Functional lumen imaging probe: The FLIP side of esophageal disease

A Software Framework for the Functional Lumen Imaging Probe-Mechanics (MechView)

BACKGROUND

The functional lumen imaging probe (FLIP) has proven to be a versatile device for diagnosing esophageal motility disorders and estimating esophageal wall compliance, but there is a lack of viable software for quantitative assessment of FLIP measurements.

METHODS

A Python-based web framework was developed for a unified assessment of FLIP measurements including clinical metrics such as esophagogastric junction (EGJ) distensibility index (DI), maximum EGJ opening diameter, mechanics-based metrics for estimating strength, and effectiveness of contractions, such as contraction power and displaced volume, and machine learning-based clustering and predictive algorithms such as the virtual disease landscape (VDL) and EGJ obstruction probability. The clinical and VDL probability metrics were then validated using FLIP data from 121 subjects constituting different categories of EGJ opening which were diagnosed by expert clinicians.

RESULTS

The clinical metrics estimated by the framework matched the manual diagnosis of the clinicians. Misclassifications were minimal and were mostly between neighboring groups, that is, normal and borderline normal or borderline normal and borderline reduced EGJ opening. Similar results were also obtained for the VDL probability metrics. The misclassifications were further analyzed by clinicians and approved.

CONCLUSION

The FLIP web framework was developed and validated to reliably estimate various clinical, mechanical, and machine learning-based metrics for diagnosing esophageal motility disorders.

Disorders of secondary peristalsis are associated with the development of esophagitis

BACKGROUND

Disorders of primary peristalsis are associated with a higher percent time pH <4 in the esophagus suggesting poor acid clearance. However, there are no studies of secondary peristalsis and its relationship to microscopic or erosive esophagitis. The goal of this study was to determine the relationship between secondary peristalsis using functional luminal imaging probes (EndoFLIP) and the presence or absence of esophagitis.

METHODS

We reviewed the endoscopic and EndoFLIP 2.0 tracings for 103 consecutive patients including those with a history of upper gastrointestinal surgery undergoing upper endoscopy. Esophagogastric junction (EGJ) distensibility and diameter, repetitive antegrade contraction (RACs) presence and frequency, and occlusive diameters were measured. Measurements were then compared between patients with and without microscopic and/or erosive esophagitis. Means were compared using t-tests. Proportions were compared using Chi-Squared analyses.

KEY RESULTS

One hundred and three patients were included (mean age: 14.4 + 6.4 years). Ten patients had erosive esophagitis and 28 patients had microscopic esophagitis. Erosive and microscopic esophagitis were associated with abnormal or absent of RACs (p < 0.001). Occlusive diameters were higher in patients with esophagitis compared to those without (p < 0.001). There was no relationship between EGJ distensibility and the presence of erosive or microscopic esophagitis (p = 0.4). The absence of RACs was the only independent predictor of esophagitis (erosive and microscopic), after controlling for age, proton pump inhibitors (PPI) use and EGJ distensibility (p < 0.001).

CONCLUSIONS & INFERENCES

Abnormal secondary peristalsis is associated with microscopic and gross esophagitis, suggesting that EndoFLIP should be part of the diagnostic algorithm for esophagitis.

A Comparison of Functional Luminal Imaging Probe With High-resolution Manometry, Timed Barium Esophagram, and pH Impedance Testing to Evaluate Functional Luminal Imaging Probe's Diagnostic Capabilities

OBJECTIVE

The aims of this study are to determine the functional luminal imaging probe's (FLIP) diagnostic utility by comparing FLIP measurements with results from other esophageal evaluation standards.

BACKGROUND

The FLIP is an esophageal evaluation technique performed at the time of endoscopy. Few studies have evaluated FLIP diagnostic capabilities compared with the established testing techniques, including high-resolution manometry (HRIM), time barium esophagram (TBE), and 24-hour impedance-pH monitoring.

PATIENTS AND METHODS

A retrospective review was performed for 413 preintervention patients who underwent FLIP testing during endoscopy. Data from HRIM, 24-hour pH monitoring, and TBE were compared.

