Latin American consensus on diagnosis of gastroesophageal reflux disease.

BACKGROUND: Diagnosing gastroesophageal reflux disease (GERD) can be challenging given varying symptom presentations, and complex multifactorial pathophysiology. The gold standard for GERD diagnosis is esophageal acid exposure time (AET) measured by pH-metry. A variety of additional diagnostic tools are available. The goal of this consensus was to assess the individual merits of GERD diagnostic tools based on current evidence, and provide consensus recommendations following discussion and voting by experts. METHODS: This consensus was developed by 15 experts from nine countries, based on a systematic search of the literature, using GRADE (grading of recommendations, assessment, development and evaluation) methodology to assess the quality and strength of the evidence, and provide recommendations regarding the diagnostic utility of different GERD diagnosis tools, using AET as the reference standard. KEY RESULTS: A proton pump inhibitor (PPI) trial is appropriate for patients with heartburn and no alarm symptoms, but nor for patients with regurgitation, chest pain, or extraesophageal presentations. Severe erosive esophagitis and abnormal reflux monitoring off PPI are clearly indicative of GERD. Esophagram, esophageal biopsies, laryngoscopy, and pharyngeal pH monitoring are not recommended to diagnose GERD. Patients with PPI-refractory symptoms and normal endoscopy require reflux monitoring by pH or pH-impedance to confirm or exclude GERD, and identify treatment failure mechanisms. GERD confounders need to be considered in some patients, pH-impedance can identify supragrastric belching, impedance-manometry can diagnose rumination. CONCLUSIONS: Erosive esophagitis on endoscopy and abnormal pH or pH-impedance monitoring are the most appropriate methods to establish a diagnosis of GERD. Other tools may add useful complementary information.

Updates to the modern diagnosis of GERD: Lyon consensus 2.0.

The Lyon Consensus provides conclusive criteria for and against the diagnosis of gastro-oesophageal reflux disease (GERD), and adjunctive metrics that consolidate or refute GERD diagnosis when primary criteria are borderline or inconclusive. An international core and working group was assembled to evaluate research since publication of the original Lyon Consensus, and to vote on statements collaboratively developed to update criteria. The Lyon Consensus 2.0 provides a modern definition of actionable GERD, where evidence from oesophageal testing supports revising, escalating or personalising GERD management for the symptomatic patient. Symptoms that have a high versus low likelihood of relationship to reflux episodes are described. Unproven versus proven GERD define diagnostic strategies and testing options. Patients with no prior GERD evidence (unproven GERD) are studied using prolonged wireless pH monitoring or catheter-based pH or pH-monitoring off antisecretory medication, while patients with conclusive GERD evidence (proven GERD) and persisting symptoms are evaluated using pH-impedance monitoring while on optimised antisecretory therapy. The major changes from the original Lyon Consensus criteria include establishment of Los Angeles grade B oesophagitis as conclusive GERD evidence, description of metrics and thresholds to be used with prolonged wireless pH monitoring, and inclusion of parameters useful in diagnosis of refractory GERD when testing is performed on antisecretory therapy in proven GERD. Criteria that have not performed well in the diagnosis of actionable GERD have been retired. Personalisation of investigation and management to each patient's unique presentation will optimise GERD diagnosis and management.

Are the Chicago 3.0 manometric diagnostics consistent with Chicago 4.0?

There is little information on the degree of concordance between the results obtained using the Chicago 3.0 (CCv3.0) and Chicago 4.0 (CCv4.0) protocols to interpret high-resolution manometry (HRM) seeking to determine the value provided by the new swallowing maneuvers included in the last protocol. This is a study of diagnostic tests, evaluating concordance by consistency between the results obtained by the CCv3.0 and CCv4.0 protocols, in patients undergoing HRM. Concordance was assessed with the kappa test. Bland-Altman scatter plots, and Lin's correlation-concordance coefficient (CCC) were used to assess the agreement between IRP measured with swallows in the supine and seated position or with solid swallows. One hundred thirty-two patients were included (65% women, age 53 ± 17 years). The most frequent HRM indication was dysphagia (46.1%). Type I was the most common type of gastroesophageal junction. The most frequent CCv4.0 diagnoses were normal esophageal motility (68.9%), achalasia (15.5%), and ineffective esophageal motility (IEM; 5.3%). The agreement between the results was substantial (Kappa 0.77 ± 0.05), with a total agreement of 87.9%. Diagnostic reclassification occurred in 12.1%, from IEM in CCv3.0 to normal esophageal motility in CCv4.0. Similarly, there was a high level of agreement between the IRP measured in the supine compared to the seated position (CCC0.92) and with solid swallows (CCC0.96). In conclusion, the CCv4.0 protocol presents a high concordance compared to CCv3.0. In the majority of manometric diagnoses there is no reclassification of patients with provocation tests. However, the more restrictive criteria of CCv4.0 achieve a better reclassification of patients with IEM.

