High-resolution Colonic Manometry Research Articles

Sacral nerve stimulation effect on colonic motility in pediatric patients.

Sacral nerve stimulation (SNS) is a minimally invasive surgical procedure used to treat refractory constipation in children. While its efficacy in improving symptoms has been studied, its effect on colonic motor function remains unclear. This case series explores SNS's impact on colonic motor function in pediatric patients with idiopathic constipation, using high-resolution colonic manometry (HRCM). Four pediatric patients with chronic idiopathic constipation underwent SNS placement for intractable symptoms and were subsequently evaluated via HRCM. Clinical characteristics, comorbidities, treatment regimens, and outcomes were reviewed. HRCM was conducted during the SNS-off and SNS-on phases. The motility index (MI) was measured during the SNS-off (fasting and postprandial) and SNS-on phases. Four pediatric patients aged 8 to 21 years met the inclusion criteria. In three patients, SNS-induced high-amplitude propagating contractions (HAPCs) were noted, and in one patient, low-amplitude propagating contractions (LAPCs) were noted. In one patient, propagating contractions were induced only when SNS was turned on. MI changes with SNS-on were variable among different patients with an increase in MI in two patients after turning SNS on and a decrease in the other two compared with baseline. Adverse effects following SNS placement remained minimal across all cases. This case series is the first to report SNS effects on colonic motility evaluated by HRCM in pediatrics. We demonstrate that propagating colonic contractions are promptly induced when SNS is turned on. Although the initial effects of SNS on colonic motility were observable, additional investigation is necessary to comprehend the fundamental mechanisms and long-term effectiveness of SNS in pediatric patients.

Validation of body surface colonic mapping (BSCM) against high resolution colonic manometry for evaluation of colonic motility

Abnormal cyclic motor pattern (CMP) activity is implicated in colonic dysfunction, but the only tool to evaluate CMP activity, high-resolution colonic manometry (HRCM), remains expensive and not widely accessible. This study aimed to validate body surface colonic mapping (BSCM) through direct correlation with HRCM. Synchronous meal-test recordings were performed in asymptomatic participants with intact colons. A signal processing method for BSCM was developed to detect CMPs. Quantitative temporal analysis was performed comparing the meal responses and motility indices (MI). Spatial heat maps were also compared. Post-study questionnaires evaluated participants’ preference and comfort/distress experienced from either test. 11 participants were recruited and 7 had successful synchronous recordings (5 females/2 males; median age: 50 years [range 38–63]). The best-correlating MI temporal analyses achieved a high degree of agreement (median Pearson correlation coefficient (Rp) value: 0.69; range 0.47–0.77). HRCM and BSCM meal response start and end times (Rp = 0.998 and 0.83; both p < 0.05) and durations (Rp = 0.85; p = 0.03) were similar. Heat maps demonstrated good spatial agreement. BSCM is the first non-invasive method to be validated by demonstrating a direct spatio-temporal correlation to manometry in evaluating colonic motility.

Gastrocolonic Response.

The gastrocolonic response (GCR), is a physiologic increase in motor activity of the colon, which usually occurs within minutes following meal ingestion. Over the years several triggers that provoke GCR were recognized including gastric dilation, caloric intake, and fat component of the meal. The response is mediated by the vagal nerve and neurohumoral mechanisms, and it can be modified by several pharmacological factors. Assessment of GCR is part of high-resolution colonic manometry studies, performed in patients with suspected colonic dysmotility. This review highlights the physiologic basis of GCR as well as its clinical and diagnostic features and implementation in variable pathological conditions and clinical practice. GCR has a role in patients with constipation, diabetes, dumping syndrome, bowel hyper and hypomotility and irritable bowel syndrome. Novel sensory triggers for GCR were recently recognized. GCR is a physiological response which is evaluated during colonic manometry studies. Abnormal GCR is a marker of an underlying pathology, which can provide a potential target for treatment.

