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Readmissions after colorectal cancer surgery are common, despite advancements in surgical care, and have a significant impact on both individual patients and overall healthcare costs. The aim of this study was to determine the 30-and 90-day readmission rate after colorectal cancer surgery, and to investigate the risk factors and clinical reasons for unplanned readmissions.A multicenter, population-based study including all patients discharged after index colorectal cancer resection from 2010 to 2020 in Aotearoa New Zealand (AoNZ) was completed. The Ministry of Health National Minimum Dataset was used. Rates of readmission at 30-days and 90-days were calculated. Mixed-effect logistic regression models were built to investigate factors associated with unplanned readmission. Reasons for readmission were described.Data were obtained on 16,885 patients. Unplanned 30-day and 90-day hospital readmission rates were 15.1% and 23.7% respectively. The main readmission risk factors were comorbidities, advanced disease, and postoperative complications. Hospital level variation was not present. Despite risk adjustment, RReadmissions following colorectal resections in AoNZ are higher than other comparable healthcare systems and rates have remained constant over time. While patient comorbidities and postoperative complications are associated with readmission, the explanatory value of these variables is poor. To reduce unplanned readmissions, efforts should be focused on prevention and early detection of post-discharge complications.

Patients with irritable bowel syndrome (IBS) have recurrent lower abdominal pain, associated with altered bowel habit (diarrhea and/or constipation). As bowel habit is altered, abnormalities in colonic motility are likely to contribute, however, characterization of colonic motor patterns in IBS patients remains poor. Utilizing fiber-optic manometry, we aimed to characterize distal colonic postprandial colon motility in diarrhea predominant IBS. Methods: After an overnight fast, a 72 sensor (spaced at 1cm intervals) manometry catheter was colonoscopically placed to the proximal colon, in 13 patients with IBS-D and 12 healthy adults. Recordings were taken for two hours pre and post a 700kCal meal. Data were analyzed with our two developed automated techniques. Results: In both healthy adults and patients with IBS-D the dominant frequencies of pressure waves throughout the colon are between 2-4 cycles per minute (cpm) and the power of these frequencies increased significantly after a meal. While these pressure waves formed propagating contractions in both groups, the post-prandial propagating contraction increase was significantly smaller in patients compared to healthy adults. In healthy adults during the meal period, retrograde propagation between 2-8 cpm was significantly greater than antegrade propagation at the same frequencies. This difference was not observed in IBS-D.Conclusion: IBS-D patients show reduced prevalence of the retrograde cyclic motor pattern post-prandially compared to the marked prevalence in healthy adults. We hypothesize that this reduction may allow premature rectal filling, leading to postprandial urgency and diarrhea.

The contractions of the stomach are governed by bioelectrical slow waves that can be detected non-invasively from the body-surface. Diagnosis of gastric motility disorders remains challenging due to the limited information provided by symptoms and tests, including standard electrogastrography (EGG). Body-surface gastric mapping (BSGM) is a novel technique that measures the resultant body-surface potentials using an array of multiple cutaneous electrodes. However, there is no established protocol to guide the placement of the mapping array and to account for the effects of biodiversity on the interpretation of gastric BSGM data. This study aims to quantify the effect of anatomical variation of the stomach on body surface potentials. To this end, 93 subject specific models of the stomach and torso were developed. Anatomical models were developed based on data obtained from the Cancer Imaging Archive. For each subject a set of points were created to model general anatomy the stomach and the torso, using a finite element mesh. A bidomain model was used to simulate the gastric slow waves in the antegrade wave (AW) direction and formation of colliding waves (CW). The resultant dipole was calculated, and a forward modeling approach was employed to simulate body-surface potentials. Simulated data were sampled from a 55 array of electrodes from the body-surface and compared between AW and CW cases. Anatomical parameters such as the Euclidean distance from the xiphoid process (8.6 2.2 cm), orientation relative to the axial plane (195 20.0) were quantified. Electrophysiological simulations of AW and CW were both correlated to specific metrics derived from BSGM signals. In general, the maximum amplitude () and orientation () of the signals provided consistent separation of AW and CW. The findings of this study will aid gastric BSGM electrode array design and placement protocol in clinical practices.

