrafish model and then tested the recovery effect of the constipation-resistant probiotic. The results showed that 4-day environmental pollutants exposures on the zebrafish embryos at 1 day post fertilization clearly decreased the intestinal peristalsis through decreasing the serotonin (5-HT) production and down-regulating the expression of key genes involved in 5-HT synthesis. Pollutants-evoked change of gut motility could be normalized in the presence of Lactobacillus rhamnosus GG (LGG) via increasing 5-HT secretion. Exogenous 5-hydroxytryptophan (100 µg/L) could also rescue the dysfunction of gut motility in pollutants-treated zebrfish. The data identified that LGG normalized disorder of intestinal peristalsis induced by environmental pollutants through increasing 5-HT level. The stimulant effect of LGG on peristalsis may be associated with 5-HT system, which could provide references for the application of probiotics in regulation of gut dysmotility.

DIAGNOSIS AND MANAGEMENT OF CHRONIC IDIOPATHIC CONSTIPATION: A NARRATIVE REVIEW FROM A BRAZILIAN EXPERT TASK FORCE

ABSTRACT Background Chronic idiopathic constipation (CIC) is a condition that widely affects the global population, represents relevant healthcare resource utilization and costs, and impacts the individual’s well-being. Objective To review the consensus of expert societies and published guidelines on the diagnosis and treatment of CIC in adults, seeking to assist reasoning and decision-making for medical management of patients with CIC and provide a practical reference material. Methods A Brazilian medical task force searched the scientific literature in the following electronic databases: MEDLINE/PubMed, SciELO, EMBASE and Cochrane, using the following descriptors: chronic constipation, diagnosis, management of chronic constipation. In addition, a review of articles on the mechanism of action, safety, and efficacy of therapeutic options available in Brazil was carried out. Results The diagnostic approach and the understanding of the pathophysiology present in CIC are essential items to indicate the appropriate therapy and to understand the ecosystem of the patient’s needs. Conclusion CIC is a common condition in adults, occurring more frequently in the elderly and in women. Proper management is defined by detailed medical history and physical examination, together with appropriate therapeutics, regardless pharmacological or not, and depending on the best moment of indication. This way, the impact on quality of life is also optimized.

Colonic Response to Physiological, Chemical, Electrical and Mechanical Stimuli; What Can Be Used to Define Normal Motility?

The colon plays an important functional role in the bacterial fermentation of carbohydrates, transmural exchange of fluid and short-chain fatty acids, and the formation, storage and evacuation of faeces and gaseous contents. Coordinated colonic motor patterns are essential for these functions to occur. Our understanding of human colonic motor patterns has largely come through the use of various forms of colonic manometry catheters, combined with a range of stimuli, both physiological and artificial. These stimuli are used in patients with colonic disorders such as constipation, irritable bowel syndrome and faecal incontinence to understand the pathophysiology mechanisms that may cause the disorder and/or the associated symptoms. However, our understanding of a "normal" colonic response remains poor. This review will assess our understanding of the normal colonic response to commonly used stimuli in short duration studies (<8 hrs) and the mechanisms that control the response.

Generation of Gut Motor Patterns Through Interactions Between Interstitial Cells of Cajal and the Intrinsic and Extrinsic Autonomic Nervous Systems

The musculature of the gastrointestinal tract is a vast network of collaborating excitable cell types. Embedded throughout are the interstitial cells of Cajal (ICC) intertwined with enteric nerves. ICC sense external stimuli such as distention, mediate nerve impulses to smooth muscle cells, and provide rhythmic excitation of the musculature. Neural circuitry involving both the intrinsic and extrinsic autonomic nervous systems, in collaboration with the ICC, orchestrate an array of motor patterns that serve to provide mixing of content to optimize digestion and absorption, microbiome homeostasis, storage, transit, and expulsion. ICC are specialized smooth muscle cells that generate rhythmic depolarization to the musculature and so provide the means for peristaltic and segmenting contractions. Some motor patterns are purely myogenic, but a neural stimulus initiates most, further depolarizing the primary pacemaker cells and the musculature and/or initiating transient pacemaker activity in stimulus-dependent secondary ICC pacemaker cells. From stomach to rectum, ICC networks rhythmically provide tracks along which contractions advance.

Understanding the physiology of human defaecation and disorders of continence and evacuation

The act of defaecation, although a ubiquitous human experience, requires the coordinated actions of the anorectum and colon, pelvic floor musculature, and the enteric, peripheral and central nervous systems. Defaecation is best appreciated through the description of four phases, which are, temporally and physiologically, reasonably discrete. However, given the complexity of this process, it is unsurprising that disorders of defaecation are both common and problematic; almost everyone will experience constipation at some time in their life and many will develop faecal incontinence. A detailed understanding of the normal physiology of defaecation and continence is critical to inform management of disorders of defaecation. During the past decade, there have been major advances in the investigative tools used to assess colonic and anorectal function. This Review details the current understanding of defaecation and continence. This includes an overview of the relevant anatomy and physiology, a description of the four phases of defaecation, and factors influencing defaecation (demographics, stool frequency/consistency, psychobehavioural factors, posture, circadian rhythm, dietary intake and medications). A summary of the known pathophysiology of defaecation disorders including constipation, faecal incontinence and irritable bowel syndrome is also included, as well as considerations for further research in this field.

Luminal Fluid Motion Inside an In Vitro Dissolution Model of the Human Ascending Colon Assessed Using Magnetic Resonance Imaging

Knowledge of luminal flow inside the human colon remains elusive, despite its importance for the design of new colon-targeted drug delivery systems and physiologically relevant in silico models of dissolution mechanics within the colon. This study uses magnetic resonance imaging (MRI) techniques to visualise, measure and differentiate between different motility patterns within an anatomically representative in vitro dissolution model of the human ascending colon: the dynamic colon model (DCM). The segmented architecture and peristalsis-like contractile activity of the DCM generated flow profiles that were distinct from compendial dissolution apparatuses. MRI enabled different motility patterns to be classified by the degree of mixing-related motion using a new tagging method. Different media viscosities could also be differentiated, which is important for an understanding of colonic pathophysiology, the conditions that a colon-targeted dosage form may be subjected to and the effectiveness of treatments. The tagged MRI data showed that the DCM effectively mimicked wall motion, luminal flow patterns and the velocities of the contents of the human ascending colon. Accurate reproduction of in vivo hydrodynamics is an essential capability for a biorelevant mechanical model of the colon to make it suitable for in vitro data generation for in vitro in vivo evaluation (IVIVE) or in vitro in vivo correlation (IVIVC). This work illustrates how the DCM provides new insight into how motion of the colonic walls may control luminal hydrodynamics, driving erosion of a dosage form and subsequent drug release, compared to traditional pharmacopeial methods.

Changes in gut microbiota in the acute phase after spinal cord injury correlate with severity of the lesion

After spinal cord injury (SCI), patients face many physical and psychological issues including intestinal dysfunction and comorbidities, strongly affecting quality of life. The gut microbiota has recently been suggested to influence the course of the disease in these patients. However, to date only two studies have profiled the gut microbiota in SCI patients, months after a traumatic injury. Here we characterized the gut microbiota in a large Italian SCI population, within a short time from a not only traumatic injury. Feces were collected within the first week at the rehabilitation center (no later than 60 days after SCI), and profiled by 16S rRNA gene-based next-generation sequencing. Microbial profiles were compared to those publicly available of healthy age- and gender-matched Italians, and correlated to patient metadata, including type of SCI, spinal unit location, nutrition and concomitant antibiotic therapies. The gut microbiota of SCI patients shows distinct dysbiotic signatures, i.e. increase in potentially pathogenic, pro-inflammatory and mucus-degrading bacteria, and depletion of short-chain fatty acid producers. While robust to most host variables, such dysbiosis varies by lesion level and completeness, with the most neurologically impaired patients showing an even more unbalanced microbial profile. The SCI-related gut microbiome dysbiosis is very likely secondary to injury and closely related to the degree of completeness and severity of the lesion, regardless of etiology and time interval. This microbial layout could variously contribute to increased gut permeability and inflammation, potentially predisposing patients to the onset of severe comorbidities.