The colonic motility and classification of patients with slow transit constipation by high-resolution colonic manometry

BackgroundThis study aimed to evaluate the colonic motility of slow transit constipation (STC) patients using high-resolution colonic manometry (HRCM) and classify the patients’ subtypes to instruct treatment based on HRCM characteristics. MethodsThis study enrolled one hundred and twenty-six STC patients and 35 volunteers (healthy controls, HCs). Ambulatory HRCM was performed in all participants by placing a 36-sensor water-perfused probe up to the cecum. Quantitative and qualitative manometric analysis was conducted in the state of rest, postprandial, during sleep, and wakefulness. ResultsThe occurrence rate and times of high amplitude propagated contraction (HAPC) in STC patients were lower than HCs. As for the HAPC contraction characteristics, the mean velocity was similar, contraction length, amplitude, area under the curve (AUC) of pressure wave, and duration were reduced in STC patients compared with HCs. In addition, the occurrence rate and times of low amplitude propagated contraction (LAPC) in STC patients were similar compared to HCs. There was no difference in HAPC occurrence, LAPC occurrence, and most detailed HAPC characteristics between STC patients ≤60 years and STC patients >60 years or between male STC patients and female STC patients. Based on the HRCM characteristics (including HAPC, neostigmine induced HAPC, LAPC, and waking/gastrocolic response), STC patients were classified into four types, respectively, with recommended treatment by clinical experience. ConclusionHRCM serves as a valuable tool in characterizing, classifying the pathophysiology, and guiding clinical management for STC.

Faecal incontinence is associated with an impaired rectosigmoid brake and improved by sacral neuromodulation.

The rectosigmoid brake, characterised by retrograde cyclic motor patterns on high-resolution colonic manometry, has been postulated as a contributor to the maintenance of bowel continence. Sacral neuromodulation (SNM) is an effective therapy for faecal incontinence, but its mechanism of action is unclear. This study aims to investigate the colonic motility patterns in the distal colon of patients with faecal incontinence, and how these are modulated by SNM. A high-resolution fibreoptic colonic manometry catheter, containing 36 sensors spaced at 1-cm intervals, was positioned in patients with faecal incontinence undergoing stage 1 SNM. One hour of pre- and post meal recordings were obtained followed by pre- and post meal recordings with suprasensory SNM. A 700-kcal meal was given. Data were analysed to identify propagating contractions. Fifteen patients with faecal incontinence were analysed. Patients had an abnormal meal response (fewer retrograde propagating contractions compared to controls; p= 0.027) and failed to show a post meal increase in propagating contractions (mean 17 ± 6/h premeal vs. 22 ± 9/h post meal, p= 0.438). Compared to baseline, SNM significantly increased the number of retrograde propagating contractions in the distal colon (8± 3/h premeal vs. 14 ± 3/h premeal with SNM, p= 0.028). Consuming a meal did not further increase the number of propagating contractions beyond the baseline upregulating effect of SNM. The rectosigmoid brake was suppressed in this cohort of patients with faecal incontinence. SNM may exert a therapeutic effect by modulating this rectosigmoid brake.

Diagnosis of colonic dysmotility associated with autonomic dysfunction in patients with chronic refractory constipation

We report the first study assessing human colon manometric features and their correlations with changes in autonomic functioning in patients with refractory chronic constipation prior to consideration of surgical intervention. High-resolution colonic manometry (HRCM) with simultaneous heart rate variability (HRV) was performed in 14 patients, and the resulting features were compared to healthy subjects. Patients were categorized into three groups that had normal, weak, or no high amplitude propagating pressure waves (HAPWs) to any intervention. We found mild vagal pathway impairment presented as lower HAPW amplitude in the proximal colon in response to proximal colon balloon distention. Left colon dysmotility was observed in 71% of patients, with features of (1) less left colon HAPWs, (2) lower left colon HAPW amplitudes (69.8 vs 102.3 mmHg), (3) impaired coloanal coordination, (4) left colon hypertonicity in patients with coccyx injury. Patients showed the following autonomic dysfunction: (1) high sympathetic tone at baseline, (2) high sympathetic reactivity to active standing and meal, (3) correlation of low parasympathetic reactivity to the meal with absence of the coloanal reflex, (4) lower parasympathetic and higher sympathetic activity during occurrence of HAPWs. In conclusion, left colon dysmotility and high sympathetic tone and reactivity, more so than vagal pathway impairment, play important roles in refractory chronic constipation and suggests sacral neuromodulation as a possible treatment.

