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.

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.

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.

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.

ANTECEDENTES: Las ostomías y las fístulas entero-atmosféricas de alto débito son causas frecuentes de insuficiencia intestinal y pueden precisar nutrición parenteral (NP) y una hospitalización prolongada. Se sabe que la reinfusión del quimo perdido en el intestino distal es beneficiosa, pero su práctica se ha visto limitada porque la reinfusión manual es desagradable, laboriosa y no hay dispositivos disponibles. Se presenta un nuevo dispositivo para reinfundir el quimo de forma fácil y eficiente, junto con los primeros datos en humanos. MÉTODOS: El dispositivo constaba de una bomba centrífuga compacta que cabe dentro de una bolsa de ostomía estándar. Esta bomba iba conectada a una sonda intestinal colocada en el intestino distal. La bomba se activa manualmente mediante el acoplamiento magnético de una manivela, que evita el contacto con el efluente y permite efectuar la reinfusión de bolos discontinuos. Se evaluaron factores de seguridad, técnicos y clínicos. RESULTADOS: Después de las pruebas de seguridad microbiológica, se evaluó el dispositivo en 10 pacientes (mediana de tiempo de funcionamiento 39,5 días; total 740 días). Las indicaciones abarcaron la paliación de pérdidas cuantiosas (n = 8), la dependencia de NP (n = 5) y la rehabilitación intestinal antes de la cirugía (n = 10). La reinfusión se toleró bien utilizando bolos repetidos de ~200 ml, y no hubo efectos adversos graves relacionados con el dispositivo. Los beneficios clínicos incluyeron la reanudación de la dieta oral, el cese de la NP (4/5 pacientes), la corrección de trastornos electrolitos y de las enzimas hepáticas y el alta hospitalaria (6/10). De los 7 pacientes en los que se reconstruyó el tránsito digestivo, uno experimentó un íleo postoperatorio. CONCLUSIÓN: Se ha desarrollado un nuevo dispositivo de reinfusión de quimo que ha demostrado su seguridad y beneficios potenciales para paliar pérdidas cuantiosas, restaurar el equilibrio hidroelectrolítico, retirar la NP y mejorar la recuperación quirúrgica. Están en marcha los ensayos clínicos pivotales y el proceso para obtener los permisos reglamentarios.

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.

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.

ANTECEDENTES: El tratamiento del dolor postoperatorio después de cirugía colorrectal sigue siendo difícil. Los opiáceos sistémicos administrados a demanda o mediante una bomba controlada por el paciente ha sido tradicionalmente el principal tratamiento. Sin embargo, la analgesia con opiáceos se asocia con una recuperación gastrointestinal más lenta y con efectos secundarios desagradables, lo que dado lugar al desarrollo de numerosas técnicas analgésicas regionales y locales como modalidades alternativas. MÉTODOS: Se realizaron búsquedas sistemáticas en las bases de datos Medline, Embase y CENTRAL para identificar ensayos controlados aleatorizados (randomized controlled trials, RCTs) que compararan técnicas analgésicas después de una resección colorrectal mayor. Se realizó un metaanálisis en red utilizando un marco bayesiano de efectos aleatorios con una distribución a priori no informativa. Los criterios de valoración primarios incluyeron dolor en reposo y el consumo de opiáceos a las 24 horas después de la operación. Los criterios de valoración secundarios incluyeron dolor en reposo y el consumo de opiáceos a las 48 horas, dolor con el movimiento y al toser (a las 24 y 48 horas), tiempo hasta la primera deposición, tiempo hasta tolerar la dieta oral, duración de la estancia hospitalaria, náuseas y vómitos, y complicaciones postoperatorias. RESULTADOS: Se incluyeron 74 RCTs, con un total de 5.101 pacientes y 11 técnicas diferentes. Se encontró cierta inconsistencia y heterogeneidad. Las puntuaciones de dolor en reposo más bajas y la menor ingesta de opiáceos postoperatorios a las 24 horas correspondieron a la analgesia espinal. Los bloqueos del plano transverso del abdomen fueron efectivos para reducir el dolor y el consumo de opiáceos a las 24 horas después de la cirugía. El análisis de subgrupos mostró resultados similares para los abordajes quirúrgicos abiertos versus mínimamente invasivos y para los programas de recuperación intensificada después de la cirugía (Enhanced Recovery After Surgery, ERAS). CONCLUSIÓN: La analgesia espinal y el bloqueo del plano transverso del abdomen consiguieron un mejor control del dolor y una disminución de los opiáceos en el postoperatorio inmediato tras la cirugía colorrectal. La analgesia multimodal reduce el dolor, minimiza el uso de opiáceos sistémicos y optimiza la recuperación postoperatoria.

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.

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.