Characterization of haustral activity in the human colon

Contraction patterns of the human colon are rarely discussed from the perspective of its haustra. Colonic motility was analyzed in 21 healthy subjects using 84-sensor manometry catheters with 1-cm sensor spacing. Capsule endoscopy and manometry showed evidence of narrow rhythmic circular muscle contractions. X-ray images of haustra and sensor locations allowed us to identify manometry motor activity as intrahaustral activity. Two common motor patterns were observed that we infer to be associated with individual haustra: rhythmic pressure activity confined to a single sensor, and activity confined to a section of the colon of 3-6 cm length. Intrahaustral activity was observed by 3-4 sensors. Approximately 50% of the haustra were intermittently active for ∼30% of the time; 2,402 periods of haustral activity were analyzed. Intrahaustral activity showed rhythmic pressure waves, propagating in mixed direction, 5-30 mmHg in amplitude at a frequency of ∼3 cpm (range 2-6) or ∼12 cpm (range 7-15), or exhibiting a checkerboard segmentation pattern. Boundaries of the haustra showed rhythmic pressure activity with or without elevated baseline pressure. Active haustra often showed no boundary activity probably allowing transit to neighboring haustra. Haustral boundaries were seen at the same sensor for the 6- to 8-h study duration, indicating that they did not propagate, thereby likely contributing to continence. The present study elucidates the motility characteristics of haustral boundaries and the nature of intrahaustral motor patterns and paves the way for investigating their possible role in pathophysiology of defecation disorders.NEW & NOTEWORTHY Here, we present the first full characterization and quantification of motor patterns that we infer to be confined to single haustra, both intrahaustral activity and haustral boundary activity, in the human colon using high-resolution manometry. Haustral activity is intermittent but consistently present in about half of the haustra. Intrahaustral activity presents as a cyclic motor pattern of mixed propagation direction dominated by simultaneous pressure waves that can resolve into checkerboard segmentation, allowing for mixing, absorption, and stool formation.

Chronic constipation in adults: Contemporary perspectives and clinical challenges. 1: Epidemiology, diagnosis, clinical associations, pathophysiology and investigation

BACKGROUND

Chronic constipation is a prevalent disorder that affects patients' quality of life and consumes resources in healthcare systems worldwide. In clinical practice, it is still considered a challenge as clinicians frequently are unsure as to which treatments to use and when. Over a decade ago, a Neurogastroenterology & Motility journal supplement devoted to the investigation and management of constipation was published (2009; 21 (Suppl.2)). This included seven articles, disseminating all themes covered during a preceding 2-day meeting held in London, entitled "Current perspectives in chronic constipation: a scientific and clinical symposium." In October 2018, the 3rd London Masterclass, entitled "Contemporary management of constipation" was held, again over 2 days. All faculty members were invited to author two new review articles, which represent a collective synthesis of talks presented and discussions held during this meeting.

PURPOSE

This article represents the first of these reviews, addressing epidemiology, diagnosis, clinical associations, pathophysiology, and investigation. Clearly, not all aspects of the condition can be covered in adequate detail; hence, there is a focus on particular "hot topics" and themes that are of contemporary interest. The second review addresses management of chronic constipation, covering behavioral, conservative, medical, and surgical therapies.

High-Resolution Colonic Manometry Pressure Profiles Are Similar in Asymptomatic Diverticulosis and Controls

BACKGROUND

Elevated colonic pressures and increased colonic activity have been thought to contribute to the pathophysiology of diverticulosis. However, evidence for this has been limited to low-resolution manometry, which is of limited accuracy.

AIMS

This study aimed to evaluate the contraction pressures, counts, and distance of propagation recorded by high-resolution colonic manometry in diverticulosis vs control patients.

METHODS

High-resolution colonic manometry was used to record descending and sigmoid colon activity pre- and post-meal in patients with established, asymptomatic diverticulosis and in healthy controls. Antegrade and retrograde propagating contractions, distance of propagation (mm), and mean contraction pressures (mmHg) in the descending and sigmoid colon were compared between patients and controls for all isolated propagating contractions, the cyclic motor pattern, and high-amplitude propagating contractions independently.

RESULTS

Mean manometry pressures were not different between controls and diverticulosis patients (p > 0.05 for all comparisons). In the descending colon, diverticulosis patients had lower post-meal mean distance of propagation for all propagating contractions [10.8 (SE1.5) mm vs 20.0 (2.0) mm, p = 0.003] and the cyclic motor pattern [6.0 (2.5) mm vs 17.1 (2.8) mm, p = 0.01]. In the sigmoid colon, diverticulosis patients showed lower post-meal mean distance of propagation for all propagating contractions [10.8 (1.5) mm vs 20.2 (5.9) mm, p = 0.01] and a lower post-meal increase in retrograde propagating contractions (p = 0.04).

CONCLUSIONS

In this first high-resolution colonic manometry study of patients with diverticular disease, we did not find evidence for increased manometric pressures or increased colonic activity in patients with diverticular disease.

Automated Analysis Using a Bayesian Functional Mixed-Effects Model With Gaussian Process Responses for Wavelet Spectra of Spatiotemporal Colonic Manometry Signals

Manual analysis of human high-resolution colonic manometry data is time consuming, non-standardized and subject to laboratory bias. In this article we present a technique for spectral analysis and statistical inference of quasiperiodic spatiotemporal signals recorded during colonic manometry procedures. Spectral analysis is achieved by computing the continuous wavelet transform and cross-wavelet transform of these signals. Statistical inference is achieved by modeling the resulting time-averaged amplitudes in the frequency and frequency-phase domains as Gaussian processes over a regular grid, under the influence of categorical and numerical predictors specified by the experimental design as a functional mixed-effects model. Parameters of the model are inferred with Hamiltonian Monte Carlo. Using this method, we re-analyzed our previously published colonic manometry data, comparing healthy controls and patients with slow transit constipation. The output from our automated method, supports and adds to our previous manual analysis. To obtain these results took less than two days. In comparison the manual analysis took 5 weeks. The proposed mixed-effects model approach described here can also be used to gain an appreciation of cyclical activity in individual subjects during control periods and in response to any form of intervention.

Simultaneous assessment of colon motility in children with functional constipation by cine-MRI and colonic manometry: a feasibility study

BACKGROUND

Colonic manometry is the current reference standard for assessing colonic neuromuscular function in children with intractable functional constipation (FC). Recently, cine magnetic resonance imaging (cine-MRI) has been proposed as a non-invasive alternative. We compared colonic motility patterns on cine-MRI with those obtained by manometry in children, by stimulating high-amplitude propagating contractions (HAPCs) with bisacodyl under manometric control while simultaneously acquiring cine-MRI.

METHODS

After Institutional Review Board approval, adolescents with FC scheduled to undergo colonic manometry were included. A water-perfused 8-lumen catheter was used for colonic manometry recordings. After an intraluminal bisacodyl infusion, cine-MRI sequences of the descending colon were acquired for about 30 min simultaneously with colonic manometry. Manometry recordings were analysed for HAPCs. MRI images were processed with spatiotemporal motility MRI techniques. The anonymised motility results of both techniques were visually compared for the identification of HAPCs in the descending colon.

RESULTS

Data regarding six patients (three males) were analysed (median age 14 years, range 12-17). After bisacodyl infusion, three patients showed a total of eleven HAPCs with colonic manometry. Corresponding cine-MRI recorded high colonic activity during two of these HAPCs, minimal activity during seven HAPCs, while two HAPCs were not recorded. In two of three patients with absent HAPCs on manometry, colonic activity was recorded with cine-MRI.