High-resolution colonic manometry interobserver analysis trial.

Colonic high-resolution manometry (HRM) is a novel, not widely used diagnostic method used in the final workup of chronic constipation before surgery. Since its introduction, different motor patterns have been defined. However, it remains to be established whether these patterns are easily and reproducibly identified by different investigators. The primary aim of this study was to determine agreement for motor pattern identification with HRM. To calculate the interobserver agreement (IOA), the Fleiss's kappa statistic for multiple observers was used. Seven participants analyzed 106 one-min time frames, derived from five measurements in healthy volunteers and five in patients with chronic constipation. The time frames were chosen to show a variety and combination of motor patterns consisting of short antegrade, short retrograde, cyclic anterograde, cyclic retrograde, long antegrade, long retrograde, slow retrograde motor pattern, high-amplitude propagating motor patterns, and pancolonic pressurizations. All of the measurements were performed with a solid-state colonic HRM catheter, comprising 40 pressure sensors spaced 2.5cm apart. A median of 10.25h (range 6-20) were required to analyze all time frames. High-amplitude propagating contractions achieved an almost perfect level of agreement (k=0.91). Several motor patterns achieved substantial agreement; these included the short antegrade (k=0.63), long antegrade (k=0.68), cyclic retrograde (k=0.70), slow retrograde motor pattern (k=0.80), and abdominal pressure or movement artifacts (k=0.67). Moderate agreement was found for short retrograde (k=0.57), cyclic anterograde (k=0.59), long retrograde motor patterns (k=0.59) and simultaneous pressure waves (k=0.59). For the majority of motor patterns, the overall IOA for colonic manometry was substantial or high. This high level of agreement supports the use of colonic manometry application in clinical and research settings. Harmonization has the potential to improve agreement for long anterograde motor patterns with high amplitudes and for mixed direction patterns.

Potential causes of the preoperative increase in the rectosigmoid cyclic motor pattern: A high-resolution manometry study.

BackgroundCyclic motor patterns (CMPs) are the most common motor pattern in the distal colon. This study used high‐resolution (HR) colonic manometry to quantify trends in distal colonic motor activity before elective colonic surgery, determine the effect of a preoperative carbohydrate load, and compare this with a meal response in healthy controls.MethodsFiber‐optic HR colonic manometry (36 sensors, 1 cm intervals) was used to investigate distal colonic motor activity in 10 adult patients prior to elective colonic surgery, 6 of whom consumed a preoperative carbohydrate drink (200 kCal). Data were compared with nine healthy volunteers who underwent HR colonic manometry recordings while fasted and following a 700 kCal meal. The primary outcome was the percentage of recording occupied by CMPs, defined as propagating contractions at 2–4 cycles per minute (cpm). Secondary outcomes included amplitude, speed, and distance of propagating motor patterns.ResultsThe occurrence of CMPs progressively increased in time periods closer to surgery (p = 0.001). Consumption of a preoperative drink resulted in significantly increased CMP occurrence (p = 0.04) and propagating distance (p = 0.04). There were no changes in amplitude or speed of propagating motor patterns during the preoperative period. The increase in activity following a preoperative drink was of similar magnitude to the colonic meal response observed in healthy controls, despite the lesser caloric nutrient load.ConclusionDistal colonic CMP increased in occurrence prior to surgery, amplified by ingestion of preoperative carbohydrate drinks. We hypothesize that anxiety, which is also known to rise with proximity to surgery, could play a contributing role.