High-Resolution Manometry Thresholds and Motor Patterns Among Asymptomatic Individuals.

OBJECTIVE: High-resolution manometry (HRM) is the current standard for characterization of esophageal body and esophagogastric junction (EGJ) function. We aimed to examine the prevalence of abnormal esophageal motor patterns in health, and to determine optimal thresholds for software metrics across HRM systems. DESIGN: Manometry studies from asymptomatic adults were solicited from motility centers worldwide, and were manually analyzed using integrated relaxation pressure (IRP), distal latency (DL), and distal contractile integral (DCI) in standardized fashion. Normative thresholds were assessed using fifth and/or 95th percentile values. Chicago Classification v3.0 criteria were applied to determine motor patterns across HRM systems, study positions (upright vs supine), ages, and genders. RESULTS: Of 469 unique HRM studies (median age 28.0, range 18-79 years). 74.6% had a normal HRM pattern; none had achalasia. Ineffective esophageal motility (IEM) was the most frequent motor pattern identified (15.1% overall), followed by EGJ outflow obstruction (5.3%). Proportions with IEM were lower using stringent criteria (10.0%), especially in supine studies (7.1%-8.5%). Other motor patterns were rare (0.2%-4.1% overall) and did not vary by age or gender. DL thresholds were close to current norms across HRM systems, while IRP thresholds varied by HRM system and study position. Both fifth and 95th percentile DCI values were lower than current thresholds, both in upright and supine positions. CONCLUSIONS: Motor abnormalities are infrequent in healthy individuals and consist mainly of IEM, proportions of which are lower when using stringent criteria in the supine position. Thresholds for HRM metrics vary by HRM system and study position.

Breaks in peristaltic integrity predict abnormal esophageal bolus clearance better than contraction vigor or residual pressure at the esophagogastric junction.

BACKGROUND: High-resolution impedance manometry (HRIM) evaluates esophageal peristalsis and bolus transit. We used esophageal impedance integral (EII), the ratio between bolus presence before and after an expected peristaltic wave, to evaluate predictors of bolus transit. METHODS: From HRIM studies performed on 61 healthy volunteers (median age 27 years, 48%F), standard metrics were extracted from each of 10 supine water swallows: distal contractile integral (DCI, mmHg cm s), integrated relaxation pressure (IRP, mmHg), and breaks in peristaltic integrity (cm, using 20 mmHg isobaric contour). Pressure and impedance coordinates for each swallow were exported into a dedicated, python-based program for EII calculation (EII ratio ≥ 0.3 = abnormal bolus clearance). Univariate and multivariate analyses were performed to assess predictors of abnormal bolus clearance. KEY RESULTS: Of 591 swallows, 80.9% were intact, 10.5% were weak, and 8.6% failed. Visual analysis overestimated abnormal bolus clearance compared to EII ratio (p ≤ 0.01). Bolus clearance was complete (median EII ratio 0.0, IQR 0-0.12) in 82.0% of intact swallows in contrast to 53.3% of weak swallows (EII ratio 0.29, IQR 0.0-0.57), and 19.6% of failed swallows (EII ratio 0.5, IQR 0.34-0.73, p < 0.001). EII correlated best with break length (ρ = 0.52, p < 0.001), compared to IRP (ρ: -0.17) or DCI (ρ: -0.42). On ROC analysis, breaks predicted abnormal bolus transit better than DCI or IRP (AUC 0.79 vs. 0.25 vs. 0.44, p ≤ 0.03 for each). On logistic regression, breaks remained independently predictive of abnormal bolus transit (p < 0.001). CONCLUSIONS & INFERENCES: Breaks in peristaltic integrity predict abnormal bolus clearance better than DCI or IRP in healthy asymptomatic subjects.

The Brief Esophageal Dysphagia Questionnaire shows better discriminative capacity for clinical and manometric findings than the Eckardt score: Results from a multicenter study.