IntroductionBody surface gastric mapping (BSGM) is a new non-invasive test of gastric function. BSGM offers several novel and improved biomarkers of gastric function capable of differentiating patients with overlapping symptom-profiles. The aim of this study was to define normative reference intervals for BSGM spectral metrics in a population of healthy controls.MethodsBSGM was performed in healthy controls using Gastric Alimetry (Alimetry, New Zealand) comprising a stretchable high-resolution array (8×8 electrodes; 196 cm2), wearable Reader, and validated symptom-logging App. The evaluation encompassed a fasting baseline (30 min), 482 kCal meal, and 4-hr postprandial recording. Normative reference intervals were calculated for BSGM metrics including the Principal Gastric Frequency, Gastric Alimetry Rhythm Index (GA-RI; a measure of the concentration of power in the gastric frequency band over time), BMI-adjusted amplitude (µV), and fed:fasted amplitude ratio (ff-AR). Data are reported as median and reference interval (5th and/or 95th percentiles).Results110 subjects (55% female, median age 32 (IQR 24 – 50), median BMI 23.8 kg/m2 (IQR 21.4 – 26.9)) were included. The median Principal Gastric Frequency was 3.04 cpm; reference interval: 2.65 – 3.35 cpm. Median GA-RI was 0.50; reference interval: !0.25. Median BMI-adjusted amplitude was 37.6 µV; reference interval: 20-70 µV. The median ff-AR was 1.85; reference interval !1.08. Higher BMI was associated with a shorter meal-response duration (p=0.014).ConclusionsThis study provides normative reference intervals for BSGM spectral data that will be used in clinical practice to inform diagnostic interpretations of abnormal gastric function.

Gastric peristalsis is critically dependent on an underlying electrical conduction system. Recent years have witnessed substantial progress in clarifying the operations of this system, including its pacemaking units, its cellular architecture, and slow-wave propagation patterns. Advanced techniques have been developed for assessing its functions at high spatiotemporal resolutions. This review synthesizes and evaluates this progress, with a focus on human and translational physiology. A current conception of the initiation and conduction of slow-wave activity in the human stomach is provided first, followed by a detailed discussion of its organization at the cellular and tissue level. Particular emphasis is then given to how gastric electrical disorders may contribute to disease states. Gastric dysfunction continues to grow in their prevalence and impact, and while gastric dysrhythmia is established as a clear and pervasive feature in several major gastric disorders, its role in explaining pathophysiology and informing therapy is still emerging. New insights from high-resolution gastric mapping are evaluated, together with historical data from electrogastrography, and the physiological relevance of emerging biomarkers from body surface mapping such as retrograde propagating slow waves. Knowledge gaps requiring further physiological research are highlighted.

Objectives To assess the efficacy of transcutaneous electrical nerve stimulation (TENS) for neurogenic bladder dysfunction secondary to spinal cord injury (SCI). Materials and methods A systematic search of MEDLINE, EMBASE, Web of Science, Scopus, and Cochrane libraries up to February 2021 was performed using PRISMA methodology. All randomized controlled trials (RCTs) that studied TENS for neurogenic bladder in a SCI population were included. The primary outcomes of interest were maximum cystometric capacity (MCC) and maximum detrusor pressure (Pdet). Meta-analysis was conducted with RevMan v5.3. Results Six RCTs involving 353 participants were included. Meta-analysis showed that TENS significantly increased MCC (standardized mean difference 1.11, 95% confidence interval [CI] 0.08-2.14, p = 0.03, I2 = 54%) in acute SCI. No benefits were seen for maximum Pdet. TENS was associated with no major adverse events. Conclusions TENS may be an effective, safe intervention for neurogenic bladder dysfunction following SCI. Further studies are essential to confirm these results and more work is required to determine optimal stimulation parameters and duration of the treatment.