Assessment of Gastrointestinal Autonomic Dysfunction: Present and Future Perspectives.

The autonomic nervous system delicately regulates the function of several target organs, including the gastrointestinal tract. Thus, nerve lesions or other nerve pathologies may cause autonomic dysfunction (AD). Some of the most common causes of AD are diabetes mellitus and α-synucleinopathies such as Parkinson’s disease. Widespread dysmotility throughout the gastrointestinal tract is a common finding in AD, but no commercially available method exists for direct verification of enteric dysfunction. Thus, assessing segmental enteric physiological function is recommended to aid diagnostics and guide treatment. Several established assessment methods exist, but disadvantages such as lack of standardization, exposure to radiation, advanced data interpretation, or high cost, limit their utility. Emerging methods, including high-resolution colonic manometry, 3D-transit, advanced imaging methods, analysis of gut biopsies, and microbiota, may all assist in the evaluation of gastroenteropathy related to AD. This review provides an overview of established and emerging assessment methods of physiological function within the gut and assessment methods of autonomic neuropathy outside the gut, especially in regards to clinical performance, strengths, and limitations for each method.

A35 ASSOCIATIONS BETWEEN AUTONOMIC DYSFUNCTION, COLONIC DYSMOTILITY AND ABSENT DEFECATION REFLEXES IN PATIENTS WITH CHRONIC REFRACTORY CONSTIPATION

Abstract Background A defecation reflex involves sensory information from the colon sent to the central nervous system which results in propulsive motor patterns in the colon through programmed neural activity from the autonomic nervous system. Neurological causes of constipation are recognized but specific neurological pathways that contribute to pathophysiology of the disease is underexplored. Diagnosis and treatment usually do not involve the autonomic nervous system. Aims Our objective was to assess autonomic dysfunction and abnormal defecation reflexes as a possible cause of chronic constipation. Methods Defecation reflexes were assessed by high-resolution colonic manometry through balloon distention, meal intake, and rectal bisacodyl. Specific heart rate variability (HRV) parameters were used to assess general orthostatic autonomic reactivity, and autonomic functioning during high resolution colonic manometry, in 14 patients with chronic refractory constipation considered for surgery. Results All patients had a unique combination of motility, reflex ability and HRV profiles. Patients overall did not generate HAPWs or had lower HAPW amplitude and lower propulsive activity compared to healthy individuals. Half of the 14 patients were tested to have high sympathetic tone based on Baevsky’s stress index prior to HRCM, and 11 of the patients had sympathetic hyper-reactivity and/or low parasympathetic reactivity to at least one type of colonic stimulation during HRCM. Abnormal autonomic tone or autonomic reactivity to colonic stimulation was present in all four patients with absence of the vagosacral defecation reflex. Five of the seven patients with absence of the sacral defecation reflex showed high sympathetic tone or high sympathetic reactivity to stimulation. Only two patients had abnormality in coloanal coordination and this was associated with low parasympathetic reactivity to stimulation in both patients. Conclusions The assumption that colonic resection was needed to remove an inert colon was wrong in most patients, but most patients had some form of reflex abnormality. Sympathetic dominance far outweighed parasympathetic dysfunction. Incorporation of assessments of defecation reflexes and autonomic nervous system activity into diagnosis of chronic refractory constipation provides a comprehensive pathophysiological understanding of specific defective neurological pathways contributing to dysmotility. This forms the basis for our individualized treatment efforts through sacral neuromodulation. Funding Agencies CIHR

