Risk prediction algorithms for prolonged postoperative ileus: A systematic review.

AIM: Prolonged postoperative ileus (PPOI) is common and is associated with a significant healthcare burden. Previous studies have attempted to predict PPOI clinically using risk prediction algorithms. The aim of this work was to systematically review and compare risk prediction algorithms for PPOI following colorectal surgery. METHOD: A systematic literature search was conducted using MEDLINE, Embase, Web of Science and CINAHL Plus. Studies that developed and/or validated a risk prediction algorithm for PPOI in adults following colorectal surgery were included. Data were collected on study design, population and operative characteristics, the definition of PPOI used and risk prediction algorithm design and performance. Quality appraisal was assessed using the PROBAST tool. RESULTS: Eleven studies with 87 549 participants were included in our review. Most were retrospective, single-centre analyses (6/11, 55%) and rates of PPOI varied from 10% to 28%. The most commonly used variables were sex (8/11, 73%), age (6/11, 55%) and surgical approach (5/11, 45%). Area under the curve ranged from 0.68-0.78, and only three models were validated. However, there was significant variation in the definition of PPOI used. No study reported sensitivity, specificity or positive/negative predictive values. CONCLUSION: Currently available risk prediction algorithms for PPOI appear to discriminate moderately well, although there is a lack of validation data. Future studies should aim to use a standardized definition of PPOI, comprehensively report model performance and validate their findings using internal and external methodologies.

Variation in the definition of 'failure to rescue' from postoperative complications: a systematic review and recommendations for outcome reporting.

BACKGROUND: Failure to rescue is the rate of death amongst patients with postoperative complications and has been proposed as a perioperative quality indicator. However, variation in its definition has limited comparisons between studies. We systematically reviewed all surgical literature reporting failure to rescue rates and examined variations in the definition of the 'numerator,' 'denominator,' and timing of failure to rescue measurement. METHODS: Databases were searched from inception to 31 December 2022. All studies reporting postoperative failure to rescue rates as a primary or secondary outcome were included. We examined the complications included in the failure to rescue denominator, the percentage of deaths captured by the failure to rescue numerator, and the timing of measurement for complications and mortality. RESULTS: A total of 359 studies, including 212,048,069 patients, were analyzed. The complications included in the failure to rescue denominator were reported in 295 studies (82%), with 131 different complications used. The median number of included complications per study was 10 (interquartile range 8-15). Studies that included a higher number of complications in the failure-to-rescue denominator reported lower failure-to-rescue rates. Death was included as a complication in the failure to rescue the denominator in 65 studies (18%). The median percentage of deaths captured by the failure to rescue calculation when deaths were not included in the denominator was 79%. Complications (52%) and mortality (40%) were mostly measured in-hospital, followed by 30-days after surgery. CONCLUSION: Failure to rescue is an important concept in the study of postoperative outcomes, although its definition is highly variable and poorly reported. Researchers should be aware of the advantages and disadvantages of different approaches to defining failure to rescue.

Interventions to Improve Patient Care on Surgical Ward Rounds: A Systematic Review.

BACKGROUND: Ward rounds are an essential component of surgical and perioperative care. However, the relative effectiveness of different interventions to improve the quality of surgical ward rounds remains uncertain. The aim of this systematic review was to evaluate the efficacy of various ward round interventions among surgical patients. METHODS: A systematic literature search of the MEDLINE (OVID), EMBASE (OVID), Scopus, Cumulative Index of Nursing and Allied Health (CINAHL), and PsycInfo databases was performed on 7 October 2022 in accordance with PRISMA guidelines. All studies investigating surgical ward round quality improvement strategies with measurable outcomes were included. Data were analysed via narrative synthesis based on commonly reported themes. RESULTS: A total of 28 studies were included. Most were cohort studies (n = 25), followed by randomised controlled trials (n = 3). Checklists/proformas were utilised most commonly (n = 22), followed by technological (n = 3), personnel (n = 2), and well-being (n = 1) quality improvement strategies. The majority of checklist interventions (n = 21, 95%) showed significant improvements in documentation compliance, staff understanding, or patient satisfaction. Other less frequently reported ward round interventions demonstrated improvements in communication, patient safety, and reductions in patient stress levels. CONCLUSIONS: Use of checklists, technology, personnel, and well-being improvement strategies have been associated with improvements in ward round documentation, communication, as well as staff and patient satisfaction. Future studies should investigate the ease of implementation and long-term durability of these interventions, in addition to their impact on clinically relevant outcomes such as patient morbidity and mortality.

