Measurement of esophago-gastric junction cross-sectional area and distensibility by an endolumenal functional lumen imaging probe for the diagnosis of gastro-esophageal reflux disease

Post-bariatric Surgery Changes in Secondary Esophageal Motility and Distensibility Parameters

INTRODUCTION

Despite the increasing number of bariatric procedures over the recent years, the physiological changes in secondary esophageal motility and distensibility parameters after surgery remain unknown.

METHODS

This is a retrospective, single-center cohort study comparing esophageal planimetry and gastroesophageal junction (GEJ) distensibility in post-bariatric surgery patients (Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), and conversion/revisional patients (DH)) and native-anatomy patients with obesity (NAC). Distensibility refers to the area achieved with a certain amount of pressure, and secondary peristalsis represents the esophageal response to an intended obstruction. Patients with pre-surgical dysmotility symptoms were excluded from the study.

RESULTS

From November 2018 to January 2023, 167 patients were evaluated and eligible for this study (RYGB = 87, SG = 33, NAC = 22, DH = 25). In NAC cohort, 17/22 (77%) patients presented normal motility patterns compared to 35/87 (40%) RYGB, 12/33 (36%) SG, and 5/25 (20%) DH (p < 0.05 for all comparisons). The most common abnormal motility pattern for all three bariatric cohorts was absent contractions. DH patients generally had the highest mean maximum distensibility index averages, followed by SG, RYGB, and NAC.

CONCLUSION

Bariatric surgery affects esophageal and GEJ physiology, and it is associated with higher rates of secondary dysmotility. DH patients have even higher rates of dysmotility. Further studies assessing clinical data and their correlation with manometric and pH-metric findings are needed.

Functional lumen imaging probe topography identifies patients with normal acid exposure and esophageal hypervigilance amongst proton-pump inhibitor non-responders

BACKGROUND

Multiple factors contribute to symptom generation and treatment response in proton-pump inhibitor non-responders (PPI-NRs). We aimed to test whether PPI-NRs with normal acid exposure have a higher degree of esophageal hypersensitivity and hypervigilance and can be identified using functional lumen imaging probe (FLIP) topography at the time of endoscopy.

METHODS

Data from PPI-NRs whom underwent endoscopy, FLIP and wireless 96-h pH-metry were retrospectively analyzed. Patients were grouped according to acid exposure time (AET) as (a) 0 days abnormal (AET > 6%), (b) 1-2 days abnormal, or (c) 3-4 days abnormal. The esophageal hypervigilance and anxiety scale (EHAS) score and other symptom scores were compared between groups. The discriminatory ability of the esophagogastric junction (EGJ) distensibility index (DI) and max EGJ diameter in identifying patients with 0 days abnormal AET was tested via receiver-operating-characteristic (ROC) curve analysis.

RESULTS

EHAS score was 38.6 in the 0 days abnormal AET group, 30.4 in the 1-2 days abnormal AET group (p = 0.073 when compared to 0 days abnormal) and 28.2 in the 3-4 days abnormal AET group (p = 0.031 when compared to 0 days abnormal). Area-under-the-curve (AUC) for the DI in association with 0 days AET > 6% was 0.629. A DI of < 2.8 mm2/mmHg had a sensitivity of 83.3%, and negative predictive value of 88% in classifying patients with 0 days abnormal acid exposure (p = 0.004).

CONCLUSIONS

FLIP complements prolonged wireless pH-metry in distinguishing the subset of PPI-NRs with completely normal acid exposure and a higher burden of esophageal hypervigilance. Proper identification of patients along the functional heartburn spectrum can improve overall surgical outcomes.

Use of endolumenal functional lumen imaging probe in investigating paediatric gastrointestinal motility disorders

Investigating gastrointestinal (GI) motility disorders relies on diagnostic tools to assess muscular contractions, peristalsis propagation and the integrity and coordination of various sphincters. Manometries are the gold standard to study the GI motor function but it is increasingly acknowledged that manometries do not provide a complete picture in relation to sphincters competencies and muscle fibrosis. Endolumenal functional lumen imaging probe (EndoFLIP) an emerging technology, uses impedance planimetry to measure hollow organs cross sectional area, distensibility and compliance. It has been successfully used as a complementary tool in the assessment of the upper and lower oesophageal sphincters, oesophageal body, the pylorus and the anal canal. In this article, we aim to review the uses of EndoFLIP as a tool to investigate GI motility disorders with a special focus on paediatric practice. The majority of EndoFLIP studies were conducted in adult patients but the uptake of the technology in paediatrics is increasing. EndoFLIP can provide a useful complementary data to the existing GI motility investigation in both children and adults.

Preoperative esophageal testing predicts postoperative reflux status in sleeve gastrectomy patients

BACKGROUND

Patients who undergo vertical sleeve gastrectomy (VSG) are at risk of postoperative GERD. The reasons are multifactorial, but half of conversions to Roux-en Y gastric bypass are for intractable GERD. Our institution routinely performs preoperative pH and high-resolution manometry studies to aid in operative decision making. We hypothesize that abnormal pH studies in concert with ineffective esophageal motility would lead to higher rates of postoperative reflux after VSG.

METHODS

A single institution retrospective review was conducted of adult patients who underwent preoperative pH and manometry testing and VSG between 2015 and 2021. Patients filled out a symptom questionnaire at the time of testing. Postoperative reflux was defined by patient-reported symptoms at 1-year follow-up. Univariate logistic regression was used to examine the relationship between esophageal tests and postoperative reflux. The Lui method was used to determine the cutpoint for pH and manometric variables maximizing sensitivity and specificity for postoperative reflux.

RESULTS

Of 291 patients who underwent VSG, 66 (22.7%) had a named motility disorder and 67 (23%) had an abnormal DeMeester score. Preoperatively, reflux was reported by 122 patients (41.9%), of those, 69 (56.6%) had resolution. Preoperative pH and manometric abnormalities, and BMI reduction did not predict postoperative reflux status (p = ns). In a subgroup analysis of patients with an abnormal preoperative pH study, the Lui cutpoint to predict postoperative reflux was a DeMeester greater than 24.8. Postoperative reflux symptoms rates above and below this point were 41.9% versus 17.1%, respectively (p = 0.03).

CONCLUSION

While manometry abnormalities did not predict postoperative reflux symptoms, GERD burden did. Patients with a mildly elevated DeMeester score had a low risk of postoperative reflux compared to patients with a more abnormal DeMeester score. A preoperative pH study may help guide operative decision-making and lead to better counseling of patients of their risk for reflux after VSG.

Novel Diagnostic Techniques in the Evaluation of Gastroesophageal Reflux Disease (GERD)

In our present clinical paradigm, patient symptoms and presentation in the setting of traditional findings from endoscopy (erosive esophagitis, Barrett's esophagus, reflux-mediated stenosis), esophageal high-resolution manometry, and/or ambulatory reflux monitoring (distal esophageal acid exposure time, numbers of reflux events, reflux-symptom association) guide the care of patients with suspected GERD. However, novel metrics and techniques acquired from or performed at endoscopy, manometry, or pH-impedance monitoring, beyond conventional evaluation, are of great interest to the gastroenterology community given the frequent (and sometimes challenging) presentation of suspected GERD. These novel and evolving diagnostic approaches have the potential to enhance the evaluation of these patients and optimize their management. In this invited review, we discuss the present evidence and potential clinical utility of selected GERD metrics and techniques of interest at endoscopy (dilated intercellular spaces, mucosal impedance), manometry (contractile integral, impedance analysis, straight leg raise, multiple rapid swallow maneuvers), and reflux monitoring (mean nocturnal baseline impedance, post-reflux swallow-induced peristaltic wave indices), and how these tools may be most optimally adopted and utilized for clinical care (Fig. 1).