INTRODUCTION: Grading dysphagia is crucial for clinical management of patients. The Eckardt score (ES) is the most commonly used for this purpose. We aimed to compare the ES with the recently developed Brief Esophageal Dysphagia Questionnaire (BEDQ) in terms of their correlation and discriminative capacity for clinical and manometric findings and evaluate the effect of gastroesophageal reflux symptoms on both. METHODS: Symptomatic patients referred for high-resolution manometry (HRM) were prospectively recruited from seven centers in Spain and Latin America. Clinical data and several scores (ES, BEDQ, GERDQ) were collected and contrasted to HRM findings. Standard statistical analysis was performed. KEY RESULTS: 426 patients were recruited, 31.2% and 41.5% being referred exclusively for dysphagia and GERD symptoms, respectively. Both BEDQ and ES were independently associated with achalasia. Only BEDQ was independently associated with being referred for dysphagia and with relevant HRM findings. ROC curve analysis for achalasia diagnosis showed AUC of 0.809 for BEDQ and 0.765 for ES, with the main difference being higher BEDQ sensitivity (80.0% vs 70.8% for ES). GERDQ independently predicted ES but not BEDQ. In the absence of dysphagia (BEDQ = 0), GERD symptoms significantly determine ES. CONCLUSIONS AND INFERENCES: Our study suggests both the BEDQ and ES can complementarily describe symptomatic burden in achalasia. BEDQ has several advantages over the ES in the dysphagia evaluation, basically due to its higher sensitivity for manometric diagnosis and independence of GERD symptoms. ES should be used as an achalasia-specific metric, while BEDQ is a better symptom-generic evaluating tool.

Chicago Classification update (V4.0): Technical review on diagnostic criteria for ineffective esophageal motility and absent contractility.

Esophageal hypomotility disorders manifest with abnormal esophageal body contraction vigor, breaks in peristaltic integrity, or failure of peristalsis in the context of normal lower esophageal sphincter relaxation on esophageal high-resolution manometry (HRM). The Chicago Classification version 4.0 recognizes two hypomotility disorders, ineffective esophageal motility (IEM) and absent contractility, while fragmented peristalsis has been incorporated into the IEM definition. Updated criteria for ineffective swallows consist of weak esophageal body contraction vigor measured using distal contractile integral (DCI, 100-450 mmHg·cm·s), transition zone defects >5 cm measured using a 20 mmHg isobaric contour, or failure of peristalsis (DCI < 100 mmHg·cm·s). More than 70% ineffective swallows and/or ≥50% failed swallows are required for a conclusive diagnosis of IEM. When the diagnosis is inconclusive (50%-70% ineffective swallows), supplementary evidence from multiple rapid swallows (absence of contraction reserve), barium radiography (abnormal bolus clearance), or HRM with impedance (abnormal bolus clearance) could support a diagnosis of IEM. Absent contractility requires 100% failed peristalsis, consistent with previous versions of the classification. Consideration needs to be given for the possibility of achalasia in absent contractility with dysphagia despite normal IRP, and alternate complementary tests (including timed upright barium esophagram and functional lumen imaging probe) are recommended to confirm or refute the presence of achalasia. Future research to quantify esophageal bolus retention on stationary HRM with impedance and to understand contraction vigor thresholds that predict bolus clearance will provide further refinement to diagnostic criteria for esophageal hypomotility disorders in future iterations of the Chicago Classification.

The Spanish version of the esophageal hypervigilance and anxiety score shows strong psychometric properties: Results of a large prospective multicenter study in Spain and Latin America.

BACKGROUND: Anxiety is a significant modulator of sensitivity along the GI tract. The recently described Esophageal Hypervigilance and Anxiety Score (EHAS) evaluates esophageal-specific anxiety. The aims of this study were as follows: 1. translate and validate an international Spanish version of EHAS. 2. Evaluate its psychometric properties in a large Hispano-American sample of symptomatic individuals. METHODS: A Spanish EHAS version was developed by a Delphi process and reverse translation. Patients referred for high-resolution manometry (HRM) were recruited prospectively from seven Spanish and Latin American centers. Several scores were used: EHAS, Hospital Anxiety and Depression Scale (HADS), Eckardt score (ES), Gastroesophageal Reflux Questionnaire (GERDQ), and the Brief Esophageal Dysphagia Questionnaire (BEDQ). Standardized psychometric analyses were performed. KEY RESULTS: A total of 443 patients were recruited. Spanish EHAS showed excellent reliability (Cronbach´s alpha = 0.94). Factor analysis confirmed the presence of two factors, corresponding to the visceral anxiety and hypervigilance subscales. Sufficient convergent validity was shown by moderate significant correlations between EHAS and other symptomatic scores. Patients with high EHAS scores had significantly more dysphagia. There was no difference in EHAS scores when compared normal vs abnormal or major manometric diagnosis. CONCLUSIONS AND INFERENCES: A widely usable Spanish EHAS version has been validated. We confirm its excellent psychometric properties in our patients, confirming the appropriateness of its use in different populations. Our findings support the appropriateness of evaluating esophageal anxiety across the whole manometric diagnosis spectrum.

