Feasibility of esophagogastric junction distensibility measurement during Nissen fundoplication

Impedance planimetry (EndoFLIPTM) and surgical outcomes after Hill compared to Toupet fundoplication

INTRODUCTION

Endoluminal functional lumen imaging probe (EndoFLIP) provides a real-time assessment of gastroesophageal junction (GEJ) compliance during fundoplication. Given the limited data on EndoFLIP measurements during the Hill procedure, we investigated the impact of the Hill procedure on GEJ compliance compared to Toupet fundoplication.

METHODS

Patients who underwent robotic Hill or Toupet fundoplication with intraoperative EndoFLIP between 2017 and 2022 were included. EndoFLIP measurements of the GEJ included cross sectional surface area (CSA), intra-balloon pressure, high pressure zone length (HPZ), distensibility index (DI), and compliance. Subjective reflux symptoms, gastroesophageal reflux disease-health related quality of life (GERD-HRQL) score, and dysphagia score were assessed pre-operatively as well as at short- and longer-term follow-up.

RESULTS

One-hundred and fifty-four patients (71.9%) had a Toupet fundoplication while sixty (28%) patients underwent the Hill procedure. The CSA [27.7 ± 10.9 mm2 vs 42.2 ± 17.8 mm2, p < 0.0001], pressure [29.5 ± 6.2 mmHg vs 33.9 ± 8.5 mmHg, p = 0.0009], DI [0.9 ± 0.4 mm2/mmHg vs 1.3 ± 0.6 mm2/mmHg, p = 0.001], and compliance [25.9 ± 12.8 mm3/mmHg vs 35.4 ± 13.4 mm3/mmHg, p = 0.01] were lower after the Hill procedure compared to Toupet. However, there was no difference in post-fundoplication HPZ between procedures [Hill: 2.9 ± 0.4 cm, Toupet: 3.1 ± 0.6 cm, p = 0.15]. Follow-up showed no significant differences in GERD-HRQL scores, overall dysphagia scores or atypical symptoms between groups (p > 0.05).

CONCLUSION

The Hill procedure is as effective to the Toupet fundoplication in surgically treating gastroesophageal reflux disease (GERD) despite the lower CSA, DI, and compliance after the Hill procedure. Both procedures led to DI < 2 mm2/mmHg with no significant differences in dysphagia reporting (12-24) months after the procedure. Further studies to elucidate a cutoff value for DI for postoperative dysphagia development are still warranted.

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.

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.

Development and Evaluation of a Flexible PVDF-Based Balloon Sensor for Detecting Mechanical Forces at Key Esophageal Nodes in Esophageal Motility Disorders

Prevailing methods for esophageal motility assessments, such as perfusion manometry and probe-based function imaging, frequently overlook the intricate stress fields acting on the liquid-filled balloons at the forefront of the probing device within the esophageal lumen. To bridge this knowledge gap, we innovatively devised an infusible flexible balloon catheter, equipped with a quartet of PVDF piezoelectric sensors. This design, working in concert with a bespoke local key-node analytical algorithm and a sensor array state analysis model, seeks to shed new light on the dynamic mechanical characteristics at pivotal esophageal locales. To further this endeavor, we pioneered a singular closed balloon system and a complementary signal acquisition and processing system that employs a homogeneously distributed PVDF piezoelectric sensor array for the real-time monitoring of dynamic mechanical nuances in the esophageal segment. An advanced analytical model was established to scrutinize the coupled physical fields under varying degrees of balloon inflation, thereby facilitating a thorough dynamic stress examination of local esophageal nodes. Our rigorous execution of static, dynamic, and simulated swallowing experiments robustly substantiated the viability of our design, the logical coherence of our esophageal key-point stress analytical algorithm, and the potential clinical utility of a flexible esophageal key-node stress detection balloon probe outfitted with a PVDF array. This study offers a fresh lens through which esophageal motility testing can be viewed and improved upon.

Quantifying physiologic parameters of the gastroesophageal junction during robotic sleeve gastrectomy and identifying predictors of post-sleeve gastroesophageal reflux disease

BACKGROUND

Sleeve gastrectomy is among the most commonly-performed procedures for morbid obesity. However, patients occasionally develop post-sleeve gastroesophageal reflux disease (GERD). Identifying patients most at risk for this complication remains difficult. We aimed to correlate intra-operative physiologic measurements of the lower esophageal sphincter (LES) at the gastroesophageal junction (GEJ) during robotic sleeve gastrectomy in an attempt to identify predictors of post-sleeve GERD symptoms.