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.

"Failure to Rescue" following Colorectal Cancer Resection: Variation and Improvements in a National Study of Postoperative Mortality.

OBJECTIVE: To examine variation in "failure to rescue" (FTR) as a driver of differences in mortality between centres and over time for patients undergoing colorectal cancer surgery. BACKGROUND: Wide variation exists in postoperative mortality following colorectal cancer surgery. FTR has been identified as an important determinant of variation in postoperative outcomes. We hypothesized that differences in mortality both between hospitals and over time are driven by variation in FTR. METHODS: A national population-based study of patients undergoing colorectal cancer resection from 2010 to 2019 in Aotearoa New Zealand was conducted. Rates of 90-day FTR, mortality, and complications were calculated overall, and for surgical and nonoperative complications. Twenty District Health Boards (DHBs) were ranked into quartiles using risk- and reliability-adjusted 90-day mortality rates. Variation between DHBs and trends over the 10-year period were examined. RESULTS: Overall, 15,686 patients undergoing resection for colorectal adenocarcinoma were included. Increased postoperative mortality at high-mortality centers (OR 2.4, 95% CI 1.8-3.3) was driven by higher rates of FTR (OR 2.0, 95% CI 1.5-2.8), and postoperative complications (OR 1.4, 95% CI 1.3-1.6). These trends were consistent across operative and nonoperative complications. Over the 2010 to 2019 period, postoperative mortality halved (OR 0.5, 95% CI 0.4-0.6), associated with a greater improvement in FTR (OR 0.5, 95% CI 0.4-0.7) than complications (OR 0.8, 95% CI 0.8-0.9). Differences between centers and over time remained when only analyzing patients undergoing elective surgery. CONCLUSION: Mortality following colorectal cancer resection has halved over the past decade, predominantly driven by improvements in "rescue" from complications. Differences in FTR also drive hospital-level variation in mortality, highlighting the central importance of "rescue" as a target for surgical quality improvement.

Hyperactive Distal Colonic Motility and Recovery Patterns Following Right Colectomy: A High-Resolution Manometry Study.