The broad impact of functional lumen imaging probe panometry in addition to high-resolution manometry in an esophageal clinical practice

High-resolution manometry (HRM) with the Chicago Classification (CC) is the standard paradigm to define esophageal motility disorders. Functional lumen imaging probe (FLIP) panometry utilizes impedance planimetry to characterize esophageal compliance and secondary peristalsis. The aim of this study was to explore the clinical impact of FLIP panometry in addition to HRM. A retrospective chart review was performed on FLIP panometry cases utilizing the 322N catheter. Cases with prior foregut surgeries or botulinum injection within 6 months of FLIP panometry were excluded. EGJ-diameter and distensibility index (DI) and secondary contraction patterns at increasing balloon volumes were recorded. An EGJ-DI of ≥2.8 mm2/mm Hg at 60 mL was considered as a normal EGJ distensibility. CC diagnosis, Eckhardt score, Brief Esophageal Dysphagia Questionnaire, and clinical outcomes were obtained for each FLIP case. A total of 186 cases were included. Absent contractility and achalasia types 1 and 2 showed predominantly absent secondary contraction patterns, while type 3 had a variety of secondary contractile patterns on FLIP panometry. Among 77 cases with EGJ outflow obstruction (EGJOO), 60% had a low EGJ-DI. Among those with no motility disorder or ineffective esophageal motility on HRM, 27% had a low DI and 47% had sustained contractions on FLIP, raising concern for an esophageal dysmotility process along the achalasia and/or spastic spectrum. FLIP panometry often confirmed findings on HRM in achalasia and absent contractility. FLIP panometry is useful in characterizing EGJOO cases. Spastic features on FLIP panometry may raise concern for a motility disorder on the spastic spectrum not captured by HRM. Further studies are needed on FLIP panometry to determine how to proceed with discrepancy with HRM and explore diagnoses beyond the CC.

Role of Endoscopy in Motility Disorders of Upper Gastrointestinal Tract

Gastrointestinal motility disorders have a wide range of symptoms and affect patients' quality of life. With the advancement of endoscopy, the diagnostic and therapeutic roles of endoscopy in motility disorders is becoming more significant. Endoscopy is necessary to rule out possible organic diseases in patients with suspected motility disorders and provide significant clues for their diagnosis. Moreover, interventional endoscopy may be a primary or alternative treatment option for selected patients with motility disorders, and it is becoming a promising field as new therapeutic applications are developed and utilized for various motility disorders. This review may provide suitable indications for the use of endoscopy in diagnosing and treating motility disorders of the upper gastrointestinal tract.

Normative values for esophageal functional lumen imaging probe measurements: A meta-analysis

BACKGROUND

The functional lumen imaging probe (Endoflip™) is increasingly used for evaluation of patients with esophageal symptoms. To improve the interpretation of Endoflip™ in clinical practice, normative values with appropriate cut-off values are required.

METHODS

Original clinical studies describing Endoflip™ use for measurements of esophageal motility in healthy adults were considered. Meta-analysis was performed based on published values.

RESULTS

A total of 17 articles were included in the systematic review, 15 of which were included in the meta-analysis, representing 154 unique subjects. At 40 ml distention, the 5th-95th and 10th-90th percentiles for esophagogastric junction distensibility index (EGJ-DI) were 1.96-10.95 mm² /mmHg and 2.36-8.95 mm² /mmHg, respectively. An EGJ-DI below 2 mm² /mmHg was found in 5.4%, and below 3 mm² /mmHg in 20.1% of healthy subjects. At 50 ml distention, the 5th-95th and 10th-90th percentiles for EGJ-DI are 2.86-10.66 mm² /mmHg and 3.28-9.12 mm² /mmHg, respectively (below 2 mm² /mmHg: 0.6%, 3 mm² /mmHg: 6.3%). The 5th-95th and 10th-90th percentiles for EGJ-DI at 60 ml distention were 3.06-8.14 mm² /mmHg and 3.33-7.18 mm² /mmHg, respectively (below 2 mm² /mmHg: 0.0%, 3 mm² /mmHg: 7%). A clear cut-off for lower values was identified while a large spread in values was observed for upper limits of normal for EGJ-DI for all filling volumes.

CONCLUSIONS

Given these observations, we recommend using a cut-off of 2 mm² /mmHg for clinical practice, values below can be considered abnormal. Given that 5.4% of the healthy subjects will have an EGJ-DI below 2 mm² /mmHg at 40 ml, we recommend using the 50 and 60 ml distention volumes. The clinical use of an upper limit for normality of EGJ-DI seems questionable.

Functional luminal imaging probe in the evaluation of esophago-gastric junction outflow obstruction

PURPOSE OF REVIEW

Esophagogastric junction outflow obstruction (EGJOO) comprises a heterogeneous group of conditions that demonstrate impaired deglutitive relaxation of the esophagogastric junction (EGJ) with intact esophageal peristalsis on high-resolution manometry. Functional luminal imaging probe (FLIP) panometry is a powerful tool that can help to clarify the etiology of this manometric diagnosis. The aim of this review is to summarize the use of FLIP for the evaluation and management of EGJOO.

RECENT FINDINGS

FLIP panometry provides measures of esophageal compliance at the EGJ and information on esophageal body contractile responses to balloon distention that have important implications for the management of patients with EGJOO. After excluding anatomic causes of impaired EGJ distensibility, FLIP panometry is useful in differentiating true lower esophageal sphincter dysfunction from manometric artifact. FLIP panometry has been shown to be useful in determining the need for invasive treatment in patients with EGJOO, and in intraoperative tailoring of myotomy procedures.

SUMMARY

FLIP panometry is easy to perform during endoscopy and provides useful information for characterizing the EGJOO population. FLIP panometry can be used to guide treatment and improve outcomes in the management of patients with EGJOO.

A Comparative Assessment of the Diagnosis of Swallowing Impairment and Gastroesophageal Reflux in Canines and Humans

Swallowing impairment is a highly prevalent and clinically significant problem affecting people and dogs. There are myriad causes of swallowing impairment of which gastroesophageal reflux is the most common in both species. Similarities in anatomy and physiology between humans and canines results in analogous swallowing disorders including cricopharyngeus muscle achalasia, esophageal achalasia, hiatal herniation, and gastroesophageal reflux with secondary esophagitis and esophageal dysmotility. Accordingly, the diagnostic approach to human and canine patients with swallowing impairment is similar. Diagnostic procedures such as swallowing fluoroscopy, high-resolution manometry, pH/impedance monitoring, and endolumenal functional luminal imaging probe can be performed in both species; however, nasofacial conformation, increased esophageal length, and the difficulty of completing several of these procedures in awake dogs are inherent challenges that need to be considered. Human patients can convey their symptoms and respond to verbal cues, whereas veterinarians must rely on clinical histories narrated by pet owners followed by comprehensive physical examination and observation of the animal eating different food consistencies and drinking water. Dogs may also be unwilling to drink or eat in the hospital setting and may be resistant to physical restraint during diagnostic procedures. Despite the species differences and diagnostic challenges, dogs are a natural animal model for many oropharyngeal and esophageal disorders affecting people, which presents a tremendous opportunity for shared learnings. This manuscript reviews the comparative aspects of esophageal anatomy and physiology between humans and canines, summarizes the diagnostic assessment of swallowing impairment in both species, and discusses future considerations for collaborative medicine and translational research.

GASTROESOPHAGEAL REFLUX DISEASE: A PRACTICAL APPROACH

Gastroesophageal reflux disease (GERD) presents typical manifestations such as heartburn and/or regurgitation as well as atypical manifestations such as throat symptoms, laryngitis, hoarseness, chronic cough, asthma, and sleep alterations. There are two phenotypes of the disease: erosive GERD, when erosions are identified by upper digestive endoscopy, and non-erosive GERD, when the esophageal mucosa presents a normal endoscopic aspect. Relevant clinical findings are usually absent in the physical examination, but it should be highlighted that obesity is an important aggravating factor of reflux. The treatment is established based on clinical findings and, according to the clinical situation, on complementary exams such as upper digestive endoscopy. In dubious cases where a precise diagnosis is required, the indicated test is esophageal pHmetry or impedance-pHmetry. Clinical treatment is divided into behavioral/dietary measures and pharmacological measures. Most patients benefit from clinical treatment, but surgical treatment may be indicated in the presence of a larger hiatal hernia and complications of the disease.