CONCLUSIONS

Simultaneous acquisition of colonic cine-MRI and manometry in children with FC is feasible. Their motility results did not completely overlap in the identification of HAPCs. Research is needed to unravel the role of cine-MRI in this setting.

Comparison of the effects of colonic electrical stimulation and prucalopride on gastrointestinal transit and defecation in a canine model of constipation

OBJECTIVE

The aim of this study was to compare the effects of colonic electrical stimulation (CES) and prucalopride on gastrointestinal transit and defecation and to verify the safety of CES in a canine model of constipation.

METHODS

Eight beagles received CES implantation and induction drugs for slow transit constipation (STC). In the STC model, the gastrointestinal transit time (GITT), colonic transit time (CTT), stool frequency and stool consistency were assessed to compare the effects of CES and prucalopride on gastrointestinal transit and defecation. The histocompatibility of the implantable device was evaluated.

RESULTS

The individualized parameters for CES varied greatly among the animals, and the GITTs were not significantly shortened by CES or prucalopride; however, both the CES and prucalopride treatment significantly accelerated CTT and improved stool consistency compared with sham stimulation. CES treatment also resulted in significantly higher stool frequency than prucalopride treatment, which did not significantly change the stool frequency. No severe inflammation response was detected in the gross and microscopic appearance around the implants.

CONCLUSION

CES and prucalopride treatment may yield similar short-term effects for improving gastrointestinal transit and stool consistency, and CES outperformed prucalopride treatment in terms of defecation inducement in the short term. There were ideal levels of endurance and histocompatibility for the animals that underwent CES.

Colonic motility in patients with type 1 diabetes and gastrointestinal symptoms

BACKGROUND

Gastrointestinal (GI) symptoms are common in patients with diabetes mellitus (DM). The electromagnetic 3D-Transit system allows assessment of regional transit times and motility patterns throughout the GI tract. We aimed to compare GI transit times and detailed motility patterns of the colon in patients with DM and GI symptoms to those of healthy controls (HC). We further aimed to determine whether any abnormalities in motility were reversible by cholinergic stimulation.

METHODS

We compared 18 patients with DM with 20 HC by means of the 3D-Transit system. Patients were studied before and during oral administration of 60 mg pyridostigmine.

KEY RESULTS

Compared to HC, patients had prolonged gastric emptying (DM: 3.3 hours (interquartile range (IQR) 2.6-4.6); HC: 2.3 hours (IQR 1.7-2.7) (P < .01)), colonic transit time (DM: 52.6 hours (IQR 23.3-83.0); HC: 22.4 hours (IQR 18.9-43.6) (P = .02)), and whole gut transit time (DM: 69.4 hours (IQR 32.9-103.6); HC: 30.3 hours (IQR 25.2-49.9) (P < .01)). In addition, compared to HC, patients had prolonged transit time in the ascending colon (DM: 20.5 hours (IQR 11.0-44.0); HC: 8.0 hours (IQR 3.8-21.0) (P < .05)) and more slow retrograde movements in the colon (DM: 2 movements (IQR 1-4); HC: 1 movement (IQR 0-1) (P = .01)). In patients, pyridostigmine increased the number of bowel movements (P < .01) and reduced small intestine transit times (P < .05).

CONCLUSIONS

Patients with DM and GI symptoms have longer than normal GI transit times. This is only partly reversible by pyridostigmine. The increased number of retrograde colonic movements in patients could potentially explain the abnormally long transit time in proximal colon.

Development and feasibility of an ambulatory acquisition system for fiber-optic high-resolution colonic manometry

BACKGROUND

High-resolution colonic manometry is an emerging technique that has provided new insights into the pathophysiology of functional colorectal diseases. Prior studies have been limited by bulky, non-ambulatory acquisition systems, which have prevented mobilization during prolonged recordings.

METHODS

A novel ambulatory acquisition system for fiber-optic high-resolution colonic manometry was developed. Benchtop validation against a standard non-ambulatory system was performed using standardized calibration metrics. Clinical feasibility studies were conducted in three patients undergoing right hemicolectomy.

RESULTS

Pressure profiles obtained from benchtop testing were near-identical using the ambulatory and the non-ambulatory systems. Clinical studies successfully demonstrated ambulatory data capture with patients freely mobilizing postoperatively during continuous recordings of >60 hours. The occurrence (P = .56), amplitude (P = .65), velocity (P = .10), and extent (P = .12) of colonic motor patterns were similar to those obtained in non-ambulatory studies.

CONCLUSIONS

A novel ambulatory system for high-resolution colonic manometry has been developed and validated. This technique will facilitate prolonged ambulatory recordings of colonic motor activity, assisting with investigations into the role of colonic motility in disease states.

First translational consensus on terminology and definitions of colonic motility in animals and humans studied by manometric and other techniques

Alterations in colonic motility are implicated in the pathophysiology of bowel disorders, but high-resolution manometry of human colonic motor function has revealed that our knowledge of normal motor patterns is limited. Furthermore, various terminologies and definitions have been used to describe colonic motor patterns in children, adults and animals. An example is the distinction between the high-amplitude propagating contractions in humans and giant contractions in animals. Harmonized terminology and definitions are required that are applicable to the study of colonic motility performed by basic scientists and clinicians, as well as adult and paediatric gastroenterologists. As clinical studies increasingly require adequate animal models to develop and test new therapies, there is a need for rational use of terminology to describe those motor patterns that are equivalent between animals and humans. This Consensus Statement provides the first harmonized interpretation of commonly used terminology to describe colonic motor function and delineates possible similarities between motor patterns observed in animal models and humans in vitro (ex vivo) and in vivo. The consolidated terminology can be an impetus for new research that will considerably improve our understanding of colonic motor function and will facilitate the development and testing of new therapies for colonic motility disorders.

Chronic idiopathic constipation in adults: epidemiology, pathophysiology, diagnosis and clinical management

Chronic idiopathic constipation (CIC) is one of the most common gastrointestinal disorders, with a global prevalence of 14%. It is commoner in women and its prevalence increases with age. There are three subtypes of CIC: dyssynergic defaecation, slow transit constipation and normal transit constipation, which is the most common subtype. Clinical assessment of the patient with constipation requires careful history taking, in order to identify any red flag symptoms that would necessitate further investigation with colonoscopy to exclude colorectal malignancy. Screening for hypercalcaemia, hypothyroidism and coeliac disease with appropriate blood tests should be considered. A digital rectal examination should be performed to assess for evidence of dyssynergic defaecation. If this is suspected, further investigation with high resolution anorectal manometry should be undertaken. Anorectal biofeedback can be offered to patients with dyssynergic defaecation as a means of correcting the associated impairment of pelvic floor, abdominal wall and rectal functioning. Lifestyle modifications, such as increasing dietary fibre, are the first step in managing other causes of CIC. If patients do not respond to these simple changes, then treatment with osmotic and stimulant laxatives should be trialled. Patients not responding to traditional laxatives should be offered treatment with prosecretory agents such as lubiprostone, linaclotide and plecanatide, or the 5-HT4 receptor agonist prucalopride, where available. If there is no response to pharmacological treatment, surgical intervention can be considered, but it is only suitable for a carefully selected subset of patients with proven slow transit constipation.

Efficacy, long-term safety, and impact on quality of life of elobixibat in more severe constipation: Post hoc analyses of two phase 3 trials in Japan

BACKGROUND

In two phase 3 trials, elobixibat, a locally acting ileal bile acid transporter inhibitor, resolved constipation and was well tolerated in Japanese patients with chronic constipation. We analyzed the efficacy, safety, and impact on quality of life (QOL) of elobixibat in patients with symptomatically more severe constipation in the two phase 3 trials.

