Designing, Developing, and Validating a Set of Standardized Pictograms to Support Pediatric-Reported Gastroduodenal Symptoms

OBJECTIVE

To develop and validate a set of static and animated gastroduodenal symptom pictograms for children.

STUDY DESIGN

There were 3 study phases: 1: cocreation using experience design methods to develop pediatric gastroduodenal symptom pictograms (static and animated); 2: an online survey to assess acceptability, as well as face and content validity; and 3: a preference study. Phases 2 and 3 compared the novel pediatric pictograms with existing pictograms used with adult patients.

RESULTS

Eight children aged 6-15 years (5 female) participated in phase 1, and 69 children in phase 2 (median age 13 years: IQR 9-15); an additional 49 participants were included in phase 3 (median age 15: IQR 12-17). Face and content validity were higher for the pediatric static and animated pictogram sets compared with pre-existing adult pictograms (78% vs 78% vs 61%). Participants with worse gastric symptoms had superior comprehension of the pediatric pictograms (χ2 [8, N = 118] P < .001). All participants preferred the pediatric static pictogram set was over both the animated and adult sets (χ2 [2, N = 118] P < .001).

CONCLUSIONS

The cocreation phase resulted in the symptom concept confirmation and design of 10 acceptable static and animated gastroduodenal pictograms with high face and content validity when evaluated with children aged 6-18. Validity was superior when children reported more problematic symptoms. Therefore, these pictograms could be used in clinical and research practice to enable standardized symptom reporting for children with gastroduodenal disorders.

The Effects of Corticotropin-Releasing Hormone on Gastric Electrical Activity and Sensorimotor Function in Healthy Volunteers: A Double-blinded Crossover Study

Biopsychosocial factors are associated with disorders of gut brain interaction and exacerbate gastrointestinal symptoms. The mechanisms underlying pathophysiological alterations of stress remain unclear. Corticotropin-releasing hormone (CRH) is a central regulator of the hormonal stress response and has diverse impact on different organ systems. The aim of the present study was to investigate the effects of peripheral CRH infusion on meal-related gastrointestinal symptoms, gastric electrical activity and gastric sensorimotor function in healthy volunteers (HVs). In a randomized, double-blinded, placebo-controlled, crossover study, we evaluated the effects of CRH on gastric motility and sensitivity. HVs were randomized to receive either peripheral administered CRH (100 µg bolus + 1 µg/kg/hr) or placebo (saline), followed by at least a 7-day washout period and assignment to the opposite treatment. Tests encompassed saliva samples, gastric emptying (GE) testing, body surface gastric mapping (BSGM, Gastric Alimetry®; Alimetry) to assess gastric myoelectrical activity with real-time symptom profiling, and a gastric barostat study to assess gastric sensitivity to distention and accommodation. 20 HVs (13 women, mean age 29.2±5.3 years, BMI 23.3±3.8 kg/m2) completed GE tests, of which 18 also underwent BSGM measurements during the GE tests. The GE half time decreased significantly after CRH exposure (65.2±17.4 vs 78.8±24.5 minutes, p=0.02) with significantly increased gastric amplitude (49.7 (34.7-55.6) vs 31.7 (25.7-51.0) µV, p<0.01), saliva cortisol levels and postprandial symptom severity. Eleven HVs also underwent gastric barostat studies on a separate day. However, the thresholds for discomfort during isobaric distensions, gastric compliance, and accommodation did not differ between CRH and placebo.

Transcutaneous Auricular Vagus Nerve Stimulation Normalizes Induced Gastric Myoelectrical Dysrhythmias in Controls Assessed by Body-Surface Gastric Mapping

OBJECTIVES

Transcutaneous auricular vagus nerve stimulation (TaVNS) is a supplementary treatment for gastric symptoms resulting from dysrhythmias. The main objective of this study was to quantify the effects of 10, 40, and 80 Hz TaVNS and sham in healthy individuals in response to a 5-minute water-load (WL5) test.

MATERIALS AND METHODS

Eighteen healthy volunteers aged between 21 and 55 years (body mass index: 27.1 ± 3.2) were recruited. Each subject fasted for up to eight hours and participated in four 95-minute sessions, which consisted of 30 fasted baseline, 30 minutes TaVNS, WL5, and 30 minutes post-WL5. Heart rate variability was assessed using sternal electrocardiogram. Body-surface gastric mapping and bloating (/10) were recorded. One-way ANOVA with post hoc Tukey test was performed to test the difference between TaVNS protocols in terms of frequency, amplitude, bloating scores, root mean square of the successive differences (RMSSD), and stress index (SI).

RESULTS

On average, the subjects consumed 526 ± 160 mL of water, with volume ingested correlated to bloating (mean score 4.1 ± 1.8; r = 0.36, p = 0.029). In general, the reduction in frequency and rhythm stability during the post-WL5 period in sham was normalized by all three TaVNS protocols. Both 40- and 80-Hz protocols also caused increases in amplitude during the stim-only and/or post-WL5 periods. RMSSD increased during the 40-Hz protocol. SI increased during the 10-Hz protocol but decreased during the 40- and 80-Hz protocols.

CONCLUSION

TaVNS proved effective in normalizing gastric dysrhythmias by WL5 in healthy subjects by altering both parasympathetic and sympathetic pathways.

Longitudinal outcome monitoring in patients with chronic gastroduodenal symptoms investigated using the Gastric Alimetry system: study protocol

INTRODUCTION

The Gastric Alimetry platform offers a multimodal assessment of gastric function through body surface gastric mapping (BSGM) and concurrent symptom-tracking via a validated App. We aim to perform a longitudinal cohort study to examine the impact of Gastric Alimetry, and changes in clinical management on patient symptoms, quality of life and psychological health.

METHODS AND ANALYSIS

This is a prospective multicentre longitudinal observational cohort study of participants with chronic gastroduodenal symptoms. Consecutive participants undergoing Gastric Alimetry will be invited to participate. Quality of life will be assessed via EuroQol-5D and the Patient Assessment of Upper Gastrointestinal Disorders-Quality of Life score. Gastrointestinal symptoms will be assessed via the Patient Assessment of Upper Gastrointestinal Symptom Severity index, and the Gastroparesis Cardinal Symptom Index. Psychometrics will be assessed, including anxiety via the General Anxiety Disorder-7, perceived stress using the Perceived Stress Scale 4, and depression via the Patient Health Questionnaire 9. Clinical parameters including diagnoses, investigations and treatments (medication and procedures) will also be captured. Assessments will be made the week after the BSGM test, at 30 days, 90 days, 180 days and 360 days thereafter. The primary outcome is feasibility of longitudinal follow-up of a cohort that have undergone Gastric Alimetry testing; from which patients' continuum of care can be characterised. Secondary outcomes include changes in patient-reported symptoms, quality of life and psychometrics (anxiety, stress and depression). Inferential causal analyses will be performed at the within patient level to explore causal associations between treatment changes and clinical outcomes. The impact of Gastric Alimetry on clinical management will also be captured.