METHODS

A retrospective chart review of a prospectively maintained database identified 28 patients in whom robotic sleeve gastrectomy was performed utilizing EndoFLIP™ technology between January and September 2021. Intraoperative LES measurements at the GEJ including cross-sectional area (CSA), distensibility index (DI), intra-balloon pressure, and high-pressure zone (HPZ length) were correlated with post-operative GERD.

RESULTS

GEJ CSA, pressure, and DI increased over the course of the surgery (CSA pre-op: 31 (IQR 19.3-39.5) mm² vs. post-op: 67 (IQR 40.8-95.8) mm², p < 0.001; pressure: 25.8 (IQR 20.2-33.1) mmHg vs. 31.5 (IQR 28.9-37.0) mmHg, p = 0.007; DI 1.1 (IQR 0.8-1.8) mm²/mmHg vs. 2.0 (IQR 1.2-3.0) mm²/mmHg, p =  < 0.001), whereas HPZ length decreased (2.5 (IQR 2.5-3) cm vs. 2.0 (IQR 1.3-2.5) cm, p = 0.022). Twenty-three patients (82.1%) completed a post-operative GERD questionnaire. Fifteen (65.2%) had no GERD symptoms before or after surgery; 5 (21.7%) reported new post-sleeve GERD symptoms; 3 (13.0%) reported exacerbation of pre-existing GERD symptoms. Patients with new or worsening GERD symptoms had higher post-sleeve DIs (3.2 (IQR 1.9-4.5) mm²/mmHg vs. 1.5 (IQR 1.2-2.4) mm²/mmHg, p = 0.024) and lower post-sleeve LES pressures (29.9 (IQR 26.3-32.9) mmHg vs. 35.2 (IQR 31.0-38.0) mmHg, p = 0.023) than those without.

CONCLUSIONS

An increase in GEJ CSA, pressure, and DI, and a decrease in GEJ length can be expected during robotic sleeve gastrectomy. Patients with new or worsening post-sleeve GERD symptoms have higher post-sleeve DI and lower post-sleeve LES pressure than their asymptomatic counterparts.

Use of an intragastric trocar to perform a novel stapling procedure for reflux disease

Background and study aims  A percutaneous intragastric trocar (PIT) enables intraluminal use of laparoscopic tools and helps overcome traditional limitations of endoscopy. The aim of this study was to determine the efficacy of using a PIT to perform an anti-reflux stapling procedure. Materials and methods  Trocars were placed in four animals and an articulating stapler was used to perform fundoplication under endoscopic guidance. Animals were monitored for 14 days post-procedure. Functional lumen imaging of the esophagogastric junction (EGJ) was performed at baseline, immediately post-intervention, and at 14 days. Results  The procedure was successful in all animals who survived to day 14 without distress or significant adverse events. Baseline EGJ distensibility was 5.0 ± 1.2 mm ² /mmHg, 2.7 ± 0.7 mm ² /mmHg post-procedurally, and 3.0 ± 0.8mm ² /mmHg on day 14. Average change in distensibility pre- and post-procedure was -2.3 ± 1.8 mm ² /mmHg (95 % confidence interval [CI] -0.5 to 5.1, P  = 0.08) while change in pre- and day 14 distensibility was -2.0 ± 1.4 mm ² /mmHg (95 % CI -0.1 to 4.2, P  = 0.06). Conclusions  An intragastric trocar allows for use of large-diameter laparoscopic instruments to safely and effectively perform endoluminal fundoplication with anti-reflux properties that persist for at least 14 days.

Impedance Planimetry (Endoflip) and Ideal Distensibility Ranges for Optimal Outcomes after Nissen and Toupet Fundoplication

BACKGROUND

Previous research has shown that impedance planimetry-based functional lumen imaging probe (FLIP) measurements are associated with patient-reported outcomes after laparoscopic antireflux surgery. We hypothesize that Nissen and Toupet fundoplications have different ideal FLIP profiles, such as distensibility.

STUDY DESIGN

A retrospective review of a prospectively maintained quality database was performed. Patients who had FLIP measurements during fundoplications between 2013 and 2021 were included. Reflux Symptom Index, Gastroesophageal Reflux Disease-Health Related Quality of Life Questionnaire, and dysphagia score were collected for up to 2 years postoperatively. The Wilcoxon rank-sum test was used to compare FLIP measurements vs outcomes.