METHODS

This post hoc analysis of elobixibat treatment outcomes included data from a 2-week, randomized, placebo-controlled, phase 3 trial (10 mg/d), and a 52-week, open-label trial (5-15 mg/d) in subgroups with severe constipation defined as ≤2 spontaneous bowel movements (SBMs) and ≤3 Bristol Stool Form Scale score during the second week of the 2-week run-in period. We also analyzed the rates of abdominal pain, diarrhea, and QOL in subgroups according to sex, presence of constipation-predominant irritable bowel syndrome (IBS-C) and side effects.

KEY RESULTS

In patients with severe constipation, there was significant improvement in the 10 mg elobixibat group compared to the placebo group in change in SBMs from baseline at week 1 (primary endpoint) of the 2-week trial. The differences between groups were reduced in patients with more severe constipation. Increasing the dose to 15 mg was effective for more severe constipation in improving the number of SBMs per week in the 52-week trial. Overall, elobixibat was well tolerated and improved QOL scores, irrespective of gender, presence of IBS-C or side effects.

CONCLUSIONS & INFERENCES

Elobixibat is effective for symptomatically severe constipation, is well tolerated and improves QOL, irrespective of potentially confounding patient characteristics.

Prucalopride for the treatment of constipation: a view from 2015 and beyond

Prucalopride is a prokinetic drug, that has been commercially available in recent years for the treatment of chronically constipated patients. In this update of a previous 2016 article, we reviewed the more recent data supporting its role in the treatment of constipation and constipation-associated conditions. Areas covered: We carried out an extensive literature review on the effects of prucalopride for the years 2012-2018 by means of scientific databases and manual research. More evidence was found on its possible therapeutic role in conditions in which constipation plays a role as an associated symptom, such as opioid-induced constipation, constipation-predominant irritable bowel syndrome, post-operative ileus, colonic diverticular disease, drug-related constipation, and chronic intestinal pseudo-obstruction. Expert opinion: Based on the added literature evidence, we feel that prucalopride is an effective, although expensive, drug for the treatment of primary and secondary forms of constipation, and of other clinical conditions associated with constipation.

Usefulness of Bisacodyl Testing on Therapeutic Outcomes in Refractory Constipation

BACKGROUND

Although chronically constipated patients usually respond to medical treatment, there is a subgroup with scarce/no response, generally labeled as refractory or intractable. However, whether this lack of response is real or due to ancillary causes (suboptimal dosage, lack of compliance etc.) is unknown.

AIMS

To see whether a pharmacologic test (bisacodyl colonic intraluminal infusion during manometric assessment) may predict the therapeutic outcome.

METHODS

Data of patients undergoing 24/h colonic manometry for severe intractable constipation in whom the bisacodyl test (10 ml of drug dissolved into saline and injected through the more proximal recording port) had been carried out were retrieved and analysed, and correlations with the therapeutic outcome made.

RESULTS

Overall, charts from 38 patients (5 men) were available; of these, only 21% displayed naive high-amplitude propagated contractions (average, less than 2/24 h), mostly meal-induced, during the recordings. A bisacodyl response was present in 31.6% patients, with a mean number of events of 1.8 per patient. After bisacodyl testing, 47.3% patients underwent intensive medical treatment, 44.7% surgery (medical failures), and 8% transanal irrigation, a procedure employed to treat refractory patients. The presence of naive propulsive contractions significantly correlated with the response to bisacodyl infusion (p < 0.0001), and with a favourable outcome to intensive medical treatment (p < 0.0001).

CONCLUSIONS

The bisacodyl test may be clinically useful to better categorize constipated patients erroneously labelled as intractable and to exclude true colonic inertia, thus avoiding surgery in more than 30% of these subjects.

Safety and efficacy of elobixibat for chronic constipation: results from a randomised, double-blind, placebo-controlled, phase 3 trial and an open-label, single-arm, phase 3 trial

BACKGROUND

A subset of patients with constipation has reduced colonic bile acid concentrations, which are associated with slow colonic transit. In a previous study, elobixibat, a locally acting ileal bile acid transporter inhibitor, accelerated colonic transit in Japanese patients with functional constipation. In this study, we aimed to determine the efficacy of elobixibat for short-term treatment of chronic constipation, and safety, patient satisfaction, and quality of life with long-term treatment.

METHODS

We did two phase 3 studies of patients aged 20-80 years in Japan with at least 6 months of chronic constipation, who satisfied Rome III criteria for functional constipation, including fewer than three spontaneous bowel movements per week. The first trial, including patients enrolled at 16 clinics, was a 2-week, randomised, double-blind, placebo-controlled study in which (after a 2-week run-in period) patients were randomly assigned (1:1) to either elobixibat 10 mg/day for 2 weeks or placebo. Randomisation was done with permuted block method (block size six) without stratification. Masking to treatment allocation was achieved with identical appearances of elobixibat and placebo, which were supplied in sealed, opaque containers. Group assignment was concealed from patients, investigators, and analysts. The second trial, including patients enrolled at 34 clinics or hospitals, was an open-label, 1-year study in which all patients received elobixibat; participants could titrate the dose to 5 mg/day or 15 mg/day, or maintain the 10 mg/day dose. In both studies, participants took the study drug as an oral tablet once per day before breakfast. The primary outcome of the 2-week randomised trial was the change from baseline (ie, last week of the 2-week run-in) in the frequency of spontaneous bowel movements during week 1 of treatment. The primary outcome of the 52-week open-label trial was safety (type, severity, and incidence of adverse drug reactions) at all times from treatment initiation. All efficacy analyses were based on the modified intention-to-treat (ITT) population without imputation for any missing data. Safety analyses included all patients who received at least one dose of study drug. These trials are registered with the Japan Pharmaceutical Information Center (numbers JapicCTI-153061 and JapicCTI-153062) and have been completed.

FINDINGS

Between Nov 4, 2015, and June 11, 2016, we assigned 133 patients to treatment in the 2-week randomised trial: 70 to elobixibat (69 included in the modified ITT and safety populations) and 63 to placebo. The frequency of spontaneous bowel movements per week during week 1 of treatment was greater with elobixibat (least-squares mean 6·4, 95% CI 5·3-7·6) than with placebo (1·7, 1·2-2·2), p<0·0001). Between Oct 31, 2015, and March 15, 2017, we allocated 341 patients to 52 weeks of elobixibat (340 included in the modified ITT and safety populations). 163 (48%) patients in the 52-week trial had an adverse drug reaction, the most common of which were mild gastrointestinal disorders (in 135 [40%] patients). Inguinal hernia was reported in one patient with elobixibat in the 52-week study as a moderate adverse drug reaction. The most common adverse drug reactions in both trials were mild abdominal pain (13 [19%] patients with elobixibat and one [2%] with placebo in the 2-week randomised trial, and 82 [24%] patients in the 52-week trial) and diarrhoea (nine [13%] patients with elobixibat and none with placebo in the 2-week randomised trial and 50 [15%] in the 52-week trial).

INTERPRETATION

Elobixibat resolved constipation in the short-term, and was well tolerated with both short-term and long-term treatment. The evidence supports the use of this novel approach to increase intracolonic concentrations of endogenous bile acid for the treatment of chronic constipation.

FUNDING

EA Pharma and Mochida Pharmaceutical.

Increased Tone of the Human Colon Muscle by Bisacodyl In Vitro

Background/Aims

Although bisacodyl is a widely administered laxative, its underlying mechanism of action remains generally unknown. This study focuses on investigating the effects of bisacodyl on the human colon muscle contraction, and elucidating its mechanism of action.

Methods

Sigmoid colon muscle strips (20 longitudinal and 18 circular muscles) were obtained from 20 subjects who underwent colectomy for colon cancer. Isometric force measurements were calculated in response to electrical field stimulation (EFS, 0.3 milliseconds in trains of 10 Hz for 20 seconds, 150 V). Peak and nadir (tone) during and after EFS, were measured in a controlled state, and after sequential addition of bisacodyl (1 μM), atropine (1 μM), N-nitro-L-arginine (L-NNA, 100 μM), MRS2500 (1 μM), and tetrodotoxin (TTX, 1 μM) to the organ bath.