ETHICS AND DISSEMINATION

The protocol has been approved in Aotearoa New Zealand by the Auckland Health Research Ethics Committee. Results will be submitted for conference presentation and peer-reviewed publication.

Efficacy of different surgical treatments for management of anal fistula: a network meta-analysis

PURPOSE

Currently, the anal fistula treatment which optimises healing and preserves bowel continence remains unclear. The aim of our study was to compare the relative efficacy of different surgical treatments for AF through a network meta-analysis.

METHODS

Systematic searches of MEDLINE, EMBASE and CENTRAL databases up to October 2022 identified randomised controlled trials (RCTs) comparing surgical treatments for anal fistulae. Fistulae were classified as simple (inter-sphincteric or low trans-sphincteric fistulae crossing less than 30% of the external anal sphincter (EAS)) and complex (high trans-sphincteric fistulae involving more than 30% of the EAS). Treatments evaluated in only one trial were excluded from the primary analyses to minimise bias. The primary outcomes were rates of success in achieving AF healing and bowel incontinence.

RESULTS

Fifty-two RCTs were included. Of the 14 treatments considered, there were no significant differences regarding short-term (6 months or less postoperatively) and long-term (more than 6 months postoperatively) success rates between any of the treatments in patients with both simple and complex anal fistula. Ligation of the inter-sphincteric fistula tract (LIFT) ranked best for minimising bowel incontinence in simple (99.1% of comparisons; 3 trials, n = 70 patients) and complex anal fistula (86.2% of comparisons; 3 trials, n = 102 patients).

CONCLUSIONS

There is insufficient evidence in existing RCTs to recommend one treatment over another regarding their short and long-term efficacy in successfully facilitating healing of both simple and complex anal fistulae. However, LIFT appears to be associated with the least impairment of bowel continence, irrespective of AF classification.

Optimization of Gastric Pacing Parameters Using High-Resolution Mapping

OBJECTIVE

Abnormal slow-wave activity has been associated with functional motility disorders. Gastric pacing has been investigated to correct slow-wave abnormalities, but clinical therapies are yet to be established. This study aimed to define optimal parameters to advance the application of gastric pacing.

METHODS

High-resolution gastric mapping was utilized to evaluate four pacing parameters in in-vivo pig studies: (i) orientation of the pacing electrodes (longitudinal vs circumferential), (ii) pacing energy (900 vs 10,000 ms mA2), (iii) the pacing location (corpus vs antrum), and (iv) pacing period (between 12 and 36 s).

RESULTS

The probability of slow-wave initiation and entrainment with the pacing electrodes oriented longitudinally was significantly higher than with electrodes orientated circumferentially (86 vs 10%). High-energy pacing accelerated entrainment over the entire mapped field compared to low-energy pacing (3.1±1.5 vs 7.3±2.4 impulses, p < 0.001). Regardless of the location of the pacing site, the new site of slow-wave initiation was always located 4-12 mm away from the pacing site, between the greater curvature and negative pacing electrode. A pacing period between 14-30 s resulted in stable slow-wave initiation and entrainment.

CONCLUSION

These data will now inform effective application of gastric pacing in future studies, including human translation.

Principles and clinical methods of body surface gastric mapping: Technical review

BACKGROUND AND PURPOSE

Chronic gastric symptoms are common, however differentiating specific contributing mechanisms in individual patients remains challenging. Abnormal gastric motility is present in a significant subgroup, but reliable methods for assessing gastric motor function in clinical practice are lacking. Body surface gastric mapping (BSGM) is a new diagnostic aid, employs multi-electrode arrays to measure and map gastric myoelectrical activity non-invasively in high resolution. Clinical adoption of BSGM is currently expanding following studies demonstrating the ability to achieve specific patient subgrouping, and subsequent regulatory clearances. An international working group was formed in order to standardize clinical BSGM methods, encompassing a technical group developing BSGM methods and a clinical advisory group. The working group performed a technical literature review and synthesis focusing on the rationale, principles, methods, and clinical applications of BSGM, with secondary review by the clinical group. The principles and validation of BSGM were evaluated, including key advances achieved over legacy electrogastrography (EGG). Methods for BSGM were reviewed, including device design considerations, patient preparation, test conduct, and data processing steps. Recent advances in BSGM test metrics and reference intervals are discussed, including four novel metrics, being the 'principal gastric frequency', BMI-adjusted amplitude, Gastric Alimetry Rhythm Index™, and fed: fasted amplitude ratio. An additional essential element of BSGM has been the introduction of validated digital tools for standardized symptom profiling, performed simultaneously during testing. Specific phenotypes identifiable by BSGM and the associated symptom profiles were codified with reference to pathophysiology. Finally, knowledge gaps and priority areas for future BSGM research were also identified by the working group.

Anaesthesia by intravenous propofol reduces the incidence of intra-operative gastric electrical slow-wave dysrhythmias compared to isoflurane

Gastric motility is coordinated by bioelectrical slow-wave activity, and abnormal electrical dysrhythmias have been associated with nausea and vomiting. Studies have often been conducted under general anaesthesia, while the impact of general anaesthesia on slow-wave activity has not been studied. Clinical studies have shown that propofol anaesthesia reduces postoperative nausea and vomiting (PONV) compared with isoflurane, while the underlying mechanisms remain unclear. In this study, we investigated the effects of two anaesthetic drugs, intravenous (IV) propofol and volatile isoflurane, on slow-wave activity. In vivo experiments were performed in female weaner pigs (n = 24). Zolazepam and tiletamine were used to induce general anaesthesia, which was maintained using either IV propofol (n = 12) or isoflurane (n = 12). High-resolution electrical mapping of slow-wave activity was performed. Slow-wave dysrhythmias occurred less often in the propofol group, both in the duration of the recorded period that was dysrhythmic (propofol 14 ± 26%, isoflurane 43 ± 39%, P = 0.043 (Mann-Whitney U test)), and in a case-by-case basis (propofol 3/12, isoflurane 8/12, P = 0.015 (Chi-squared test)). Slow-wave amplitude was similar, while velocity and frequency were higher in the propofol group than the isoflurane group (P < 0.001 (Student's t-test)). This study presents a potential physiological biomarker linked to recent observations of reduced PONV with IV propofol. The results suggest that propofol is a more suitable anaesthetic for studying slow-wave patterns in vivo.