RESULTS

Two hundred fifty patients (171 Toupet, 79 Nissen) were analyzed. Distensibility ranges were categorized as tight, ideal, or loose. The ideal distensibility index range of Toupet patients with the 30- and 40-mL balloon fills were 2.6 to 3.7 mm2/mmHg. This range was associated with less dysphagia at 1 year compared with the tight group (p = 0.02). For Nissen patients, the 30- and 40-mL ideal threshold was a distensibility index of ≥2.2 mm2/mmHg. Patients with distensibility exceeding this threshold had a better quality of life than the tight group, reporting better Gastroesophageal Reflux Disease-Health Related Quality of Life Questionnaire (p = 0.02) and lower dysphagia scores (p = 0.01) at 2 years.

CONCLUSIONS

Impedance planimetry revealed different ideal distensibility ranges after Toupet and Nissen fundoplications that are associated with improved patient-reported outcomes, suggesting that intraoperative FLIP has the potential to tailor fundoplication.

Quantifying physiologic parameters of the gastroesophageal junction during re-operative anti-reflux surgery

BACKGROUND

Hiatal hernia re-approximation during index anti-reflux surgery (ARS) contributes approximately 80% of overall change in distensibility index (DI) and, potentially, compliance of the gastroesophageal (GEJ), while sphincter augmentation contributes approximately 20%. Whether this is seen in re-operative ARS is unclear. We quantify the physiologic parameters of the GEJ at each step of robotic re-operative ARS and compare these to index ARS.

METHODS

Robotic ARS with hiatal hernia repair was performed on 195 consecutive patients with pathologic reflux utilizing EndoFLIP™, of which 26 previously had ARS. Intra-operative GEJ measurements, including cross-sectional area (CSA), pressure, DI, and high-pressure zone (HPZ) length were collected pre-repair, post-diaphragmatic re-approximation, post-mesh placement, and post-lower-esophageal sphincter (LES) augmentation.

RESULTS

Both cohorts were similar by sex and BMI and underwent similar procedures. The re-operative cohort was older (60.6 ± 15.3 vs. 52.7 ± 16.2 years, p = 0.03), had more frequent pre-operative dysphagia (69.2% vs. 42.6%, p = 0.01) and esophageal dysmotility on barium swallow (75.0% vs. 35.0%, p < 0.001) but lower rates of hiatal hernia on endoscopy (30.8% vs. 68.7%, p < 0.001) compared to index procedures. Among the re-operative cohort, the CSA decreased by 34 (IQR - 80, - 15) mm2 and DI 1.1 (IQR - 2.4, - 0.6) mm2/mmHg (both p < 0.001). Pressure increased by 11.2 (IQR 4.7, 14.9) mmHg and HPZ by 1.5 (1,2) cm (both p < 0.001). These changes were similar to those seen in index ARS. Diaphragmatic re-approximation contributed to a greater percentage of overall change to the GEJ than did the augmentation procedure, with 72% of the change in DI occurring during hiatal closure, similar to that seen during index ARS.

CONCLUSIONS

During re-operative ARS, dynamic intra-operative monitoring can quantify the effects of each operative step on GEJ physiologic parameters. Diaphragmatic re-approximation appears to have a greater effect on GEJ physiology than does LES-sphincter augmentation during both index and re-operative ARS.

Devices for esophageal function testing

BACKGROUND AND AIMS

Esophageal function testing is an integral component of the evaluation of refractory GERD and esophageal motility disorders. This review summarizes the current technologies available for esophageal function testing, including the functional luminal imaging probe (FLIP), high-resolution esophageal manometry (HRM), and multichannel intraluminal impedance (MII) and pH monitoring.

METHODS

We performed a MEDLINE, PubMed, and MAUDE database literature search to identify pertinent clinical studies through March 2021 using the following key words: esophageal manometry, HRM, esophageal impedance, FLIP, MII, and esophageal pH testing. Technical data were gathered from traditional and web-based publications, proprietary publications, and informal communications with pertinent vendors. The report was drafted, reviewed, and edited by the American Society for Gastrointestinal Endoscopy Technology Committee and approved by the Governing Board of the American Society for Gastrointestinal Endoscopy.

RESULTS

FLIP is a high-resolution impedance planimetry system used for pressure and dimension measurement in the esophagus, pylorus, and anal sphincter. FLIP provides complementary information to HRM for esophageal motility disorders, especially achalasia. The Chicago classification, based on HRM data, is a widely adopted algorithmic scheme used to diagnose esophageal motility disorders. MII detects intraluminal bolus movement and, combined with pH measurement or manometry, provides information on acid and non-acid gastroesophageal reflux and bolus transit in patients with refractory GERD and for preoperative evaluation for anti-reflux procedures.

CONCLUSIONS

Esophageal function testing techniques (FLIP, HRM, and MII-pH) have diagnostic and prognostic value in the evaluation of esophageal motility disorders and refractory GERD. Newer technologies and classification systems have enabled an increased understanding of these diseases.