Cholecystectomy is one of the most commonly performed abdominal operations. Rising demands on acute operating theater availability and resource utilization in the daytime have led to acute cholecystectomy being performed out-of-hours (in the evenings, at night, or on weekends), although it remains unknown whether outcomes differ between out-of-hours and in-hours (during the daytime on weekdays) acute cholecystectomy. This systematic review and meta-analysis aimed to compare outcomes following out-of-hours versus in-hours acute cholecystectomy.The study protocol was prospectively registered on PROSPERO (ID: CRD42021226127). MEDLINE, EMBASE, and Scopus databases were systematically searched for studies comparing outcomes following out-of-hours and in-hours acute cholecystectomy in adults with any acute benign gallbladder disease. The outcomes of interest were rates of bile leakage, bile duct injury, overall postoperative complications, conversion to open cholecystectomy, specific intraoperative and postoperative complications, length of stay, readmission, and mortality. Subgroup (evening/night-time vs. daytime, weekend vs. weekday, acute surgical unit [ASU]-only, non-ASU, and laparoscopic-only) and sensitivity analyses of adjusted multivariate regression analysis results was also performed.Eleven studies were included. There were no differences between out-of-hours and in-hours acute cholecystectomy for rates of bile leakage, bile duct injury, overall postoperative complications, conversion to open cholecystectomy, operative duration, readmission, mortality, and postoperative length of stay. Higher rates of postoperative sepsis (odds ratio, 1.58; 95% confidence interval, 1.04-2.41; p = 0.03) and pneumonia (odds ratio, 1.55; 95% confidence interval, 1.06-2.26; p = 0.02) were observed following out-of-hours acute cholecystectomy on univariate meta-analysis, but not after the adjusted multivariate meta-analysis. Higher conversion rates were observed when out-of-hours cholecystectomy was performed in centers without an ASU.This systematic review and meta-analysis has not shown an increased risk in overall or specific complications associated with out-of-hours compared with in-hours acute cholecystectomy. However, future studies should assess the potential impact of structural hospital factors, such as an ASU, on outcomes following out-of-hours acute cholecystectomy.Systematic Review and Meta-Analysis Study, Level IV.

Ablation has recently emerged as a tool for modulating gastric electrical activation and may hold interventional potential for disorders of gastric function. However, previous studies have been limited to the acute intraoperative setting. This study now presents the safety of gastric ablation after postsurgical recovery and healing. Localized electrical conduction blocks created by ablation remained after 2 wk of healing, and no perforation or other complications were observed over the postsurgical period.

Background Delayed gastric emptying (DGE) is a frequent complication after pancreaticoduodenectomy (PD). The diagnosis of DGE is based on International Study Group for Pancreatic Surgery (ISGPS) clinical criteria and objective assessments of DGE are infrequently used. The present literature review aimed to identify objective measures of DGE following PD and determine whether these measures correlate with the clinical definition of DGE. Methods A systematic search was performed using the MEDLINE Ovid, EMBASE, Google Scholar and CINAHL databases for studies including pancreatic surgery, delayed gastric emptying and gastric motility until June 2022. The primary outcome was modalities undertaken for the objective measurement of DGE following PD and correlation between objective measurements and clinical diagnosis of DGE. Relevant risk of bias analysis was performed. Results The search revealed 4881 records, of which 46 studies were included in the final analysis. There were four objective modalities of DGE assessment including gastric scintigraphy (n = 28), acetaminophen/paracetamol absorption test (n = 10), fluoroscopy (n = 6) and the 13C-acetate breath test (n = 3). Protocols were inconsistent, and reported correlations between clinical and objective measures of DGE were variable; however, amongst these measures, at least one study directly or indirectly inferred a correlation, with the greatest evidence accumulated for gastric scintigraphy. Conclusion Several objective modalities to assess DGE following PD have been identified and evaluated, however are infrequently used. Substantial variability exists in the literature regarding indications and interpretation of these tests, and there is a need for a real-time objective modality which correlates with ISGPS DGE definition after PD.

Functional nausea and vomiting syndromes and gastroparesis, collectively grouped as nausea and vomiting syndromes (NVS), are overlapping conditions with incompletely understood pathophysiology. Gastric slow wave abnormalities are thought to contribute. This study aimed to systematically review and meta-analyze the prevalence of slow wave abnormalities measured by electrogastrography (EGG) in patients with NVS. MEDLINE, EMBASE, EMBASE classic, and CENTRAL databases were systematically searched for articles using EGG in adults (≥ 18 years) with NVS. EGG metrics of interest were percentage time in bradygastria, normogastria, and tachygastria as well as dominant frequency and dominant power. Outcomes were also compared with functional dyspepsia (FD), gastroesophageal reflux disease (GORD), and control cohorts. Seven hundred and sixty NVS patients and 308 controls were included from 24 studies. Overall, 64% of patients had EGG abnormalities. Average percent time in normogastria was low during fasting (50%; 95% CI 40–63%) and fed (53%; 95% CI 41–68%) states in patients, with substantial periods in fasting bradygastria (34.1%; 95% CI 25–47%) and postprandial tachygastria (21%; 95% CI 17–26%). Across gastric disorders, pooling of 84 studies showed a comparably high prevalence of EGG abnormalities in NVS (24 studies; n = 760) and GORD (13 studies; n = 427), compared to FD (47 studies; n = 1751) and controls (45 studies; n = 1027). Frequency-based gastric slow wave abnormalities are prominent in NVS. The strength and consistency of these associations across many studies suggests that gastric dysrhythmia may be an important factor in NVS, motivating the development of more reliable methods for their clinical assessment.

