Mechanisms of repetitive retrograde contractions in response to sustained esophageal distension: a study evaluating patients with postfundoplication dysphagia

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

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

Chronic opioid users with dysphagia are indistinguishable from symptomatic nonusers on functional lumen imaging probe evaluation

BACKGROUND

Opioid-induced esophageal dysmotility (OIED) includes spastic esophageal motility disorders, increasingly recognized in the contemporary opioid epidemic. We assessed functional lumen imaging probe (FLIP) findings in diagnosing OIED.

METHODS

Symptomatic patients undergoing FLIP with no prior foregut surgery who completed validated questionnaires were identified and segregated into chronic opioid users and nonusers in this cohort study. Esophagogastric junction (EGJ) distensibility index (DI), EGJ diameter, and esophageal body contraction patterns were extracted. Symptom profiles were compared to FLIP findings between chronic opioid users and nonusers. Outcome was evaluated in a subset using the same validated questionnaires.

RESULTS

Over the 18-months study period, of 116 patients (median age 62 years, 70.7% female), 33 (28.4%) were chronic opioid users, with median morphine milligram equivalent of 30 mg. While presenting symptoms were similar, chronic opioid users reported higher perceptive symptoms (p = 0.008) and worse quality of life (p = 0.01) compared to nonusers. Median DI trended lower in chronic opioid users (p = 0.08), with more retrograde repetitive contractions (p < 0.001) and less absent contractility (p = 0.007), but final FLIP diagnoses were similar compared to nonusers. There was no correlation between opioid dose and FLIP metrics. In the subset with follow-up, perceptive symptoms trended higher in chronic opioid users (p = 0.08), but symptom improvement following therapy was similar in both groups.

CONCLUSIONS & INFERENCES

Symptomatic chronic opioid users have FLIP diagnoses that are similar to nonusers, despite higher perceptive symptoms and worse quality of life. Dominant symptoms improve both in chronic opioid users and nonusers following treatment directed by FLIP.

Nasal Continuous Positive Airway Pressure as a Preferred Airway Management During IV Sedation of Obese Patients With Obstructive Sleep Apnea Undergoing Functional Luminal Imaging Probe Panometry

The functional luminal imaging probe (FLIP) utilizes high-resolution planimetry to provide information regarding esophagogastric junction (EGJ) diameter, EGJ distensibility, and reactive contractile patterns of the esophageal body. This is an FDA-approved measurement tool utilized to both diagnose and measure various upper gastrointestinal disorders. While patients are sedated during FLIP panometry, significant respiratory variations can affect the quality of FLIP panometry results. Nasal continuous positive airway pressure (CPAP) can be utilized to prevent intraoperative or postoperative hypoxia in obese patients as well as those with obstructive sleep apnea (OSA). In this retrospective chart review, we compared obese patients with a diagnosis of OSA who underwent FLIP panometry utilizing nasal CPAP as airway management against a group who underwent the same procedure with a nasal cannula to evaluate the incidence of hypoxia, hypercapnia, variation in cardiovascular dynamics, and the quality of FLIP panometry readings.

Validation of secondary peristalsis classification using FLIP panometry in 741 subjects undergoing manometry

BACKGROUND AND AIMS

This study aimed to systematically evaluate a classification scheme of secondary peristalsis using functional luminal imaging probe (FLIP) panometry through comparison with primary peristalsis on high-resolution manometry (HRM).

METHODS

706 adult patients that completed FLIP and HRM for primary esophageal motility evaluation and 35 asymptomatic volunteers ("controls") were included. Secondary peristalsis, that is, contractile responses (CRs), was classified on FLIP panometry by the presence and pattern of contractility as normal (NCR), borderline (BCR), impaired/disordered (IDCR), absent (ACR), or spastic-reactive (SRCR). Primary peristalsis on HRM was assessed according to the Chicago Classification.

RESULTS

All 35 of the controls had antegrade contractions on FLIP panometry with either NCR (89%) or BCR (11%). The average percentages of normal swallows on HRM varied across contractile response patterns from 84% in NCR, 68% in BCR, 39% in IDCR, to 11% in ACR, as did the percentage of failed swallows on HRM: 4% in NCR, 12% in BCR, 36% in IDCR, and 79% in ACR. SRCR on FLIP panometry was observed in 18/57 (32%) patients with type III achalasia, 4/15 (27%) with distal esophageal spasm, and 7/15 (47%) with hypercontractile esophagus on HRM.