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.

How a modified Nissen procedure works: a mechanistic study using intraoperative esophageal high-resolution manometry

OBJECTIVE

We aimed at demonstrating how a modified Nissen procedure works by analyzing intraoperatively the variations of the low esophageal sphincter pressure values using high resolution manometry.

METHODS

This study included 15 patients with documented gastroesophageal reflux disease who underwent a laparoscopic modified Nissen procedure. Data regarding the changes in the pressure values were recorded at each step of the procedures using high resolution manometry and after the progressive insufflation of air in the stomach. Categorical data were compared between the preoperative and postoperative periods using Fisher's test, and continuous data were compared using Mann-Whitney U non-parametric test. Preoperative versus postoperative variations in continuous data were assessed using Wilcoxon's non-parametric test for paired data.

RESULTS

Intraoperative manometric data showed a rise of basal LES pressure until the creation of the wrap. An evident increase of pressure values was recorded after gastric air insufflation, as consequence of the increase of intragastric pressure. No intraoperative and postoperative complications were observed. All patients experienced a significant reduction in terms of intensity and frequency of gastroesophageal reflux symptoms and no patients complained of dysphagia.

CONCLUSIONS

Intraoperative high resolution manometry was feasible in all patients and demonstrated that the modified Nissen procedure works by increasing the LES pressure in response to gastric distension, without impeding the progression of the bolus into the stomach.

Estimation of mechanical work done to open the esophagogastric junction using functional lumen imaging probe panometry

In this study, we quantify the work done by the esophagus to open the esophagogastric junction (EGJ) and create a passage for bolus flow into the stomach. Work done on the EGJ was computed using functional lumen imaging probe (FLIP) panometry. Eighty-five individuals underwent FLIP panometry with a 16-cm catheter during sedated endoscopy including asymptomatic controls (n = 14), 45 patients with achalasia (n = 15 each, three subtypes), those with gastroesophageal reflux disease (GERD; n = 13), those with eosinophilic esophagitis (EoE; n = 8), and those with systemic sclerosis (SSc; n = 5). Luminal cross-sectional area (CSA) and pressure were measured by the FLIP catheter positioned across the EGJ. Work done on the EGJ (EGJW) was computed (millijoules, mJ) at 40-mL distension. Additionally, a separate method was developed to estimate the "work required" to fully open the EGJ (EGJROW) when it did not open during the procedure. EGJW for controls had a median [interquartile range (IQR)] value of 75 (56-141) mJ. All achalasia subtypes showed low EGJW compared with controls (P < 0.001). Subjects with GERD and EoE had EGJW 54.1 (6.9-96.3) and 65.9 (10.8-102.3) mJ, similar to controls (P < 0.08 and P < 0.4, respectively). The scleroderma group showed low values of EGJW, 12 mJ (P < 0.001). For patients with achalasia, EGJROW was the greatest and had a value of 210.4 (115.2-375.4) mJ. Disease groups with minimal or absent EGJ opening showed low values of EGJW. For patients with achalasia, EGJROW significantly exceeded EGJW values of all other groups, highlighting its unique pathophysiology. Balancing the relationship between EGJW and EGJROW is potentially useful for calibrating achalasia treatments and evaluating treatment response.NEW & NOTEWORTHY Changes in pressure and diameter occur at the EGJ during esophageal emptying. Similar changes can be observed during FLIP panometry. Data from healthy and diseased individuals were used to estimate the mechanical work done on the EGJ during distension-induced relaxation or, in instances of failed opening, work required to open the EGJ. Quantifying these parameters is potentially valuable to calibrate treatments and gauge treatment efficacy for subjects with disorders of EGJ function, especially achalasia.

The impact of pneumoperitoneum on esophagogastric junction distensibility during anti-reflux surgery

OBJECTIVE

We aimed to quantify the contribution of pneumoperitoneum on compliance of the esophagogastric junction (EGJ) during anti-reflux surgery.

BACKGROUND

Compliance of the EGJ is reduced with anti-reflux surgery. EndoFLIP® planimetry can be used to assess dynamic changes of EGJ compliance intraoperatively. It is unclear how pneumoperitoneum impacts intraoperative measurements by EndoFLIP® and the implications thereof on validity of the results. Therefore, determining variability in EndoFLIP® measurements based on pneumoperitoneum is warranted to establish guidelines to interpret clinical outcomes.

METHODS

Primary anti-reflux surgery was performed on 39 consecutive patients with pathologic reflux. Intraoperative EGJ measurements including distensibility index (DI), cross-sectional area (CSA), and intrabag pressure were collected using EndoFLIP® at 0, 10, and 15 mmHg of intraperitoneal pressure. Data were acquired pre-procedure, post-hiatal hernia repair, and post-LES augmentation with fundoplications.