Gastric motility is coordinated by underlying bioelectrical “slow wave” activity. Slow wave dysrhythmias are associated with motility disorders, including gastroparesis, offering an underexplored potential therapeutic target. Although ablation is widely used to treat cardiac arrhythmias, this approach has not yet been trialed for gastric electrical abnormalities. We hypothesized that ablation can create localized conduction blocks and modulate slow wave activation. Radiofrequency ablation was performed on the porcine serosa in vivo, encompassing a range of parameters (55–85°C, adjacent points forming a line, 5–10 s/point). High-resolution electrical mapping (16 × 16 electrodes; 6 × 6 cm) was applied to define baseline and acute postablation activation patterns. Tissue damage was evaluated by hematoxylin and eosin and c-Kit stains. Results demonstrated that RF ablation successfully induced complete conduction block and a full thickness lesion in the muscle layer at energy doses of 65–75°C for 5–10 s/point. Gastric ablation may hold therapeutic potential for gastric electrical abnormalities in the future. NEW & NOTEWORTHY This study presents gastric ablation as a new method for modulating slow wave activation and propagation in vivo, by creating localized electrical conduction blocks in the stomach, validated by high-resolution electrical mapping and histological tissue analysis. The results define the effective energy dose range for creating conduction blocks, while maintaining the mucosal and submucosal integrity, and demonstrate the electrophysiological effects of ablation. In future, gastric ablation can now be translated toward disrupting dysrhythmic slow wave activation.

Objectives Electrogastrography (EGG) is a non-invasive method of measuring gastric electrophysiology. Abnormal gastric electrophysiology is thought to contribute to disease pathophysiology in patients with gastroduodenal symptoms, but this has not been comprehensively quantified in pediatric populations. This study aimed to quantify the abnormalities in gastric electrophysiology on EGG in neonatal and pediatric patients. Methods Databases were systematically searched for articles utilizing EGG in neonatal and pediatric patients (≤18 years). Primary outcomes were prevalence of abnormality, percentage of time in normal rhythm and power ratio. Secondary outcomes were correlations between patient symptoms and abnormal gastric electrophysiology on EGG. Results A total of 33 articles (1,444 participants) were included. EGG methodologies were variable. Pooled prevalence of abnormalities on EGG ranged from 61-86% in patients with functional dyspepsia (FD), gastro-esophageal reflux disease (GERD) and type 1 diabetes mellitus (T1DM). FD patients averaged 20.8% (p=0.011) less preprandial and 21.6% (p = 0.031) less postprandial time in normogastria compared to controls. Electrophysiological abnormalities were inconsistent in GERD. T1DM patients averaged 46.2% (p = 0.0003) less preprandial and similar (p = 0.32) postprandial time in normogastria compared to controls, and had a lower power ratio (SMD -2.20, 95%CI: -4.25, -0.15; p = 0.036). Symptom correlations with gastric electrophysiology were inconsistently reported. Conclusions Abnormalities in gastric electrophysiology were identifiable across a range of pediatric patients with gastroduodenal symptoms on meta-analysis. However, techniques have been inconsistent, and standardized and more reliable EGG methods are desirable to further define these findings and their potential utility in clinical practice.