RESULTS

Abnormal Distensibility Index (DI) was associated with abnormal integrated relaxation pressure (IRP; P = 0.003). Average DI was higher in patients with abnormal IRP (>15 mm Hg) when a hiatal hernia was present ( P = 0.025). The total agreement between correlated diagnoses from FLIP and HRIM was 33.5%. DI was not associated with acid exposure time on pH monitoring. Agreement between FLIP and TBE was 49% with a sensitivity of 98.1% and a specificity of 36.5%. A 60 mL distension had a significantly lower detection rate than 40 mL and 50 mL for active peristalsis and was unaffected by pressure ( P < 0.05).

CONCLUSIONS

FLIP as an adjunct to HRIM is supported by strong metric correlation. FLIP was not correlated to pH monitoring findings, suggesting FLIP is not useful in reflux assessment. The agreement between FLIP and TBE was lower than in previous studies. Hiatal hernia impacted the normality between DI and IRP, not between FLIP and TBE. We suggest analyzing peristaltic patterns on panometry at all fill volumes to optimize detection.

A Review of In Vitro and In Silico Swallowing Simulators: Design and Applications

Swallowing is a primary and complex behaviour that transports food and drink from the oral cavity, through the pharynx and oesophagus, into the stomach at an appropriate rate and speed. To understand this sophisticated behaviour, a tremendous amount of research has been carried out by utilising the in vivo approach, which is often challenging to perform, poses a risk to the subjects if interventions are undertaken and are seldom able to control for confounding factors. In contrast, in silico (computational) and in vitro (instrumental) methods offer an alternate insight into the process of the human swallowing system. However, the appropriateness of the design and application of these methods have not been formally evaluated. The purpose of this review is to investigate and evaluate the state of the art of in vitro and in silico swallowing simulators, focusing on the evaluation of their mechanical or computational designs in comparison to the corresponding swallowing mechanisms during various phases of swallowing (oral phase, pharyngeal phase and esophageal phase). Additionally, the potential of the simulators is also discussed in various areas of applications, including the study of swallowing impairments, swallowing medications, food process design and dysphagia management. We also address current limitations and recommendations for the future development of existing simulators.

Endoscopic impedance planimetry versus high-resolution manometry (HRM) for pre-operative motility evaluation in anti-reflux surgery

INTRODUCTION

Pre-operative evaluation of patients with gastroesophageal reflux disease (GERD) includes assessment of esophageal motility. High-resolution manometry (HRM) is the gold standard; endoscopic impedance planimetry (IP) with Endoflip 2.0 is increasingly utilized in esophageal disorders of motility. We hypothesized that normal IP motility would correlate with normal HRM motility and tested this in a prospective cohort study.

METHODS

Patients presenting for surgical evaluation of GERD between 9/2020 and 10/2021 were prospectively enrolled under an IRB-approved protocol. Patients with prior esophageal/gastric surgery, known motility disorders, or large paraesophageal hernias were excluded. All underwent HRM and IP, with normal motility defined by Chicago 3.0 classification for HRM and the presence of repetitive antegrade contractions for IP. Logistic regression and t test were used to analyze the data; p value < 0.05 was considered significant.

RESULTS

Of 63 patients enrolled, 48 completed both IP and HRM testing. The cohort was 50% male with a median age of 52.5 [42.0, 66.0] years, mostly ASA class 1-2 (75.1%, n = 36) and had an average BMI of 31.4 ± 6.3 kg/m2. Normal motility tracings were in 62.5% of IP and 75% of HRM tests. Using HRM as the gold standard, IP detected normal motility with a sensitivity of 65.8% and a specificity of 50% (positive predictive value 83.3%, negative predictive value 27.8%). Normal IP was not statistically significant in predicting normal HRM (OR 3.182, 95% CI 0.826-12.262, p = 0.0926). Tolerability of IP was significantly better than HRM with lower rates of discomfort (10.9% vs. 93.4%, p < 0.0001) and higher willingness to repeat testing (100% vs. 47.8%, p < 0.0001).

CONCLUSION

Esophageal motility testing with Endoflip 2.0 is well tolerated by patients. The low specificity (50%), poor negative predictive value (27.8%), and lack of statistically significant concordance between IP and HRM raises concern for the reliability of this test as a stand-alone replacement for HRM in the pre-operative evaluation for GERD.