Normative Values for Body Surface Gastric Mapping Evaluations of Gastric Motility Using Gastric Alimetry: Spectral Analysis

INTRODUCTION

Body surface gastric mapping (BSGM) is a new noninvasive 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.

METHODS

BSGM was performed in healthy controls using Gastric Alimetry (Alimetry, New Zealand) comprising a stretchable high-resolution array (8 × 8 electrodes; 196 cm 2 ), wearable Reader, and validated symptom-logging App. The evaluation encompassed a fasting baseline (30 minutes), 482 kCal meal, and 4-hour postprandial recording. Normative reference intervals were calculated for BSGM metrics including the Principal Gastric Frequency, Gastric Alimetry Rhythm Index (a measure of the concentration of power in the gastric frequency band over time), body mass index (BMI)-adjusted amplitude (μV), and fed:fasted amplitude ratio. Data were reported as median and reference interval (5th and/or 95th percentiles).

RESULTS

A total of 110 subjects (55% female, median age 32 years [interquartile range 24-50], median BMI 23.8 kg/m 2 [interquartile range 21.4-26.9]) were included. The median Principal Gastric Frequency was 3.04 cycles per minute; reference interval: 2.65-3.35 cycles per minute. The median Gastric Alimetry Rhythm Index was 0.50; reference interval: ≥0.25. The median BMI-adjusted amplitude was 37.6 μV; reference interval: 20-70 μV. The median fed:fasted amplitude ratio was 1.85; reference interval ≥1.08. A higher BMI was associated with a shorter meal-response duration ( P = 0.014).

DISCUSSION

This study provides normative reference intervals for BSGM spectral data to inform diagnostic interpretations of abnormal gastric function.

Characterising nationwide reasons for unplanned hospital readmission after colorectal cancer surgery

BACKGROUND

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 days readmission rate after colorectal cancer surgery, and to investigate the risk factors and clinical reasons for unplanned readmissions.

METHOD

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.

RESULTS

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, R² value of models was low (30 days: 4.3%, 90 days: 5.2%). The most common reasons for readmission were gastrointestinal causes (32.1%) and wound complications (14.4%). Rates of readmission did not improve over the 11 years study period (p = 0.876).

CONCLUSION

Readmissions 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.

Localized bioelectrical conduction block from radiofrequency gastric ablation persists after healing: safety and feasibility in a recovery model

Gastric ablation has demonstrated potential to induce conduction blocks and correct abnormal electrical activity (i.e., ectopic slow-wave propagation) in acute, intraoperative in vivo studies. This study aimed to evaluate the safety and feasibility of gastric ablation to modulate slow-wave conduction after 2 wk of healing. Chronic in vivo experiments were performed in weaner pigs (n = 6). Animals were randomly divided into two groups: sham-ablation (n = 3, control group; no power delivery, room temperature, 5 s/point) and radiofrequency (RF) ablation (n = 3; temperature-control mode, 65°C, 5 s/point). In the initial surgery, high-resolution serosal electrical mapping (16 × 16 electrodes; 6 × 6 cm) was performed to define the baseline slow-wave activation profile. Ablation (sham/RF) was then performed in the mid-corpus, in a line around the circumferential axis of the stomach, followed by acute postablation mapping. All animals recovered from the procedure, with no sign of perforation or other complications. Two weeks later, intraoperative high-resolution mapping was repeated. High-resolution mapping showed that ablation successfully induced sustained conduction blocks in all cases in the RF-ablation group at both the acute and 2 wk time points, whereas all sham-controls had no conduction block. Histological and immunohistochemical evaluation showed that after 2 wk of healing, the lesions were in the inflammation and early proliferation phase, and interstitial cells of Cajal (ICC) were depleted and/or deformed within the ablation lesions. This safety and feasibility study demonstrates that gastric ablation can safely and effectively induce a sustained localized conduction block in the stomach without disrupting the surrounding slow-wave conduction capability.NEW & NOTEWORTHY 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.

Validation of noninvasive body-surface gastric mapping for detecting gastric slow-wave spatiotemporal features by simultaneous serosal mapping in porcine

Gastric disorders are increasingly prevalent, but reliable noninvasive tools to objectively assess gastric function are lacking. Body-surface gastric mapping (BSGM) is a noninvasive method for the detection of gastric electrophysiological features, which are correlated with symptoms in patients with gastroparesis and functional dyspepsia. Previous studies have validated the relationship between serosal and cutaneous recordings from limited number of channels. This study aimed to comprehensively evaluate the basis of BSGM from 64 cutaneous channels and reliably identify spatial biomarkers associated with slow-wave dysrhythmias. High-resolution electrode arrays were placed to simultaneously capture slow waves from the gastric serosa (32 × 6 electrodes at 4 mm spacing) and epigastrium (8 × 8 electrodes at 20 mm spacing) in 14 porcine subjects. BSGM signals were processed based on a combination of wavelet and phase information analyses. A total of 1,185 individual cycles of slow waves were assessed, out of which 897 (76%) were classified as normal antegrade waves, occurring in 10 (71%) subjects studied. BSGM accurately detected the underlying slow wave in terms of frequency (r = 0.99, P = 0.43) as well as the direction of propagation (P = 0.41, F-measure: 0.92). In addition, the cycle-by-cycle match between BSGM and transitions of gastric slow wave dysrhythmias was demonstrated. These results validate BSGM as a suitable method for noninvasively and accurately detecting gastric slow-wave spatiotemporal profiles from the body surface.NEW & NOTEWORTHY Gastric dysfunctions are associated with abnormalities in the gastric bioelectrical slow waves. Noninvasive detection of gastric slow waves from the body surface can be achieved through multichannel, high-resolution, body-surface gastric mapping (BSGM). BSGM matched the spatiotemporal characteristics of gastric slow waves recorded directly and simultaneously from the serosal surface of the stomach. Abnormal gastric slow waves, such as retrograde propagation, ectopic pacemaker, and colliding wavefronts can be detected by changes in the phase of BSGM.

The role of colonic motility in low anterior resection syndrome

Low anterior resection syndrome (LARS) describes the symptoms and experiences of bowel dysfunction experienced by patients after rectal cancer surgery. LARS is a complex and multifactorial syndrome exacerbated by factors such as low anastomotic height, defunctioning of the colon and neorectum, and radiotherapy. There has recently been growing awareness and understanding regarding the role of colonic motility as a contributing mechanism for LARS. It is well established that rectosigmoid motility serves an important role in coordinating rectal filling and maintaining continence. Resection of the rectosigmoid may therefore contribute to LARS through altered distal colonic and neorectal motility. This review evaluates the role of colonic motility within the broader pathophysiology of LARS and outlines future directions of research needed to enable targeted therapy for specific LARS phenotypes.

