|Year : 2021 | Volume
| Issue : 2 | Page : 75-81
High-resolution esophageal manometry in clinical practice – An Indian perspective
Arihant Hospital and Research Centre, Indore, Madhya Pradesh, India
|Date of Submission||31-Aug-2020|
|Date of Acceptance||08-Sep-2020|
|Date of Web Publication||23-Mar-2021|
Arihant Hospital and Research Centre, 283-A Gumasta Nagar, Indore - 452 009, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
High-resolution esophageal manometry (HREM) is a technique to determine the function of esophageal musculature and the integrity of the lower esophageal sphincter. This test is commonly used for evaluation of nonobstructive dysphagia, assessment of peristaltic reserve before anti-reflux surgery, symptoms of regurgitation, and noncardiac chest pain unexplained by endoscopic evaluation. The current review deals with the spectrum of esophageal motility disorders in India and reviews the technique and reporting of HREM. The clinical utility of HREM in Indian setting with special reference to challenges faced has been discussed in detail.
Keywords: Chest pain, dysphagia, esophagus, motility, swallowing
|How to cite this article:|
Jain M. High-resolution esophageal manometry in clinical practice – An Indian perspective. Gastroenterol Hepatol Endosc Pract 2021;1:75-81
| Introduction|| |
The human esophagus is a 25–35 cm long muscular tube. The muscular contractions in this tube help to propel food into the stomach and clear the acid that refluxes back from the stomach. The lower esophageal sphincter (LES) prevents the reflux of acid from the stomach to the esophagus. LES relaxes during swallowing, vomiting, and belching to allow foods and gastric contents to pass into and out of the stomach. High-resolution esophageal manometry (HREM) is a technique to determine the function of esophageal musculature and integrity of LES.
HREM is performed using either a water-perfused or solid-state system. The solid-state system is more sensitive to pressure changes. However, it is expensive and fragile. Most centers in India use a water perfusion system. Such a system consists of several capillary tubes connected to a multilumen perfusion catheter and external transducers. These tubes are continuously perfused with deaerated water at a constant rate (approximately 0.5 ml/min) by a low-compliance pneumohydraulic pump. Each lumen of the catheter has side holes which sense the intraluminal pressure of the esophagus by relative obstruction to the flow of perfused water.
HREM has gained popularity in India for evaluation of esophageal motor function. The present review highlights the spectrum of esophageal motor disorders in India. Moreover, the technique of HREM, interpretation of results, and challenges faced in the use of HREM in Indian setting have been discussed. Upper esophageal sphincter (UES) manometry is not a part of Chicago classification (CC) and hence is not covered in this review.
| Spectrum of Esophageal Motor Disorders in India|| |
Single-center experiences from Lucknow and Indore have highlighted that achalasia cardia is the most common primary esophageal motor disorder in Indian setting. A multicentric study involving three tertiary care teaching hospitals in Chennai, Indore, and New Delhi noted that motor dysphagia is more common in males and the median age of presentation is the fifth decade. Dysphagia and regurgitation are the most common symptoms. Achalasia is the most common disorder, though the predominant subtype (type 1, 2, and 3) varies from center to center. Ineffective motility is the second most common finding across all centers. Distal esophageal spasm and hypertensive peristalsis were only reported from Central India. Another single-center experience from northern India reported HREM findings in 400 patients with dysphagia and noncardiac chest pain using MMS system, The Netherlands. The authors noted that achalasia is the most common motor disorder, followed by fragmented peristalsis.
Thus, achalasia cardia is the most common esophageal motor disorder in Indian setting. Minor peristaltic disorders are also frequently noted, more so in patients with gastroesophageal reflux disease. The subject of regional variations needs to be explored further.
| Indications for High-Resolution Esophageal Manometry Study|| |
The common indications for HREM evaluation include evaluation of nonobstructive dysphagia, assessment of peristaltic reserve before anti-reflux surgery, symptoms of regurgitation and noncardiac chest pain unexplained by endoscopic evaluation, and transit symptoms following foregut intervention like fundoplication or per-oral endoscopic myotomy (POEM) and before placement of pH probe.