Interventional functional diagnostics in gastrointestinal endoscopy: Combining diagnostic and therapeutic tools in the endoscopy suite with the functional lumen imaging probe

With technical progress of gastrointestinal functional testing, there has been a demand for more comprehensive examination of esophageal physiology and pathophysiology beyond high-resolution manometry. A new interventional technology based on impedance planimetry, the functional lumen imaging probe (FLIP), enables intraluminal measurement of distensibility and compliance of hollow organs. EndoFLIP uses balloon catheters to measure diameter and distension pressure to calculate cross-sectional area and distensibility in different organs (mostly esophagus, stomach, anorectal region) and can be used in wide variety of indications (diagnostics, pre- and post-treatment evaluation) and currently serves as a helpful adjunctive tool in ambiguous clinical cases. EsoFLIP is a therapeutic variation that uses a stiffer balloon catheter allowing for dilation. The trend to simplify the clinical process from diagnosis to treatment tends to a one-session procedure combining diagnostics and therapeutic interventions. In specified conditions like e.g. achalasia or gastroparesis, a combination of EndoFLIP and EsoFLIP procedures may therefore be useful. The aim of this narrative review is to introduce the clinical use of FLIP and its potential benefit in combined diagnostic-therapeutic procedures.

Modern Achalasia: Diagnosis, Classification, and Treatment

Achalasia is a major esophageal motor disorder featured by the altered relaxation of the esophagogastric junction in the absence of effective peristaltic activity. As a consequence of the esophageal outflow obstruction, achalasia patients present with clinical symptoms of dysphagia, chest pain, weight loss, and regurgitation of indigested food. Other less specific symptoms can also present including heartburn, chronic cough, and aspiration pneumonia. The delay in diagnosis, particularly when the presenting symptoms mimic those of gastroesophageal reflux disease, may be as long as several years. The widespread use of high-resolution manometry has permitted earlier detection and uncovered achalasia phenotypes which can have prognostic and therapeutic implications. Other tools have also emerged to help define achalasia severity and which can be used as objective measures of response to therapy including the timed barium esophagogram and the functional lumen imaging probe. Such diagnostic innovations, along with the increased awareness by clinicians and patients due to the availability of alternative therapeutic approaches (laparoscopic and robotic Heller myotomy, and peroral endoscopic myotomy) have radically changed the natural history of the disorder. Herein, we report the most recent advances in the diagnosis, classification, and management of esophageal achalasia and underline the still-grey areas that needs to be addressed by future research to reach the goal of personalizing treatment.

Virtual disease landscape using mechanics-informed machine learning: Application to esophageal disorders

Esophageal disorders are related to the mechanical properties and function of the esophageal wall. Therefore, to understand the underlying fundamental mechanisms behind various esophageal disorders, it is crucial to map mechanical behavior of the esophageal wall in terms of mechanics-based parameters corresponding to altered bolus transit and increased intrabolus pressure. We present a hybrid framework that combines fluid mechanics and machine learning to identify the underlying physics of various esophageal disorders (motility disorders, eosinophilic esophagitis, reflux disease, scleroderma esophagus) and maps them onto a parameter space which we call the virtual disease landscape (VDL). A one-dimensional inverse model processes the output from an esophageal diagnostic device called the functional lumen imaging probe (FLIP) to estimate the mechanical "health" of the esophagus by predicting a set of mechanics-based parameters such as esophageal wall stiffness, muscle contraction pattern and active relaxation of esophageal wall. The mechanics-based parameters were then used to train a neural network that consists of a variational autoencoder that generated a latent space and a side network that predicted mechanical work metrics for estimating esophagogastric junction motility. The latent vectors along with a set of discrete mechanics-based parameters define the VDL and formed clusters corresponding to specific esophageal disorders. The VDL not only distinguishes among disorders but also displayed disease progression over time. Finally, we demonstrated the clinical applicability of this framework for estimating the effectiveness of a treatment and tracking patients' condition after a treatment.

Nasal trumpet harmoniously improves tolerance to high-resolution impedance manometry catheter placement

Background.

High-resolution impedance manometry (HRiM) is the gold-standard test to accurately diagnose esophageal dysmotility and a component of 24-hour pH testing for gastroesophageal reflux disease (GERD). Most commonly, HRiM is performed without sedation in a motility laboratory setting. Occasionally, patients are unable to complete this test due to poor tolerance, inability to traverse the nasopharynx, or inability to navigate through a hypertonic LES or large hiatal hernia. We report our two-center experience utilizing a nasopharyngeal airway (nasal trumpet) to facilitate insertion of the manometry catheter among patients who failed initial placement through the nasopharynx.

Methods.