Esophageal motility disorders on high-resolution manometry: Chicago classification version 4.0©.

Chicago Classification v4.0 (CCv4.0) is the updated classification scheme for esophageal motility disorders using metrics from high-resolution manometry (HRM). Fifty-two diverse international experts separated into seven working subgroups utilized formal validated methodologies over two-years to develop CCv4.0. Key updates in CCv.4.0 consist of a more rigorous and expansive HRM protocol that incorporates supine and upright test positions as well as provocative testing, a refined definition of esophagogastric junction (EGJ) outflow obstruction (EGJOO), more stringent diagnostic criteria for ineffective esophageal motility and description of baseline EGJ metrics. Further, the CCv4.0 sought to define motility disorder diagnoses as conclusive and inconclusive based on associated symptoms, and findings on provocative testing as well as supportive testing with barium esophagram with tablet and/or functional lumen imaging probe. These changes attempt to minimize ambiguity in prior iterations of Chicago Classification and provide more standardized and rigorous criteria for patterns of disorders of peristalsis and obstruction at the EGJ.

Validation and psychometric evaluation of the Spanish version of Brief Esophageal Dysphagia Questionnaire (BEDQ): Results of a multicentric study.

BACKGROUND: The recently developed Brief Esophageal Dysphagia Questionnaire (BEDQ) evaluates esophageal obstructive symptoms. Its initial evaluation showed strong psychometric properties. The aims of this study were to (a) translate and validate an international Spanish version of BEDQ and (b) evaluate its psychometric properties in a large Hispano-American sample of symptomatic individuals. METHODS: A Spanish BEDQ version was performed by Hispano-American experts using a Delphi process and reverse translation. Patients were prospectively recruited from seven centers in Spain and Latin America among individuals referred for high-resolution manometry (HRM). Patients completed several scores: Hospital Anxiety & Depression Scale (HADS), Eckardt score (ES), Gastroesophageal Reflux Questionnaire (GERDQ), and the BEDQ. Standardized psychometric analyses were performed. KEY RESULTS: A total of 426 patients were recruited. Spanish BEDQ showed excellent reliability (Cronbach's alpha = 0.91). Factor analysis confirmed its unidimensional character. Moderate significant correlations between BEDQ and other symptomatic scores were found, suggesting sufficient convergent validity. Patients with abnormal or obstructive HRM findings scored significantly higher when compared to normal or non-obstructive findings, respectively. Using a cutoff of 10, BEDQ showed a sensitivity of 65.38% and a specificity of 66.21% and an area under the curve of 0.71 for obstructive or major manometric diagnosis. CONCLUSIONS AND INFERENCES: A widely usable Spanish BEDQ version has been validated. We confirm its excellent psychometric properties in our patients, confirming the appropriateness of its use in different populations.

Esophagogastric junction morphology and contractile integral on high-resolution manometry in asymptomatic healthy volunteers: An international multicenter study.

BACKGROUND: Esophagogastric junction contractile integral (EGJ-CI) and EGJ morphology are high-resolution manometry (HRM) metrics that assess EGJ barrier function. Normative data standardized across world regions and HRM manufacturers are limited. METHODS: Our aim was to determine normative EGJ metrics in a large international cohort of healthy volunteers undergoing HRM (Medtronic, Laborie, and Diversatek software) acquired from 16 countries in four world regions. EGJ-CI was calculated by the same two investigators using a distal contractile integral-like measurement across the EGJ for three respiratory cycles and corrected for respiration (mm Hg cm), using manufacturer-specific software tools. EGJ morphology was designated according to Chicago Classification v3.0. Median EGJ-CI values were calculated across age, genders, HRM systems, and regions. RESULTS: Of 484 studies (28.0 years, 56.2% F, 60.7% Medtronic studies, 26.0% Laborie, and 13.2% Diversatek), EGJ morphology was type 1 in 97.1%. Median EGJ-CI was similar between Medtronic (37.0 mm Hg cm, IQR 23.6-53.7 mm Hg cm) and Diversatek (34.9 mm Hg cm, IQR 22.1-56.1 mm Hg cm, P = 0.87), but was significantly higher using Laborie equipment (56.5 mm Hg cm, IQR 35.0-75.3 mm Hg cm, P < 0.001). 5th percentile EGJ-CI values ranged from 6.9 to 12.1 mm Hg cm. EGJ-CI values were consistent across world regions, but different between manufacturers even within the same world region (P ≤ 0.001). Within Medtronic studies, EGJ-CI and basal LESP were similar in younger and older individuals (P ≥ 0.3) but higher in women (P < 0.001). CONCLUSIONS: EGJ morphology is predominantly type 1 in healthy adults. EGJ-CI varies widely in health, with significant gender influence, but is consistent within each HRM system. Manufacturer-specific normative values should be utilized for clinical HRM interpretation.