BACKGROUND: Postoperative ileus results in morbidity, prolonged hospitalization, and increased health care expenditure. However, the underlying abnormalities in motility remain poorly understood. Recent high-resolution manometry studies demonstrated that the distal colon becomes hyperactive with a cyclic motor pattern postoperatively, but they did not track this activity beyond 16 hours after surgery. OBJECTIVE: This study used high-resolution manometry to evaluate distal colonic motility during the first 4 days after right-sided colectomy. DESIGN: An observational study of perioperative high-resolution colonic manometry using a 36-sensor catheter with 1-cm resolution. SETTING: A single tertiary hospital. PATIENTS: Adult patients undergoing elective laparoscopic or open right-sided colonic resection. MAIN OUTCOME MEASURES: Occurrence of distal colonic motor patterns during the perioperative period, defined according to a published classification system. Clinical markers of gut recovery included time to first stool, oral diet, and prolonged postoperative ileus. RESULTS: Seven patients underwent perioperative manometry recordings. Hyperactive cyclic motor patterns emerged intraoperatively and peaked in the first 12 hours postoperatively, occupying 81.8% ± 3.9% of the recording. This gradually returned to normal during the first 4 days, reaching 19.0% ± 4.4% ( p = 0.002). No patient had a bowel movement before this hyperactivity resolved. High-amplitude propagating sequences were absent in early postoperative recordings, and their return temporally correlated with the passage of stool. Abnormal high-amplitude repetitive 0.5 to 1 cycle per minute activity was observed in the left colon of 1 patient with prolonged ileus. LIMITATIONS: The invasive nature of recordings limited this study to a small sample size. CONCLUSIONS: Cyclic motor patterns are markedly hyperactive in the distal colon after right-sided colectomy and resolve during the first 4 postoperative days. High-amplitude propagating sequences are inhibited by surgery and gradually recover. Bowel function may not return until these changes resolve. Other abnormal repetitive hyperactive patterns could contribute to the development of prolonged ileus. See Video Abstract at http://links.lww.com/DCR/B967 . MOTILIDAD HIPERACTIVA DEL COLON DISTAL Y PATRONES DE RECUPERACIN DESPUS DE COLECTOMA DERECHA UN ESTUDIO DE MANOMETRA DE ALTA RESOLUCIN: ANTECEDENTES:El íleo post-operatorio produce una morbilidad significativa, una hospitalización prolongada y un aumento del gasto sanitario. Sin embargo, las anomalías subyacentes en la motilidad siguen siendo poco conocidas. Estudios recientes de manometría de alta resolución demostraron que el colon distal se vuelve hiperactivo con un patrón motor cíclico en el post-operatorio, pero no registraron esta actividad más allá de las 16 horas posteriores a la cirugía.OBJETIVO:Utilizar la manometría de alta resolución para evaluar la motilidad del colon distal durante los primeros cuatro días después de la colectomía del lado derecho.DISEÑO:Estudio observacional de pacientes sometidos a manometría colónica perioperatoria de alta resolución mediante catéter de 36 sensores con 1 cm de resolución.AJUSTE:Un solo hospital terciario.PACIENTES:Pacientes adultos sometidos a resección laparoscópica o abierta de colon del lado derecho de forma electiva.PRINCIPALES MEDIDAS DE RESULTADO:AAparición de patrones motores del colon distal durante el período perioperatorio, definidos según un sistema de clasificación publicado. Los marcadores clínicos de recuperación intestinal incluyeron, tiempo hasta la primera evacuación, dieta oral e íleo posoperatorio prolongado.RESULTADOS:Siete pacientes fueron sometidos a registros de manometría perioperatoria. Los patrones motores cíclicos hiperactivos emergieron intraoperatoriamente y alcanzaron su punto máximo en las primeras 12 horas post-operatorias, ocupando 81,8 ± 3,9% del registro. Esto volvió gradualmente a la normalidad durante los primeros cuatro días, alcanzando el 19,0 ± 4,4% (p = 0,002). Ningún paciente tuvo una evacuación intestinal antes de que se resolviera esta hiperactividad. Las secuencias de propagación de alta amplitud estaban ausentes en las grabaciones post-operatorias tempranas y su retorno se correlacionó temporalmente con el paso de las heces. Se observó actividad anormal de alta amplitud repetitiva de 0,5-1 ciclo / minuto en el colon izquierdo de un paciente con íleo prolongado.LIMITACIONES:La naturaleza invasiva de las grabaciones limitó este estudio a un tamaño de muestra pequeño.CONCLUSIONES:Los patrones motores cíclicos son marcadamente hiperactivos en el colon distal después de la colectomía del lado derecho y se resuelven gradualmente durante los primeros cuatro días posoperatorios. Las secuencias de propagación de gran amplitud se inhiben mediante cirugía y se recuperan gradualmente. Es posible que la función intestinal no regrese hasta que estos cambios se resuelvan. Otros patrones hiperactivos repetitivos anormales podrían contribuir al desarrollo de íleo prolongado. Consulte Video Resumen en http://links.lww.com/DCR/B967 . (Traducción-Dr. Mauricio Santamaria ).

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.

Short- and long-term impact of sarcopenia on outcomes after emergency laparotomy: A systematic review and meta-analysis.