CONCLUSIONS

The FLIP panometry contractile response patterns reflect a pathophysiologic transition from normal to abnormal esophageal peristaltic function with shared features with primary peristaltic function/dysfunction on HRM. Thus, these patterns of the contractile response to distension can facilitate the evaluation of esophageal motility using FLIP panometry.

Achalasia subtypes can be identified with functional luminal imaging probe (FLIP) panometry using a supervised machine learning process

BACKGROUND

Achalasia subtypes on high-resolution manometry (HRM) prognosticate treatment response and help direct management plan. We aimed to utilize parameters of distension-induced contractility and pressurization on functional luminal imaging probe (FLIP) panometry and machine learning to predict HRM achalasia subtypes.

METHODS

One hundred eighty adult patients with treatment-naïve achalasia defined by HRM per Chicago Classification (40 type I, 99 type II, 41 type III achalasia) who underwent FLIP panometry were included: 140 patients were used as the training cohort and 40 patients as the test cohort. FLIP panometry studies performed with 16-cm FLIP assemblies were retrospectively analyzed to assess distensive pressure and distension-induced esophageal contractility. Correlation analysis, single tree, and random forest were adopted to develop classification trees to identify achalasia subtypes.

KEY RESULTS

Intra-balloon pressure at 60 mL fill volume, and proportions of patients with absent contractile response, repetitive retrograde contractile pattern, occluding contractions, sustained occluding contractions (SOC), contraction-associated pressure changes >10 mm Hg all differed between HRM achalasia subtypes and were used to build the decision tree-based classification model. The model identified spastic (type III) vs non-spastic (types I and II) achalasia with 90% and 78% accuracy in the train and test cohorts, respectively. Achalasia subtypes I, II, and III were identified with 71% and 55% accuracy in the train and test cohorts, respectively.

CONCLUSIONS AND INFERENCES

Using a supervised machine learning process, a preliminary model was developed that distinguished type III achalasia from non-spastic achalasia with FLIP panometry. Further refinement of the measurements and more experience (data) may improve its ability for clinically relevant application.

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.

Repetitive Antegrade Contractions: A novel response to sustained esophageal distension is modulated by cholinergic influence

BACKGROUND & AIMS

A unique motor response to sustained esophageal distension, repetitive antegrade contractions (RACs), is observed using functional luminal imaging probe (FLIP) panometry. However, physiologic mechanisms related to this response are unexplored. This study aimed to evaluate the impact of cholinergic inhibition with atropine on the esophageal contractile response to sustained distention, including RACs, among healthy volunteers.

METHODS

8 asymptomatic volunteers (ages 22-45) were evaluated in a crossover study design with 16-cm FLIP positioned across the esophagogastric junction and distal esophagus during sedated upper endoscopy. The FLIP study involving stepwise volumetric distension was performed twice in each subject, at baseline and again after atropine (15 mcg/kg) was administered intravenously. FLIP panometry was analyzed to assess the contractile response to distension.

RESULTS

Antegrade contractions, lumen-occluding contractions, and a RAC pattern were observed in 8/8, 8/8, and 7/8(88%) subjects, respectively, at baseline and in 5/8 (63%), 2/8 (25%) and 2/8 (25%) subjects after atropine. The rate of contractions in the RAC pattern was similar (6-7 contractions per minute) before and after atropine. Compared with the baseline study, distension-induced contractility was triggered at higher fill volumes after atropine. FLIP pressures were lower in response to volumetric filling after atropine than at baseline.

CONCLUSIONS

The vigor and triggering of the esophageal contractile response to distension is reduced by cholinergic inhibition in asymptomatic controls. The observation that the rate of contractions did not change when patients developed repetitive contractile responses suggests that this rate is not modified by cholinergic inhibition once contractility is triggered.

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.

Flip Technology for Assessing Esophageal Structural and Motor Disorders: a Skeptic's View

PURPOSE OF REVIEW

Functional lumen impedance (FLIP) technology has become commercially available to assess structural and motor abnormalities of the esophagus. Increasing numbers of papers have described novel findings with this technology. This review examines the validity of the FLIP technique, how it compares with existing diagnostic modalities, and evidence to date on diagnostic accuracy.