Ineffective esophageal motility and bolus clearance. A study with combined high-resolution manometry and impedance in asymptomatic controls and patients.

BACKGROUND: The definition and relevance of ineffective esophageal motility (IEM) remains debated. Our aim was to determine motility patterns and symptoms associated with IEM defined as impaired bolus clearance. METHODS: To define altered bolus clearance, normal range of swallows with complete bolus transit (CBT) on high-resolution impedance manometry (HRIM) was determined in 44 asymptomatic controls. The results were then applied to a cohort of 81 patients with esophageal symptoms to determine the motility patterns which best predicted altered bolus clearance. Subsequently, in a cohort of 281 consecutive patients the identified motility patterns were compared with patients' customary symptoms. KEY RESULTS: In asymptomatic controls, the normal range of swallows with CBT was 50%-100%. In patients, altered bolus transit (<50% CBT) was only associated with 30% or more failed contractions (P < .001). Neither weak peristalsis nor absence of contraction reserve (CR) was associated with altered bolus clearance. The patterns which best predicted altered bolus clearance were failed contractions ≥30% (specificity 88.2% and sensitivity of 84.6%), and ≥70% ineffective (failed + weak) contractions (sensitivity 84.6% and specificity 80.9%). No motility pattern was correlated to symptom scores. CONCLUSIONS AND INFERENCES: Based on bolus clearance assessed by HRIM, ≥30% failed contractions and ≥70% ineffective contractions have the best sensitivity and specificity to predict altered bolus clearance. Weak contractions and absence of CR are not relevant with respect to bolus clearance.

Fair reliability of eckardt scores in achalasia and non-achalasia patients: Psychometric properties of the eckardt spanish version in a multicentric study.

BACKGROUND: Eckardt symptom score (ESS) is the most used tool for the evaluation of esophageal symptoms. Recent data suggest that it might have suboptimal reliability and validity. The aims of this study were as follows: (a) Develop and validate an international Spanish ESS version. (b) Perform psychometric ESS evaluation in patients with achalasia and non-achalasia patients. METHODS: Eckardt symptom score translation was performed by Delphi process. ESS psychometric evaluation was done in two different samples of patients referred for manometry. First sample: 430 dysphagia non-achalasia patients. Second sample: 161 achalasia patients. Internal consistency was evaluated using Cronbach's α and Guttman coefficient (<0.5 = unacceptable. 0.5-0.7 = fair. >0.7 = acceptable). KEY RESULTS: Our data show that in patients without and with achalasia, ESS behaves similarly. Both show a fair reliability with Cronbach's α of 0.57 and 0.65, respectively. Based on our results, we recommend interpretation of the Spanish ESS be done with caution. The psychometric quality of the ESS could not be improved by removal of any items based on the single-factor structure of the scale and no items meeting criteria for elimination. CONCLUSIONS AND INFERENCES: Eckardt symptom score Spanish translation was developed. ESS showed a fair reliability for the evaluation of patients with any causes of dysphagia. Our results highlight the need for development and psychometric validation of new dysphagia scoring tools.

Abdominothoracic mechanisms of functional abdominal distension and correction by biofeedback.