Outcomes following out-of-hours acute cholecystectomy: A systematic review and meta-analysis

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

LEVEL OF EVIDENCE

Systematic Review and Meta-Analysis Study, Level IV.

The gastric conduction system in health and disease: a translational review

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.

Comparison of gold and PEDOT:PSS contacts for high-resolution gastric electrical mapping using flexible printed circuit arrays

Motility of the stomach is governed by an electrophysiological event termed gastric slow waves. High-resolution (HR) bioelectrical mapping involves placing array of electrodes over the surface of the stomach to record gastric slow waves. Conductive polymer materials have recently been applied to great effect in cardiology and neurophysiology due to its compliant and biocompatible properties. The aim of this study was to quantify the performance of poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) deposited on a flexible print circuit electrode array for gastric slow wave HR mapping. The Au electrodes were coated with PEDOT:PSS at 1 V and different levels of charges (0.3-1.2 mC). HR mapping alongside standard Au electrodes was performed in three anesthetized pigs. Overall, the PEDOT:PSS electrodes detected both antegrade and retrograde slow wave propagations, with comparable frequency, velocity and signal-to-noise ratio to the Au electrodes. Differences between the two electrodes were noted in terms of amplitude and downstroke gradient. The findings of this study will inform designs of future stretchable and implantable HR mapping electrode arrays for gastrointestinal recording and stimulation therapies.

322 Clinical Factors Predictive of Both Successful and Unsuccessful Arterial Embolization in The Management of Lower Gastrointestinal Bleeding

Aim

To develop a model of clinical factors that may predict: (1) technically and clinically successful embolization of a bleeding vessel at Digital Subtraction Angiography (DSA) for lower gastrointestinal bleed (LGIB); (2) a negative DSA in the presence of positive CT-mesenteric angiography (CTMA) for LGIB.

Method

A retrospective cohort study of all DSAs conducted with intent for embolization for acute LGIB over a 10-year period was undertaken. Pre-procedural and intra-procedural clinical variables were evaluated using uni- and multi-variate analysis.

Results

123 DSAs were evaluated. Technical success was 81% (64/78) with clinical success 78%. Technical success was associated with super-selective approach, contrast extravasation on CT, haemoglobin drop, anatomical source and time from CT to DSA on univariate analysis. On multivariate analysis time from CT to DSA was significant with a higher success probability within 120 minutes with different factors being salient depending on degree of delay. Clinical success was only associated with APTT (&lt;27.5s). Technical failure from a negative DSA following a positive CTMA was associated with anatomical source, haemodynamic stability, platelet count and time from CT to DSA on univariate analysis. The latter three remained so on multivariate analysis.

Conclusions

A triaging approach to utilising emergency DSA may be helpful. If prolonged delay between a positive CT and DSA is anticipated, with haemodynamic stability and a near normal platelet count, the DSA may not be fruitful. Technical success may be more likely if DSA occurs within 120mins. Clinical success may be more likely if APTT is within normal range.

Gastric dysrhythmia in gastroesophageal reflux disease: a systematic review and meta-analysis

BACKGROUND

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.

METHODS

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.

RESULTS

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 < 0.0001]. Correlations between GERD symptoms and EGG recordings were inconsistently studied. EGG techniques were heterogeneous.

CONCLUSIONS

Consistent abnormalities in gastric slow-wave activity, as measured by EGG, were identified in adults with GERD. Further investigation into these abnormalities using novel emerging electrophysiology techniques is desirable, to better define their contribution toward GERD pathophysiology.

Transcutaneous Electrical Stimulation for Neurogenic Bladder Dysfunction Following Spinal Cord Injury: Meta-Analysis of Randomized Controlled Trials

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.

Impact of gastric resection and enteric anastomotic configuration on delayed gastric emptying after pancreaticoduodenectomy: a network meta-analysis of randomized trials

Introduction

Delayed gastric emptying (DGE) is frequent after pancreaticoduodenectomy (PD). Several RCTs have explored operative strategies to minimize DGE, however, the optimal combination of gastric resection approach, anastomotic route, configuration and the use of enteroenterostomy remains unclear.

Methods

MEDLINE, Embase and CENTRAL databases were systematically searched for RCTs comparing gastric resection (classic Whipple, pylorus-resecting, pylorus-preserving), anastomotic route (antecolic, retrocolic), configuration (loop gastroenterostomy/Billroth II, Roux-en-Y), and use of enteroenterostomy (Braun). A random-effects, Bayesian network meta-analysis with non-informative priors was conducted to determine the optimal combination of approaches to PD for minimizing DGE.

Results

Twenty-four RCTs, including 2526 patients and 14 approaches were included. There was some heterogeneity, although inconsistency was low. The overall incidence of DGE was 25.6 per cent (647 patients). Pylorus-resecting, antecolic, Billroth II with Braun enteroenterostomy was associated with the lowest rates of DGE and ranked the best in 35 per cent of comparisons. Classic Whipple, retrocolic, Billroth II with Braun ranked the worst for DGE in 32 per cent of comparisons. Pairwise meta-analysis of retrocolic versus antecolic route for gastrojejunostomy found increased risk of DGE with the retrocolic route (odds ratio 2.10, 95 per cent credibility interval (cr.i.) 0.92 to 4.70). Pairwise meta-analysis of enteroenterostomy found a trend towards lower DGE rates when this was used (odds ratio 1.90, 95 per cent cr.i. 0.92 to 3.90). Having a Braun enteroenterostomy ranked the best in 96 per cent of comparisons.

Conclusion

Based on existing RCT evidence, a pylorus-resecting, antecolic, Billroth II with Braun enteroenterostomy seems to be associated with the lowest rates of DGE.

Preregistration

PROSPERO submitted 23 December 2020. CRD42021227637

Risk factors for readmission with dehydration after ileostomy formation: A systematic review and meta-analysis

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 a 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 readmission following ileostomy formation. The secondary outcome was the incidence of dehydration-related readmission.

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 readmission: age ≥65 years, body mass index ≥30 kg/m² , diabetes mellitus, hypertension, renal comorbidity, regular diuretic use, ileal pouch-anal anastomosis procedure and length of stay after index admission. A preoperative diagnosis of colorectal cancer was less likely to result in readmission with dehydration.

CONCLUSION

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 personalized prevention strategies.