A novel EndoFLIP marker during hiatal hernia repair is associated with short-term postoperative dysphagia

BACKGROUND

Endoluminal functional lumen imaging probe (EndoFLIP) provides an objective measure of the distensibility index (DI) during different parts of hiatal hernia repair. However, the absolute DI measure above a cut-off after creating a barrier alone has not shown a relationship to dysphagia after surgery. We wanted to determine if the change in DI with volume change is associated with dysphagia.

METHODS

We included patients who had hiatal hernia repair with EndoFLIP values, including two values taken at the end of the surgical case with different volumes of fluid in the balloon (30 mL and 40 mL). We compared the absolute and change in DI during hiatal hernia repair and performed an analysis to determine if there was a correlation with short-term clinical outcomes.

RESULTS

A total of 103 patients met the inclusion and exclusion criteria. Most of the patients underwent Toupet fundoplication (n = 56, 54%), followed by magnetic sphincter augmentation (LINX, n = 28, 27%) and Nissen fundoplication (n = 19, 18%). There was a significant reduction in the DI from the initial DI taken after mobilization of the hiatus (3 mm²/mmHg) and after the creation of the barrier (1.4 mm²/mmHg, p < 0.001). A minority of patients had a decrease or no change in the DI with an increase in balloon volume increased from 30 to 40 mL (n = 37, 36%). Overall, after 1 month, there was a significant decrease in the GERD-HRQL score from 23 to 4 (p < 0.001) and bloat score from 3 to 2 (p = 0.003) with a non-significant decrease in the dysphagia score from 1 to 0 (p = 0.11). Patients who had a decreased or unchanged DI with an increase in the balloon volume from 30 to 40 mL had a significant decrease in their dysphagia score by 2 points (p = 0.04).

CONCLUSION

The decreased or unchanged DI with an increase in the balloon volume on EndoFLIP is associated with a significant reduction in dysphagia after surgery. The decrease in DI denotes the esophagus's ability to create higher pressure relative to the change in the cross-sectional area with a larger bolus across the gastroesophageal junction. This measure may be a new marker that can predict short-term outcomes in patients undergoing hiatal hernia repair.

The Usefulness of the Measurement of Esophagogastric Junction Distensibility by EndoFLIP in the Diagnosis of Gastroesophageal Reflux Disease

Background/Aims

Increased esophagogastric junction (EGJ) relaxation is the most important mechanism involved in gastroesophageal reflux disease (GERD). An endoscopic functional luminal imaging probe (EndoFLIP^Ⓡ) is a device used to quantify EGJ distensibility in routine endoscopy. The aim of the current study was to assess the usefulness of EndoFLIP^Ⓡ for the diagnosis of GERD compared to normal controls.

Methods

We analyzed EndoFLIP^Ⓡ data from 204 patients with erosive reflux disease (ERD), 310 patients with nonerosive reflux disease (NERD), and 277 normal subjects. EndoFLIP^Ⓡ uses impedance planimetry to measure 16 cross-sectional areas (CSAs) in conjunction with the corresponding intrabag pressure within a 4.6 cm cylindrical segment of a fluid-filled bag. The EGJ distensibility was assessed using 40 mL volume-controlled distensions.

Results

The mean distensibility index values were 13.98 mm²/mm Hg in ERD patients, 11.42 mm²/mm Hg in NERD patients, and 9.1 mm²/mm Hg in normal subjects. There were significant differences in EGJ distensibility among the three groups (p<0.001). In addition, the CSAs were significantly higher in the ERD (291.03±160.77 mm²) and NERD groups (285.87±155.47 mm²) than in the control group (249.78±144.76 mm², p=0.004). We determined the distensibility index cutoff value of EGJ as 10.95 for the diagnosis of GERD by receiver operating characteristic curve analysis.

Conclusions

The EGJ distensibilities of GERD patients were higher than those of normal subjects, regardless of the presence of reflux esophagitis. Thus, the measurement of EGJ distensibility using the EndoFLIP^Ⓡ system could be useful in the diagnosis of GERD.

Evaluation of the Esophagogastric Junction on High Resolution Manometry

The esophagogastric junction (EGJ) is a complex barrier between the thoracic and abdominal luminal gut compartments, comprised primarily of the lower esophageal sphincter (LES) and crural diaphragm. Although closed at rest, the EGJ relaxes to allow antegrade bolus transit and retrograde venting of air. Abnormal relaxation is the hallmark of achalasia spectrum disorders, while increased frequency of transient lower esophageal sphincter relaxations and/or EGJ disruption are seen in gastroesophageal reflux disease. High resolution manometry (HRM) is the modern day gold standard for assessment of EGJ morphology and function, with better performance characteristics compared with endoscopy and barium esophagography. Conventional LES metrics defining EGJ function include resting LES pressure as well as postswallow residual pressures. Newer HRM-based metrics include EGJ contractile integral, which measures static barrier function at rest, and EGJ morphology, which characterizes the relationship between LES and crural diaphragm. Provocative maneuvers assess dynamic EGJ function during physiological or pharmacologic stress. The most useful of these maneuvers, the rapid drink challenge, assesses for latent obstruction, while multiple rapid swallows evaluate adequacy of deglutitive inhibition. Amyl nitrate and cholecystokinin administration can segregate motor from structural obstruction. Newer provocative tests (straight leg raise maneuver, abdominal compression) and novel diagnostic tools (functional lumen imaging probe) complement HRM evaluation of the EGJ. Although current HRM metrics and maneuvers show promise in identifying clinically relevant EGJ abnormalities, future investigations evaluating management outcomes will improve segregation of normal from abnormal EGJ morphology and function.

Prolonged Wireless pH Monitoring in Patients With Persistent Reflux Symptoms Despite Proton Pump Inhibitor Therapy

BACKGROUND & AIMS

Wireless pH monitoring measures esophageal acid exposure time (AET) for up to 96 hours. We evaluated competing methods of analysis of wireless pH data.

METHODS

Adult patients with persisting reflux symptoms despite acid suppression (n = 322, 48.5 ± 0.9 years, 61.7% women) from 2 tertiary centers were evaluated using symptom questionnaires and wireless pH monitoring off therapy, from November 2013 through September 2017; 30 healthy adults (control subjects; 26.9 ± 1.5 years; 60.0% women) were similarly evaluated. Concordance of daily AET (physiologic <4%, borderline 4%-6%, pathologic>6%) for 2 or more days constituted the predominant AET pattern. Each predominant pattern (physiologic, borderline, or pathologic) in relation to data from the first day, and total averaged AET, were compared with other interpretation paradigms (first 2 days, best day, or worst day) and with symptoms.

RESULTS

At least 2 days of AET data were available from 96.9% of patients, 3 days from 90.7%, and 4 days from 72.7%. A higher proportion of patients had a predominant pathologic pattern (31.4%) than control subjects (11.1%; P = .03). When 3 or more days of data were available, 90.4% of patients had a predominant AET pattern; when 2 days of data were available, 64.1% had a predominant AET pattern (P < .001). Day 1 AET was discordant with the predominant pattern in 22.4% of patients and was less strongly associated with the predominant pattern compared with 48 hour AET (P = .059) or total averaged AET (P = .02). Baseline symptom burden was higher in patients with a predominant pathologic pattern compared with a predominant physiologic pattern (P = .02).

CONCLUSIONS

The predominant AET pattern on prolonged wireless pH monitoring can identify patients at risk for reflux symptoms and provides gains over 24 hours and 48 hours recording, especially when results from the first 2 days are discordant or borderline.