Aim Ileostomy formation is a commonly performed procedure with substantial associated morbidity. Patients with an ileostomy experience high rates of unplanned hospital readmission with dehydration and such events have long term health and economic impact. Reports of the significant risk factors associated with these readmissions have been inconsistent. This study aimed to identify the significant risk factors for readmission with dehydration following ileostomy formation. Method A systematic search was conducted using the Medline, Embase, Cochrane and CINAHL databases. All original research articles reporting risk factors for readmission with dehydration following ileostomy formation in adults were included. The primary outcome was the pooled risk ratio of clinically relevant variables potentially associated with dehydration-related readmissions following ileostomy formation. The secondary outcome was the incidence of dehydration-related readmissions. Results Ten studies (27,089 patients) were included. The incidences of 30- and 60-day readmission with dehydration were 5.0% (range: 2.1-13.2%) and 10.3% (range: 7.3-14.1%), respectively. Eight variables were found to be significantly associated with dehydration-related readmissions: age ≥65 years, body mass index ≥30kg/m2 , diabetes mellitus, hypertension, renal comorbidity, regular diuretic use, ileal-pouch-anal-anastomosis procedure and index admission length of stay. A pre-operative diagnosis of colorectal cancer was less likely to result in readmission with dehydration. Conclusions Readmission with dehydration following ileostomy formation is a significant issue with several risk factors. Awareness of these risk factors will help inform the design of future studies addressing risk prediction, allow risk stratification of ileostomates and aid in the development of personalised prevention strategies.

Gastroesophageal reflux disease (GERD) is a commonly diagnosed gastrointestinal disorder, with a substantial impact on the quality of life. The underlying pathophysiology of GERD is multifactorial and incompletely understood. Abnormal gastric electrical activity, measured using electrogastrography (EGG), may contribute. This study aimed to systematically review and meta-analyse the existing literature in which EGG was used in patients with GERD. Databases were systematically searched for studies using EGG in adults with GERD. The primary outcome was the percentage of recording time in the normogastric frequency range. Secondary outcomes were dominant frequency, dominant power, power ratio and prevalence of any EGG abnormality. In total, 591 participants (427 patients with GERD; 164 healthy controls) from 13 studies were included. GERD patients spent 17.3% (SMD − 1.18, 95%CI: − 1.84, − 0.52) and 18.7% (SMD − 1.11, 95%CI: − 1.55, − 0.68) less of the preprandial and postprandial recording time in normogastric frequency ranges, respectively, compared to healthy controls. The dominant frequency, dominant power and power ratio were not significantly different to healthy controls in the preprandial and postprandial periods. The pooled prevalence of any EGG abnormality was significantly greater in patients with GERD than in healthy controls [46% (95%CI: 39–64%) vs. 10% (95%CI: 4–23%); p

Colonic high-resolution manometry (cHRM) is an emerging clinical tool for defining colonic function in health and disease. Current analysis methods are conducted manually, thus being inefficient and open to interpretation bias. The main objective of the study was to build an automated system to identify propagating contractions and compare the performance to manual marking analysis. cHRM recordings were performed on 5 healthy subjects, 3 subjects with diarrhea-predominant irritable bowel syndrome, and 3 subjects with slow transit constipation. Two experts manually identified propagating contractions, from five randomly selected 10-min segments from each of the 11 subjects (72 channels per dataset, total duration 550 min). An automated signal processing and detection platform was developed to compare its effectiveness to manually identified propagating contractions. In the algorithm, individual pressure events over a threshold were identified and were then grouped into a propagating contraction. The detection platform allowed user-selectable thresholds, and a range of pressure thresholds was evaluated (2 to 20 mmHg). The automated system was found to be reliable and accurate for analyzing cHRM with a threshold of 15 mmHg, resulting in a positive predictive value of 75%. For 5-h cHRM recordings, the automated method takes 22 ± 2 s for analysis, while manual identification would take many hours. An automated framework was developed to filter, detect, quantify, and visualize propagating contractions in cHRM recordings in an efficient manner that is reliable and consistent.

Objectives Transcutaneous electrical nerve stimulation (TENS) is a noninvasive analgesic neurostimulation modality. Difficulties in clinical trial blinding and therapy administration have limited conclusions of previous trials. The aims of this study were to first investigate the feasibility and acceptability of patient-administered TENS after surgery, and second, the feasibility of using sub-sensory TENS as a proxy sham group for patient-blinding. Materials and methods Over a four-month period, patients undergoing laparoscopic cholecystectomy at a single center were randomized to receive maximally tolerable high-intensity (HI) TENS or sub-sensory low-intensity (LI) TENS. Patients and outcome assessors were blinded. Primary outcomes were the feasibility, tolerability, and acceptability of patient self-administered TENS, measured by patient-reported outcomes, and the strength of patient-blinding, measured using the James Blinding Index (JBI). Secondary outcomes explored clinical recovery and analgesic efficacy. Results Nineteen patients were screened for inclusion; ten patients were randomized and completed the feasibility study. TENS therapy was variably utilized (median duration of TENS 5.3 hours/day [IQR: 4.1-6.9]). The JBI was 0.7, indicating a strong strength of blinding. Majority of patients found the TENS unit easy to use (90%) and were confident with self-administration (100%). No patients experienced adverse effects of TENS use. Conclusions Patient-administered TENS is safe and acceptable. Future studies may use sub-sensory TENS as a proxy sham control to more reliably blind patients. A larger, double-blinded RCT employing these techniques is now needed to determine the analgesic efficacy of TENS in an enhanced recovery setting, and its potential to reduce opiate usage.