Design and Validation of a Surface-Contact Electrode for Gastric Pacing and Concurrent Slow-Wave Mapping

OBJECTIVE

Gastric contractions are, in part, coordinated by slow-waves. Functional motility disorders are correlated with abnormal slow-wave patterns. Gastric pacing has been attempted in a limited number of studies to correct gastric dysmotility. Integrated electrode arrays capable of pacing and recording slow-wave responses are required.

METHODS

New flexible surface-contact pacing electrodes (SPE) that can be placed atraumatically to pace and simultaneously map the slow-wave activity in the surrounding area were developed. SPE were applied in pigs in-vivo for gastric pacing along with concurrent high-resolution slow wave mapping as validation. Histology was conducted to assess for tissue damage around the pacing site. SPE were compared against temporary cardiac pacing electrodes (CPE), and hook-shaped pacing electrodes (HPE), for entrainment rate, entrainment threshold, contact quality, and slow-wave propagation patterns.

RESULTS

Pacing with SPE (amplitude: 2 mA, pulse width: 100 ms) consistently achieved pacemaker initiation. Histological analysis illustrated no significant tissue damage. SPE resulted in a higher rate of entrainment (64%) than CPE (37%) and HPE (24%), with lower entrainment threshold (25% of CPE and 16% of HPE). High resolution mapping showed that there was no significant difference between the initiated slow-wave propagation speed for SPE and CPE (6.8 ± 0.1 vs 6.8 ± 0.2 mm/s, P>0.05). However, SPE had higher loss of tissue lead contact quality than CPE (42 ± 16 vs 13 ± 10% over 20 min).

CONCLUSION

Pacing with SPE induced a slow-wave pacemaker site without tissue damage.

SIGNIFICANCE

SPE offered an atraumatic pacing electrode with a significant reduction of power consumption and placement time compared to impaled electrodes.

Relationships between serum electrolyte concentrations and ileus: A joint clinical and mathematical modeling study

Aim

Prolonged postoperative ileus (PPOI) occurs in around 15% of patients after major abdominal surgery, posing a significant clinical and economic burden. Significant fluid and electrolyte changes may occur peri‐operatively, potentially contributing to PPOI; however, this association has not been clearly elucidated. A joint clinical‐theoretical study was undertaken to evaluate peri‐operative electrolyte concentration trends, their association with ileus, and predicted impact on bioelectrical slow waves in interstitial cells of Cajal (ICC) and smooth muscle cells (SMC).

Methods

Data were prospectively collected from 327 patients undergoing elective colorectal surgery. Analyses were performed to determine associations between peri‐operative electrolyte concentrations and prolonged ileus. Biophysically based ICC and SMC mathematical models were adapted to evaluate the theoretical impacts of extracellular electrolyte concentrations on cellular function.

Results

Postoperative day (POD) 1 calcium and POD 3 chloride, sodium were lower in the PPOI group (p < 0.05), and POD3 potassium was higher in the PPOI group (p < 0.05). Deficits beyond the reference range in PPOI patients were most notable for sodium (Day 3: 29.5% ileus vs. 18.5% no ileus, p = 0.04). Models demonstrated an 8.6% reduction in slow‐wave frequency following the measured reduction in extracellular NaCl on POD5, with associated changes in cellular slow‐wave morphology and amplitude.

Conclusion

Low serum sodium and chloride concentrations are associated with PPOI. Electrolyte abnormalities are unlikely to be a primary mechanism of ileus, but their pronounced effects on cellular electrophysiology predicted by modeling suggest these abnormalities may adversely impact motility recovery. Resolution and correction of electrolyte abnormalities in ileus may be clinically relevant.

ManoMap: an automated system for characterization of colonic propagating contractions recorded by high-resolution manometry

RATIONALE

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.

OBJECTIVE

The main objective of the study was to build an automated system to identify propagating contractions and compare the performance to manual marking analysis.

METHODS

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).

KEY RESULTS

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.

CONCLUSIONS

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.

The impact of transanal tube design for preventing anastomotic leak in anterior resection: a systematic review and meta-analysis

BACKGROUND

Placement of a transanal tube (TAT) into the rectum is a strategy used to attempt to prevent anastomotic leak (AL) in anterior resection surgery. There is a wide variation in materials and tube design in devices used as TATs and previous meta-analyses have not considered TAT design in their analyses. This study reviews the impact that design of TAT has on AL rates.

METHODS

A systematic review of the literature was performed with the aim of identifying studies evaluating the use of TATs for preventing AL and then defining the design of TATs. Studies were then compared in groups based on TAT design in a meta-analysis to evaluate whether design is an important variable in outcomes.

RESULTS

Thirty-three studies were included. There was a wide variety of tubes used as TATs. On meta-analysis, catheter-type TATs were associated with a substantially lower rate of AL (OR: 0.46; 95% CI 0.30, 0.68). By contrast, stent-type TATs were not associated with any reduction in the incidence of AL (OR: 1.06, 95% CI 0.50, 2.22). Catheter-type TATs were also associated with substantial reductions in the rate of reoperation (OR: 0.32; 95% CI 0.20, 0.50), whereas stent-type TATs showed no benefit in the rate of reoperation (OR: 0.79; 95% CI 0.37, 1.65).

CONCLUSIONS

Off-the-shelf catheter-type transanal tubes appeared effective in preventing AL, whereas custom-designed stent-type TATs were not demonstrated to be effective; although high quality evidence is limited. TAT design should be an important consideration in further research of the use of TATs in anterior resection surgery.

Effects of Anatomical Variations on Body Surface Gastric Mapping

The contractions of the stomach are governed by an electrophysiological event that can be detected noninvasively from the body-surface. Diagnosis of gastric motility disorders remains challenging due to the limited information provided by symptoms and 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, 44 subject specific models of the stomach and torso were developed. Anatomical parameters such as the Euclidean distance from the xiphoid process (88.1 ± 21.9 mm), orientation relative to the axial plane (202.8 ± 14.0°) and tissue volume (47.5 ± 29.5 mL) were quantified. Electrophysiological simulations demonstrated strong correlation (0.73 ± 0.16) between stomach and body-surface activities, with variations in the location of maximum amplitude relative to the xiphoid process (103.7 ± 44.2 mm). In general, there was an agreement between the location of the stomach and the location of the maximum amplitude, and an extended coverage was required to account for the biodiversity. The findings of this study will aid BSGM electrode array design and placement protocol in clinical practices.

Re-admissions after ileostomy formation: a retrospective analysis from a New Zealand tertiary centre

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.

A Novel High-Density Electromyography Probe for Evaluating Anorectal Neurophysiology: Design, Human Feasibility Study, and Validation with Trans-Sacral Magnetic Stimulation

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.