A232 AUTONOMIC FUNCTION ANALYSIS VIA HEART RATE VARIABILITY ASSOCIATED WITH PROPULSIVE MOTOR PATTERNS OF THE HUMAN COLON

Abstract Background Although parasympathetic activity is the primary driver of colonic propulsive activity, and sympathetic activity a major inhibitor of colonic motility, they are rarely measured and almost play no role in diagnosis of dysfunction or standard treatments. Aims Our aim was to develop assessment of autonomic nervous system activity associated with the major propulsive motor patterns, an essential part of defecation reflexes in the human colon orchestrated by neural reflexes. Methods One hundred and forty-five motor patterns were recorded from eleven healthy volunteers using high resolution colonic manometry (HRCM) with concurrent electro- and impedance cardiography to evaluate changes in parameters of heart rate variability (HRV). Results High-amplitude propagating pressure waves (HAPWs) that often start in the proximal colon, traverse distally and end with anal sphincter relaxation, were associated with a 8.2% (P&amp;lt;0.02) increase in the respiratory sinus arrhythmia (RSA) value, a 24.6% increase in the root mean square of successive differences of beat to beat intervals (RMSSD), indicated a strong parasympathetic reactivity that subsided within 2 min of termination of the HAPW (Figure 1). The measure of sympathetic reactivity to motor patterns was best reflected by the Baevsky Stress Index (or Sympathetic Index, SI) that reduced by 45% (P&amp;lt;0.02). We developed a measure of autonomic balance, the SI/RSA ratio that changed from 18.8 to 8.7 (54%; P&amp;lt;0.01) during motor activity and recovered to 16.1 immediately after (P&amp;lt;0.005). The SI/RMSSD reduced by 65% (P&amp;lt;0.01). When HAPWs occurred in quick succession, the parasympathetic activity showed rhythmicity at the HAPW frequency that slowly terminated when motor activity stopped. During motor activity, the heart rate did not significantly change. Conclusions The major propulsive motor pattern of the human colon, the HAPW as measured by HRCM that is part of the major defecation reflexes, is associated with marked changes in parasympathetic and sympathetic activity that is reflected and measurable as heart rate variability parameters. This opens the way to evaluate autonomic dysfunction in patients with colon motor disorders. Funding Agencies CIHRNSERC, Farncombe Institute

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.

The Sphincter of O'Beirne - Part 1: Study of 18 Normal Subjects.

Gastroenterologists have ignored or emphasized the importance of the rectosigmoid junction in continence or constipation on and off for 200years. Here, we revisit its significance using high-resolution colonic manometry. Manometry, using an 84-channel water-perfused catheter, was performed in 18 healthy volunteers. The rectosigmoid junction registers as an intermittent pressure band of 26.2 ± 7.2mmHg, or intermittent phasic transient pressure increases at a dominant frequency of 3cpm and an amplitude of 28.6 ± 8.6mmHg; or a combination of tone and transient pressures, at a single sensor, 10-17cm above the anal verge. Features are its relaxation or contraction in concert with relaxation or contraction of the anal sphincters when a motor pattern such as a high-amplitude propagating pressure wave or a simultaneous pressure wave comes down, indicating that such pressure increases or decreases at the rectosigmoid junction are part of neurally driven programs. We show that the junction is a site where motor patterns end, or where they start; e.g. retrogradely propagating cyclic motor patterns emerge from the junction. The rectosigmoid junction is a functional sphincter that should be referred to as the sphincter of O'Beirne; it is part of the "braking mechanism," contributing to continence by keeping content away from the rectum. In an accompanying case report, we show that its excessive presence in a patient with severe constipation can be a primary pathophysiology.

Altered colonic motility is associated with low anterior resection syndrome.