Results

Transient phasic contractions were observed during EFS, and after cessation of EFS. In the longitudinal muscles, nadir during EFS, and tone after EFS, significantly increased after addition of bisacodyl, and persisted after sequential addition of atropine, L-NNA, MRS2500, and TTX, indicating a direct action of bisacodyl on the smooth muscle. In the second experiment, pretreatment of TTX abolished EFS-induced phasic contractions. Although no phasic contraction was produced after perfusion of bisacodyl, tone was increased, thereby supporting evidence of a direct mechanism of action of bisacodyl on the colon smooth muscle.

Conclusions

Bisacodyl increases the tone of longitudinal muscle in the human sigmoid colon through a direct action on the smooth muscle. Further study is warranted to investigate the neural mechanism of action of bisacodyl.

The "rectosigmoid brake": Review of an emerging neuromodulation target for colorectal functional disorders

The regulation of gastrointestinal motility encompasses several overlapping mechanisms including highly regulated and coordinated neurohormonal circuits. Various feedback mechanisms or "brakes" have been proposed. While duodenal, jejunal, and ileal brakes are well described, a putative distal colonic brake is less well defined. Despite the high prevalence of colonic motility disorders, there is little knowledge of colonic motility owing to difficulties with organ access and technical difficulties in recording detailed motor patterns along its entire length. The motility of the colon is not under voluntary control. A wide range of motor patterns is seen, with long intervals of intestinal quiescence between them. In addition, the use of traditional manometric catheters to record contractile activity of the colon has been limited by the low number of widely spaced sensors, which has resulted in the misinterpretation of colonic motor patterns. The recent advent of high-resolution (HR) manometry is revolutionising the understanding of gastrointestinal motor patterns. It has now been observed that the most common motor patterns in the colon are repetitive two to six cycles per minute (cpm) propagating events in the distal colon. These motor patterns are prominent soon after a meal, originate most frequently in the rectosigmoid region, and travel in the retrograde direction. The distal prominence and the origin of these motor patterns raise the possibility of them serving as a braking mechanism, or the "rectosigmoid brake," to limit rectal filling. This review aims to describe what is known about the "rectosigmoid brake," including its physiological and clinical significance and potential therapeutic applications.

Chronic constipation

Chronic constipation is a prevalent condition that severely impacts the quality of life of those affected. Several types of primary chronic constipation, which show substantial overlap, have been described, including normal-transit constipation, rectal evacuation disorders and slow-transit constipation. Diagnosis of primary chronic constipation involves a multistep process initiated by the exclusion of 'alarm' features (for example, unintentional weight loss or rectal bleeding) that might indicate organic diseases (such as polyps or tumours) and a therapeutic trial with first-line treatments such as dietary changes, lifestyle modifications and over-the-counter laxatives. If symptoms do not improve, investigations to diagnose rectal evacuation disorders and slow-transit constipation are performed, such as digital rectal examination, anorectal structure and function testing (including the balloon expulsion test, anorectal manometry or defecography) or colonic transit tests (such as the radiopaque marker test, wireless motility capsule test, scintigraphy or colonic manometry). The mainstays of treatment are diet and lifestyle interventions, pharmacological therapy and, rarely, surgery. This Primer provides an introduction to the epidemiology, pathophysiological mechanisms, diagnosis, management and quality of life associated with the commonly encountered clinical problem of chronic constipation in adults unrelated to opioid abuse.

Prokinetics in the Management of Functional Gastrointestinal Disorders

PURPOSE OF REVIEW

The goal of this review is to review the current status of prokinetics and to place it in historical context. Impaired motility and thus propulsion have long been thought to play important roles in the pathogenesis of a number of gastrointestinal disorders including gastroesophageal reflux disease (GERD), gastroparesis, chronic idiopathic pseudo-obstruction, and constipation. Historically, disordered motility was also thought to contribute to a number of functional gastrointestinal disorders such as functional dyspepsia (FD) and irritable bowel syndrome (IBS).

RECENT FINDINGS

As we learn more of the pathophysiology of FD, IBS, GERD, constipation, and gastroparesis, the limitations of a therapeutic strategy based on the stimulation of motility (i.e., the use of a prokinetic) have become apparent and the disappointments of the past explained. The development of prokinetic drugs has also been hampered by the non-selective nature of many of the agents studied to date which resulted in some unexpected side effects. There is still an unmet need for an effective and safe prokinetic, but drug development in this area must be mindful of the challenges of the area and the need for selectivity for a given target receptor.

Recording In Vivo Human Colonic Motility: What Have We Learnt Over the Past 100 Years?

To understand the abnormalities that underpin functional gut disorders we must first gain insight into the normal patterns of gut motility. While detailed information continually builds on the motor patterns (and mechanisms that control them) of the human esophagus and anorectum, our knowledge of normal and abnormal motility in the more inaccessible regions of the gut remains poor. This particularly true of the human colon. Investigation of in vivo colonic motor patterns is achieved through measures of transit (radiology, scintigraphy and, more recently, "smart pills") or by direct real-time recording of colonic contractility (intraluminal manometry). This short review will provide an overview of findings from the past and present and attempt to piece together the complex nature of colonic motor patterns. In doing so it will build a profile of human colonic motility and determine the likely mechanisms that control this motility.

Mechanisms of Action of Probiotics and the Gastrointestinal Microbiota on Gut Motility and Constipation

Constipation is a common and burdensome gastrointestinal disorder that may result from altered gastrointestinal motility. The effect of probiotics on constipation has been increasingly investigated in both animal and human studies, showing promising results. However, there is still uncertainty regarding the mechanisms of action of probiotics on gut motility and constipation. Several factors are vital to normal gut motility, including immune and nervous system function, bile acid metabolism and mucus secretion, and the gastrointestinal microbiota and fermentation; an imbalance or dysfunction in any of these components may contribute to aberrant gut motility and, consequently, symptoms of constipation. For example, adults with functional constipation have significantly decreased numbers of bifidobacteria (with one study showing a mean difference of 1 log₁₀/g) and lactobacilli (mean difference, 1.4 log₁₀/g) in stool samples, as well as higher breath methane, compared with control subjects. Modifying the gut luminal environment with certain probiotic strains may affect motility and secretion in the gut and, hence, provide a benefit for patients with constipation. Therefore, this review explores the mechanisms through which probiotics may exert an effect on gut motility and constipation. Nevertheless, the majority of current evidence is derived from animal studies, and therefore, further human studies are needed to determine the mechanisms through specific probiotic strains that might be effective in constipation.

Colonic Inertia: approach and treatment

Objective Revision of the state of the art of the knowledge regarding pathophysiology, diagnosis and treatment of Colonic Inertia, which predominantly affects young women and has a significant socio-economic impact.

Methods A search was made in “colonic inertia”, “colon inertia” and “slow transit constipation” in PubMed database for articles of the last 5 years, in Portuguese or English with available abstract and full text. 59 articles and 2013 guidelines of the American Gastroenterological Association on constipation were included.

Results The pathophysiology is not completely elucidated and the reduction of the interstitial cells of Cajal is the most consistent histological finding. Diagnosis requires the exclusion of secondary causes of constipation and obstructed defecation syndrome, to which contribute several complementary diagnostic tests. Given the frequency of failure of the medical treatment, surgery is often the only possible option. Sacral nerve stimulation seems to be a promising therapeutical alternative.

Conclusion A deeper investigation of the pathophysiological mechanisms is fundamental to acquire a more global and integrated vision. Rigorous patient selection for each treatment and the discovery of new therapeutical targets may avoid the use of surgical therapies.