HREM uses beyond conventional indications – HRIM is a procedure that helps to analyze bolus transit including the esophageal impedance integral as a surrogate for bolus retention, intrabolus pressure as a marker of esophageal wall state during bolus transit, and bolus flow time as a measurement of trans-esophagogastric junction pressure gradients during flow. This technique is important is assessment of manometric responses to digestive stimuli such as transient LES relaxation episodes, rumination syndrome, and belching disorders. HREM metrics are being developed to predict response to anti-reflux surgery. HREM is also being increasingly used as a part of the speech-language pathologist's armamentarium to evaluate oropharyngeal dysphagia.
| Manometry Protocol – Technique and Reporting Parameters|| |
The section below highlights the basic protocol to be followed during HREM study, irrespective of the system used. However, the details of water-perfused system are illustrated as this is the most common system being used in India.
| Evaluation of Lower Esophageal Sphincter and Esophagogastric Junction|| |
HREM study is done using a manometry system in supine position. The catheter is passed transnasally, and the position is fixed. During the landmark phase, basal LES pressures and esophagogastric junction (EGJ) morphology are determined. Basal LES pressure is recorded after a period of quiet rest following introduction of the manometry catheter for 30–45 s at the start of HREM recording and during normal respiration. This is also called as landmark phase. Within the baseline window, the interpreter also examines UES characteristics and basal EGJ pressures, identifies the pressure inversion point (PIP), and assesses EGJ morphology. The PIP indicates the point of transition from the intra-abdominal cavity to the intrathoracic cavity and is manometrically displayed by an inverse directionality of the intra-abdominal and intrathoracic pressure signals, which magnifies with deep inspiration. The absence of PIP signifies that the manometry catheter has not traversed the LES and the study is technically incomplete. In addition, cases of a looped catheter in the esophageal body may manifest as a “butterfly” or mirror image.
EGJ morphology on HREM is defined as follows:,
- Type 1: no separation between the LES and the crural diaphragm
- Type 2: minimal separation (>1 and <2 cm) making a double-peaked pressure profile, which, however, is not indicative of a hiatus hernia
- Type 3: more than 2-cm separation between the LES and the crural diaphragm at inspiration so that two high-pressure zones can be clearly identified
- Type 3a: respiratory inversion point distal to the LES
- Type 3b: respiratory inversion point proximal to the LES.
Type I indicates the absence of hiatal hernia, type II indicates a small hernia, and type III indicates a hiatal hernia greater than 2 cm [Figure 1]a and [Figure 1]b. The presence of low basal LES pressure and hiatus >2 cm is associated with abnormal acid reflux. The clinical significance of subclassifications such as 3a and 3b is not yet clear.
|Figure 1: Esophagogastric junction pattern. (a) Normal. (b) Small hiatus (esophagogastric junction type 2)|
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| Evaluation of Peristalsis|| |
HREM recording is done using 5 mL water for 10 swallows in supine posture. The data are recorded on a computer interface and reported using computer software. Currently, CC 3.0 is followed worldwide for reporting. The details of parameters recorded and their interpretation is discussed subsequently in [Table 1] and [Figure 2]a, [Figure 2]b, [Figure 2]c, [Figure 2]d.
|Table 1: Measurements made during high-resolution esophageal manometry study|
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|Figure 2: High-resolution esophageal manometry images of various peristaltic patterns. (a) Normal peristalsis. (b) Absence of peristalsis with panesophageal pressurization, suggesting achalasia type 2. (c) Hypercontractile esophagus (distal contractile integral >8000). (d) Normal lower esophageal sphincter pressure and spastic premature contraction suggesting distal esophageal spasm|
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| Provocative Testing|| |
After recording the HREM tracings for 10 single swallows (SS) in the supine posture, multiple rapid swallows (MRS) are recorded [Figure 3]. For each MRS tracing, five rapid swallows with 2 mL water are administered within 10 s. A gap of at least 60 s is followed between each sequence.
|Figure 3: Multiple rapid swallow showing complete inhibition and poor contractile reserve|
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The following parameters were recorded for each MRS sequence.