Use of the Functional Lumen Imaging Probe in Clinical Esophagology

The functional lumen imaging probe (FLIP) measures luminal dimensions using impedance planimetry, performed most often during sedated upper endoscopy. Mechanical properties of the esophageal wall and opening dynamics of the esophagogastric junction (EGJ) can be objectively evaluated in esophageal motor disorders, eosinophilic esophagitis, esophageal strictures, during esophageal surgery and in postsurgical symptomatic states. Distensibility index, the ratio of EGJ cross sectional area to intraballoon pressure, is the most useful FLIP metric. Secondary peristalsis from balloon distension can be displayed topographically as repetitive anterograde or retrograde contractile activity in the esophageal body, similar to high-resolution manometry. Real-time interpretation and postprocessing of FLIP metadata can complement the identification of esophageal outflow obstruction and achalasia, especially when findings are inconclusive from alternate esophageal tests in symptomatic patients. FLIP can complement the diagnosis of achalasia when manometry and barium studies are inconclusive or negative in patients with typical symptoms. FLIP can direct adequacy of disruption of the EGJ in achalasia when used during and immediately after myotomy and pneumatic dilation. Lumen diameter measured using FLIP in eosinophilic esophagitis and in complex strictures can potentially guide management. An abbreviated modification of the Grading of Recommendations Assessment, Development, and Evaluation was used to determine the quality of available evidence and recommendations regarding FLIP utilization. FLIP metrics that are diagnostic or suggestive of an abnormal motor pattern and metrics that define normal esophageal physiology were developed by consensus and are described in this review.

Understanding the relationship between esophageal motor disorders and reflux disease

INTRODUCTION

The management of gastro-esophageal reflux disease (GERD) patients is often complex as the clinical presentation is heterogeneous and the mechanisms underlying symptoms are multifactorial. In the past decades, investigations conducted with conventional manometry and, above all, the more accurate high resolution manometry (HRM), helped us in exploring the field of esophageal motility and in understanding the link between motor features and GERD pathogenesis.

AREAS COVERED

Several studies carried out with conventional manometry and HRM have confirmed a relevant role of esophageal motor function in GERD pathogenesis. In particular, HRM studies have shown a direct correlation between impaired esophageal body motility, disruption of the esophagogastric junction and reflux burden. These findings impact the clinical and therapeutical management of GERD patients. Moreover, HRM findings might be helpful in evaluating patients with proton pump inhibitor (PPI) resistance and inconclusive evidences of GERD.

EXPERT OPINION

The relationship between esophageal motility and GERD pathogenesis needs to be further evaluated by multicenter outcome studies involving a large number of GERD patients and healthy controls. However, other more promising areas could be progressed.

ACG Clinical Guidelines: Clinical Use of Esophageal Physiologic Testing

Esophageal symptoms are common and may indicate the presence of gastroesophageal reflux disease (GERD), structural processes, motor dysfunction, behavioral conditions, or functional disorders. Esophageal physiologic tests are often performed when initial endoscopic evaluation is unrevealing, especially when symptoms persist despite empiric management. Commonly used esophageal physiologic tests include esophageal manometry, ambulatory reflux monitoring, and barium esophagram. Functional lumen imaging probe (FLIP) has recently been approved for the evaluation of esophageal pressure and dimensions using volumetric distension of a catheter-mounted balloon and as an adjunctive test for the evaluation of symptoms suggestive of motor dysfunction. Targeted utilization of esophageal physiologic tests can lead to definitive diagnosis of esophageal disorders but can also help rule out organic disorders while making a diagnosis of functional esophageal disorders. Esophageal physiologic tests can evaluate obstructive symptoms (dysphagia and regurgitation), typical and atypical GERD symptoms, and behavioral symptoms (belching and rumination). Certain parameters from esophageal physiologic tests can help guide the management of GERD and predict outcomes. In this ACG clinical guideline, we used the Grading of Recommendations Assessment, Development and Evaluation process to describe performance characteristics and clinical value of esophageal physiologic tests and provide recommendations for their utilization in routine clinical practice.

EndoFLIP in the Esophagus: Assessing Sphincter Function, Wall Stiffness, and Motility to Guide Treatment

The functional luminal imaging probe (FLIP) uses high-resolution planimetry to provide a three-dimensional image of the esophageal lumen by measuring diameter, volume, and pressure changes. Literature surrounding use of FLIP has demonstrated its clinical utility as a diagnostic tool and as a device to guide and measure response to therapy. FLIP can assess and guide treatments for esophageal disease states including gastroesophageal reflux disease, achalasia, and eosinophilic esophagitis. FLIP may become the initial test for patients with undifferentiated dysphagia at their index endoscopy. This article summarizes use of FLIP in assessing sphincter function, wall stiffness, and motility to guide treatments.

Esophageal Functional Lumen Imaging Probe (FLIP): How Can FLIP Enhance Your Clinical Practice?

Recent innovations in esophageal diagnostic testing have enhanced gastroenterology clinical practice by facilitating more nuanced and advanced evaluation of esophageal symptoms. Among these pivotal advances is the FDA-approved functional lumen imaging probe (FLIP), which utilizes impedance planimetry via volumetric distension of a catheter-mounted balloon at the time of sedated upper endoscopy, to acquire esophageal dimensions and pressures. In real time, FLIP can display cross-sectional areas (CSA) and distensibility indices (ratios of CSA to intra-balloon pressures) throughout the esophagus, most notably at the esophagogastric junction, as well as secondary peristaltic esophageal body contractile patterns. As the use of FLIP has progressively spread and permeated into the practice of clinical gastroenterology since its introduction, increasing data on and experiences with its applications have accumulated to guide its utility in clinical practice. In this current review developed for gastroenterologists and foregut surgeons across clinical practice, we provide an introduction to FLIP technology and metrics and discuss the clinical scenarios in which performance of or referral for FLIP may be helpful in the evaluation and management of patients with commonly encountered esophageal symptoms and disorders. Specifically, we discuss the potential applications and limitations of FLIP as a complementary diagnostic modality in patients with non-obstructive dysphagia, established or suspected achalasia spectrum disorders, eosinophilic esophagitis, gastroesophageal reflux disease and those undergoing esophageal surgery.

The use of impedance planimetry (Endoscopic Functional Lumen Imaging Probe, EndoFLIP® ) in the gastrointestinal tract: A systematic review

BACKGROUND AND PURPOSE

The EndoFLIP® system is a method of delineating impedance and was first designed to investigate the characteristics of the esophago-gastric junction. In the last decade, its use was widened to investigate other sphincteric and non-sphincteric systems of the gastrointestinal tract. The objective of the present systematic review was to summarize the available data in literature on the use of the EndoFLIP® system in the gastrointestinal tract, including sphincteric and non-sphincteric regions. We performed a systematic review in accordance with recommendations for systematic review using PRISMA guidelines without date restriction, until June 2020, using MEDLINE-PubMed, Cochrane Library, and Google Scholar databases. Only articles written in English were included in the present review. Five hundred and six unique citations were identified from all database combined. Of those, 95 met the inclusion criteria. There was a lack of standardization among studies in terms of anesthetic drugs use, probe placement, and inflation protocol. In most cases, only small cohorts of patients were included. Most studies investigated the EGJ, with a potential use of the EndoFLIP® to identify a subgroup of patients with achalasia and for intraoperative assessment of treatment efficacy in achalasia. However, the use of EndoFLIP® in the esophageal body (esophageal panometry), other esophageal diseases (gastro-esophageal reflux disease, eosinophilic esophagitis), and other sphincter regions (anal canal, pylorus) will need further confirmatory studies. The EndoFLIP® system provides detailed geometric data of the gastrointestinal lumen but further works are needed to determine its use in clinical practice.

The functional lumen imaging probe in gastrointestinal disorders: the past, present, and future

The functional lumen imaging probe (FLIP) is a diagnostic tool that utilizes impedance planimetry to allow the assessment of luminal diameter and distensibility. It has been used primarily in esophageal diseases, in particular, in the assessment of achalasia, esophagogastric junction outflow obstruction, and eosinophilic esophagitis (EoE). The usage and publications have increased over the past decade and it is now an essential tool in the armamentarium of the esophagologist. Indications are emerging outside of the esophagus, in particular with regard to gastroparesis. Our paper will review the history of FLIP, optimal current usage, data for key esophageal disorders (including achalasia, reflux, and EoE), data for nonesophageal disorders, and our sense as to whether FLIP is ready for prime time, as well as gaps in evidence and suggestions for future research.