Patients frequently suffer from low anterior resection syndrome (LARS) after distal colorectal resection. The pathophysiology of LARS has not been clearly elucidated. We hypothesized that rectosigmoid resection could impair motility patterns in the distal colon, such as the rectosigmoid brake, which contribute to control of stool form and frequency. High-resolution colonic manometry was performed in patients who had previously undergone distal colorectal resection (mean 6.8years after resection) and non-operative controls before and after a standardized meal. Symptoms were assessed using the LARS score. Propagating contractions were compared between patients with and without LARS, and controls. Data were analysed from 23 patients (11 no-LARS; 12 LARS) and nine controls. All groups demonstrated a significant meal response. LARS patients had fewer post-prandial antegrade propagating contractions than controls (P=0.028), and fewer retrograde propagating contractions both pre- (P=0.005) and post-prandially (P=0.004). Post-prandially, the LARS group had a significantly lower percentage of propagating contractions that met the criteria for the cyclic motor pattern compared to the control group (26% vs. 58%; P=0.009). There were significant differences in antegrade and retrograde amplitude (P=0.049; P=0.018) and distance of propagation (P=0.003; P=0.002) post-prandially between LARS patients and controls. Rectosigmoid resection alters the meal response following anterior resection, including impairment of the rectosigmoid brake cyclic motor pattern. These findings help to quantify the impaired functional motility after rectosigmoid resection and offer new insights into the mechanisms of LARS.

The Defecation Reflex Assessed by High-Resolution Colonic Manometry.

The Defecation Reflex Assessed by High-Resolution Colonic Manometry.

The cyclic motor patterns in the human colon.

High-resolution colonic manometry gives an unprecedented window into motor patterns of the human colon. Our objective was to characterize motor activities throughout the entire colon that possessed persistent rhythmicity and spanning at least 5cm. High-resolution colonic manometry using an 84-channel water-perfused catheter was performed in 19 healthy volunteers. Rhythmic activity was assessed during baseline, proximal balloon distention, meal, and bisacodyl administration. Throughout the entire colon, a cyclic motor pattern occurred either in isolation or following a high-amplitude propagating pressure wave (HAPW), consisting of clusters of pressure waves at a frequency centered on 11-13cycles/min, unrelated to breathing. The cluster duration was 1-6minutes; the pressure waves traveled for 8-27cm, lasting 5-8seconds. The clusters itself could be rhythmic at 0.5-2cpm. The propagation direction of the individual pressure waves was mixed with >50% occurring simultaneous. This high-frequency cyclic motor pattern co-existed with the well-known low-frequency cyclic motor pattern centered on 3-4cpm. In the rectum, the low-frequency cyclic motor pattern dominated, propagating predominantly in retrograde direction. Proximal balloon distention, a meal and bisacodyl administration induced HAPWs followed by cyclic motor patterns. Within cyclic motor patterns, retrograde propagating, low-frequency pressure waves dominate in the rectum, likely keeping the rectum empty; and mixed propagation, high-frequency pressure waves dominate in the colon, likely promoting absorption and storage, hence contributing to continence. Propagation and frequency characteristics are likely determined by network properties of the interstitial cells of Cajal.

Associations Between Colonic Motor Patterns and Autonomic Nervous System Activity Assessed by High-Resolution Manometry and Concurrent Heart Rate Variability.

Abnormal colonic motility may be associated with dysfunction of the autonomic nervous system (ANS). Our aim was to evaluate if associations between colonic motor patterns and autonomic neural activity could be demonstrated by assessing changes in heart rate variability (HRV) in healthy volunteers. A total of 145 colonic motor patterns were assessed in 11 healthy volunteers by High-Resolution Colonic Manometry (HRCM) using an 84-channel water-perfused catheter. Motor patterns were evoked by balloon distention, a meal and luminal bisacodyl. The electrocardiogram (ECG) and cardiac impedance were assessed during colonic manometry. Respiratory sinus arrhythmia (RSA) and root mean square of successive differences of beat-to-beat intervals (RMSSD) served as measures of parasympathetic reactivity while the Baevsky’s Stress Index (SI) and the pre-ejection period (PEP) were used as measures of sympathetic reactivity. Taking all motor patterns into account, our data show that colonic motor patterns are accompanied by increased parasympathetic activity and decreased sympathetic activity that may occur without eliciting a significant change in heart rate. Motor Complexes (more than one motor pattern occurring in close proximity), High-Amplitude Propagating Pressure Waves followed by Simultaneous Pressure Waves (HAPW-SPWs) and HAPWs without SPWs are all associated with an increase in RSA and a decrease in SI. Hence RSA and SI may best reflect autonomic activity in the colon during these motor patterns as compared to RMSSD and PEP. SI and PEP do not measure identical sympathetic reactivity. The SPW, which is a very low amplitude pressure wave, did not significantly change the autonomic measures employed here. In conclusion, colonic motor patterns are associated with activity in the ANS which is reflected in autonomic measures of heart rate variability. These autonomic measures may serve as proxies for autonomic neural dysfunction in patients with colonic dysmotility.