BACKGROUND: Sarcopenia refers to the progressive age and pathology-associated loss of skeletal muscle, which has been shown to independently predict mortality in patients undergoing major elective surgery. Emergency laparotomy is commonly performed for a range of procedures and is associated with high rates of mortality. However, the prognostic utility of sarcopenia after emergency laparotomy remains unknown. The aim of this study was to compare short and long-term survival between patients with and without sarcopenia undergoing emergency laparotomy. METHODS: MEDLINE, EMBASE, and Scopus databases were systematically searched for articles comparing survival outcomes between adults with and without radiologically defined sarcopenia after emergency gastrointestinal surgery regardless of indication and approach (open/laparoscopic). The primary outcome was postoperative mortality. Sensitivity analysis of adjusted multivariate analyses was performed. RESULTS: Twenty articles comprising 6,737 patients were included. Sarcopenia was most commonly assessed using axial abdominal computerized tomography at L3, although cut-off thresholds were heterogeneous and rarely sex-specific. Postoperative mortality was higher among patients with sarcopenia than without in the in-hospital setting, and at 30- and 90-day follow-up on univariate but not on multivariate meta-analysis. However, mortality was significantly higher among sarcopenic cohorts in the 1-year (odds ratio 2.8, 95% confidence interval: 1.5-5.6; P = .002) follow-up period, despite adjusting for confounding preoperative and patient factors. CONCLUSION: The meta-analysis has shown sarcopenia to provide useful long-term prognostic information following emergency laparotomy. This may aid with preoperative risk assessment, patient counseling, and in perioperative decision-making for patients undergoing emergency laparotomy.

Wearable devices to monitor recovery after abdominal surgery: scoping review.

BACKGROUND: Wearable devices have been proposed as a novel method for monitoring patients after surgery to track recovery, identify complications early, and improve surgical safety. Previous studies have used a heterogeneous range of devices, methods, and analyses. This review aimed to examine current methods and wearable devices used for monitoring after abdominal surgery and identify knowledge gaps requiring further investigation. METHODS: A scoping review was conducted given the heterogeneous nature of the evidence. MEDLINE, EMBASE, and Scopus databases were systematically searched. Studies of wearable devices for monitoring of adult patients within 30 days after abdominal surgery were eligible for inclusion. RESULTS: A total of 78 articles from 65 study cohorts, with 5153 patients were included. Thirty-one different wearable devices were used to measure vital signs, physiological measurements, or physical activity. The duration of postoperative wearable device use ranged from 15 h to 3 months after surgery. Studies mostly focused on physical activity metrics (71.8 per cent). Continuous vital sign measurement and physical activity tracking both showed promise for detecting postoperative complications earlier than usual care, but conclusions were limited by poor device precision, adherence, occurrence of false alarms, data transmission problems, and retrospective data analysis. Devices were generally well accepted by patients, with high levels of acceptance, comfort, and safety. CONCLUSION: Wearable technology has not yet realized its potential to improve postoperative monitoring. Further work is needed to overcome technical limitations, improve precision, and reduce false alarms. Prospective assessment of efficacy, using an intention-to-treat approach should be the focus of further studies.

The Longitudinal Course of Low-anterior Resection Syndrome: An individual Patient Meta-analysis.

OBJECTIVE: We aimed to better understand the longitudinal course of low anterior resection syndrome (LARS) to guide patient expectations and identify those at risk of persisting dysfunction. SUMMARY BACKGROUND DATA: LARS describes disordered bowel function after rectal resection that significantly impacts quality of life. METHODS: MEDLINE, EMBASE, CENTRAL, and CINAHL databases were systematically searched for studies that enrolled adults undergoing anterior resection for rectal cancer and used the LARS score to assess bowel function at ≥2 postoperative time points. Regression analyses were performed on deidentified patient-level data to identify predictors of change in LARS score from baseline (3-6months) to 12-months and 18-24 months. RESULTS: Eight studies with a total of 701 eligible patients were included. The mean LARS score improved over time, from 29.4 (95% confidence interval 28.6-30.1) at baseline to 16.6 at 36 months (95% confidence interval 14.2%-18.9%). On multivariable analysis, a greater improvement in mean LARS score between baseline and 12 months was associated with no ileostomy formation [mean difference (MD) -1.7 vs 1.7, P < 0.001], and presence of LARS (major vs minor vs no LARS) at baseline (MD -3.8 vs -1.7 vs 5.4, P < 0.001). Greater improvement in mean LARS score between baseline and 18-24 months was associated with partial mesorectal excision vs total mesorectal excision (MD-8.6 vs 1.5, P < 0.001) and presence of LARS (major vs minor vs no LARS) at baseline (MD -8.8 vs -5.3 vs 3.4, P < 0.001). CONCLUSIONS: LARS improves by 18 months postoperatively then remains stable for up to 3 years. Total mesorectal excision, neoadjuvant radiotherapy, and ileostomy formation negatively impact upon bowel function recovery.