Short-term outcome of routine use of EndoFLIP during hiatal hernia repair

BACKGROUND

Endoluminal functional lumen imaging probe (EndoFLIP) technology is a tool that can be used to provide intraoperative objective real-time feedback during hiatal hernia repair. We wanted to determine the implication of initial distensibility index (DI) after mobilization of hiatus and final DI after creation of barrier in short-term clinical outcomes.

METHODS

We performed a retrospective analysis of prospectively collected data on the intraoperative use of EndoFLIP during hiatal hernia repair at a single institution from 2017 to 2019. We analyzed the initial DI and final DI with the short-term clinical outcomes.

RESULTS

There were 163 patients who had Nissen (n = 16), Toupet (n = 79) or magnetic sphincter augmentation (n = 68) with (n = 158) or without (n = 5) hiatal hernia repair with median initial DI was 3.2 mm²/mmHg. We used 3 mm²/mmHg as the cutoff for low (n = 84) vs. high (n = 79) initial DI group. There was no difference in DeMeester score (p = 0.76), the peristalsis on manometry (p = 0.13), type of hiatal hernia (p = 0.98), and GERD-HRQL score prior to surgery (p = 0.73) between the groups. There was significantly higher final DI in the high initial DI group compared to low initial DI group; however, there was no significant difference in the GERD-HRQL score at 1-3 months (p = 0.28). All of the patients had a final DI > 0.5 mm²/mmHg at the end of the case with median final DI of 1.6 mm^2/mmHg. None of these patients required steroids (0%) and only one patient (0.6%) required EGD and dilatation as well as re-operation for dysphagia within 3 months.

CONCLUSIONS

The initial DI was associated with final DI, but it did not correlate with improvement in short-term GERD-HRQL score. Final DI maintained above the cutoff value led to most of the patients not to require intervention for dysphagia. Use of the EndoFLIP can provide objective data during the operation and prevent severe dysphagia after repair.

Impedance in the evaluation of the esophagus

The aim of this paper is to review esophageal electrical impedance technologies and to discuss the use of these technologies for physiological measurements, diagnostics, and therapy of esophageal disease. In order to develop a better understanding of the pathophysiology of and improve the diagnosis of esophageal disorders, such as gastroesophageal reflux disease (GERD) and achalasia, several new diagnostic tests, including intraluminal impedance, esophageal mucosal impedance, and the functional luminal imaging probe, have been developed. These technologies have proven valuable for assessment of the esophagus in recent years. They provide information on esophageal flow properties, mucosal integrity, lumen shape, and distensibility in esophageal disorders, in particular for GERD and achalasia. Despite their promise and novel clinical studies, the potential of these technologies has been far from realized. New multidisciplinary approaches will contribute to our understanding and interpretation of esophageal impedance data and disease mechanisms.

Using Impedance Planimetry (EndoFLIP) to Evaluate Myotomy and Predict Outcomes After Surgery for Achalasia

BACKGROUND

The functional lumen imaging probe (FLIP) is an innovative tool that uses impedance planimetry to assess esophageal geometry in real time. It has been used to diagnose achalasia and evaluate treatment failure after laparoscopic Heller myotomy (LHM) and peroral endoscopic myotomy (POEM). We hypothesize that impedance planimetry can be utilized intra-operatively to assess adequacy of myotomy and assist in predicting patient outcomes.

METHODS

A prospectively maintained patient database at a single center was queried. Seventy-seven patients with achalasia underwent POEM or LHM by a single surgeon. The FLIP was used to measure cross-sectional area (CSA), minimum diameter (D_min), balloon pressure, and distensibility index (DI) of the lower esophageal sphincter (LES) before and after the procedure. Clinical outcomes were measured up to 2 years after treatment.

RESULTS

Post-operative CSA, D_min, balloon pressure, and DI values were significantly different from pre-operative values (p < 0.001). Patients with a post-operative Eckardt score ≥ 3 were significantly more likely to have a final DI ≤ 3.1 mm²/mmHg (p = 0.014) or a change in DI ≤ 3.0 mm²/mmHg (p = 0.010). Additionally, a final CSA > 96 mm² or D_min > 11.0 mm was predictive of worse reflux at 2 years (p = 0.01).

CONCLUSION

Impedance planimetry using the FLIP can offer intra-operative feedback about the geometry of the LES. The most useful parameters in predicting patient outcomes have yet to be clearly defined, but our results demonstrate that final DI and CSA are predictive of post-operative treatment response.

New Developments in the Diagnosis and Management of Gastroesophageal Reflux

PURPOSE OF REVIEW

To examine recent key developments in the pathophysiology, diagnosis, and treatment of gastroesophageal reflux disease (GERD).

RECENT FINDINGS

Newer research has suggested cytokine-mediated inflammation may play a role in the physiology of GERD, implying that the underlying mechanism may not be entirely related to chemical damage due to acid. Aided by novel technologies, diagnostic testing is also moving toward elucidating individual mechanisms and better defining specific GERD phenotypes with the goal of providing directed therapy. This is especially important in current times given the increase in coverage of adverse events reportedly linked to long-term proton pump inhibitor use.

SUMMARY

As patients are looking for potential alternatives, we highlight the key recent updates in pathophysiology and understanding of GERD and current medical and endoscopic/surgical options and explore the exciting treatments in the pipeline.

Applying the Functional Luminal Imaging Probe to Esophageal Disorders

PURPOSE OF REVIEW

The functional luminal imaging probe (FLIP) uses high-resolution planimetry to provide a three-dimensional image of the esophageal lumen by measuring diameter, volume, and pressure changes. The goal of this review is to summarize the most recent advances in applying the (FLIP) to esophageal disorders.

RECENT FINDINGS

The FLIP has been studied in esophageal disease states including gastroesophageal reflux disease (GERD), achalasia, and eosinophilic esophagitis. It has also been used in the investigation of dysphagia. The FLIP is a valuable tool for the diagnosis of esophageal diseases as well as guiding treatments and predicting treatment response. As further research is done, the FLIP may become the initial test for the patient with undifferentiated dysphagia at the time of their index endoscopy.

Functional lumen imaging probe in gastrointestinal motility diseases

Dysfunction of gastrointestinal (GI) sphincters, including the lower esophageal sphincter (LES) at the esophagogastric junction (EGJ) and the pyloric sphincter, plays a vital role in GI motility disorders, such as achalasia, gastroesophageal reflux disease (GERD), gastroparesis, and fecal incontinence. Using multi-detector high-resolution impedance planimetry, the functional luminal imaging probe (FLIP) system measures simultaneous data on tissue distensibility and luminal geometry changes in the sphincter in a real-time manner. In this review we focus on the emerging data on FLIP, which can be used as an innovative diagnostic method during endoscopic or surgical procedures in GI motility disorders. Subsequent large, prospective, standardizing studies are needed to validate these findings before it can be put to routine clinical use.

Pharmacologic interrogation of patients with esophagogastric junction outflow obstruction using amyl nitrite

BACKGROUND

The Chicago Classification of esophageal motility includes a group of patients who show evidence of esophagogastric junction outflow obstruction (EGJOO) as demonstrated by elevated integrated relaxation pressure (IRP) and preserved peristalsis. Our aim is to classify EGJOO patients based on response to amyl nitrite (AN) during high-resolution manometry.

METHODS

Patients were considered to have true EGJOO if elevated IRP during supine swallow persisted in the upright position and was associated with high intrabolus pressure. The EGJ response to AN was compared between patients with achalasia type 2 (A2) and normal esophageal motility. Based on the relaxation gain (deglutitive IRP-AN IRP) value that best discriminated these two groups (10 mm Hg), patients with true EGJOO were categorized as being in either the AN-responsive (AN-R) or AN-unresponsive (AN-U) subgroups.