RESULTS

Patients underwent Nissen (13.2%), Toupet (68.4%), LINX (10.5%), or Hill-fundoplications (7.9%). There was no difference between 0 and 10 mmHg of pneumoperitoneum in CSA, pressure, or DI measurements pre-procedure; however, there was a difference between 0 and 15 mmHg in pressure (p = 0.016) and DI (p = 0.023) measurements. After LES augmentation, 10 mmHg intraperitoneal pressure reduced DI, though the absolute difference is small (2.0 vs. 1.5 mm²/mmHg, p = 0.002).

CONCLUSION

Pneumoperitoneum affected EGJ distensibility at 15 mmHg, but not 10 mmHg, of insufflation prior to anti-reflux procedures. After anti-reflux surgery, there was a significant variance between 0 and 10 mmHg of pneumoperitoneum in pressure and distensibility. The change in pressure appears linear and needs to be considered if procedural modifications are performed based on intraoperative findings and when evaluating clinical outcomes.

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.

Using a standardized intra-operative endoflip protocol during fundoplication to identify factors that affect distensibility

INTRODUCTION

The Endoluminal Functional Lumen Imaging Probe (Endoflip) can be used to provide objective measurements of the gastroesophageal junction during fundoplication, and recent publications have suggested that this device could improve surgical outcomes. However, the impact of operative variables has not been clearly reported. The aim of this study is to determine the effect of these variables on functional lumen imaging probe (FLIP) measurements.

METHODS

Following implementation of a standardized operative FLIP protocol, all data were collected prospectively and entered into a quality database. This database was queried for patients undergoing hiatal hernia repair and fundoplication. The protocol utilized various balloon volumes (30 and 40 ml), patient positions (flat and reverse Trendelenburg) and amounts of insufflation (15 mmHg pneumoperitoneum and no pneumoperitoneum).

RESULTS

Between August 2018 and February 2020, 97 fundoplications were performed by a single surgeon. Multivariable analysis without interactions demonstrated that a 40 ml volume fill resulted in significantly higher minimum diameter (Dmin), cross-sectional area (CSA), intra-balloon pressure (IBP) and distensibility index (DI) compared to a 30 ml volume fill (p < 0.001). While reverse Trendelenburg positioning resulted in a significantly higher Dmin, IBP and CSA compared to the flat position (all p < 0.05), there was little impact of positioning on DI. Lastly, pneumoperitoneum significantly increased IBP (p < 0.001) but did not affect Dmin (p = 0.697) or CSA (p = 0.757), which resulted in a significant decrease in DI (p < 0.001) when compared to measurements without pneumoperitoneum. Multivariable analysis allowing for interactions demonstrated significant two-way interactions between balloon volume and pneumoperitoneum (p = 0.047), as well as patient position and pneumoperitoneum (p < 0.001).

CONCLUSION

Surgeons should consider balloon volume and the presence or absence of pneumoperitoneum when interpreting distensibility during or after fundoplication. Additionally, we suggest a formal standardized protocol for FLIP measurements to utilize a 40 ml volume fill in reverse Trendelenburg without pneumoperitoneum.

Comparing short-term patient outcomes after fundoplication performed over a traditional bougie versus a functional lumen imaging probe

BACKGROUND

The functional lumen imaging probe is a balloon-based catheter that can be used as a bougie during fundoplication. Our goal was to compare the short-term, quality-of-life outcomes and esophageal-injury rate after fundoplication over a functional lumen imaging probe compared to a traditional bougie.

METHODS

This is a retrospective review of a quality database at a single center. Three-week and 6-month Reflux Symptom Index, Gastroesophageal Reflux Disease-health Related Quality of Life, and dysphagia scores were compared. The need for endoscopy and dilation between the groups was also compared.

RESULTS

Between 2008 and 2020, 423 fundoplications were performed over a bougie and 62 over the functional lumen imaging probe. Six months after surgery, the functional lumen imaging probe group reported significantly worse dysphagia scores (1.5 ± 1.0 vs 1.1 ± 0.3, P = .007), but rates of endoscopy (4.8% vs 5.0%, P = .966) and dilation (4.8% vs 3.8%, P = .723) were similar. There were no differences between Reflux Symptom Index and Gastroesophageal Reflux Disease-health Related Quality of Life scores. The rate of bougie-related injuries was 2.1% vs 0% for the functional lumen imaging probe group.