We used size 24 French nasal trumpets in patients who had failed typical insertion of HRiM catheters during the index unsedated procedure. Topical anesthetic was applied transnasally followed by nasal trumpet insertion. The manometry catheter was introduced through the nasal trumpet, circumventing anatomical barriers to placement.

Results.

We successfully completed HRiM studies in 8 such consecutive patients. Indications for procedure included dysphagia and GERD. Each patient tolerated nasal trumpet use, and there were no complications.

Conclusion.

The addition of the nasal trumpets to the motility lab toolbox can assist with challenging motility catheter placement. This device is inexpensive, widely available, and reduces procedure failure rates due to nasopharyngeal barriers to successful placement.

Use of the functional luminal imaging probe in pediatrics: A comparison study of patients with achalasia before and after endoscopic dilation and non-achalasia controls

BACKGROUND

Achalasia is an esophageal motility disorder characterized by esophagogastric junction (EGJ) dysfunction and impaired esophageal peristalsis with significant impact on quality of life. While the functional luminal imaging probe (FLIP) has been used to assess EGJ distensibility in achalasia, its clinical utility in pediatrics is limited due to absence of normative values and correlations with clinical outcomes in children. Thus, we sought to evaluate FLIP's use in a pediatric achalasia cohort undergoing dilations and non-achalasia controls.

METHODS

We conducted a retrospective study of pediatric patients with achalasia who underwent FLIP before and immediately after balloon dilations and compared to a non-achalasia cohort.

KEY RESULTS

Thirty patients with achalasia (mean age, 15.2 years; 40% female), including fourteen treatment-naïve and thirteen controls (mean age, 7.9 years; 61% female) were identified. Median EGJ distensibility index (EGJ-DI) 2.07 mm²  mmHg^-1 and diameter (9.23 mm) in treatment-naïve patients were significantly lower compared to controls (EGJ-DI 6.8 mm²  mmHg^-1 ; diameter 18.61 mm; (p < 0.001). Balloon dilations resulted in a significant increase in EGJ-DI immediately after the dilation, particularly in treatment-naïve patients (p < 0.001), and a significant improvement in Eckardt scores (p < 0.001).

CONCLUSIONS & INFERENCES

Functional luminal imaging probe measurements of EGJ-DI in pediatric patients with achalasia are mostly consistent with adult findings. However, normal EGJ-DI is seen in symptomatic patients, including treatment-naive, highlighting the need for pediatric reference data. Balloon dilations achieve a significant increase in EGJ-DI with improvement in Eckardt scores, confirming the therapeutic value of dilations in achalasia management.

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.

Comparison of preoperative, intraoperative, and follow-up functional luminal imaging probe measurements in patients undergoing myotomy for achalasia

BACKGROUND AND AIMS

The functional luminal imaging probe (FLIP) is a novel catheter-based device that measures esophagogastric junction (EGJ) distensibility index (DI) in real time. Previous studies have demonstrated DI to be a predictor of post-treatment clinical outcomes in patients with achalasia. We sought to evaluate EGJ DI in patients with achalasia before, during, and after peroral endoscopic myotomy (POEM) and laparoscopic Heller myotomy (LHM) and to assess the correlation of DI with postoperative outcomes.

METHODS

DI (defined as the minimum cross-sectional area at the EGJ divided by distensive pressure) was measured at 4 time points in patients undergoing surgical myotomy for achalasia: (1) during outpatient preoperative endoscopy (preoperative DI), (2) at the start of each operation after the induction of anesthesia (induction DI), (3) at the conclusion of each operation (postmyotomy DI), and (4) at routine follow-up endoscopy 12 months postoperatively (follow-up DI). Routine Eckardt symptom score, endoscopy, timed barium esophagram, and pH study were obtained 12 months postoperatively.

RESULTS

Forty-six patients (35 POEM, 11 LHM) underwent FLIP measurements at all 4 time points. Preoperative and induction mean DI were similar for both groups (POEM, 1 vs .9 mm²/mm Hg; LHM, 1.7 vs 1.5 mm²/mm Hg). POEM resulted in a significant increase in DI (induction .9 vs postmyotomy 7 mm²/mm Hg, P < .001). There was a subsequent decrease in DI in the follow-up period (postmyotomy 7 vs follow-up 4.8 mm²/mm Hg, P < .01), but DI at follow-up was still significantly improved from preoperative values (P < .001). For LHM patients, DI also increased as a result of surgery (induction 1.5 vs postmyotomy 5.9 mm²/mm Hg, P < .001); however, the increase was smaller than in POEM patients (DI increase 4.4 vs 6.2 mm²/mm Hg, P < .05). After LHM, DI also decreased in the follow-up period, but this change was not statistically significant (5.9 vs 4.4 mm²/mm Hg, P = .29). LHM patients with erosive esophagitis on follow-up endoscopy had a significantly higher postmyotomy DI compared with those without esophagitis (9.3 vs 4.8 mm²/mm Hg, P < .05).