Network meta-analysis of local and regional analgesia following colorectal resection

BACKGROUND

Postoperative pain management after colorectal surgery remains challenging. Systemic opiates delivered on demand or via a patient-controlled pump have traditionally been the mainstay of treatment. Opiate analgesia is associated with slower gastrointestinal recovery and unpleasant side-effects; many regional and local analgesic techniques have been developed as alternatives.

METHODS

MEDLINE, Embase and CENTRAL databases were searched systematically for RCTs comparing analgesic techniques after major colorectal resection. A network meta-analysis was performed using a Bayesian random-effects framework with a non-informative prior. Primary outcomes included pain at rest and cumulative opiate consumption 24 h after surgery. Secondary outcomes included pain at rest and cumulative opiate consumption at 48 h, pain on movement and cough at 24 and 48 h, time to first stool, time to tolerance of oral diet, duration of hospital stay, nausea and vomiting, and postoperative complications.

RESULTS

Seventy-four RCTs, including 5101 patients and 11 different techniques, were included. Some inconsistency and heterogeneity was found. SUCRA scores showed that spinal analgesia was the best intervention for postoperative pain and opiate reduction at 24 h. Transversus abdominus plane blocks were effective in reducing pain and opiate consumption 24 h after surgery. Subgroup analysis showed similar results for open versus minimally invasive surgical approaches, and enhanced recovery after surgery programmes.

CONCLUSION

Spinal analgesia and transversus abdominus plane blocks best balanced pain control and opiate minimization in the immediate postoperative phase following colorectal resection. Multimodal analgesia reduces pain, minimizes systemic opiate use and optimizes postoperative recovery.

Comparison of bowel dysfunction between colorectal cancer survivors and a non-operative non-cancer control group

AIM

Low anterior resection syndrome (LARS) detrimentally affects quality of life in colorectal cancer survivors. This study assessed the prevalence for LARS in colorectal cancer survivors and the same symptoms in a matched control group.

METHOD

Validated instruments, the LARS score and Short Form Survey 12, used to collect functional and quality of life outcomes from patients who had undergone distal colorectal resection at Auckland Hospital (2008-2015) or Dunedin Hospital (2008-2017). A matched non-operative control group was drawn from patients undergoing surveillance colonoscopy.

RESULTS

The response rate was 79%. Cross-sectional prevalence of major LARS in rectal cancer patients was 52% at a median follow-up of 52 months. Major LARS prevalence in the sigmoid cancer resection and non-cancer control groups was similar (25% vs 26%, P = 0.6). On univariate analysis anastomotic height [risk ratio (RR) for low anterior resection 4.6, P < 0.001; ultralow anterior resection RR = 15.5, P < 0.001], radiotherapy (RR = 2.6; P = 0.009), stoma (RR = 3.6; P = 0.001) and J pouch reconstruction (vs straight anastomosis, RR = 4.6; P = 0.008) were associated with major LARS for rectal cancer patients. These factors were not significant when the analysis was stratified for anastomotic height. Despite correlation between LARS and Short Form Survey 12 outcomes (physical ρ = -0.2; mental ρ = -0.2) there was no difference in quality of life outcomes between the groups.

CONCLUSION

Bowel dysfunction after low anterior resection affects the majority of rectal cancer patients. The high background rate of bowel dysfunction must be considered when assessing the prevalence of LARS.

Novel chyme reinfusion device for gastrointestinal fistulas and stomas: feasibility study

Background

High-output enterostomies and enteroatmospheric fistulas are common causes of intestinal failure, and may necessitate parenteral nutrition and prolonged hospital stay. Reinfusing lost chyme into the distal gut is known to be beneficial, but implementation has been limited because manual reinfusion is unpleasant and labour-intensive, and no devices are available. A new device is presented for reinfusing chyme easily and efficiently, with first-in-human data.

Methods

The device comprises a compact centrifugal pump that fits inside a standard stoma appliance. The pump is connected to an intestinal feeding tube inserted into the distal intestinal limb. The pump is activated across the appliance by magnetic coupling to a hand-held driver unit, effecting intermittent bolus reinfusion while avoiding effluent contact. Safety, technical and clinical factors were evaluated.

Results

Following microbiological safety testing, the device was evaluated in ten patients (median duration of installation 39·5 days; total 740 days). Indications included remediation of high-output losses (8 patients), dependency on parenteral nutrition (5), and gut rehabilitation before surgery (10). Reinfusion was well tolerated with use of regular boluses of approximately 200 ml, and no device-related serious adverse events occurred. Clinical benefits included resumption of oral diet, cessation of parenteral nutrition (4 of 5 patients), correction of electrolytes and liver enzymes, and hospital discharge (6 of 10). Of seven patients with intestinal continuity restored, one experienced postoperative ileus.

Conclusion

A novel chyme reinfusion device was developed and found to be safe, demonstrating potential benefits in remediating high-output losses, improving fluid and electrolyte balance, weaning off parenteral nutrition and improving surgical recovery. Pivotal trials and regulatory approvals are now in process.

Manometry of the Human Ileum and Ileocaecal Junction in Health, Disease and Surgery: A Systematic Review

Background: The terminal ileum and ileocaecal junction form a transition zone in a relatively inaccessible portion of the gastrointestinal tract. Little is known about the motility of this region with few detailed studies, indicating the need for a robust synthesis of current knowledge. This review aimed to evaluate the quantitative and qualitative data on the manometry findings of the terminal ileum and ileocaecal junction during the fasting and post-prandial periods in healthy individuals and patients with motility disorders or patients after bowel surgery.

Methods: A systematic search of five databases (Medline, Pubmed, Embase, Scopus, and Cochrane Library) was performed. Studies that presented manometry data from the human ileum or ileocaecal junction were included.

Results: Forty-two studies met the inclusion criteria. The main motility patterns reported in the terminal ileum during fasting were the migrating motor complex, discrete clustered contractions, prolonged propagated contractions and phasic contractions. Post-prandial motility featured irregular, intense contractions. Some studies found a region of sustained increased pressure at the ileocaecal junction while others did not. Patients with motility disorders showed differences in manometry including retrograde propagation of phase III. Patients post-bowel surgery showed differences including higher incidence of phase III.

Conclusion: Motility patterns of the terminal ileum differ between fasting and fed states. Large variability existed in manometry recordings of the terminal ileum. Technical challenges and lack of standardized definitions may reduce accuracy of manometry assessment. Further research is needed to understand how this key portion of the gut physiologically functions.