- Inhibition phase (MRS-induced esophageal body inhibition) – Considered incomplete if a contraction measuring >3 cm is identified using the 30-mmHg isobaric contour tool and complete if no contraction is seen, or small diminutive contraction fragment of ≤3 cm is seen
- Contraction phase (for assessment of rebound contraction) – The average distal contractile integral (DCI) was calculated for 10 SS and compared with DCI of MRS swallow. DCI is a measure of the force of peristaltic contraction in the smooth muscle segment of the esophagus. It is denoted as amplitude × duration × length of distal esophageal contraction that exceeds 20 mmHg from the transition zone to the LES. Based on the DCI metrics, the MRS patterns are classified as:
- Normal: ratio of MRS-DCI: SS-DCI >1,
- Type ineffective esophageal motility (IEM)-A: Ratio of MRS-DCI/SS-DCI <1 and MRS-DCI >450mmHg/s/cm. This simulates normal motility
- Type IEM-B: MRS-DCI <450 mmHg/s/cm. IEM-B has greater reflux episodes, poor bolus transit, and prolonged esophageal clearance.
Rapid drink challenge test (using 200 ml water to be taken over 30 s) is another provocative test. Three different patterns of responses have been described. These include hypopressive or normal pattern, brief hyperpressive pattern, and prolonged hyperpressive pattern. Nearly 17% of patients with esophageal symptoms but normal single-swallow manometry have abnormal responses to the drink challenge test.
These provocative tests are used as per the discretion of the physician and are especially useful in preoperative assessment of patients undergoing fundoplication surgery and those with ineffective motility. Diagnosis of an esophageal motility disorder requires assessment of the integrated relaxation pressure (IRP), contractile function, and pressurization. The details of these measurements are shown in [Table 1].
| Diagnosing an Esophageal Motility Pattern|| |
The CC v3.0 is a hierarchical analytic scheme used to determine an esophageal motility diagnosis. This is highlighted in [Table 2].
| Challenges in Availability, Techniques, and Reporting of High-Resolution Esophageal Manometry in Indian Setting|| |
Lack of awareness regarding high-resolution esophageal manometry
The awareness regarding HREM is limited to predominantly gastrointestinal physicians and surgeons. These tests are seldom used by doctors from other specialties. The most common primary esophageal motor disorder, achalasia cardia, is frequently diagnosed late in Indian circumstances. Urban residence, greater symptom severity, and first presentation to a gastrointestinal disease specialist contribute to early diagnosis. The major hindrance to diagnosing esophageal motor disorders remains lack of awareness of this essential tool among the general public and doctors alike. With the rising popularity of advanced endoscopic interventions like POEM, there is an increasing interest in HREM and I hope that this increases the availability as well as accessibility of this modality.
Equipment availability, training, and cost
Unlike endoscopy, the availability of manometry equipment is limited in Indian setting. There were a handful of centers offering these facilities a decade back. However, today around 100 centers in India have HREM systems. Very few centers in India have access to solid-state systems. Majority of the systems being used in India are water perfused. The various esophageal manometry systems available in India include MMS solid state, MMS water perfused, Jeff Hebbard (Trace 1.2, 1.3), Medtronic, and Alice. Many gastroenterology training institutes do not offer these facilities, and recovery of cost in private practice is difficult. There are no formal training courses to train gastroenterologists in HREM. Considering the fact that around 50% of outpatient consultations in India are for functional bowel diseases and reflux symptoms, it is disheartening to note that HREM has not made as big a splash as advanced therapeutic endoscopy and hepatology training.