CONCLUSIONS

EGJ DI improved dramatically as a result of both POEM and LHM, with POEM resulting in a larger increase. Mean DI decreased at intermediate follow-up but remained well above previously established thresholds for symptom recurrence. DI at the conclusion of LHM was predictive of erosive esophagitis in the postoperative period, which supports the potential use of FLIP for calibration of partial fundoplication construction during LHM.

Eosinophilic esophagitis, Barrett's esophagus and esophageal neoplasms in the pediatric patient: a narrative review

There are several esophageal disorders that can occur in the pediatric population. Eosinophilic esophagitis (EoE) is an eosinophil predominant inflammatory disease of the esophagus that was first characterized in the early 1900's. EoE is the most common pediatric esophageal inflammatory condition after gastroesophageal reflux disease (GERD). Longstanding GERD is a known risk factor for the development of Barrett's esophagus (BE) in both children and adults. BE is associated with the development of dysplasia and, if left undiagnosed, may progress to the development of esophageal adenocarcinoma (EAC). EAC and esophageal squamous cell carcinoma (ESCC) comprise the majority of childhood esophageal malignant neoplasms. The prevalence of EoE continues to rise within the pediatric population. On the other hand, both BE and esophageal neoplasms remain extremely rare in children. The relationship between a chronic inflammatory condition like EoE to BE and/or esophageal neoplasms remains unclear. The current research of these disease entities is prioritized to further understanding the disease pathogenesis and disease progression, exploring new diagnostic modalities, and developing novel treatments or less invasive therapeutic options. The focus of the following narrative review is to provide a summary of the current clinical practices, future research and their implications on these various esophageal disorders.

A deep-learning-based unsupervised model on esophageal manometry using variational autoencoder

High-resolution manometry (HRM) is the primary method for diagnosing esophageal motility disorders and its interpretation and classification are based on variables (features) from data of each swallow. Modeling and learning the semantics directly from raw swallow data could not only help automate the feature extraction, but also alleviate the bias from pre-defined features. With more than 32-thousand raw swallow data, a generative model using the approach of variational auto-encoder (VAE) was developed, which, to our knowledge, is the first deep-learning-based unsupervised model on raw esophageal manometry data. The VAE model was reformulated to include different types of loss motivated by domain knowledge and tuned with different hyper-parameters. Training of the VAE model was found sensitive on the learning rate and hence the evidence lower bound objective (ELBO) was further scaled by the data dimension. Case studies showed that the dimensionality of latent space have a big impact on the learned semantics. In particular, cases with 4-dimensional latent variables were found to encode various physiologically meaningful contraction patterns, including strength, propagation pattern as well as sphincter relaxation. Cases with so-called hybrid L2 loss seemed to better capture the coherence of contraction/relaxation transition. Discriminating capability was further evaluated using simple linear discriminative analysis (LDA) on predicting swallow type and swallow pressurization, which yields clustering patterns consistent with clinical impression. The current work on modeling and understanding swallow-level data will guide the development of study-level models for automatic diagnosis as the next stage.

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.

Intraoperative use of FLIP is associated with clinical success following POEM for achalasia

BACKGROUND

Esophagogastric junction distensibility index (DI), measured using the functional luminal imaging probe (FLIP), correlates with symptomatic outcomes after interventions for achalasia. The objective of this study was to determine if the intraoperative measurement of DI using FLIP was associated with improved clinical outcomes following per-oral endoscopic myotomy (POEM) for achalasia when compared with procedures in which FLIP was not utilized.

METHODS

Patients undergoing POEM from 2012 to 2017 at a single institution by a single surgeon were studied. Use of FLIP during this time period was based on catheter and technician availability, resulting in two patient cohorts. In patients in whom FLIP was used, operative video recordings were reviewed to determine when DI measurements led to the performance of additional myotomy. Postoperative Eckardt symptom scores (ES) at 12 months and postoperative physiologic studies were compared between patients with and without intraoperative FLIP. Associations were assessed using Mann-Whitney U and Chi-square tests.