Pan-Colonic Pressurizations Associated With Relaxation of the Anal Sphincter in Health and Disease: A New Colonic Motor Pattern Identified Using High-Resolution Manometry

OBJECTIVES

Only a few studies have applied high-resolution manometry (HRM) to the study of colonic motility in adults and none of them have concurrently evaluated colonic and anal motor activity. The aim of the study was to evaluate colonic and anal motor activity by means of HRM in healthy subjects. As the present study revealed the presence of a new colonic motor pattern (pan-colonic pressurizations) in healthy subjects, three additional studies were conducted: the first and the second to exclude that this motor event results from an artifact due to abdominal wall contraction and to confirm its modulation by cholinergic stimulation, and the third, as pilot study, to test the hypothesis that this colonic pattern is defective in patients with chronic constipation refractory to current pharmacological treatments.

METHODS

In both volunteers and patients the HRM catheter was advanced proximally during colonoscopy.

RESULTS

In all subjects, pressure increases of 15±3 mm Hg and 24±4 s simultaneously occurring in all colonic sensors (pan-colonic pressurizations) and associated with anal sphincter relaxation were identified. Subjects had 85±38 pan-colonic pressurizations, which increased significantly during meal (P=0.007) and decreased afterward (P=0.01), and were correlated with feelings of and desire to evacuate gas. The mean number of propagating sequences was 47±39, and only retrograde increased significantly postprandially (P=0.01). Pan-colonic pressurizations differed from strain artifacts and significantly increased after prostigmine. In patients pan-colonic pressurizations were significantly reduced as compared with volunteers.

CONCLUSIONS

Pan-colonic pressurizations associated with relaxations of the anal sphincter represent a new colonic motor pattern that seems to be defective in patients with treatment-refractory chronic constipation and may have a role in the transport of colonic gas and in the facilitation of the propagating sequence-induced colonic transport.

Intraluminal pressure patterns in the human colon assessed by high-resolution manometry

Assessment of colonic motor dysfunction is rarely done because of inadequate methodology and lack of knowledge about normal motor patterns. Here we report on elucidation of intraluminal pressure patterns using High Resolution Colonic Manometry during a baseline period and in response to a meal, in 15 patients with constipation, chronically dependent on laxatives, 5 healthy volunteers and 9 patients with minor, transient, IBS-like symptoms but no sign of constipation. Simultaneous pressure waves (SPWs) were the most prominent propulsive motor pattern, associated with gas expulsion and anal sphincter relaxation, inferred to be associated with fast propagating contractions. Isolated pressure transients occurred in most sensors, ranging in amplitude from 5–230 mmHg. Rhythmic haustral boundary pressure transients occurred at sensors about 4–5 cm apart. Synchronized haustral pressure waves, covering 3–5 cm of the colon occurred to create a characteristic intrahaustral cyclic motor pattern at 3–6 cycles/min, propagating in mixed direction. This activity abruptly alternated with erratic patterns resembling the segmentation motor pattern of the small intestine. High amplitude propagating pressure waves (HAPWs) were too rare to contribute to function assessment in most subjects. Most patients, dependent on laxatives for defecation, were able to generate normal motor patterns in response to a meal.

High-resolution colonic motility recordings in vivo compared with ex vivo recordings after colectomy, in patients with slow transit constipation

BACKGROUND

The pathogenesis of slow transit constipation (STC) remains poorly understood, with intrinsic and extrinsic abnormalities implicated. Here, we present high-resolution colonic manometry recordings from four STC patients recorded before total colectomy, and subsequently, ex vivo, after excision.

METHODS

In four female, treatment-resistant STC patients (median age 35.5 years), a fiber-optic manometry catheter (72 sensors spaced at 1 cm intervals) was placed with the aid of a colonoscope, to the mid-transverse colon. Colonic manometry was recorded 2 h before and after a meal. After the colectomy, ex vivo colonic manometry was recorded in an organ bath. Ex vivo recordings were also made from colons from 4 patients (2 male; median age 67.5 years) undergoing anterior resection for nonobstructive carcinoma ('control' tissue).

KEY RESULTS

A large increase in 'short single propagating contractions' was recorded in STC colon ex vivo compared to in vivo (ex vivo 61.3 ± 32.7 vs in vivo 2.5 ± 5/h). In STC patients, in vivo, the dominant frequency of contractile activity was 2-3 cycle per minute (cpm), whereas 1-cpm short-single propagating contractions dominated ex vivo. This same 1-cpm frequency was also dominant in control colons ex vivo.

CONCLUSIONS & INFERENCES

In comparison to control adults, the colon of STC patients demonstrates significantly less propagating motor activity. However, once the STC colon is excised from the body it demonstrates a regular and similar frequency of propagating activity to control tissue. This paper provides interesting insights into the control of colonic motor patterns.

Sequential incremental doses of bisacodyl increase the diagnostic accuracy of colonic manometry

BACKGROUND

Colonic manometry is the standard diagnostic modality for evaluating colonic motility in children. Intraluminal bisacodyl is routinely used to trigger high-amplitude propagating contractions (HAPCs), a feature of normal colonic motility. Usually, only a single dose (0.2 mg/kg) is suggested. We retrospectively explored whether the use of an additional higher (0.4 mg/kg) dose of bisacodyl increases the yield of colonic manometry.

METHODS

In 103 children (median age: 8.8 years, range 3.2-15.7 years) with a diagnosis of slow transit constipation, colonic motility was recorded for 1 h before and 1 h after each of two incremental doses of bisacodyl (low, L, dose: 0.2 mg/kg, max 10 mg; high, H, dose: 0.4 mg/kg, max 20 mg) and the characteristics of HAPCs analyzed.

KEY RESULTS

High-amplitude propagating contractions were seen in 85 children. H dose significantly increased the proportion of patients with fully propagated HAPCs (H dose: 57/103 [55%], L dose: 27/103 [26%], p < 0.001), paralleling the significant decrease in the proportion with partially propagated HAPCs (H dose: 29/103 [28%], L dose: 47/103 [46%], p < 0.01). Mean HAPC number significantly increased throughout the colon at H compared to L dose (7.2 ± 5.05 vs 5.6 ± 5.1, p < 0.05). Finally, the proportion of patients with normal pressure wave morphology of HAPCs significantly increased with higher dose (H dose: 55/85 [65%], L dose: 27/85 [32%], p < 0.001).

CONCLUSIONS & INTERFERENCES

An additional higher dose of bisacodyl during colonic manometry improves colonic neuromuscular function suggesting its use might improve interpretation and decision making in children with slow transit constipation.

Diagnosis and management of chronic constipation in adults

Constipation is a heterogeneous, polysymptomatic, multifactorial disease. Acute or transient constipation can be due to changes in diet, travel or stress, and secondary constipation can result from drug treatment, neurological or metabolic conditions or, rarely, colon cancer. A diagnosis of primary chronic constipation is made after exclusion of secondary causes of constipation and encompasses several overlapping subtypes. Slow-transit constipation is characterized by prolonged colonic transit in the absence of pelvic floor dysfunction. This subtype of constipation can be identified using either the radio-opaque marker test or wireless motility capsule test, and is best treated with laxatives such as polyethylene glycol or newer agents such as linaclotide or lubiprostone. If unsuccessful, subspecialist referral should be considered. Dyssynergic defecation results from impaired coordination of rectoanal and pelvic floor muscles, and causes difficulty with defecation. The condition can be identified using anorectal manometry and balloon expulsion tests and is best managed with biofeedback therapy. Opioid-induced constipation is an emerging entity, and several drugs including naloxegol, methylnaltrexone and lubiprostone are approved for its treatment. In this Review, we provide an overview of the burden and pathophysiology of chronic constipation, as well as a detailed discussion of the available diagnostic tools and treatment options.