BACKGROUND Successful treatments following electrical nerve stimulation have been commonly reported in patients with fecal incontinence and constipation. However, many of these nerve stimulation trials have not implemented sham controls, and are, therefore, unable to differentiate overall treatment responses from placebo. This systematic review aimed to quantify placebo effects and responses following sham electrical nerve stimulation in patients with fecal incontinence and constipation. MATERIAL AND METHODS A literature search of Ovid MEDLINE, PubMed, EMBASE, and Cochrane databases was conducted from inception to April 2017. Randomized sham-controlled trials investigating the effect of lower gastrointestinal electrical nerve stimulation in fecal incontinence and constipation were included. Pediatric and non-sham controlled trials were excluded. RESULTS Ten randomized sham-controlled trials were included. Sham stimulation resulted in improvements in fecal incontinence episodes by 1.3 episodes per week (95% CI -2.53 to -0.01, p = 0.05), fecal urgency by 1.5 episodes per week (CI -3.32 to 0.25, p = 0.09), and Cleveland Clinic Severity scores by 2.2 points (CI 1.01 to 3.36, p = 0.0003). Sham also improved symptoms of constipation with improved stool frequency (1.3 episodes per week, CI 1.16 to 1.42, p

Background Ileostomy formation is a commonly performed procedure in colorectal surgery. The morbidity associated with ileostomies is substantial, particularly for unplanned hospital re-admissions and re-admissions with dehydration. Studies of post-ileostomy re-admissions from an Australasian institution are currently lacking. This retrospective study aimed to quantify the 60-day re-admission rate after ileostomy formation in a New Zealand tertiary centre and to determine the predictive factors. Methods The surgical database of Auckland City Hospital was searched for all patients aged ≥18 years with a new ileostomy formed between first January 2015 and first January 2019. Patient electronic medical records were reviewed to obtain data regarding the primary outcome of re-admissions within 60 days of discharge, as well as patient and operative variables. Multivariate regression analysis was performed to identify independent predictors of all-cause re-admissions and re-admissions with dehydration. Results A total of 246 patients with 266 ileostomy formations were included. The 60-day re-admission rate was 29.3%, with dehydration present in 27.0% of these re-admissions. Renal impairment at discharge (odds ratio 2.819, 95% confidence interval 1.087-7.310) and the presence of at least one Clavien-Dindo 1 complication (odds ratio 2.268, 95% confidence interval 1.301-3.954) were independently associated with all-cause re-admission. The independent predictors of re-admission with dehydration were renal impairment at discharge, codeine prescribed on discharge, Charlson Comorbidity Index and body mass index. Conclusion Unplanned hospital re-admission following ileostomy formation is a significant issue in the New Zealand patient population. Some patient groups are at particularly high risk, such as those with renal impairment at discharge.

Fecal incontinence (FI) substantially impairs quality of life and imparts a major socioeconomic burden. Anal sphincter injury and possibly pudendal nerve damage are considered common causes, however, current clinical methods for evaluating their function remain suboptimal. Electromyography (EMG) and pudendal nerve terminal latencies have been applied with some success, but are not considered standard practice due to uncertain accuracy and clinical value. In this study we developed and applied a novel anorectal high-density (HD) EMG probe in humans and pigs to acquire quantitative electrophysiological metrics of the anorectum. In the human trial we assessed somatic pathways and showed that EMG amplitude was greater for tight voluntary squeezes than light voluntary squeezes (0.03 ± 0.02 mV vs. 0.05 ± 0.03 mV). In a porcine model we applied trans-sacral magnetic stimulation to evoke extrinsically activated involuntary pathways and the resulting motor evoked potentials (MEP) were captured using the HD-EMG probe. The mean MEP amplitude at 50% magnetic stimulation intensity output (MSO) was significantly lower that the MEP amplitude at 85, 95 and 100% MSO (1.52 ± 0.50 mV vs. 3.10 ± 0.60 mV). In conclusion, the use of HD-EMG probe in conjunction with trans-sacral magnetic stimulation, for spatiotemporal mapping of anorectal EMG and MEP activity is anticipated to achieve new insights into FI and could offer improved diagnostic and prognostic biomarkers for anorectal dysfunction.