Normative values of high-resolution esophageal manometry for the Indian population
With advances in technology, multiple manometry systems are now commercially available. These differ in various ways including cost, analysis software, and catheter specifications (e.g., number and type sensors, water-perfused or solid-state sensors, catheter coating material, and dimensions). The International Working Group on HREM states that the differences in outcome between patient populations and the available systems cannot be neglected, and it was advised to establish sets of normal value of each system., Pressure rise rates in water-perfused systems are comparatively low than solid systems which are responsible for some variation in pressure measurement and parameters of esophageal motility.
The currently used normative data by different manometry systems have been obtained in the Caucasian population. This may not be applicable in the Indian population. Two recently done studies from South India highlight this point., Srinivas et al. reported the normative data for the 16-channel water-perfused system in supine posture. They noted lower IRP and DCI in 53 healthy volunteers with no gastrointestinal complaints and highlighted the need for modification of cutoffs for this system in the Indian population. Another study from the same group reported the normative values in physiological seated position and noted that IRP was higher and DCI lower in sitting position. This highlights the need for posture specific cutoffs as well.
The current need is to establish normative values in upright and supine postures in the Indian population for the available manometry systems.
Studies from the West have highlighted that technical glitches like sensor or thermal sensor malfunction and artifacts are noted in up to 13% of cases undergoing manometry study. A single-center, retrospective Indian study noted that technical problems were encountered in 13.5% procedures. These included improper swallows (55.8%), difficulty in measuring basal LES pressures during the landmark phase due to repeated swallowing (30.8%), and difficulty in traversing the probe across the EGJ (13.4%). The most frequent causes of the difficulty were large hiatal hernias, achalasia, and postfundoplication status. These conditions are associated with impaired EGJ opening and dilation, leading to coiling of the catheter in the distal esophagus. Gentle maneuvers to guide the catheter tip across the EGJ should be followed in such patients. If these fail, then catheter placement under endoscopic guidance is recommended. Radiological contrast swallow may be used to identify functional or anatomical anomaly, such as impaired esophageal outflow or a slipped fundoplication.,,
To establish uniformity in reporting CC, initially 2.0 and later 3.0 were proposed by experts. These changes have resulted in newer nomenclature of peristaltic findings but with no significant consequence to patient care. Two studies have highlighted that the use of CC 3.0 helps to classify patients with minor peristaltic disorders better, thereby enhancing the number of normal studies.,
| Challenges in Application of High-Resolution Esophageal Manometry Findings in Clinical Practice|| |
Symptom correlation with findings on high-resolution esophageal manometry
HREM is regarded as a gold standard investigation of motility disorders of the esophagus. However, numerous factors that may affect transit and motility, such as bolus shape, surface, and consistency, cannot be measured with manometry. Dysphagia and noncardiac chest pain are considered to be the predominant symptoms in motility disorders. Regurgitation, heartburn, hoarseness, and asthma are hallmarks of reflux disease. In a study done by our group, we noted that most patients presenting with dysphagia had a demonstrable abnormality on HREM, while those with noncardiac chest pain had a normal study. In patients with reflux symptoms, minor peristaltic abnormalities, and normal manometry were the commonly reported findings. Interestingly, in the subset of esophageal belchers, we picked up major motility disorders in one-third of cases. Another study by Saha et al. reported that manometry showed abnormalities in 54.83%, 68.42%, and 38.70% of patients with reflux, dysphagia, and noncardiac chest pain, respectively. Thus, HREM has limited utility in the study of patients with reflux symptoms refractory to medical management and noncardiac chest pain.
A retrospective study from our cohort showed that HREM is normal in three-fifths of patients with refractory reflux disease. Basal LES pressure <10 mmHg was noted in nearly half of such cases. Major motility disorders were detected in 8 cases (9.75%). These included achalasia cardia (6) and distal esophageal spasm (2). After exclusion of these cases, ineffective esophageal motility was noted in 32.4% and normal motility in 67.6%. Patients with achalasia or other esophageal motility disorders may present with symptoms similar to reflux and are often misdiagnosed. A recent study highlighted that one-third of achalasia patients complain of heartburn. Regurgitation and chest pain are also common presenting features of achalasia in Indian setting and may lead to confusion with reflux disease.