Establishing core outcome sets for gastrointestinal recovery in studies of postoperative ileus and small bowel obstruction: protocol for a nested methodological study

INTRODUCTION

Gastrointestinal recovery describes the restoration of normal bowel function in patients with bowel disease. This may be prolonged in two common clinical settings: postoperative ileus and small bowel obstruction. Improving gastrointestinal recovery is a research priority but researchers are limited by variation in outcome reporting across clinical studies. This protocol describes the development of core outcome sets for gastrointestinal recovery in the contexts of postoperative ileus and small bowel obstruction.

METHOD

An international Steering Group consisting of patient and clinician representatives has been established. As overlap between clinical contexts is anticipated, both outcome sets will be co-developed and may be combined to form a common output with disease-specific domains. The development process will comprise three phases, including definition of outcomes relevant to postoperative ileus and small bowel obstruction from systematic literature reviews and nominal-group stakeholder discussions; online-facilitated Delphi surveys via international networks; and a consensus meeting to ratify the final output. A nested study will explore if the development of overlapping outcome sets can be rationalized.

DISSEMINATION AND IMPLEMENTATION

The final output will be registered with the Core Outcome Measures in Effectiveness Trials initiative. A multi-faceted, quality improvement campaign for the reporting of gastrointestinal recovery in clinical studies will be launched, targeting international professional and patient groups, charitable organizations and editorial committees. Success will be explored via an updated systematic review of outcomes 5 years after registration of the core outcome set.

Feasibility of High-Resolution Electrical Mapping for Characterizing Conduction Blocks Created by Gastric Ablation

The interstitial cells of Cajal (ICC) initiate, coordinate and propagate bioelectrical slow wave activity that drives gastric motility. In the healthy human stomach, slow wave activity is highly organized. Gastric motility disorders are associated with dysrhythmias. While ablation is widely used to treat cardiac dysrhythmias, this approach has yet to be trialed in the stomach. In this study, radiofrequency (RF) ablation was applied in pig stomachs in vivo to create targeted electrical conduction blocks. Ablations were performed at temperature control mode (55-70°C), and resultant conduction blocks were identified and verified using high-resolution electrical mapping. Termination of slow wave propagation at ablation sites was confirmed by a decrease in extracellular slow wave amplitude from 1.7 ± 0.2 mV to an undetectable amplitude, as well as spatiotemporal pattern analysis of conduction blocks. The use of high-resolution electrical mapping can now be employed to investigate ablation as a potential therapy for gastric dysrhythmias in motility disorders.

Placebo Response Rates in Electrical Nerve Stimulation Trials for Fecal Incontinence and Constipation: A Systematic Review and Meta-Analysis

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 < 0.00001), Wexner Constipation scores (5.0 points, CI -7.45 to -2.54 p < 0.0001), and Gastrointestinal Quality of Life scores (7.9 points, CI -0.46 to 16.18, p = 0.06).

CONCLUSIONS

Sham stimulation is associated with clinical and statistically meaningful improvements in symptoms of fecal incontinence and constipation, as well as quality of life scores, highlighting the importance of sham controls in nerve stimulation trials. Noncontrolled studies should be interpreted with caution.

Quantification of gastric emptying caused by impaired coordination of pyloric closure with antral contraction: a simulation study

Proper coordination of gastric motor functions is required for healthy gastric emptying. However, pyloric function may be impaired by functional disorders or surgical procedures. Here, we show how coordination between pyloric closure and antral contraction affects the emptying of liquid contents. We numerically simulated fluid dynamics using an anatomically realistic gastrointestinal geometry. Peristaltic contractions in the proximal stomach resulted in gastric emptying at a rate of 3-8 ml min-1. When the pylorus was unable to close, the emptying rate increased to 10-30 ml min-1, and instantaneous retrograde flow from the duodenum to the antrum occurred during antral relaxation. Rapid emptying occurred if the pylorus began to open during the terminal antral contraction, and the emptying rate was negative if the pylorus only opened during the antral relaxation phase. Our results showed that impaired coordination between antral contraction and pyloric closure can result in delayed gastric emptying, rapid gastric emptying and bile reflux.

Functional outcomes from a randomized trial of early closure of temporary ileostomy after rectal excision for cancer

BACKGROUND

Low anterior resection syndrome (LARS) has a significant impact on postoperative quality of life. Although early closure of an ileostomy is safe in selected patients, functional outcomes have not been investigated. The aim was to compare bowel function and the prevalence of LARS in patients who underwent early or late closure of an ileostomy after rectal resection for cancer.

METHODS

Early closure (8-13 days) was compared with late closure (after 12 weeks) of the ileostomy following rectal cancer surgery in a multicentre RCT. Exclusion criteria were: signs of anastomotic leakage, diabetes mellitus, steroid treatment and postoperative complications. Bowel function was evaluated using the LARS score and the Memorial Sloan Kettering Cancer Center Bowel Function Instrument (BFI).

RESULTS

Following index surgery, 112 participants were randomized (55 early closure, 57 late closure). Bowel function was evaluated at a median of 49 months after stoma closure. Eighty-two of 93 eligible participants responded (12 had died and 7 had a permanent stoma). Rates of bowel dysfunction were higher in the late closure group, but this did not reach statistical significance (major LARS in 29 of 40 participants in late group and 25 of 42 in early group, P = 0·250; median BFI score 63 versus 71 respectively, P = 0·207). Participants in the late closure group had worse scores on the urgency/soiling subscale of the BFI (14 versus 17; P = 0·017). One participant in the early group and six in the late group had a permanent stoma (P = 0·054).

CONCLUSION

Patients undergoing early stoma closure had fewer problems with soiling and fewer had a permanent stoma, although reduced LARS was not demonstrated in this cohort. Dedicated prospective studies are required to evaluate definitively the association between temporary ileostomy, LARS and timing of closure.

Multi-day, multi-sensor ambulatory monitoring of gastric electrical activity

OBJECTIVE

Bioelectrial signals known as slow waves play a key role in coordinating gastric motility. Slow wave dysrhythmias have been associated with a number of functional motility disorders. However, there have been limited human recordings obtained in the consious state or over an extended period of time. This study aimed to evaluate a robust ambulatory recording platform.

APPROACH

A commercially available multi-sensor recording system (Shimmer3, ShimmerSensing) was applied to acquire slow wave information from the stomach of six humans and four pigs. First, acute experiments were conducted in pigs to verify the accuracy of the recording module by comparing to a standard widely employed electrophysiological mapping system (ActiveTwo, BioSemi). Then, patients with medically refractory gastroparesis undergoing temporary gastric stimulator implantation were enrolled and gastric slow waves were recorded from mucosally-implanted electrodes for 5 d continuously. Accelerometer data was also collected to exclude data segments containing excessive patient motion artefact.