RECENT FINDINGS

FLIP studies require deep sedation at the time of endoscopy to complete. They assess a simulated state of esophageal obstruction in only a distal part of the esophagus rather than deglutitive motor function of the entire esophagus. The available normative dataset is small and not matched to the older age of patients typically being evaluated. The test-retest agreement in health and disease is unknown, as is the operator dependence on performing and interpreting findings. Studies to date have largely excluded patients with structural disorders, which FLIP cannot reliably distinguish from motor disorders. FLIP is an expensive technology that has been made clinically available without its true utility being established. For FLIP to be deemed a device ready for widespread clinical use, additional studies on validity, diagnostic accuracy, and outcomes need to be performed. Prospective clinical studies need to include all patients and assess the incremental cost-effectiveness of FLIP over more innovative use of existing technology, such as high-resolution manometry with provocative challenges.

Functional Luminal Imaging Probe Assessment in Postfundoplication Patients Changes Management Beyond Manometry

OBJECTIVES

Fundoplication is a commonly performed pediatric surgery but the surgery can result in nonspecific symptoms that merit further evaluation. The goal of this study was to determine the utility of Functional Luminal Imaging Probe (FLIP) compared with high-resolution manometry with impedance (HRIM) in the evaluation of fundoplication symptoms.

METHODS

We reviewed the FLIP and HRIM tracings of symptomatic fundoplication patients. We compared FLIP results of fundoplication patients to those of pediatric achalasia and control patients. We also compared the role of FLIP to HRIM in clinical decision-making and clinical outcomes.

RESULTS

EGJ distensibilities of fundoplication patients ranged from 0.6 to 8.2 mm/mmHg. Because of the different pediatric patient sizes (8.9--73.5 kg), balloon size inflations varied but, after adjusting balloon fill volume by weight, there was a linear relationship between inflation and distensibility. When compared with control patients and achalasia patients, distensibilities of fundoplication patients were lower than control patients and higher than achalasia patients (P = 0.0001). Patients who had an EGJ intervention had a mean EGJ distensibility of 2.3 ± 1.1 mm/mmHg compared with 5.1 ± 1.6 mm/mmHg in medically managed patients (P = 0.0001). Patients who had an esophagogastric junction (EGJ) intervention had a mean IRP of 13.9 ± 6.1 mmHg compared with medically managed patients who had a mean IRP of 9.9 ± 3.9 mmHg (P = 0.3).

CONCLUSIONS

We show FLIP may provide additional insight into EGJ physiology in symptomatic fundoplication patients and complements HRIM.

Dysphagia Lusoria: Is the Dysmotility Connection Illusory or Real?

Dysphagia lusoria is rare embryologic defect of the aortic arch vasculature characterized by an aberrant retro-esophageal course of the right subclavian artery (RSA), comprising a vascular sling. This may manifest clinically with symptoms of dysphagia or reflux. Given the rarity of this pathology, there remains uncertainty regarding the most effective treatment algorithm. Vascular decompression procedure surgery is often used to rectify the aberrant vascular morphology. However, a low percentage of aberrant arteries result in trachea-esophageal symptoms. As such, we suggest (1) one must exclude co-morbid esophageal motility disorders in patients with dysphagia; and (2) aberrant RSA may be a cause of dysphagia, so-called dysphagia lusoria, but represents an unlikely mechanism, since this morphological arrangement typically does not result in a highly constrictive, circumferential vascular ring. It follows, therefore, that directly addressing the esophageal motility issue should take precedence over complex and potentially noncurative vascular procedures directed to the aberrant RSA. However, the presence of marked aneursymal dilation of the aberrant RSA, and/or the presence of a bicarotid (socalled bovine) trunk, would favor vascular repair in the clinical decision-making due to the elevated risk of rupture and more severe esophageal compression in these specific situations.

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.