RESULTS

143 patients were included in the analysis (61 with intraoperative FLIP and 82 without FLIP). Video recordings were available for 85% of the FLIP cohort. Review of these operative recordings revealed that 65% of patients who underwent FLIP had additional myotomy performed following the initial postmyotomy FLIP measurement. At 12 months after POEM, the FLIP cohort had significantly more clinical successes (defined as ES ≤ 3) than patients in whom FLIP was not used (93% vs. 81%, p < 0.05).

CONCLUSIONS

Use of intraoperative FLIP during POEM resulted in the surgeon performing additional myotomy in over half of cases and was associated with improved clinical outcomes. This study demonstrates the potential for a FLIP-tailored myotomy to improve outcomes in patients undergoing surgical myotomy for achalasia.

Intraoperative FLIP distensibility during POEM varies according to achalasia subtype

BACKGROUND

The functional luminal imaging probe (FLIP) can be used to measure the esophagogastric junction distensibility index (DI) during myotomy for achalasia and increased DI has been shown to predict superior clinical outcomes. The objective of this study was to determine if the intraoperative DI and the changes produced by per oral endoscopic myotomy (POEM) differed between achalasia subtypes.

METHODS

FLIP measurements were performed during POEM for achalasia at a single institution. DI (defined as the minimum cross-sectional area (CSA) at the EGJ divided by distensive pressure) was measured at three time points: after induction of anesthesia, after submucosal tunneling, and after myotomy. Measurements were reported at the 40 mL fill volume for the 8 cm FLIP (EF-325) and at the 60 mL fill volume for the 16 cm FLIP (EF-322). Measurements were compared using chi-square and Kruskal-Wallis tests.

RESULTS

142 patients had intraoperative FLIP performed during POEM for achalasia between 2012 and 2019 (30 type I, 68 type II, 27 type III, and 17 variant). Patients with type I achalasia had a significantly higher induction DI (median 1.7 mm²/mmHg) than type II (0.8 mm²/mmHg), type III (0.9 mm²/mmHg), and variants (1.1 mm²/mmHg; p < 0.001). These differences persisted after submucosal tunneling and final DI after myotomy was also significantly higher in type I patients (median 8.0 mm²/mmHg) compared to type II (5.8 mm²/mmHg), type III (3.9 mm²/mmHg), and variants (5.4 mm²/mmHg; p < 0.001). Achalasia subtypes were found to have similar CSA at all time points, whereas pressure differed with type I having the lowest pressure and type III the highest.

CONCLUSION

The DI at each operative step during POEM was found to differ significantly between achalasia subtypes. These differences in DI were due to pressure, as CSA was similar between subtypes. Achalasia subtype should be accounted for when using FLIP as an intraoperative calibration tool and in future studies examining the relationship between DI and clinical outcomes.

Intraoperative use of a functional lumen imaging probe during peroral endoscopic myotomy in patients with achalasia: A single-institute experience and systematic review

Aim

The functional lumen imaging probe (FLIP) is a recently developed technique to evaluate the esophagogastric junction (EGJ) distensibility. Unlike timed barium esophagogram (TBE) and high-resolution manometry (HRM), FLIP can be used during peroral endoscopic myotomy (POEM). The aim of this study was to evaluate the association of intraoperative FLIP parameters with clinical outcomes as recorded in a single-center database and to investigate a systematic review of literatures.

Methods

We reviewed consecutive patients diagnosed with achalasia and scheduled for POEM between June 2016 and March 2019 in our tertiary referral hospital. All patients underwent intraoperative FLIP assessment during POEM. The final FLIP measurements were compared between the patients with good and poor clinical response. We comprehensively reviewed studies evaluating whether intraoperative FLIP measurements reflected clinical outcomes.

Results

We evaluated 23 patients with achalasia who underwent intraoperative FLIP before and after POEM. Two exhibited poor clinical responses after 3 months (Eckardt scores = 3). The final distensibility index (DI) did not differ significantly between good and poor responders (5.01 [4.52] vs. 4.91 [3.63–6.20] mm²/mmHg at a balloon distension of 50-mL, median [IQR], P = 0.853). The final DI did not differ significantly between post-POEM reflux esophagitis and non-reflux esophagitis groups (6.20 [5.15] vs. 4.23 [1.79] mm²/mmHg at a balloon distension of 50-mL, median [IQR], P = 0.075).