MAIN RESULTS

Slow wave signals and activation times from the Shimmer3 module were closely comparable to a standard electrophysiological mapping system. Slow waves were able to be recorded continuously for 5 d in human subjects. Over the 5 d, slow wave frequency was 2.8  ±  0.6 cpm and amplitude was 0.2  ±  0.3 mV.

SIGNIFICANCE

A commercial multi-sensor recording module was validated for recording electrophysiological slow waves for 5 d, including in ambulatory patients. Multiple modules could be used simultaneously in the future to track the spatio-temporal propagation of slow waves. This framework can now allow for patho-electrophysiological studies to be undertaken to allow symptom correlation with dysrhythmic slow wave events.

Colonic Electromechanical Abnormalities Underlying Post-operative Ileus: A Systematic and Critical Review

Post-operative ileus (POI) is an inevitable consequence of major abdominal surgery, and may be prolonged in up to 30% of patients. Ileus is commonly presumed to result from paralysis of the GI tract, though there is little direct evidence to support this view. The aim of this review is to systematically search and critically review the literature investigating post-operative colonic electrical and mechanical activity. MEDLINE and Embase databases were systematically searched for articles investigating post-operative colonic motor or electrical activity in human patients. Nineteen original articles investigating post-operative colonic motor or electrical activity were identified. Most studies have used low-resolution techniques, with intermittent recordings of colonic motility. Numerous studies have shown that colonic electrical and motor activity does not cease routinely following surgery, but is of abnormal character for 3–6 days following laparotomy. One recent high-resolution manometry study identified hyperactive cyclic motor patterns occurring in the distal colon on the first post-operative day. Low-resolution studies have shown colonic slow waves are not inhibited by surgery, and are present even in the immediate post-operative period. Recovery of normal motility appears to occur in a proximal to distal direction and is temporally correlated with the clinical return of bowel function. No studies have investigated motility specifically in prolonged POI. Future studies should use high-resolution techniques to accurately characterise abnormalities in electrical and mechanical function underlying POI, and correlate these changes with clinical recovery of bowel function.

Electrical Stimulation and Recovery of Gastrointestinal Function Following Surgery: A Systematic Review

OBJECTIVES

Postoperative ileus occurs in approximately 5-15% of patients following major abdominal surgery, and poses a substantial clinical and economic burden. Electrical stimulation has been proposed as a means to aid postoperative gastrointestinal (GI) recovery, but no methods have entered routine clinical practice. A systematic review was undertaken to assess electrical stimulation techniques and to evaluate their clinical efficacy in order to identify promising areas for future research.

MATERIALS AND METHODS

Literature was searched using MEDLINE, EMBASE, Google Scholar and by assessing relevant clinical trial databases. Studies investigating the use of electrical stimulation for postoperative GI recovery were included, regardless of methods used or outcomes measured. A critical review was constructed encompassing all included studies and evaluating and synthesizing stimulation techniques, protocols, and clinical outcomes.

RESULTS

A broad range of neuromodulation strategies and protocols were identified and assessed. Improved postoperative GI recovery following electrical stimulation was reported by 55% of studies (10/18), most commonly those assessing transcutaneous electrical nerve stimulation and electroacupuncture therapy (7/10). Several studies reported shorter time to first flatus and stool, shorter duration of hospital stay, and reduced postoperative pain. However, inconsistent reporting and limitations in trial design were common, compromising a definitive determination of electrical stimulation efficacy.

CONCLUSIONS

Electrical stimulation appears to be a promising methodology to aid postoperative GI recovery, but greater attention to mechanisms of action and clinical trial quality is necessary for progress. Future research should also aim to apply validated and standardized gut recovery outcomes and consistent neuromodulation methodologies.

Variants in ACTG2 underlie a substantial number of Australasian patients with primary chronic intestinal pseudo-obstruction

BACKGROUND

Primary chronic intestinal pseudo-obstruction (CIPO) is a rare, potentially life-threatening disorder characterized by severely impaired gastrointestinal motility. The objective of this study was to examine the contribution of ACTG2, LMOD1, MYH11, and MYLK mutations in an Australasian cohort of patients with a diagnosis of primary CIPO associated with visceral myopathy.

METHODS

Pediatric and adult patients with primary CIPO and suspected visceral myopathy were recruited from across Australia and New Zealand. Sanger sequencing of the genes encoding enteric gamma-actin (ACTG2) and smooth muscle leiomodin (LMOD1) was performed on DNA from patients, and their relatives, where available. MYH11 and MYLK were screened by next-generation sequencing.

KEY RESULTS

We identified heterozygous missense variants in ACTG2 in 7 of 17 families (~41%) diagnosed with CIPO and its associated conditions. We also identified a previously unpublished missense mutation (c.443C>T, p.Arg148Leu) in one family. One case presented with megacystis-microcolon-intestinal hypoperistalsis syndrome in utero with subsequent termination of pregnancy at 28 weeks' gestation. All of the substitutions identified occurred at arginine residues. No likely pathogenic variants in LMOD1, MYH11, or MYLK were identified within our cohort.

CONCLUSIONS AND INFERENCES

ACTG2 mutations represent a significant underlying cause of primary CIPO with visceral myopathy and associated phenotypes in Australasian patients. Thus, ACTG2 sequencing should be considered in cases presenting with hypoperistalsis phenotypes with suspected visceral myopathy. It is likely that variants in other genes encoding enteric smooth muscle contractile proteins will contribute further to the genetic heterogeneity of hypoperistalsis phenotypes.

Methods for High-Resolution Electrical Mapping in the Gastrointestinal Tract

Over the last two decades, high-resolution (HR) mapping has emerged as a powerful technique to study normal and abnormal bioelectrical events in the gastrointestinal (GI) tract. This technique, adapted from cardiology, involves the use of dense arrays of electrodes to track bioelectrical sequences in fine spatiotemporal detail. HR mapping has now been applied in many significant GI experimental studies informing and clarifying both normal physiology and arrhythmic behaviors in disease states. This review provides a comprehensive and critical analysis of current methodologies for HR electrical mapping in the GI tract, including extracellular measurement principles, electrode design and mapping devices, signal processing and visualization techniques, and translational research strategies. The scope of the review encompasses the broad application of GI HR methods from in vitro tissue studies to in vivo experimental studies, including in humans. Controversies and future directions for GI mapping methodologies are addressed, including emerging opportunities to better inform diagnostics and care in patients with functional gut disorders of diverse etiologies.