Post-operative ileus: definitions, mechanisms and controversies.

Post-operative ileus (POI) is a syndrome of impaired gastrointestinal transit which occurs following abdominal surgery. There are few effective targeted therapies for ileus, and research has been limited by inconsistent definitions and an incomplete understanding of the underlying pathophysiology. Despite considerable effort, there remains no widely-adopted definition of ileus, and recent work has identified variation in outcome reporting is a major source of heterogeneity in clinical trials. Outcomes should be clearly-defined, clinically-relevant, and reflective of the underlying biology, impacts on hospital resources and quality of life. Further collaborative efforts will be needed to develop consensus definitions and a core outcome set for postoperative gastrointestinal recovery. Investigation into the pathophysiology of POI has been hindered by use of low-resolution techniques and difficulties linking cellular mechanisms to dysmotility patterns and clinical symptoms. Recent evidence has suggested the common assumption of post-operative GI paralysis is incorrect, and that the distal colon becomes hyperactive following surgery. The post-operative inflammatory response is important in the pathophysiology of ileus, but the time course of this in humans remains unclear, with the majority of evidence coming from animal models. Future work should investigate dysmotility patterns underlying ileus, and identify biomarkers which may be used to diagnose, monitor and stratify patients with ileus.

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.

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

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

Intraoperative serosal extracellular mapping of the human distal colon: a feasibility study.

BACKGROUND: Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping. METHODS: HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 × 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm2, 0.3 mm diameter) for up to 15 min. Passive unipolar signals were obtained and analysed. RESULTS: Eleven patients (33-71 years; 6 females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artefact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2 and 6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10-180 s with frequencies of each cluster ranging between 24 and 42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded. CONCLUSIONS: Intraoperative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity. Although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period. NEW FINDINGS: The aim of this study was to assess the feasibility of detecting propagating electrical activity that may correlate to the cyclic motor pattern in the distal human colon through intraoperative, high-resolution, serosal electrical mapping. High-resolution electrical mapping of the human colon revealed no regular propagating activity, but does reveal sporadic spike-wave events. These findings indicate that further research into appropriate techniques is required to identify the mechanism of hyperactive cyclic motor pattern observed in the intra- and post-operative period in humans.

Prolonged postoperative ileus following right- versus left-sided colectomy: A systematic review and meta-analysis.

AIM: Prolonged postoperative ileus (PPOI) is a common complication following colonic surgery, and is associated with longer hospital stay, greater risk of complications and substantial cost for patients and hospitals. Some reports have recently suggested that gastrointestinal (GI) recovery varies based on the side of resection (i.e., right-sided vs. left-sided colectomy). This systematic review and meta-analysis aimed to compare GI recovery by resection side. METHODS: The MEDLINE, Embase, Cochrane Library and CENTRAL databases were systematically searched for articles reporting GI recovery outcomes in adults undergoing elective right- versus left-sided colectomy (excluding with ileostomy) of any surgical approach. The primary outcome was PPOI, and secondary outcomes included time to first passage of flatus, stool and tolerance of solid diet, and postoperative complications. Subgroup analyses of laparoscopic procedures and cohorts without inflammatory bowel disease and sensitivity analysis of adjusted multivariate results were also performed. RESULTS: Nine studies were identified, of which seven were included in the meta-analysis, comprising 29 068 colectomies (14 581 right-sided; 14 487 left-sided). PPOI was heterogeneously defined and was significantly more likely following right-sided compared to left-sided colectomy regardless of the surgical approach (OR 1.78, 95% CI 1.32-2.39; P < 0.01; I2  = 51%), as well as on subgroup analyses and adjusted multivariate meta-analysis. Secondary outcomes were reported in only a few small studies; hence meta-analysis did not produce reliable results. CONCLUSION: Based on heterogeneous definitions, consistently higher rates of PPOI were observed following right- versus left-sided colectomy. These differences are currently unexplained and highlight the need for further research into the pathophysiology of ileus.