HREM has some role in evaluation of noncardiac chest pain as well. Patients who have definitive endoscopic findings such as reflux esophagitis, Helicobacter pylori infection, or ulcer disease should be treated accordingly. In those whose endoscopy is normal, HREM and 24 h pH testing are important. We have reported that out of 42 patients with noncardiac chest pain and normal endoscopy, major peristaltic disorders (achalasia, distal esophageal spasm, and nutcracker esophagus) and minor peristaltic disorders were noted in 8 (19%) and 12 (28.6%) cases, respectively. Thus, HREM is an important adjunct in the management of refractory reflux symptoms and noncardiac chest pain.
| Significance of Minor Peristaltic Defects|| |
It is common to find a normal HREM study or the presence of minor peristaltic defects – ineffective esophageal motility and fragmented peristalsis – in symptomatic patients. The clinical significance of such findings in symptomatic patients remains unclear. To study the clinical impact of these findings, we conducted a study enrolling symptomatic patients with normal HREM and those with minor peristaltic disorders. Over a 2-year follow-up, there was a symptomatic improvement in three-fourths of cases with medical management, with no requirement of therapeutic endoscopic or surgical intervention. Ravi et al. also noted that these patients rarely required interventions related to esophageal dysfunction during long-term follow-up. These data question the significance and clinical relevance of detecting normal manometry and minor peristaltic disorders in HREM studies in symptomatic patients. It is well documented that these changes may be noted in asymptomatic healthy adults as well. Moreover, management strategies in both groups remain similar. Treatment is usually directed toward the management of reflux, and there are no effective treatments to restore impaired esophageal smooth muscle contractility. This gray area needs to be explored further using multicentric studies.
| Use of High-Resolution Esophageal Manometry in Laparoscopic Fundoplication and Per-Oral Endoscopic Myotomy|| |
The mainstay of treatment in reflux disease is pharmacologic with proton-pump inhibitors, with surgical fundoplication offered to patients who are not responsive to medications or would like to discontinue them for medical or other reasons. The presence of esophageal dysmotility documented on HREM can worsen or create dysphagia in postoperative period. This can potentially influence the choice of fundoplication (partial or complete). Most of the existing literatures demonstrate that fundoplication may be safe in the setting of ineffective or weak peristalsis and that postoperative dysphagia cannot be reliably predicted by preoperative manometry parameters. High-quality data in this subset of patients are currently lacking in Indian medical literature and needs to be addressed.
HREM is essential in characterizing achalasia subtype and the extent of affected segment to plan the myotomy starting point during POEM. However, evidence is lacking that the efficacy of POEM is improved by tailoring myotomy to the length of the spastic segment on HREM. The target of surgical or endoscopic myotomy is to reduce postprocedure LES pressure below 10 mmHg. Multicentric Indian studies are required to shed light on the utility of HREM in these two scenarios.
| Conclusion|| |
HREM is the cornerstone of the diagnosis of esophageal motor disorders. Although currently available in India, the popularity and use of this investigative modality are low in India, especially among other specialties. Reporting currently is based on CC 3.0. In India, despite the availability of various equipment, water-perfused systems are most commonly used. There is a need to determine normative values for the Indian population. Finer tuning of HREM reporting and techniques is required in Indian context. There is a need to increase training in this often neglected aspect of gastroenterology training. More studies are required to determine the exact utility of HREM in clinical practice in India, especially in those with minor peristaltic disorders and those undergoing foregut surgeries.
I would like to thank Dr. Jayanthi Venkataraman, Dr. Srinivas M, and Dr. Rajiv Baijal, who have been my co-researchers in many of the projects related to esophageal manometry. This work would not have been possible without their support and encouragement.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Pope CE. Normal anatomy and developmental anomalies of esophagus. In: Sleisenger MH, Fordtran JS, Scharschmidt BF, Feldman M, Cello JP, editors. Gastrointestinal Diseases: Pathophysiology, Diagnosis, Management. Philadelphia: WB Saunders Company; 1993. p. 311-8.