Advances in Management of Esophageal Motility Disorders

The widespread adoption of high-resolution manometry (HRM) has led to a restructuring in the classification of esophageal motility disorder classification summarized in the Chicago Classification, currently in version 3.0. It has become apparent that the cardinal feature of achalasia, impaired lower esophageal sphincter relaxation, can occur in several disease phenotypes: without peristalsis, with premature (spastic) distal esophageal contractions, with panesophageal pressurization, or even with preserved peristalsis. Furthermore, despite these advances in diagnostics, no single manometric pattern is perfectly sensitive or specific for idiopathic achalasia and complimentary assessments with provocative maneuvers during HRM or interrogating the esophagogastric junction with the functional luminal imaging probe during endoscopy can be useful in clarifying equivocal or inexplicable HRM findings. Using these tools, we have come to conceptualize esophageal motility disorders as characterized by obstructive physiology at the esophagogastric junction, smooth muscle esophagus, or both. Recognizing obstructive physiology as a primary target of therapy has become particularly relevant with the development of a minimally invasive technique for performing a calibrated myotomy of the esophageal circular muscle, the POEM procedure. Now and going forward, optimal management is to render treatment in a phenotype-specific manner: e.g. POEM calibrated to patient-specific physiology for spastic achalasia and spastic disorders of the smooth muscle esophagus, more conservative strategies (pneumatic dilation) for the disorders limited to the sphincter.

High-Resolution Anorectal Manometry - New Insights in the Diagnostic Assessment of Functional Anorectal Disorders

Functional anorectal disorders such as faecal incontinence (FI), functional anorectal pain, and functional defecation disorders (FDD) are highly prevalent and represent a high socioeconomic burden. Several tests of anorectal function exist in this setting; however, high-resolution anorectal manometry (HR-ARM) is a new tool that depicts pressure all along the anal canal and can assess rectoanal coordination. HR-ARM is used in the diagnosis of FI and especially FDD although data in health is still sparse, and pressure phenomena seen during simulated defecation, such as dyssynergia, are highly prevalent in health.

Mechanisms of repetitive retrograde contractions in response to sustained esophageal distension: a study evaluating patients with postfundoplication dysphagia

Repetitive retrograde contractions (RRCs) in response to sustained esophageal distension are a distinct contractility pattern observed with functional luminal imaging probe (FLIP) panometry that are common in type III (spastic) achalasia. RRCs are hypothesized to be indicative of either impaired inhibitory innervation or esophageal outflow obstruction. We aimed to apply FLIP panometry to patients with postfundoplication dysphagia (a model of esophageal obstruction) to explore mechanisms behind RRCs. Adult patients with dysphagia after Nissen fundoplication ( n = 32) or type III achalasia ( n = 25) were evaluated with high-resolution manometry (HRM) and upper endoscopy with FLIP. HRM studies were assessed for outflow obstruction and spastic features: premature contractility, hypercontractility, and impaired deglutitive inhibition during multiple-rapid swallows. FLIP studies were analyzed to determine the esophagogastric junction (EGJ)-distensibility index and contractility pattern, including RRCs. Barium esophagram was evaluated when available. RRCs were present in 8/32 (25%) fundoplication and 19/25 (76%) achalasia patients ( P < 0.001). EGJ outflow obstruction was detected in 21 (67%) fundoplication patients by HRM, FLIP, or esophagram [6 (29%) had RRCs]. On HRM, none of the fundoplication patients had premature contractility, whereas 3/4 with defective inhibition on multiple-rapid swallows and 2/4 with hypercontractility had RRCs. Regression analysis demonstrated HRM with spastic features, but not esophageal outflow obstruction, as a predictor for RRCs. RRCs in response to sustained esophageal distension appear to be a manifestation of spastic esophageal motility. Although future study to further clarify the significance of RRCs is needed, RRCs on FLIP panometry should prompt evaluation for a major motor disorder. NEW & NOTEWORTHY Repetitive retrograde contractions (RRCs) are a common response to sustained esophageal distension among spastic achalasia patients when evaluated with the functional luminal imaging probe. We evaluated patients with postfundoplication dysphagia, i.e., patients with suspected mechanical obstruction, and found that RRCs occasionally occurred among postfundoplication patients, but often in association with manometric features of esophageal neuromuscular imbalance. Thus, RRCs appear to be a manifestation of spastic esophageal dysmotility, likely from neural imbalance resulting in excess excitation.