KEY RESULTS

In the group of 49 patients with true EGJOO, the AN response classified 27 patients (IRP = 25 ± 10 mm Hg) with AN-R and 22 patients (IRP = 20 ± 5 mm Hg) with AN-U (P = 0.2). In AN-R, AN produced a relaxation gain and rebound after-contraction response at the EGJ comparable to A2 patients. AN-U patients had an elevated IRP after AN and a relaxation gain similar to normal esophageal motility patients. AN-U patients were obese and had higher prevalence of sleep apnea (P < 0.05).

CONCLUSIONS

Among patients with true EGJOO, only half have pharmacologic evidence of impaired LES relaxation. Pharmacologic interrogation of the EGJ is thus necessary to identify the subgroup of EGJOO patients who could be expected to benefit from LES ablative therapies.

What Is the Future of Impedance Planimetry in Gastroenterology?

The gastrointestinal (GI) tract is efficient in transporting ingested material to the site of delivery in healthy subjects. A fine balance exists between peristaltic forces, the mixing and delivery of the contents, and sensory signaling. This fine balance is easily disturbed by diseases. It is mandatory to understand the pathophysiology to enhance our understanding of GI disorders. The inaccessibility and complex nervous innervation, geometry and mechanical function of the GI tract make mechanosensory evaluation difficult. Impedance planimetry is a distension technology that assesses luminal geometry, mechanical properties including muscle dynamics, and processing of nociceptive signals from the GI tract. Since standardized models do not exist for GI muscle function in vivo, models, concepts, and terminology must be borrowed from other medical fields such as cardiac mechanophysiology. The review highlights the impedance planimetric technology, muscle dynamics assessment, and 3 applied technologies of impedance planimetry. These technologies are the multimodal probes that assesses sensory function, the functional luminal imaging probe that dynamically measures the geometry of the lumen it distends, and Fecobionics that is a simulated feces providing high-resolution measurements during defecation. The advanced muscle analysis and 3 applied technologies can enhance the quality of future interdisciplinary research for gaining more knowledge about mechanical function, sensory-motor disorders, and symptoms. This is a step in the direction of individualized treatment for GI disorders based on diagnostic subtyping. There seems to be no better alternatives to impedance planimetry, but only the functional luminal imaging probe is currently commercially available. Wider use depends on commercialization of the multimodal probe and Fecobionics.

Acotiamide Has No Effects on Esophageal Motor Activity or Esophagogastric Junction Compliance

BACKGROUND/AIMS

The novel prokinetic drug acotiamide is used for treatment of functional dyspepsia. It is still unclear how acotiamide has effects on esophageal motor function. Esophageal peristalsis and esophagogastric junction (EGJ) compliance has an important role for prevention of esophageal mucosal damage caused by gastroesophageal reflux, however, few studies have analyzed the effects of acotiamide on those former activities and none have investigated its effects on EGJ compliance. The aim of our research was to examine the effects of acotiamide on esophageal motility and EGJ compliance.

METHODS

We enrolled 3 gastroesophageal reflux disease (GERD) patients as well as 9 healthy volunteers. Using high-resolution manometry, we examined esophageal motor activity parameters, including esophageal body contractions and lower esophageal sphincter (LES) pressure. While, EGJ compliance was evaluated using a functional lumen imaging probe. Following determination of baseline values for esophageal motor activities and EGJ compliance, acotiamide at a standard dose of 300 mg/day was administered for 3 days. All measurements were performed again 2 hours after the last acotiamide administration.

RESULTS

In the healthy volunteers, as compared with the baseline values, acotiamide administration did not significantly change esophageal body contractions and LES pressure. And EGJ distensibility was not significantly changed (distensibility index in 40-mL distension: 3.5 ± 0.4 vs 3.3 ± 0.5 mm²/mmHg). Similarly in the GERD patients, there were no differences in either esophageal motility or EGJ compliance between before and after acotiamide administration (distensibility index in 40-mL distension: 6.2 ± 0.5 vs 6.5 ± 1.1 mm²/mmHg).

CONCLUSION

In both healthy individuals and GERD patients, standard dose acotiamide dose does not have significant effects on esophageal motor activities or EGJ compliance.

The relationship between esophageal acid exposure and the esophageal response to volumetric distention

BACKGROUND

Increased esophagogastric junction (EGJ) distensibility is thought to contribute to gastroesophageal reflux disease (GERD). Using the functional lumen imaging probe (FLIP), we aimed to assess the esophageal response to distension among patients undergoing esophageal pH monitoring.

METHODS

25 patients (ages 22-73; 13 females) who underwent ambulatory wireless esophageal pH testing while off proton-pump inhibitors were evaluated with FLIP during sedated upper endoscopy. Esophageal reflux was quantified by total percent acid exposure time (AET; <6% was considered normal). FLIP studies were analyzed using a customized program generate FLIP topography plots to identify esophageal contractility patterns and to calculate the EGJ-distensibility index (DI). Reflux symptoms were assessed with the GERDQ. Values reflect median (interquartile range).

RESULTS

Among all patients, the AET was 7.2% (3.7-11.1) and EGJ-DI was 4.2 (2.5-7.6) mm² /mm Hg. Repetitive antegrade contractions (RACs) were induced in 19/25 (76%) of patients; AET was lower among patients with (6.1%, 3-7.8) than without (14.9, 8.5-22.3) RACs (P = .009). Correlation was weak and insignificant between AET and EGJ-DI, GERDQ and AET, and GERDQ and EGJ-DI. Patients with abnormal AET (n = 16) and normal AET (n = 9) had similar EGJ-DI, 4.6 mm² /mm Hg (2.9-9.2) vs 3.2 (2.2-5.1), P = .207 and GERDQ, P = .138.

CONCLUSIONS

Abnormal esophageal acid exposure was associated with an impaired contractile response to volume distention of the esophagus. This supports that acid exposure is dependent on acid clearance mechanisms.

Expert consensus document: Advances in the physiological assessment and diagnosis of GERD

GERD is a common condition worldwide. Key mechanisms of disease include abnormal oesophagogastric junction structure and function, and impaired oesophageal clearance. A therapeutic trial of acid-suppressive PPI therapy is often the initial management, with endoscopy performed in the setting of alarm symptoms and to exclude other conditions. If symptoms persist and endoscopy does not reveal evidence of GERD, oesophageal function tests are performed, including oesophageal manometry and ambulatory reflux monitoring. However, reflux episodes can be physiological, and some findings on endoscopy and manometry can be encountered in asymptomatic individuals without GERD symptoms. The diagnosis of GERD on the basis of functional oesophageal testing has been previously reported, but no updated expert recommendations on indications and the interpretation of oesophageal function testing in GERD has been made since the Porto consensus over a decade ago. In this Consensus Statement, we aim to describe modern oesophageal physiological tests and their analysis with an emphasis on establishing indications and consensus on interpretation parameters of oesophageal function testing for the evaluation of GERD in clinical practice. This document reflects the collective conclusions of the international GERD working group, incorporating existing data with expert consensus opinion.

Hiatus Hernia as a Cause of Dysphagia

PURPOSE OF REVIEW

This review aims to discuss the putative relationship between hiatus hernia and dysphagia.

RECENT FINDINGS

Proposed mechanisms of dysphagia in patients with hiatus hernia are usually difficult to identify, but recent advances in technology (high-resolution manometry with or without concomitant impedance, ambulatory pH with impedance, videofluoroscopy, and the endoluminal functional lumen imaging probe (EndoFLIP)) and methodology (inclusion of swallows of various consistencies and volumes or shifting position during the manometry protocol) can help induce symptoms and identify the underlying disorder. Chronic reflux disease is often associated with hiatus hernia and is the most common underlying etiology. Dysmotility because of impaired contractility and vigor can occur as a consequence of repeated acid exposure from the acid pocket within the hernia, and the resultant poor clearance subsequently worsens this insult. As such, dysphagia appears to be more common with increasing hiatus hernia size. Furthermore, mucosal inflammation can lead to fibrotic stricture formation and in turn obstruction. On the other hand, there appears to be a difference in the pathophysiology of smaller sliding hernias, in that those with dysphagia are more likely to have extrinsic compression at the crural diaphragm as compared to those with reflux symptoms only. Sliding hiatus hernia, especially when small, does not commonly lead to dysmotility and dysphagia; however, in those patients with symptoms, the underlying etiology can be sought with new technologies and, in particular, the reproduction of normal eating and drinking during testing.