Conclusions

A systematic review of both prospective and retrospective studies including our data indicated that the final intraoperative FLIP measurements did not differ significantly between good and poor responders. Further study with more patients is necessary to explore whether FLIP can predict short- and long-term clinical responses.

Endoscope presence during endoluminal functional lumen imaging probe (FLIP) influences FLIP metrics in the evaluation of esophageal dysmotility

BACKGROUND

The functional lumen imaging probe (FLIP) system is an FDA-approved tool for dynamic evaluation of the esophagogastric junction (EGJ). Even though commercially available since 2009, FLIP utilization remains low, partly due to lack of consensus in methodology and interpretation. Therefore, we aimed to analyze the influence of concurrent endoscopy on FLIP measurements.

METHODS

In this single-center study, we reviewed data from 93 patients undergoing FLIP for symptomatic esophageal motility disorders between 2016 and 2018. During sedated endoscopy, we measured luminal values (distensibility, cross-sectional area (CSA), and balloon pressure) at the EGJ and distal esophagus using 30, 40, and 50 mL distension volumes, with and without concurrent endoscope presence. All recorded values were compared at the various distension volumes between the two measurements using a Wilcoxon rank sum test.

KEY RESULTS

There was a significant difference in distensibility and CSA with index distension volume (40 mL) at the EGJ comparing the two measurements: Lower median distensibility was 2.1 mm²  mm Hg^-1 in the group with concurrent inserted endoscope, respectively, 3.4 mm²  mm Hg^-1 without endoscope (P < .001), and median CSA was 86.0 resp. 110.0 mm² (P < .001). No significant difference could be found in the measurements of the distal esophagus.

CONCLUSIONS & INFERENCES

Our results show a significant difference in FLIP measurements with and without endoscope presence. This underlines the importance of establishing a consensus of a standardized FLIP protocol to define normal luminal values and guiding future FLIP diagnostic studies.

Mechanism and Pathophysiology of Gastroesophageal Reflux Disease

Gastroesophageal reflux (GER) describes a process in which gastric contents travel retrograde into the esophagus. GER can be either a physiologic phenomenon that occurs in asymptomatic individuals or can potentially cause symptoms. When the latter occurs, this represents GER disease (GERD). The process by which GER transforms into GERD begins at the esophagogastric junction. Impaired clearance of the refluxate also contributes to GERD. Reflux causes degradation of esophageal mucosal defense. The refluxate triggers sensory afferents leading to symptom generation.

ASGE guideline on the management of achalasia

Achalasia is a primary esophageal motor disorder of unknown etiology characterized by degeneration of the myenteric plexus, which results in impaired relaxation of the esophagogastric junction (EGJ), along with the loss of organized peristalsis in the esophageal body. The criterion standard for diagnosing achalasia is high-resolution esophageal manometry showing incomplete relaxation of the EGJ coupled with the absence of organized peristalsis. Three achalasia subtypes have been defined based on high-resolution manometry findings in the esophageal body. Treatment of patients with achalasia has evolved in recent years with the introduction of peroral endoscopic myotomy. Other treatment options include botulinum toxin injection, pneumatic dilation, and Heller myotomy. This American Society for Gastrointestinal Endoscopy Standards of Practice Guideline provides evidence-based recommendations for the treatment of achalasia, based on an updated assessment of the individual and comparative effectiveness, adverse effects, and cost of the 4 aforementioned achalasia therapies.

Recent advances in dysphagia management

The literal definition of dysphagia is "disturbed eating". However, it is more accurately described in clinical practice as a sensation of food or liquid being stuck in the esophagus or chest. If this sensation is associated with pain, it is labeled odynophagia, and if it is associated with persistent obstruction and bolus retention, it is categorized as a food impaction. Through research and technological advances, we continue to expand our understanding of the etiologies and underlying pathophysiology relating to this complaint. However, for now, our clinical algorithms focus on endoscopy and manometry to break down dysphagia into three categories: obstructive dysphagia, esophageal motility disorders, and functional dysphagia. Here, we review some critical pitfalls in our current clinical diagnoses, new proposed underlying mechanisms of esophageal motor disorders, and developing technologies to aid in diagnosis and treatment.