CONCLUSION

Patients undergoing fundoplication over the functional lumen imaging probe had comparable short-term outcomes compared with those over a traditional bougie. The rate of esophageal injury while using the functional lumen imaging probe is lower than a bougie and may be preferable for fundoplication creation.

Tailoring Endoscopic and Surgical Treatments for Gastroesophageal Reflux Disease

The incidence of gastroesophageal reflux disease (GERD) remains on the rise. Pathophysiology of GERD is multifactorial, revolving around an incompetent esophagogastric junction as an antireflux barrier, with other comorbid conditions contributing to the disease. Proton pump inhibitors remain the most common treatment of GERD. Endoscopic therapy has gained popularity as a less invasive option. The presence of esophageal dysmotility complicates the choice of surgical fundoplication. Most literature demonstrates that fundoplication is safe in the setting of ineffective or weak peristalsis and that postoperative dysphagia cannot be predicted by preoperative manometry parameters. More data are needed on the merits of endoluminal approaches to GERD.

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.

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.

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 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.

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.

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.

Use of Impedance Planimetry (Endoflip) in Foregut Surgery Practice: Experience of More than 400 Cases

BACKGROUND

We provide a comprehensive report of our institution's experience with the endoluminal functional lumen imaging probe (Endoflip) impedance planimetry system, a device that can be used intraoperatively to objectively evaluate the distensibility of any sphincter of the gastrointestinal tract. We aim to describe the variety of ways in which the Endoflip can be used in a foregut surgeon's practice.

STUDY DESIGN

This is a retrospective review of a prospectively maintained quality database of all patients in which the functional lumen imaging probe (FLIP) system was used between February 2013 and June 2019.

RESULTS

During the study period, 402 FLIP cases were performed: 226 fundoplications, 94 peroral endoscopic myotomies, 15 peroral pyloromyotomies, 12 antireflux mucosectomies, 11 magnetic sphincter augmentations, 9 laparoscopic Heller myotomies, 8 pre-esophagectomy esophagogastroduodenoscopies (EGDs), 4 diagnostic EGDs, 8 endoscopic Zenker's diverticulotomies, 5 post-peroral endoscopic myotomy EGDs, 8 EGDs with dilations, and 2 transoral incisional fundoplications.

CONCLUSIONS

Within a foregut surgeon's practice, the FLIP can be used to measure the upper esophageal sphincter, lower esophageal sphincter, and pylorus in a variety of clinical scenarios and settings.

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.

A potential simple endoscopic antireflux method, "the Ripple Procedure" to reduce distensibility at the esophagogastric junction in a porcine model

BACKGROUND AND AIMS

Currently available endoscopic or minimally invasive antireflux modalities are not widely accepted due to high procedure cost or inconsistent results. Therefore, a simpler and less technically demanding method is required. We evaluated the feasibility and efficacy of new endoscopic antireflux method (the Ripple Procedure) using functional lumen imaging probe (FLIP).

METHODS

This 5-week survival study included 10 domestic pigs (control, n = 4; experimental [Ripple], n = 6). The procedure includes the following steps: (i) semicircular marking along the lesser curvature of the cardia; (ii) submucosal injection; and (iii) semicircular mucosal incision along the marking. Endoscopic and FLIP evaluations were performed preoperatively and on postoperative days (PODs) 14 and 35. Technical feasibility was evaluated, and FLIP parameters, including the distensibility index (DI) at the esophagogastric junction (EGJ) and histopathological findings, were compared between groups.

RESULTS

The median procedure time was 28 (23.5-33.8) min. There was no significant difference in dysphagia score and body weight between groups. On POD 35, the Ripple group showed significantly lower EGJ DI at 30 mL [2.0 (1.3-2.5) vs 4.9 (2.7-5.0), P = 0.037]. The EGJ DI was significantly reduced at 30 mL, compared with that at the baseline level [- 59.0% (- 68.8% to - 32.1%) vs 27.8% (- 26.3% to 83.1%), P = 0.033]. Histologic evaluation revealed submucosal granulation tissues near the mucosal incision site, with increased intervening fibrosis between lower esophageal sphincter fibers in the Ripple group.

CONCLUSION

The EGJ DI significantly decreased after the Ripple Procedure; hence, the procedure appears to be feasible and effective in this porcine model.

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.