BACKGROUND & AIMS: In patients with functional gut disorders, abdominal distension has been associated with descent of the diaphragm and protrusion of the anterior abdominal wall. We investigated mechanisms of abdominal distension in these patients. METHODS: We performed a prospective study of 45 patients (42 women, 24-71 years old) with functional intestinal disorders (27 with irritable bowel syndrome with constipation, 15 with functional bloating, and 3 with irritable bowel syndrome with alternating bowel habits) and discrete episodes of visible abdominal distension. Subjects were assessed by abdominothoracic computed tomography (n = 39) and electromyography (EMG) of the abdominothoracic wall (n = 32) during basal conditions (without abdominal distension) and during episodes of severe abdominal distension. Fifteen patients received a median of 2 sessions (range, 1-3 sessions) of EMG-guided, respiratory-targeted biofeedback treatment; 11 received 1 control session before treatment. RESULTS: Episodes of abdominal distension were associated with diaphragm contraction (19% ± 3% increase in EMG score and 12 ± 2 mm descent; P < .001 vs basal values) and intercostal contraction (14% ± 3% increase in EMG scores and 6 ± 1 mm increase in thoracic antero-posterior diameter; P < .001 vs basal values). They were also associated with increases in lung volume (501 ± 93 mL; P < .001 vs basal value) and anterior abdominal wall protrusion (32 ± 3 mm increase in girth; P < .001 vs basal). Biofeedback treatment, but not control sessions, reduced the activity of the intercostal muscles (by 19% ± 2%) and the diaphragm (by 18% ± 4%), activated the internal oblique muscles (by 52% ± 13%), and reduced girth (by 25 ± 3 mm) (P ≤ .009 vs pretreatment for all). CONCLUSIONS: In patients with functional gut disorders, abdominal distension is a behavioral response that involves activity of the abdominothoracic wall. This distension can be reduced with EMG-guided, respiratory-targeted biofeedback therapy.

Mechanisms of postprandial abdominal bloating and distension in functional dyspepsia.

OBJECTIVE: Patients with irritable bowel syndrome and abdominal bloating exhibit abnormal responses of the abdominal wall to colonic gas loads. We hypothesised that in patients with postprandial bloating, ingestion of a meal triggers comparable abdominal wall dyssynergia. Our aim was to characterise abdominal accommodation to a meal in patients with postprandial bloating. DESIGN: A test meal (0.8 kcal/ml nutrients plus 27 g/litre polyethylenglycol 4000) was administered at 50 ml/min as long as tolerated in 10 patients with postprandial bloating (fulfilling Rome III criteria for postprandial distress syndrome) and 12 healthy subjects, while electromyographic (EMG) responses of the anterior wall (upper and lower rectus, external and internal oblique via bipolar surface electrodes) and the diaphragm (via six ring electrodes over an oesophageal tube in the hiatus) were measured. Means +/- SD were calculated. RESULTS: Healthy subjects tolerated a meal volume of 913±308 ml; normal abdominal wall accommodation to the meal consisted of diaphragmatic relaxation (EMG activity decreased by 15±6%) and a compensatory contraction (25±9% increase) of the upper abdominal wall muscles (upper rectus and external oblique), with no changes in the lower anterior muscles (lower rectus and internal oblique). Patients tolerated lower volume loads (604±310 ml; p=0.030 vs healthy subjects) and developed a paradoxical response, that is, diaphragmatic contraction (14±3% EMG increment; p<0.01 vs healthy subjects) and upper anterior wall relaxation (9±4% inhibition; p<0.01 vs healthy subjects). CONCLUSIONS: In functional dyspepsia, postprandial abdominal distension is produced by an abnormal viscerosomatic response to meal ingestion that alters normal abdominal accommodation.

Abdomino-phrenic dyssynergia in patients with abdominal bloating and distension.

OBJECTIVES: The abdomen normally accommodates intra-abdominal volume increments. Patients complaining of abdominal distension exhibit abnormal accommodation of colonic gas loads (defective contraction and excessive protrusion of the anterior wall). However, abdominal imaging demonstrated diaphragmatic descent during spontaneous episodes of bloating in patients with functional gut disorders. We aimed to establish the role of the diaphragm in abdominal distension. METHODS: In 20 patients complaining of abdominal bloating and 15 healthy subjects, we increased the volume of the abdominal cavity with a colonic gas load, while measuring abdominal girth and electromyographic activity of the anterior abdominal muscles and of the diaphragm. RESULTS: In healthy subjects, the colonic gas load increased girth, relaxed the diaphragm, and increased anterior wall tone. With the same gas load, patients developed significantly more abdominal distension; this was associated with paradoxical contraction of the diaphragm and relaxation of the internal oblique muscle. CONCLUSIONS: In this experimental provocation model, abnormal accommodation of the diaphragm is involved in abdominal distension.