Nonsteroidal anti-inflammatory drugs reduce the time to recovery of gut function after elective colorectal surgery: a systematic review and meta-analysis.

AIM: Postoperative ileus causes significant patient morbidity after abdominal surgery. Some evidence suggests nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce time to gut recovery, but there has not been a meta-analysis to assess their efficacy. This systematic review and meta-analysis aimed to determine the benefit of NSAIDs for recovery of postoperative gut function in patients undergoing elective colorectal surgery. METHOD: MEDLINE, EMBASE, CENTRAL and reference lists were searched with no date or language restrictions. Randomized controlled trials comparing the use of NSAIDs with placebo in the perioperative or postoperative period were identified. Included studies reported outcomes relevant to gut function: time to pass flatus or stool and time to tolerate an oral diet. The mean difference in time from surgery until passage of flatus, stool and tolerance of diet were meta-analysed using a random-effects model in RevMan 5.3. RESULTS: This study identified 992 relevant articles. Five randomized controlled trials on patients undergoing elective colorectal surgery met our inclusion criteria and were meta-analysed. Compared with placebo, NSAIDs significantly improved the time to pass flatus (mean difference -9.44 h, 95% CI: -17.22, -1.65, I2 = 70%, P = 0.02), time to pass stool (mean difference -12.09 h, 95% CI: -17.16, -7.02, I2 = 0%, P < 0.001) and time to tolerate a diet (mean difference -11.95 h, 95% CI: -18.66, -5.24, I2 = 0%, P < 0.001). CONCLUSION: NSAIDs significantly improve time to gut recovery after elective colorectal surgery. Current evidence is not adequate to identify whether selective or nonselective drugs should be recommended. Further high-power studies using selective drugs are required.

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.

Hyperactive cyclic motor activity in the distal colon after colonic surgery as defined by high-resolution colonic manometry.

BACKGROUND: Recovery after colonic surgery is invariably delayed by disturbed gut motility. It is commonly assumed that colonic motility becomes quiescent after surgery, but this hypothesis has not been evaluated rigorously. This study quantified colonic motility through the early postoperative period using high-resolution colonic manometry. METHODS: Fibre-optic colonic manometry was performed continuously before, during and after surgery in the left colon and rectum of patients undergoing right hemicolectomy, and in healthy controls. Motor events were characterized by pattern, frequency, direction, velocity, amplitude and distance propagated. RESULTS: Eight patients undergoing hemicolectomy and nine healthy controls were included in the study. Colonic motility became markedly hyperactive in all operated patients, consistently dominated by cyclic motor patterns. Onset of cyclic motor patterns began to a minor extent before operation, occurring with increasing intensity nearer the time of surgery; the mean(s.d.) active duration was 12(7) per cent over 3 h before operation and 43(17) per cent within 1 h before surgery (P = 0.024); in fasted controls it was 2(4) per cent (P < 0·001). After surgery, cyclic motor patterns increased markedly in extent and intensity, becoming nearly continuous (active duration 94(13) per cent; P < 0·001), with peak frequency 2-4 cycles per min in the sigmoid colon. This postoperative cyclic pattern was substantially more prominent than in non-operative controls, including in the fed state (active duration 27(20) per cent; P < 0·001), and also showed higher antegrade velocity (P < 0·001). CONCLUSION: Distal gut motility becomes markedly hyperactive with colonic surgery, dominated by cyclic motor patterns. This hyperactivity likely represents a novel pathophysiological aspect of the surgical stress response. Hyperactive motility may contribute to gut dysfunction after surgery, potentially offering a new therapeutic target to enhance recovery.

Association Between Circular Stapler Diameter and Stricture Rates Following Gastrointestinal Anastomosis: Systematic Review and Meta-analysis.

BACKGROUND: Stricture is a common complication of gastrointestinal (GI) anastomoses, associated with impaired quality of life, risk of malnutrition, and further interventions. This systematic review and meta-analysis aimed to determine the association between circular stapler diameter and anastomotic stricture rates throughout the GI tract. METHODS: A systematic literature search of EMBASE, MEDLINE and Cochrane Library was performed. The primary outcome was the rate of radiologically or endoscopically confirmed anastomotic stricture. Pooled odds ratios (OR) were calculated using random-effects models to determine the effect of circular stapler diameter on stricture rates in different regions of the GI tract. RESULTS: Twenty-one studies were identified: seven oesophageal, twelve gastric, and three lower GI. Smaller stapler sizes were strongly associated with higher anastomotic stricture rates throughout the GI tract. The oesophageal anastomosis studies showed; 21 versus 25 mm circular stapler: OR 4.39 ([95% CI 2.12, 9.07]; P < 0.0001); 25 versus 28/29 mm circular stapler: OR 1.71 ([95% CI 1.15, 2.53]; P < 0.008). Gastric studies showed; 21 versus 25 mm circular stapler: OR 3.12 ([95% CI 2.23, 4.36]; P < 0.00001); 25 versus 28/29 mm circular stapler: OR 7.67 ([95% CI 1.86, 31.57]; P < 0.005). Few lower GI studies were identified, though a similar trend was found: 25 versus 28/29 mm circular stapler: pooled OR 2.61 ([95% CI 0.82, 8.29]; P = 0.100). CONCLUSIONS: The use of larger circular stapler sizes is strongly associated with reduced risk of anastomotic stricture in the upper GI tract, though data from lower GI joins are limited.