Endoscopic augmentation of gastroesophageal junction using a full-thickness endoscopic suturing device

Background and study aims  This preliminary study was conducted to determine the feasibility and safety of endoscopic augmentation of the gastroesophageal junction (GEJ) using the Apollo OverStitch endoscopic suturing system in patients with gastroesophageal reflux disease (GERD) symptoms. Patients and methods  Endoscopic augmentation of GEJ was performed on 10 consecutive patients and the data were analyzed retrospectively. Using a double-channel gastroscope affixed to the endoscopic suturing platform, interrupted sutures were placed on the gastric side of the GEJ in 2 layers in order to create a narrowed and elongated GEJ. Results  Technical success was achieved in all patients, including those with a history of previous antireflux procedures (n = 7) and those with a hiatal hernia (n = 6). The median follow-up duration was 5 mo (range: 2 - 12). The median pre-procedure GERD-Health Related Quality of Life Questionnaire improved from 20 (range: 11 - 45) to a post-procedure score of 6 (range: 3 - 25) ( P  = 0.001). The median duration of GERD symptom improvement after the procedure was 1 mo (range: 0.5 - 4). Adverse events were limited to 1 patient who developed nausea and vomiting, which was self-limited. Conclusions  The use of a novel endoscopic suturing technique for the treatment of GERD is feasible and safe. The procedure resulted in short-term GERD symptom improvement. Further prospective studies using refined techniques are currently underway to improve durability and to prove efficacy.

UK guidelines on oesophageal dilatation in clinical practice

These are updated guidelines which supersede the original version published in 2004. This work has been endorsed by the Clinical Services and Standards Committee of the British Society of Gastroenterology (BSG) under the auspices of the oesophageal section of the BSG. The original guidelines have undergone extensive revision by the 16 members of the Guideline Development Group with representation from individuals across all relevant disciplines, including the Heartburn Cancer UK charity, a nursing representative and a patient representative. The methodological rigour and transparency of the guideline development processes were appraised using the revised Appraisal of Guidelines for Research and Evaluation (AGREE II) tool.Dilatation of the oesophagus is a relatively high-risk intervention, and is required by an increasing range of disease states. Moreover, there is scarcity of evidence in the literature to guide clinicians on how to safely perform this procedure. These guidelines deal specifically with the dilatation procedure using balloon or bougie devices as a primary treatment strategy for non-malignant narrowing of the oesophagus. The use of stents is outside the remit of this paper; however, for cases of dilatation failure, alternative techniques-including stents-will be listed. The guideline is divided into the following subheadings: (1) patient preparation; (2) the dilatation procedure; (3) aftercare and (4) disease-specific considerations. A systematic literature search was performed. The Grading of Recommendations Assessment, Develop-ment and Evaluation (GRADE) tool was used to evaluate the quality of evidence and decide on the strength of recommendations made.

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.

Pyloric sphincter characteristics using EndoFLIP® in gastroparesis

INTRODUCTION AND AIMS

Pyloric sphincter abnormalities may be detected in gastroparesis. Botulinum toxin A (BoNT/A) injection into the pylorus has been used to treat gastroparesis with varying results. The aim of the present article was to assess whether pyloric sphincter characteristics using the endoscopic functional lumen imaging probe (EndoFLIP^®) with impedance planimetry in patients with gastroparesis correlated with symptoms, gastric emptying, and therapeutic response to pyloric sphincter BoNT/A injection.

METHODS

EndoFLIP^® study was performed on patients undergoing gastroparesis treatment with BoNT/A. The gastroparesis cardinal symptom index (GCSI) was applied prior to treatment and at post-treatment weeks 2, 4, 8, and 12.

RESULTS

Forty-four patients were enrolled (30 with idiopathic gastroparesis, 14 with diabetic gastroparesis). Smaller pyloric diameter, cross-sectional area (CSA), and distensibility correlated with worse vomiting and retching severity at baseline. Greater gastric retention tended to correlate with decreased CSA and pyloric distensibility. BoNT/A treatment resulted in a significant decrease in the GCSI score at 2 and 4 weeks after treatment, but not at post-treatment weeks 8 or 12. Nausea, early satiety, postprandial fullness, and upper abdominal pain improved up to 12 weeks, whereas loss of appetite, stomach fullness, and stomach visibly larger improved only up to 4 weeks. Retching and vomiting failed to improve. Greater pyloric compliance at baseline correlated with greater improvement in early satiety and náusea at 8 weeks and greater pyloric distensibility correlated with improvement in upper abdominal pain.

CONCLUSIONS

EndoFLIP^® characteristics of the pylorus provided important pathophysiologic information in patients with gastroparesis, in relation to symptoms, gastric emptying, and predicting the response to treatment directed at the pylorus.

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.