Emerging Roles of the Endolumenal Functional Lumen Imaging Probe in Gastrointestinal Motility Disorders

Gastrointestinal sphincters play a vital role in gut function and motility by separating the gut into functional segments. Traditionally, function of sphincters including the esophagogastric junction is studied using endoscopy and manometry. However, due to its dynamic biomechanical properties, data on distensibility and compliance may provide a more accurate representation of the sphincter function. The endolumenal functional lumen imaging probe (EndoFLIP) system uses a multi-detector impedance planimetry system to provide data on tissue distensibility and geometric changes in the sphincter as measured through resistance to volumetric distention with real-time images. With the advent of EndoFLIP studies, esophagogastric junction dysfunction and other disorders of the stomach and bowels may be better evaluated. It may be utilized as a tool in predicting effectiveness of endoscopic and surgical treatments as well as patient outcomes.

Consistency and effect of body position change on measurement of upper and lower esophageal sphincter geometry using impedance planimetry in a canine model

The EndoFLIP (Endolumenal Functional Lumen Imaging Probe, Crospon Inc, Galway, Ireland) device uses the technique of impedance planimetry to evaluate dimensions and distensibility of the upper and lower esophageal sphincter. The null hypotheses for this study were that EndoFLIP variables would be stable between anesthestic episodes and would not be affected by body position when evaluating the upper and lower esophageal sphincters in healthy dogs. During each of three consecutive general anesthesia episodes administered to eight healthy adult research colony dogs with a standardized protocol, the EndoFLIP catheter was positioned to measure cross-sectional area, intrabag pressure, upper and lower esophageal sphincter length at two different balloon fill volumes (30 and 40 mL) and two body positions (lateral and dorsal recumbency). From these measured variables, a distensibility index was also calculated. Mixed effect analysis of variance was used to evaluate the fixed marginal and interaction effects of anesthesia episode, body position, and balloon volume on measured and calculated variables. For the upper esophageal sphincter significant interactions were present between anesthetic episode and body position for all variables except intrabag pressure; adjusting for body position significant differences were present between anesthetic episodes for all variables except distensibility index; adjusting for anesthetic episode cross-sectional area, intrabag pressure, upper esophageal sphincter length and distensibility index were all affected by body position. For the lower esophageal sphincter distensibility index was the only variable where a significant interaction between anesthesia episode and body position occurred; cross-sectional area, intrabag pressure, and lower esophageal length were not significantly affected by anesthesia episode when adjusting for body position; distensibility index was the only variable significantly affected by body position. Measurements of the geometry of the lower esophageal sphincter as measured by the EndoFLIP device were consistent under conditions of general anesthesia. Similar measurements taken at the upper esophageal sphincter displayed greater variability between anesthetic episodes and were affected to a greater extent by body position. Body position should be standardized in studies using the EndoFLIP to assess geometric and functional characteristics of the upper and lower esophageal sphincters.

Application of the Functional Lumen Imaging Probe to Esophageal Disorders

OPINION STATEMENT

The functional luminal imaging probe (FLIP) provides a novel method to evaluate esophageal physiology and function in both health and disease. FLIP enables assessment of a previously underexplored component of esophageal function, distensibility, by utilizing high-resolution impedance planimetry to evaluate the relationship of the esophageal luminal geometry with pressure during controlled volumetric distension. Recent studies have described the potential utility of FLIP to evaluate the severity and effectiveness of therapy for esophageal diseases including achalasia, gastroesophageal reflux disease, and eosinophilic esophagitis. This review summarizes these emerging clinical applications of FLIP in the evaluation and management of esophageal diseases.

Functional Lumen Imaging Probe for the Management of Esophageal Disorders: Expert Review From the Clinical Practice Updates Committee of the AGA Institute

The functional luminal imaging probe is a Food and Drug Administration-approved measurement tool used to measure simultaneous pressure and diameter to guide management of various upper gastrointestinal disorders. Additionally, this tool is also approved to guide therapy during bariatric procedures and specialized esophageal surgery. Although it has been commercially available since 2009 as the endolumenal functional lumen imaging probe (EndoFLIP), the functional luminal imaging probe has had limited penetrance into clinical settings outside of specialized centers. This is primarily because of a paucity of data supporting its utility in general practice and a lack of standardized protocols and data analysis methodology. However, data are accumulating that are providing guidance regarding emerging applications in the evaluation and management of foregut disorders. This clinical practice update describes the technique and reviews potential indications in achalasia, eosinophilic esophagitis, and gastroesophgeal reflux disease. Best Practice Advice 1: Clinicians should not make a diagnosis or treatment decision based on functional lumen imaging probe (FLIP) assessment alone. Best Practice Advice 2: FLIP assessment is a complementary tool to assess esophagogastric junction opening dynamics and the stiffness of the esophageal wall. Best Practice Advice 3: Utilization should follow distinct protocols and analysis paradigms based on the disease state of interest. Best Practice Advice 4: Clinicians should not utilize FLIP in routine diagnostic assessments of gastroesophageal reflux disease. Best Practice Advice 5: FLIP should not be used to diagnose eosinophilic esophagitis but may have a role in severity assessment and therapeutic monitoring.

Esophagogastric junction distensibility assessed using the functional lumen imaging probe

AIM

To assess reference values in the literature for esophageal distensibility and cross-sectional area in healthy and diseased subjects measured by the functional lumen imaging probe (FLIP).

METHODS

Systematic search and review of articles in Medline and Embase pertaining to the use of FLIP in the esophagus was conducted in accordance with the PRISMA guidelines. Cross-sectional area and distensibility at the esophagogastric junction (EGJ) were abstracted for normal subjects, achalasia, and gastroesophageal reflux disease (GERD) patients, stratified by balloon length and volume of inflation.

RESULTS

Six achalasia studies (n = 154), 3 GERD (n = 52), and 5 studies including healthy controls (n = 98) were included in the systematic review. Normative data varied widely amongst studies of healthy volunteers. In contrast, studies in achalasia patients uniformly demonstrated low point estimates in distensibility ≤ 1.6 mm²/mmHg prior to treatment that increased to ≥ 3.4 mm²/mmHg following treatment at 40mL bag volume. In GERD patients, distensibility fell to the range of untreated achalasia (≤ 2.85 mm²/mmHg) following fundoplication.

CONCLUSION

FLIP may be a useful tool in assessment of treatment efficacy in achalasia. The drastic drop in EGJ distensibility after fundoplication suggests that FLIP measurements need to be interpreted in the context of esophageal body motility and highlights the importance of pre-operative screening for dysmotility. Future studies using standardized FLIP protocol and balloon size are needed.

The Role of Esophageal Hypersensitivity in Functional Esophageal Disorders

The Rome IV diagnostic criteria delineates 5 functional esophageal disorders which include functional chest pain, functional heartburn, reflux hypersensitivity, globus, and functional dysphagia. These are a heterogenous group of disorders which, despite having characteristic symptom profiles attributable to esophageal pathology, fail to demonstrate any structural, motility or inflammatory abnormalities on standard clinical testing. These disorders are associated with a marked reduction in patient quality of life, not least considerable healthcare resources. Furthermore, the pathophysiology of these disorders is incompletely understood. In this narrative review we provide the reader with an introductory primer to the structure and function of esophageal perception, including nociception that forms the basis of the putative mechanisms that may give rise to symptoms in functional esophageal disorders. We also discuss the provocative techniques and outcome measures by which esophageal hypersensitivity can be established.

The Role of Impedance Planimetry in the Evaluation of Esophageal Disorders

PURPOSE OF REVIEW

Impedance planimetry measures tissue wall distensibility as a function of pressure and cross-sectional area. Recent interest in this technique's relevance to the gastrointestinal tract has been accelerated by the availability of the functional lumen imaging probe, a catheter-based system that dynamically quantitates these biomechanical properties. Herein, we review the device's particular utility in the setting of esophageal pathology, including processes affecting the esophageal body as well as the upper and lower esophageal sphincters.