Intra-operative high-resolution mapping of slow wave propagation in the human jejunum: Feasibility and initial results.

BACKGROUND: Bioelectrical slow waves are a coordinating mechanism of small intestine motility, but extracellular human studies have been restricted to a limited number of sparse electrode recordings. High-resolution (HR) mapping has offered substantial insights into spatiotemporal intestinal slow wave dynamics, but has been limited to animal studies to date. This study aimed to translate intra-operative HR mapping to define pacemaking and conduction profiles in the human small intestine. METHODS: Immediately following laparotomy, flexible-printed-circuit arrays were applied around the serosa of the proximal jejunum (128-256 electrodes; 4-5.2 mm spacing; 28-59 cm2 ). Slow wave propagation patterns were mapped, and frequencies, amplitudes, downstroke widths, and velocities were calculated. Pacemaking and propagation patterns were defined. KEY RESULTS: Analysis comprised nine patients with mean recording duration of 7.6 ± 2.8 minutes. Slow waves occurred at a frequency of 9.8 ± 0.4 cpm, amplitude 0.3 ± 0.04 mV, downstroke width 0.5 ± 0.1 seconds, and with faster circumferential velocity than longitudinal (10.1 ± 0.8 vs 9.0 ± 0.7 mm/s; P = .001). Focal pacemakers were identified and mapped (n = 4; mean frequency 9.9 ± 0.2 cpm). Disordered slow wave propagation was observed, including wavefront collisions, conduction blocks, and breakout and entrainment of pacemakers. CONCLUSIONS & INFERENCES: This study introduces HR mapping of human intestinal slow waves, and provides first descriptions of intestinal pacemaker sites and velocity anisotropy. Future translation to other intestinal regions, disease states, and postsurgical dysmotility holds potential for improving the basic and clinical understanding of small intestine pathophysiology.

Relationships between gastric slow wave frequency, velocity, and extracellular amplitude studied by a joint experimental-theoretical approach.

BACKGROUND: Gastric slow wave dysrhythmias are accompanied by deviations in frequency, velocity, and extracellular amplitude, but the inherent association between these parameters in normal activity still requires clarification. This study quantified these associations using a joint experimental-theoretical approach. METHODS: Gastric pacing was conducted in pigs with simultaneous high-resolution slow wave mapping (32-256 electrodes; 4-7.6 mm spacing). Relationships between period, velocity, and amplitude were quantified and correlated for each wavefront. Human data from two existing mapping control cohorts were analyzed to extract and correlate these same parameters. A validated biophysically based ICC model was also applied in silico to quantify velocity-period relationships during entrainment simulations and velocity-amplitude relationships from membrane potential equations. KEY RESULTS: Porcine pacing studies identified positive correlations for velocity-period (0.13 mm s-1 per 1 s, r2 =.63, P<.001) and amplitude-velocity (74 µV per 1 mm s-1 , r2 =.21, P=.002). In humans, positive correlations were also quantified for velocity-period (corpus: 0.11 mm s-1 per 1 s, r2 =.16, P<.001; antrum: 0.23 mm s-1 per 1 s, r2 =.55; P<.001), and amplitude-velocity (94 µV per 1 mm s-1 , r2 =.56; P<.001). Entrainment simulations matched the experimental velocity-period relationships and demonstrated dependence on the slow wave recovery phase. Simulated membrane potential relationships were close to these experimental results (100 µV per 1 mm s-1 ). CONCLUSIONS AND INFERENCES: These data quantify the relationships between slow wave frequency, velocity, and extracellular amplitude. The results from both human and porcine studies were in keeping with biophysical models, demonstrating concordance with ICC biophysics. These relationships are important in the regulation of gastric motility and will help to guide interpretations of dysrhythmias.

Defining low anterior resection syndrome: a systematic review of the literature.