High Resolution Colonic Manometry in Relation to 3D-Transit Times in Healthy Controls.

High Resolution Colonic Manometry in Relation to 3D-Transit Times in Healthy Controls.

High-resolution colonic manometry and its clinical application in patients with colonic dysmotility: A review.

The detailed process and mechanism of colonic motility are still unclear, and colonic motility disorders are associated with numerous clinical diseases. Colonic manometry is considered to the most direct means of evaluating colonic peristalsis. Colonic manometry has been studied for more than 30 years; however, the long duration of the examination, high risk of catheterization, huge amount of real-time data, strict catheter sterilization, and high cost of disposable equipment restrict its wide application in clinical practice. Recently, high-resolution colonic manometry (HRCM) has rapidly developed into a major technique for obtaining more effective information involved in the physiology and/or pathophysiology of colonic contractile activity in colonic dysmotility patients. This review focuses on colonic motility, manometry, operation, and motor patterns, and the clinical application of HRCM. Furthermore, the limitations, future directions, and potential usefulness of HRCM in the evaluation of clinical treatment effects are also discussed.

Treatment of irritable bowel syndrome with diarrhoea using titrated ondansetron (TRITON): study protocol for a randomised controlled trial

BackgroundIrritable bowel syndrome with diarrhoea (IBS-D) affects up to 4% of the general population. Symptoms include frequent, loose, or watery stools with associated urgency, resulting in marked reduction of quality of life and loss of work productivity. Ondansetron, a 5HT3 receptor antagonist, has had an excellent safety record for over 20 years as an antiemetic, yet is not widely used in the treatment of IBS-D. It has, however, been shown to slow colonic transit and in a small randomised, placebo-controlled, cross-over pilot study, benefited patients with IBS-D.MethodsThis trial is a phase III, parallel group, randomised, double-blind, multi-centre, placebo-controlled trial, with embedded mechanistic studies. Participants (n = 400) meeting Rome IV criteria for IBS-D will be recruited from outpatient and primary care clinics and by social media to receive either ondansetron (dose titrated up to 24 mg daily) or placebo for 12 weeks. Throughout the trial, participants will record their worst abdominal pain, worst urgency, stool frequency, and stool consistency on a daily basis.The primary endpoint is the proportion of “responders” in each group, using Food and Drug Administration (FDA) recommendations. Secondary endpoints include pain intensity, stool consistency, frequency, and urgency. Mood and quality of life will also be assessed.Mechanistic assessments will include whole gut transit, faecal tryptase and faecal bile acid concentrations at baseline and between weeks 8 and 11. A subgroup of participants will also undergo assessment of sensitivity (n = 80) using the barostat, and/or high-resolution colonic manometry (n = 40) to assess motor patterns in the left colon and the impact of ondansetron.DiscussionThe TRITON trial aims to assess the effect of ondansetron across multiple centres. By defining ondansetron’s mechanisms of action we hope to better identify patients with IBS-D who are likely to respond.Trial registrationISRCTN, ISRCTN17508514, Registered on 2 October 2017.