How to Optimally Apply Impedance in the Evaluation of Esophageal Dysmotility

The utilization of impedance technology has enhanced our understanding and assessment of esophageal dysmotility. Esophageal high-resolution manometry (HRM) catheters incorporated with multiple impedance electrodes help assess esophageal bolus transit, and the combination is termed high-resolution impedance manometry (HRIM). Novel metrics have been developed with HRIM-including esophageal impedance integral ratio, bolus flow time, nadir impedance pressure, and impedance bolus height-that augments the assessment of esophageal bolus transit. Automated impedance-manometry (AIM) analysis has enhanced understanding of the relationship between bolus transit and pressure phenomena. Impedance-based metrics have improved understanding of the dynamics of esophageal bolus transit into four distinct phases, may correlate with symptomatic burden, and can assess the adequacy of therapy for achalasia. An extension of the use of impedance involves impedance planimetry and the functional lumen imaging probe (FLIP), which assesses esophageal biophysical properties and distensibility, and could detect patterns of esophageal contractility not seen on HRM. Impedance technology, therefore, has a significant impact on esophageal function testing in the present day.

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.

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.

Comparison of videofluoroscopy and impedance planimetry for the evaluation of oesophageal stenosis: a retrospective study

Objectives

To compare videofluoroscopy that included a tablet test with impedance planimetry (EndoFLIP^®) for the evaluation of oesophageal stenosis in patients with dysphagia.

Methods

In 56 patients, videofluoroscopic examinations following the transit of a 14-mm tablet were retrospectively reviewed and correlated with impedance planimetry findings, a catheter-based method using impedance planimetry to display the oesophageal diameter estimates. Additional findings assessed were the occurrence of symptoms during tablet passage and evaluation of oesophageal motility.

Results

Impaction of the tablet occurred in 31/56 patients; nine showed a moderate delay (2–15 s), three a short delay (<2 s) and 13 no delay of tablet passage. Both methods showed a significant correlation between tablet impaction and oesophageal diameter <15.1 mm, as measured by impedance planimetry (p = 0.035). The feeling of the tablet getting stuck was reported by seven patients, six showing impaction of the tablet (four with an EndoFLIP-diameter < 13 mm, two with a diameter of 13–19 mm) and one showing delayed passage (EndoFLIP diameter of 17 mm).

Conclusions

Videofluoroscopy and impedance planimetry correlate significantly regarding tablet impaction and residual oesophageal lumen. A standardized 14-mm tablet is helpful in demonstrating oesophageal strictures in dysphagic patients. Triggering of subjective symptoms provides valuable information during a videofluoroscopic study.

Key Points

• A 14-mm tablet can demonstrate oesophagogastric junction narrowing in patients with dysphagia.

• Type of passage of a tablet enables estimation of oesophageal luminal diameter.

• Videofluoroscopy and impedance planimetry correlate significantly regarding tablet impaction and residual oesophageal lumen.

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.

Intraoperative distensibility measurement during laparoscopic Heller's myotomy for achalasia may reduce the myotomy length without compromising patient outcome

Our study aimed to assess whether intraoperative esophagogastric junction (EGJ) distensibility measurement using the EndoFLIP EF325 catheter (Crospon Ltd., Galway, Ireland) could potentially be used to guide laparoscopic Heller's myotomy (LHM), potentially modifying the operation outcome and comparing this clinically to our previous technique of gastroscopic assessment. Following a full diagnostic assessment with manometry and endoscopy patients with achalasia were divided into two groups. A retrospective cohort of patients operated on between 2007 and 2010 had a gastroscopy-guided LHM (G-LHM) with a standardized myotomy of 8 cm on the esophagus and 3 cm on the stomach. From 2010, patients were prospectively studied with an EndoFLIP-guided LHM (E-LHM). The length of the myotomy was dictated by intraoperative distensibility monitoring of the EGJ. All patients with achalasia recorded Urbach quality of life scoring preoperatively and 6 months postoperatively. A further group of normal laparoscopic control patients (E-LC) without any esophageal pathology also underwent intraoperative EGJ distensibility monitoring. Thirty-eight patients took part, 15 in the E-LC group, 8 in G-LHM group and 15 in the E-LHM group. We revealed that patients with achalasia in the E-LHM group had a significantly smaller EGJ cross-sectional area and distensibility than the E-LC group. Myotomy and fundoplication increased the distensibility of the EGJ to a value greater than normal control patients. Patients in the G-LHM group had a standard myotomy of 11 cm; patients in the E-LHM group had a variable length myotomy of 6 cm (IQR 5.0-6.0). In both G-LHM and E-LHM groups, there was a significant improvement in patient's quality of life with no significant difference between the groups. Our study has shown that the EndoFLIP system was effective at measuring distensibility changes during LHM. LHM significantly increases the distensibility of the EGJ and also significantly improves patient symptoms. E-LHM may reduce the overall myotomy length, and this does not appear to compromise the clinical outcome.