RECENT FINDINGS

An expanding suite of disease-specific indications for impedance planimetry includes achalasia, gastroesophageal reflux disease, and eosinophilic esophagitis. The technique has also demonstrated a role in the intraoperative guidance of therapy and in the definition of hitherto unrecognized patterns of esophageal dysmotility. Device-specific technology remains in active evolution, which, in conjunction with progressively larger datasets, sets the stage for broader clinical applicability in the near future.

Prolonged measurement improves the assessment of the barrier function of the esophago-gastric junction by high-resolution manometry

BACKGROUND

Etiology of gastro-esophageal reflux disease (GERD) is multifactorial, but incompetence of the esophago-gastric junction (EGJ) appears to be of crucial importance. Established manometric parameters for assessment of EGJ barrier function are sub-optimal, potentially because they reflect only a very brief (up to 30 seconds), not necessarily representative period. This prospective, case-control study tested the performance of novel, high-resolution manometry (HRM) parameters of EGJ function in the assessment of GERD.

METHODS

Patients with reflux symptoms and healthy controls (HC) underwent standard HRM and 24-hour pH±impedance measurements. EGJ morphology, lower esophageal sphincter pressure integral (LES-PI), EGJ contractile integral (EGJ-CI) were compared with total-EGJ-CI, a novel parameter summarizing EGJ barrier function during the entire HRM protocol. Esophageal acid exposure ≥4.2%/24 h (A-Reflux-pos) or ≥73 reflux episodes in 24 hours (V-Reflux-pos) were considered pathological.

KEY RESULTS

Sixty five HC and 452 patients completed HRM, 380 (84%) patients underwent ambulatory reflux-monitoring. LES-PI, EGJ-CI and total-EGJ-CI correlated with EGJ morphology subtypes (all P<.00001). Only total-EGJ-CI was consistently lower in A-Reflux-pos and V-Reflux-pos subjects compared with HC and patients without GERD. Total-EGJ-CI was also the single best parameter for prediction of pathological reflux (optimal cut-off 47 mmHg cm, AUC 0.746, P<.0001). This cut-off value, approximately 1 SD below the mean normal value, showed modest sensitivity 54% and positive predictive value 46%, but good specificity 85% and negative predictive value 89% for GERD diagnosis.

CONCLUSION & INFERENCES

Total EGJ-CI, a new metric that summarizes EGJ contractility over time, allows an improved assessment of EGJ barrier function. Pathological reflux is unlikely if this metric is within the upper two-thirds of the normal range.

Novel insights into esophageal diagnostic procedures

The 21st century offers new advances in diagnostic procedures and protocols in the management of esophageal diseases. This review highlights the most recent advances in esophageal diagnostic technologies, including clinical applications of novel endoscopic devices, such as ultrathin endoscopy and confocal laser endomicroscopy for diagnosis and management of Barrett's esophagus; novel parameters and protocols in high-resolution esophageal manometry for the identification and better classification of motility abnormalities; innovative connections between esophageal motility disorder diagnosis and detection of gastroesophageal reflux disease (GERD); impedance-pH testing for detecting the various GERD phenotypes; performance of distensibility testing for better pathophysiological knowledge of the esophagus and other gastrointestinal abnormalities; and a modern view of positron emission tomography scanning in metastatic disease detection in the era of accountability as a model for examining other new technologies. We now have better tools than ever for the detection of esophageal diseases and disorders, and emerging data are helping to define how well these tools change management and provide value to clinicians. This review features novel insights from multidisciplinary perspectives, including both surgical and medical perspectives, into these new tools, and it offers guidance on the use of novel technologies in clinical practice and future directions for research.

Effect of changes in intra-abdominal pressure on diameter, cross-sectional area, and distensibility of the lower esophageal sphincter of healthy dogs as determined by use of an endoscopic functional luminal imaging probe

OBJECTIVE To evaluate the effect of intra-abdominal pressure (IAP) on morphology and compliance of the lower esophageal sphincter (LES) by use of impedance planimetry in healthy dogs and to quantify the effect of changes in IAP. ANIMALS 7 healthy, purpose-bred sexually intact male hound-cross dogs. PROCEDURES Dogs were anesthetized, and cross-sectional area (CSA), minimal diameter (MD), LES length, LES volume, and distensibility index (DI) of the LES were evaluated by use of an endoscopic functional luminal imaging probe. For each dog, measurements were obtained before (baseline) and after creation of a pneumoperitoneum at an IAP of 4, 8, and 15 mm Hg. Order of the IAPs was determined by use of a randomization software program. RESULTS CSA and MD at 4 and 8 mm Hg were not significantly different from baseline measurements; however, CSA and MD at 15 mm Hg were both significantly greater than baseline measurements. The LES length and LES volume did not differ significantly from baseline measurements at any IAP. The DI differed inconsistently from the baseline measurement but was not substantially affected by IAP. CONCLUSIONS AND CLINICAL RELEVANCE Pneumoperitoneum created with an IAP of 4 or 8 mm Hg did not significantly alter LES morphology in healthy dogs. Pneumoperitoneum at an IAP of 15 mm Hg caused a significant increase in CSA and MD of the LES. Compliance of the LES as measured by the DI was not greatly altered by pneumoperitoneum at an IAP of up to 15 mm Hg.

Functional lumen imaging probe: The FLIP side of esophageal disease

PURPOSE OF REVIEW

The aim of this review is to summarize use of the functional lumen imaging probe (FLIP) for the evaluation and management of esophageal diseases.

RECENT FINDINGS

The FLIP utilizes high-resolution impedance planimetry to evaluate the functional geometry and cross-sectional area/pressure relationship (i.e. distensibility) of the esophageal sphincters and body. Recent studies have reported the potential utility of FLIP to evaluate esophageal diseases, such as achalasia, gastroesophageal reflux disease, and eosinophilic esophagitis.

SUMMARY

Esophageal distensibility measures provided by the FLIP will add to our understanding of the contribution of esophageal mechanical properties to esophageal symptoms and function. Application of the FLIP in clinical practice complements the diagnostic evaluation of esophageal function and may also be a valuable tool to help direct and target clinical management of esophageal diseases.

Esophagogastric junction distensibility in hiatus hernia

Hiatus hernia is known to be an important risk factor for developing gastroesophageal reflux disease. We aimed to use the endoscopic functional lumen imaging probe (EndoFLIP) to evaluate the functional properties of the esophagogastric junction. EndoFLIP assessments were made in 30 patients with hiatus hernia and Barrett's esophagus, and in 14 healthy controls. The EndoFLIP was placed straddling the esophagogastric junction and the bag distended stepwise to 50 mL. Cross-sectional areas of the bag and intra-bag pressures were recorded continuously. Measurements were made in the separate sphincter components and hiatus hernia cavity. EndoFLIP measured functional aspects such as sphincter distensibility and pressure of all esophagogastric junction components and visualized all hiatus hernia present at endoscopy. The lower esophageal sphincter in hiatus hernia patients had a lower pressure (e.g. 47.7 ± 13.0 vs. 61.4 ± 19.2 mm Hg at 50-mL distension volume) and was more distensible (all P < 0.001) than the common esophagogastric junction in controls. In hiatus hernia patients, the crural diaphragm had a lower pressure (e.g. 29.6 ± 10.1 vs. 47.7 ± 13.0 mm Hg at 50-mL distension volume) and was more distensible (all P < 0.001) than the lower esophageal sphincter. There was a significant association between symptom scores in patients and EndoFLIP assessment. Conclusively, EndoFLIP was a useful tool. To evaluate the presence of a hiatus hernia and to measure the functional properties of the esophagogastric junction. Furthermore, EndoFLIP distinguished the separate esophagogastric junction components in hiatus hernia patients, and may help us understand the biomechanics of the esophagogastric junction and the mechanisms behind hiatal herniation.