How I Approach Dysphagia

PURPOSE OF REVIEW

This review presents an overview of the diagnostic approach to esophageal dysphagia and summarizes recent epidemiological trends and technical advancements.

RECENT FINDINGS

The evaluation of dysphagia begins with a detailed history followed by endoscopy to evaluate for any structural abnormalities including malignancy. This is especially true given the emergence of eosinophilic esophagitis (EoE) as a dominant cause of esophageal dysphagia. In fact, it is now standard practice to obtain esophageal biopsies during endoscopy performed to evaluate dysphagia, since EoE can present without the characteristic mucosal features of rings, furrows, and exudate. Achalasia is also more frequently encountered since the introduction of high-resolution manometry (HRM) and the Chicago Classification into clinical practice. The Chicago Classification provides a stepwise diagnostic algorithm for evaluating HRM studies and systematically diagnosing esophageal motility disorders. Lastly, the functional lumen imaging probe (FLIP) is a novel technology that has added insight into both achalasia and EoE. Measuring esophageal distensibility with FLIP has useful prognostic implications for both diseases, and FLIP can identify motility abnormalities in achalasics not detected with HRM. A careful history is key to the efficient evaluation of dysphagia, and endoscopy is usually the first diagnostic study to obtain. For patients with prominent reflux symptoms, an empiric trial with proton pump inhibitors is reasonable then because reflux disease is such a common cause of dysphagia. Thereafter, patients should undergo HRM to evaluate for a motility disorder, and FLIP can provide complementary data to guide management.

Normal Values of Esophageal Distensibility and Distension-Induced Contractility Measured by Functional Luminal Imaging Probe Panometry

BACKGROUND & AIMS

Functional luminal imaging probe (FLIP) panometry provides a comprehensive evaluation of esophageal functional at the time of endoscopy, including assessment of esophageal distensibility and distension-induced esophageal contractility. However, the few and inconsistent findings from healthy individuals pose challenges to the application of FLIP to research and clinical practice. We performed FLIP panometry in asymptomatic volunteers.

METHODS

We performed a prospective study of 20 asymptomatic volunteers (ages, 23-44; 14 women) who were evaluated with 16-cm FLIP positioned across the esophagogastric junction (EGJ) and distal esophagus (and in 8 subjects also repositioned at the proximal esophagus) during sedated upper endoscopy. FLIP data were analyzed with a customized program that generated FLIP panometry plots and calculated the EGJ-distensibility index (DI) and distensibility plateaus (DP) of distal and proximal esophageal body. Distension-induced esophageal contractility was also assessed.

RESULTS

The median EGJ-DI was 5.8 mm²/mm Hg (interquartile range [IQR], 4.9-6.7 mm²/mm Hg); all 20 subjects had an EGJ-DI greater than 2.8 mm²/mm Hg. The median DP values from all subjects tested were 20.2 mm (IQR, 19.8-20.8 mm) at the distal body, 21.1 mm (IQR, 20.3-22.9 mm) at the proximal body, and greater than 18 mm at both locations. Repetitive antegrade contractions (RACs) were observed in all 20 subjects; in 19 of 20 (95%) subjects, the RAC pattern persisted for 10 or more consecutive antegrade contractions.

CONCLUSIONS

Normal parameters of FLIP panometry are EGJ-DI greater than 2.8 mm²/mm Hg, DP greater than 18 mm, and antegrade contractions that occur in a repetitive pattern (RACs)-these can be used as normal findings for esophageal distensibility and distension-induced contractility. These values can be used in comparative studies of esophageal diseases, such as achalasia and eosinophilic esophagitis, and will facilitate application of FLIP panometry to clinical practice.

Editorial: Widening the Use of the Functional Lumen Imaging Probe to Kids With Eosinophilic Esophagitis: Esophageal Narrowing is not Just an Adult Problem

The functional lumen imaging probe (FLIP) provides objective measurement of esophageal distensibility, thus offering a unique and potentially valuable assessment in eosinophilic esophagitis (EoE). Menard-Katcher and colleagues report the first study evaluating use of FLIP in pediatric patients that demonstrated a reduction in esophageal distensibility in patients with EoE compared to patients without EoE. An increase in esophageal distensibility was observed with age among pediatric patients without EoE, but not among those with EoE. While this study further supports the promise of esophageal distensibility assessment in EoE, future work remains needed to optimize FLIP utilization in both research and clinical settings.