Bowel Disorders

Functional bowel disorders are highly prevalent disorders found worldwide. These disorders have the potential to affect all members of society, regardless of age, gender, race, creed, color or socioeconomic status. Improving our understanding of functional bowel disorders (FBD) is critical as they impose a negative economic impact to the global health care system in addition to reducing quality of life. Research in the basic and clinical sciences during the past decade has produced new information on the epidemiology, etiology, pathophysiology, diagnosis and treatment of FBDs. These important findings created a need to revise the Rome III criteria for FBDs, last published in 2006. This manuscript classifies the FBDs into five distinct categories: irritable bowel syndrome (IBS); functional constipation (FC); functional diarrhea (FDr); functional abdominal bloating/distention (FAB/D); and unspecified FBD (U-FBD). Also included in this article is a new sixth category, opioid induced constipation (OIC) which is distinct from the functional bowel disorders (FBDs). Each disorder will first be defined, followed by sections on epidemiology, rationale for changes from prior criteria, clinical evaluation, physiologic features, psychosocial features and treatment. It is the hope of this committee that this new information will assist both clinicians and researchers in the decade to come.

Spatiotemporal Mapping of Motility in Ex Vivo Preparations of the Intestines

Multiple approaches have been used to record and evaluate gastrointestinal motility including: recording changes in muscle tension, intraluminal pressure, and membrane potential. All of these approaches depend on measurement of activity at one or multiple locations along the gut simultaneously which are then interpreted to provide a sense of overall motility patterns. Recently, the development of video recording and spatiotemporal mapping (STmap) techniques have made it possible to observe and analyze complex patterns in ex vivo whole segments of colon and intestine. Once recorded and digitized, video records can be converted to STmaps in which the luminal diameter is converted to grayscale or color [called diameter maps (Dmaps)]. STmaps can provide data on motility direction (i.e., stationary, peristaltic, antiperistaltic), velocity, duration, frequency and strength of contractile motility patterns. Advantages of this approach include: analysis of interaction or simultaneous development of different motility patterns in different regions of the same segment, visualization of motility pattern changes over time, and analysis of how activity in one region influences activity in another region. Video recordings can be replayed with different timescales and analysis parameters so that separate STmaps and motility patterns can be analyzed in more detail. This protocol specifically details the effects of intraluminal fluid distension and intraluminal stimuli that affect motility generation. The use of luminal receptor agonists and antagonists provides mechanistic information on how specific patterns are initiated and how one pattern can be converted into another pattern. The technique is limited by the ability to only measure motility that causes changes in luminal diameter, without providing data on intraluminal pressure changes or muscle tension, and by the generation of artifacts based upon experimental setup; although, analysis methods can account for these issues. When compared to previous techniques the video recording and STmap approach provides a more comprehensive understanding of gastrointestinal motility.

Constipation and Outcomes of Cecostomy

Constipation, defined as delay or difficulty in defecation, present for 2 or more weeks, is a common problem encountered by both primary and specialty medical providers. There are no randomized controlled trials on the use of antegrade enemas in the pediatric population. Most published papers are based on the experience at a particular center. The aim of this article is to describe the pathophysiology of constipation, review the contribution of colonic manometry to the diagnosis of constipation, summarize the advancements in the management of constipation through the use of antegrade enemas, and study the outcomes of cecostomy at different centers. This study is a comprehensive literature review generated by computerized search of literature, supplemented by review of monographs and textbooks in pathology, gastroenterology, and surgery. Literature search was performed using the publications from 1997 to 2012. The search included publications of all types presenting or reviewing data on cecostomy. The antegrade continence enema is a therapeutic option for defecation disorders when maximal conventional therapy is not successful. Symptoms of defecation disorders in children with different underlying etiologies improve significantly after a cecostomy is created. In addition, there is a benefit on the patients' physical activity, healthcare utilization, and general well-being. Based on the review of published literature it seems that antegrade enemas are a successful therapeutic option in children with severe constipation and/or fecal incontinence. With the advent of cecostomy buttons, patient compliance and the overall cosmetic appearance have improved.

Results after sacral nerve stimulation for chronic constipation

BACKGROUND

Sacral nerve stimulation is an established treatment for fecal incontinence and initial reports describe successful results also in subjects with chronic constipation.

METHODS

Consecutive patients with slow transit or outlet obstruction type constipation were offered external stimulation through a test electrode inserted in a sacral foramen during a 3-week period. The symptomatic evaluation was based on the number of bowel movements and a validated obstructed defecation score (ODS). A permanent implant was performed provided an overall 50% decrease in symptoms was observed.

KEY RESULTS

In total, 44 patients with chronic constipation were treated with a 3-week test stimulation. Fifteen experienced a 50% reduction of symptoms and received a permanent implant. Four of the 15 with permanent implants were explanted during the course of the study. Five subjects (11% of original group) reported sustained symptom relief at final follow-up after a mean of 24 months (range 4-81). Mean ODS score did not change during the treatment. Patients with predominantly slow transit constipation or outlet obstruction did not differ concerning success rate.

CONCLUSIONS & INFERENCES

Sacral nerve stimulation has limited efficacy in unselected patients with chronic constipation and cannot be recommended for treatment on routine basis.

Transabdominal electrical stimulation (TES) for the treatment of slow-transit constipation (STC)

Slow-transit constipation (STC) is a newly described subtype of intractable constipation in children which we originally identified with deficiency of substance P in axons supplying the proximal colonic muscle. When nuclear transit studies became available, the patients were found to have slow proximal colonic transit, and responded to antegrade enemas. Using the appendicostomy, we found that there was reduced frequency in propagating sequences throughout the colon. We began testing whether transcutaneous electrical stimulation (TES) could improve motility and symptoms, and over several trials have now shown that TES is remarkably effective in treating children with STC, with long-lasting effects. TES holds promise for treating STC, as well as a range of gastrointestinal motility disorders.

Effect of Atractylodes macrocephala Koidz and Rehmannia dride rhizome on gastrointestinal motility in rats with cathartic colon

AIM: To observe the influence of Atractylodes macrocephala Koidz and Rehmannia dride rhizome on gastrointestinal motility in a rat model which was given rhein suspension to induce cathartic colon.

METHODS: Seventy healthy male Wistar rats were randomly divided into seven groups: a control group, a model group, a conventional dose Atractylodes macrocephala Koidz group, a high-dose Atractylodes macrocephala Koidz group, a Rehmannia dride rhizome group, a conventional dose Atractylodes macrocephala Koidz+Rehmannia dride rhizome group, and a high-dose Atractylodes macrocephala Koidz+Rehmannia dride rhizome group, with ten rats in each group. Rhein suspension was administered to induce cathartic colon. After successful modelling, the control and model groups were given normal saline by gavage, and the rest groups were given corresponding drug(s), respectively. All rats were killed after 14 d. The gastric motility and intestinal transit function were examined.

RESULTS: Carbon black transit rate (%) in the model group was significantly lower compared with the blank control group (39.24 ± 4.28 vs 61.84 ± 3.05, P < 0.05), while gastric residual rate (%) increased significantly (72.74 ± 8.94 vs 36.30 ± 9.57, P < 0.05). Compared with the model group, each treatment significantly reduced the gastric residual rate (%) (57.90 ± 8.57, 45.65 ± 9.31, 41.75 ± 9.16, 45.05 ± 8.52, 38.10 ± 9.79 vs 72.74 ± 8.94, P < 0.05) and increased the carbon black transit rate (%) (49.10 ± 3.06, 56.76 ± 5.16, 52.13 ± 4.37, 53.72 ± 4.29, 60.96 ± 2.51 vs 39.24 ± 4.28, P < 0.05). The gastric residual rate (%) was lower and carbon black transit rate (%) was higher in the high-dose Atractylodes macrocephala Koidz group, conventional dose Atractylodes macrocephala Koidz group, conventional dose Atractylodes macrocephala Koidz+Rehmannia dride rhizome group, and high-dose Atractylodes macrocephala Koidz+Rehmannia dride rhizome group than in the Rehmannia dride rhizome group (45.65 ± 9.31, 41.75 ± 9.16, 45.05 ± 8.52, 38.10 ± 9.79 vs 57.90 ± 8.57, P < 0.05; 56.76 ± 5.16, 52.13 ± 4.37, 53.72 ± 4.29 vs 49.10 ± 3.06, P < 0.05), with the difference in carbon black transit rate (%) was most significant in the high-dose Atractylodes macrocephala Koidz+Rehmannia dride rhizome group (60.96 ± 2.51 vs 49.10 ± 3.06, 56.76 ± 5.16, 52.13 ± 4.37, 53.72 ± 4.29, P < 0.05).