AIM: There is increasing awareness of the poor functional outcome suffered by many patients after sphincter-preserving rectal resection, termed 'low anterior resection syndrome' (LARS). There is no consensus definition of LARS and varying instruments have been employed to measure functional outcome, complicating research into prevalence, contributing factors and potential therapies. We therefore aimed to describe the instruments and outcome measures used in studies of bowel dysfunction after low anterior resection and identify major themes used in the assessment of LARS. METHOD: A systematic review of the literature was performed for studies published between 1986 and 2016. The instruments and outcome measures used to report bowel function after low anterior resection were extracted and their frequency of use calculated. RESULTS: The search revealed 128 eligible studies. These employed 18 instruments, over 30 symptoms, and follow-up time periods from 4 weeks to 14.6 years. The most frequent follow-up period was 12 months (48%). The most frequently reported outcomes were incontinence (97%), stool frequency (80%), urgency (67%), evacuatory dysfunction (47%), gas-stool discrimination (34%) and a measure of quality of life (80%). Faecal incontinence scoring systems were used frequently. The LARS score and the Bowel Function Instrument (BFI) were used in only nine studies. CONCLUSION: LARS is common, but there is substantial variation in the reporting of functional outcomes after low anterior resection. Most studies have focused on incontinence, omitting other symptoms that correlate with patients' quality of life. To improve and standardize research into LARS, a consensus definition should be developed, and these findings should inform this goal.

High-resolution mapping of gastric slow-wave recovery profiles: biophysical model, methodology, and demonstration of applications.

Slow waves play a central role in coordinating gastric motor activity. High-resolution mapping of extracellular potentials from the stomach provides spatiotemporal detail on normal and dysrhythmic slow-wave patterns. All mapping studies to date have focused exclusively on tissue activation; however, the recovery phase contains vital information on repolarization heterogeneity, the excitable gap, and refractory tail interactions but has not been investigated. Here, we report a method to identify the recovery phase in slow-wave mapping data. We first developed a mathematical model of unipolar extracellular potentials that result from slow-wave propagation. These simulations showed that tissue repolarization in such a signal is defined by the steepest upstroke beyond the activation phase (activation was defined by accepted convention as the steepest downstroke). Next, we mapped slow-wave propagation in anesthetized pigs by recording unipolar extracellular potentials from a high-resolution array of electrodes on the serosal surface. Following the simulation result, a wavelet transform technique was applied to detect repolarization in each signal by finding the maximum positive slope beyond activation. Activation-recovery (ARi) and recovery-activation (RAi) intervals were then computed. We hypothesized that these measurements of recovery profile would differ for slow waves recorded during normal and spatially dysrhythmic propagation. We found that the ARi of normal activity was greater than dysrhythmic activity (5.1 ± 0.8 vs. 3.8 ± 0.7 s; P < 0.05), whereas RAi was lower (9.7 ± 1.3 vs. 12.2 ± 2.5 s; P < 0.05). During normal propagation, RAi and ARi were linearly related with negative unit slope indicating entrainment of the entire mapped region. This relationship was weakened during dysrhythmia (slope: -0.96 ± 0.2 vs -0.71 ± 0.3; P < 0.05).NEW & NOTEWORTHY The theoretical basis of the extracellular gastric slow-wave recovery phase was defined using mathematical modeling. A novel technique utilizing the wavelet transform was developed and validated to detect the extracellular slow-wave recovery phase. In dysrhythmic wavefronts, the activation-to-recovery interval (ARi) was shorter and recovery-to-activation interval (RAi) was longer compared with normal wavefronts. During normal activation, RAi vs. ARi had a slope of -1, whereas the weakening of the slope indicated a dysrhythmic propagation.

Limited evidence of abnormal intra-colonic pressure profiles in diverticular disease - a systematic review.

AIM: Abnormal colonic pressure profiles and high intraluminal pressures are postulated to contribute to the formation of sigmoid colon diverticulosis and the pathophysiology of diverticular disease. This study aimed to review evidence for abnormal colonic pressure profiles in diverticulosis. METHOD: All published studies investigating colonic pressure in patients with diverticulosis were searched in three databases (Medline, Embase, Scopus). No language restrictions were applied. Any manometry studies in which patients with diverticulosis were compared with controls were included. The Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies was used as a measure of risk of bias. A cut-off of five or more points on the NOS (fair quality in terms of risk of bias) was chosen for inclusion in the meta-analysis. RESULTS: Ten studies (published 1962-2005) met the inclusion criteria. The studies followed a wide variety of protocols and all used low-resolution manometry (sensor spacing range 7.5-15 cm). Six studies compared intra-sigmoid pressure, with five of six showing higher pressure in diverticulosis vs controls, but only two reached statistical significance. A meta-analysis was not performed as only two studies were above the cut-off and these did not have comparable outcomes. CONCLUSION: This systematic review of manometry data shows that evidence for abnormal pressure in the sigmoid colon in patients with diverticulosis is weak. Existing studies utilized inconsistent methodology, showed heterogeneous results and are of limited quality. Higher quality studies using modern manometric techniques and standardized reporting methods are needed to clarify the role of colonic pressure in diverticulosis.