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

Chronic gastrointestinal motility disorders present a significant problem in current clinical practice with new methods needed to perform routine screening and accurate diagnosis. Electrogastrography (EGG) is a non-invasive method that provides insight into the underlying gastric electrical activity. However, widespread adoption of this technique has been limited due to an incomplete sensitivity and specificity. Recent simulation studies have tried to address these issues by providing a theoretical framework for reliably distinguishing between gastric slow wave dysrhythmias. However, these studies have been limited to a singular dipole, torso, and the stomach representative model. In this paper, we aim to address those shortcomings by developing multiple stomach and torso models with multiple moving dipoles to investigate the influence of biodiversity on EGG. Four anatomically accurate models were developed based on a range of human CT scans. This allowed investigations into the influence of normal and dysrhythmic (gastric re-entry and ectopic pacemaker) gastric electrical activity on the resulting EGG. These investigations identified areas of significant morphological difference in EGG traces for all cases, but the accuracy of these methods were based on a well-defined normal baseline. The results also suggested that the areas identified varied significantly as a result of biodiversity. These findings indicate that high-resolution multichannel EGG methodologies are required to reliably account for anatomical biodiversity.

Gastric motility is coordinated by underlying bioelectrical slow waves. Gastric dysrhythmias occur in gastrointestinal (GI) motility disorders, but there are no validated methods for eliminating dysrhythmias. We hypothesized that targeted ablation could eliminate pacemaker sites in the stomach, including dysrhythmic ectopic pacemaker sites. In vivo high-resolution serosal electrical mapping (16 × 16 electrodes; 6 × 6 cm) was applied to localize normal and ectopic gastric pacemaker sites in 13 anesthetized pigs. Radiofrequency ablation was performed in a square formation surrounding the pacemaker site. Postablation high-resolution mapping revealed that ablation successfully induced localized conduction blocks after 18 min (SD 5). Normal gastric pacemaker sites were eliminated by ablation (n = 6), resulting in the emergence of a new pacemaker site immediately distal to the original site in all cases. Ectopic pacemaker sites were similarly eliminated by ablation in all cases (n = 7), and the surrounding mapped area was then entrained by normal antegrade activity in five of those cases. Histological analysis showed that ablation lesions extended through the entire depth of the muscle layer. Immunohistochemical staining confirmed localized interruption of the interstitial cell of Cajal (ICC) network through the ablation lesions. This study demonstrates that targeted gastric ablation can effectively modulate gastric electrical activation, including eliminating ectopic sites of slow wave activation underlying gastric dysrhythmias, without disrupting surrounding conduction capability or tissue structure. Gastric ablation presents a powerful new research tool for modulating gastric electrical activation and may likely hold therapeutic potential for disorders of gastric function. NEW & NOTEWORTHY This study presents gastric ablation as a novel tool for modulating gastric bioelectrical activation, including eliminating the normal gastric pacemaker site as well as abnormal ectopic pacemaker sites underlying gastric dysrhythmias. Targeted application of radiofrequency ablation was able to eliminate these pacemaker sites without disrupting surrounding conduction capability or tissue structure. Gastric ablation presents a powerful new research tool for modulating gastric electrical activation and may likely hold therapeutic potential for disorders of gastric function.

Disorders of gastric function are highly prevalent, but diagnosis often remains symptom-based and inconclusive. Body surface gastric mapping is an emerging diagnostic solution, but current approaches lack scalability and are cumbersome and clinically impractical. We present a novel scalable system for non-invasively mapping gastric electrophysiology in high-resolution (HR) at the body-surface. The system comprises a custom-designed flexible HR sensor array and portable data-logger synchronized to an App, with automated analysis and visualization algorithms. The novel system underwent performance testing then validation in 24 healthy subjects. In all subjects, gastric electrophysiology and meal responses were successfully captured and mapped non-invasively (mean frequency 2.9 ± 0.3 cycles per minute; peak amplitude at mean 60 m postprandially with return to baseline in