CONCLUSION: Atractylodes macrocephala Koidz and Rehmannia dride rhizome can promote the gastrointestinal motility, with high-dose Atractylodes macrocephala having a better effect. High-dose Atractylodes macrocephala Koidz+Rehmannia dride rhizome has the most significant effect on gastrointestinal motility.

In the clinic. Constipation

This issue provides a clinical overview of constipation, focusing on prevention, diagnosis, treatment, and patient information. The content of In the Clinic is drawn from the clinical information and education resources of the American College of Physicians (ACP), including ACP Smart Medicine and MKSAP (Medical Knowledge and Self-Assessment Program). Annals of Internal Medicine editors develop In the Clinic from these primary sources in collaboration with the ACP's Medical Education and Publishing divisions and with the assistance of science writers and physician writers. Editorial consultants from ACP Smart Medicine and MKSAP provide expert review of the content. Readers who are interested in these primary resources for more detail can consult http://smartmedicine.acponline.org, http://mksap.acponline.org, and other resources referenced in each issue of In the Clinic.

Colonic motor abnormalities in slow transit constipation defined by high resolution, fibre-optic manometry

BACKGROUND

Slow transit constipation (STC) is associated with colonic motor abnormalities. The underlying cause(s) of the abnormalities remain poorly defined. In health, utilizing high resolution fiber-optic manometry, we have described a distal colonic propagating motor pattern with a slow wave frequency of 2-6 cycles per minute (cpm). A high calorie meal caused a rapid and significant increase in this activity, suggesting the intrinsic slow wave activity could be mediated by extrinsic neural input. Utilizing the same protocol our aim was to characterize colonic meal response STC patients.

METHODS

A fiber-optic manometry catheter (72 sensors at 1 cm intervals) was colonoscopically placed with the tip clipped at the ascending or transverse colon, in 14 patients with scintigraphically confirmed STC. Manometric recordings were taken, for 2 h pre and post a 700 kCal meal. Data were compared to 12 healthy adults.

KEY RESULTS

Prior to and/or after the meal the cyclic propagating motor pattern was identified in 13 of 14 patients. However, the meal, did not increase the cyclic motor pattern (preprandial 7.4 ± 7.6 vs postprandial 8.3 ± 4.5 per/2 h), this is in contrast to the dramatic increase observed in health (8.3 ± 13.3 vs 59.1 ± 89.0 per/2 h; p < 0.001).

CONCLUSIONS & INFERENCES

In patients with STC a meal fails to induce the normal increase in the distal colonic cyclic propagating motor patterns. We propose that these data may indicate that the normal extrinsic parasympathetic inputs to the colon are attenuated in these patients.

Postoperative ileus: mechanisms and future directions for research

Postoperative ileus (POI) is an abnormal pattern of gastrointestinal motility characterized by nausea, vomiting, abdominal distension and/or delayed passage of flatus or stool, which may occur following surgery. Postoperative ileus slows recovery, increases the risk of developing postoperative complications and confers a significant financial load on healthcare institutions. The aim of the present review is to provide a succinct overview of the clinical features and pathophysiological mechanisms of POI, with final comment on selected directions for future research.Terminology used when describing POI is inconsistent, with little differentiation made between the obligatory period of gut dysfunction seen after surgery ('normal POI') and the more clinically and pathologically significant entity of a 'prolonged POI'. Both normal and prolonged POI represent a fundamentally similar pathophysiological phenomenon. The aetiology of POI is postulated to be multifactorial, with principal mediators being inflammatory cell activation, autonomic dysfunction (both primarily and as part of the surgical stress response), agonism at gut opioid receptors, modulation of gastrointestinal hormone activity and electrolyte derangements. A final common pathway for these effectors is impaired contractility and motility and gut wall oedema. There are many potential directions for future research. In particular, there remains scope to accurately characterize the gastrointestinal dysfunction that underscores an ileus, development of an accurate risk stratification tool will facilitate early implementation of preventive measures and clinical appraisal of novel therapeutic strategies that target individual pathways in the pathogenesis of ileus warrant further investigation.

Quantification of in vivo colonic motor patterns in healthy humans before and after a meal revealed by high-resolution fiber-optic manometry

BACKGROUND

Until recently, investigations of the normal patterns of motility of the healthy human colon have been limited by the resolution of in vivo recording techniques.

METHODS

We have used a new, high-resolution fiber-optic manometry system (72 sensors at 1-cm intervals) to record motor activity from colon in 10 healthy human subjects.

KEY RESULTS

In the fasted colon, on the basis of rate and extent of propagation, four types of propagating motor pattern could be identified: (i) cyclic motor patterns (at 2-6/min); (ii) short single motor patterns; (iii) long single motor patterns; and (iv) occasional retrograde, slow motor patterns. For the most part, the cyclic and short single motor patterns propagated in a retrograde direction. Following a 700 kCal meal, a fifth motor pattern appeared; high-amplitude propagating sequences (HAPS) and there was large increase in retrograde cyclic motor patterns (5.6 ± 5.4/2 h vs 34.7 + 19.8/2 h; p < 0.001). The duration and amplitude of individual pressure events were significantly correlated. Discriminant and multivariate analysis of duration, gradient, and amplitude of the pressure events that made up propagating motor patterns distinguished clearly two types of pressure events: those belonging to HAPS and those belonging to all other propagating motor patterns.

CONCLUSIONS & INFERENCES

This work provides the first comprehensive description of colonic motor patterns recorded by high-resolution manometry and demonstrates an abundance of retrograde propagating motor patterns. The propagating motor patterns appear to be generated by two independent sources, potentially indicating their neurogenic or myogenic origin.

Fasting and postprandial volumes of the undisturbed colon: normal values and changes in diarrhea-predominant irritable bowel syndrome measured using serial MRI

BACKGROUND

Previous assessments of colon morphology have relied on tests which were either invasive or used ionizing radiation. We aimed to measure regional volumes of the undisturbed colon in healthy volunteers (HV) and patients with diarrhea-predominant irritable bowel syndrome (IBS-D).

METHODS

3D regional (ascending, transverse, and descending) colon volumes were measured in fasting abdominal magnetic resonance (MR) images of 75 HVs and 25 IBS-D patients. Thirty-five of the HV and all 25 IBS-D subjects were fed a standard meal and postprandial MRI data obtained over 225 min.

KEY RESULTS

Colonic regions were identified and 3D maps from cecum to sigmoid flexure were defined. Fasted regional volumes showed wide variation in both HVs being (mean ± SD) ascending colon (AC) 203 ± 75 mL, transverse (TC) 198 ± 79 mL, and descending (DC) 160 ± 86 mL with no difference from IBS-D subjects (AC 205 ± 69 mL, TC 232 ± 100 mL, and DC 151 ± 71 mL, respectively). The AC volume expanded by 10% after feeding (p = 0.007) in the 35 HV possibly due to increased ileo-colonic inflow. A later rise in AC volume occurred from t = 90 to t = 240 min as the meal residue entered the cecum. In contrast, IBS-D subjects showed a much reduced postprandial response of the AC (p < 0.0001) and a greater increase in TC volume after 90 min (p = 0.0244) compared to HV.

CONCLUSIONS & INFERENCES

We have defined a normal range of the regional volumes of the undisturbed colon in fasted and fed states. The AC in IBS-D appeared less able to accommodate postprandial inflow which may account for faster colonic transit.