A novel mechanism for acute colonic pseudo-obstruction revealed by high-resolution manometry: A case report.

BACKGROUND: Acute colonic pseudo-obstruction (ACPO) is a severe form of colonic dysmotility and is associated with considerable morbidity. The pathophysiology of ACPO is considered to be multifactorial but has not been clarified. Although colonic motility is commonly assumed to be hypoactive, there is little direct pathophysiological evidence to support this claim. METHODS: A 56-year-old woman who developed ACPO following spinal surgery underwent 24 h of continuous high-resolution colonic manometry (1 cm resolution over 36 cm) following endoscopic decompression. Manometry data were analyzed and correlated with a three-dimensional colonic model developed from computed tomography (CT) imaging. RESULTS: The distal colon was found to be profoundly hyperactive, showing near-continuous non-propagating motor activity. Dominant frequencies at 2-6 and 8-12 cycles per minute were observed. The activity was often dissociated and out-of-phase across adjacent regions. The mean amplitude of motor activity was higher than that reported from pre- and post-prandial healthy controls. Correlation with CT imaging suggested that these disordered hyperactive motility sequences might act as a functional pseudo-obstruction in the distal colon resulting in secondary proximal dilatation. CONCLUSIONS: This is the first detailed description of motility patterns in ACPO and suggests a novel underlying disease mechanism, warranting further investigation and identification of potential therapeutic targets.

Colonoscopy quality indicators in patients with and without prior colonic resection: A single-centre prospective comparative study.

AIM: Effective colonoscopy relies on meeting rigorous quality control thresholds. Some earlier studies evaluating colonoscopy key performance indicators (KPIs) have excluded patients who have previously undergone colonic resection (i.e., they have a nonintact colon); such patients also deserve high-quality colonoscopy. This study aimed to compare colonoscopy KPIs between patients with nonintact and intact colons. METHOD: Consecutive colonoscopies performed at Whanganui Hospital (New Zealand) between September 2016 and March 2020 were included. The primary outcome was the caecal or ileal intubation rate (CIIR). Secondary outcomes were the adenoma detection rate (ADR), polyp detection rate (PDR), colonoscope withdrawal time (CWT) and caecal or ileal intubation time (CIIT). RESULTS: In total, 3017 colonoscopies were performed: 322 in nonintact colons and 2695 in intact colons. CIIR was significantly higher in nonintact than in intact colons (98.4% vs. 95.0%; P = 0.0086). When all colonoscopies were included, the CIIR was 95.4%; this value decreased to 95.0% when nonintact colonoscopies were excluded. However, the ADR (39.9% vs. 38.8%; P = 0.77) and PDR (58.4% vs. 59.1%; P = 0.86) were similar for both nonintact and intact colons. CWT (P < 0.0001) and CIIT (P < 0.0001) were significantly shorter in participants with nonintact colons. CONCLUSION: The CIIR exceeded recommended targets and was 3.4% higher in patients with nonintact than intact colons. Patients with nonintact colons comprise a small proportion of the overall colonoscopy cohort and it is unlikely that this small difference is relevant for most endoscopists or endoscopy units. The ADR and PDR were similar among patients with nonintact and intact colons, despite nonintact colonoscopies being significantly quicker. Patients with nonintact colons deserve high-quality colonoscopy and therefore their KPIs should be included in colonoscopy performance reports.

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.