Dalton CB. The esophageal motility laboratory: Materials and equipment. In: Castell DO, Richter JE, Dalton CB, editors. Esophageal Motility Testing. New York: Elsevier; 1987. p. 29-34.
Dalton CB. The manometric study. In: Castell DO, Richter JE, Dalton CB, editors. Esophageal Motility Testing. New York: Elsevier; 1987. p. 36-59.
Misra A, Chourasia D, Ghoshal UC. Manometric and symptomatic spectrum of motor dysphagia in a tertiary referral centre in Northern India. Indian J Gastroenterol 2010;29:18-22.
Jain M, Ware S, Bundiwal A, Sircar S, Jain AK. Etiological spectrum of motor dysphagia as per Chicago classification – Experience at a tertiary center in Central India. Indian J Gastroenterol 2015;34:186-7.
Jain M, Baijal R, Srinivas M, Jayanthi V. Multicentre spectrum of esophageal motility disorders in Indian Subcontinent. Int J Inn Res Med Sci 2017;2:1216-8.
Bansal RK, Nasa M, Patil GK, Shah V, Chaudhary NS, Puri R, et al
. Spectrum of esophageal motility disorders in patients with motor dysphagia and noncardiac chest pain-A single center experience. J Dig Endosc 2017;8:68-71. [Full text]
Jain M, Baijal R. Characteristics of lower esophageal sphincter function and esophageal motility noted on high resolution esophageal manometry in patients with reflux disease. Global J Res Analy 2017;6:287-8.
Gyawali CP, Patel A. Esophageal motor function: Technical aspects of manometry. Gastrointest Endosc Clin N Am 2014;24:527-43.
Yadlapati R. High-resolution esophageal manometry: Interpretation in clinical practice. Curr Opin Gastroenterol 2017;33:301-9.
Kahrilas PJ, Bredenoord AJ, Fox M, Gyawali CP, Roman S, Smout AJ, et al
. The Chicago classification of esophageal motility disorders, v3.0. Neurogastroenterol Motil 2015;27:160-74.
Martinucci I, de Bortoli N, Giacchino M, Bodini G, Marabotto E, Marchi S, et al
. Esophageal motility abnormalities in gastroesophageal reflux disease. World J Gastrointest Pharmacol Ther 2014;5:86-96.
Jain M, Srinivas M, Bawane P, Venkataraman J. Basal lower esophageal sphincter pressure in gastroesophageal reflux disease: An ignored metric in high-resolution esophageal manometry. Indian J Gastroenterol 2018;37:446-51.
Fornari F, Bravi I, Penagini R, Tack J, Sifrim D. Multiple rapid swallowing: A complementary test during standard oesophageal manometry. Neurogastroenterol Motil 2009;21:718-e41.
Shaker A, Stoikes N, Drapekin J, Kushnir V, Brunt LM, Gyawali CP. Multiple rapid swallow responses during esophageal high-resolution manometry reflect esophageal body peristaltic reserve. Am J Gastroenterol 2013;108:1706-12.
Min YW, Shin I, Son HJ, Rhee PL. Multiple rapid swallow maneuver enhances the clinical utility of high-resolution manometry in patients showing ineffective esophageal motility. Medicine (Baltimore) 2015;94:e1669.
Marin I, Serra J. Patterns of esophageal pressure responses to a rapid drink challenge test in patients with esophageal motility disorders. Neurogastroenterol Motil 2016;28:543-53.
Jain M, Srinivas M, Bawane P, Venkataraman J. Multiple rapid swallow testing in patients with gastroesophageal reflux disease. Indian J Gastroenterol 2018;37:555-8.
Jain M. Achalasia Cardia-A diagnosis often delayed! Indian J Gastro 2019;38:183-4.
Bredenoord AJ, Fox M, Kahrilas PJ, Pandolfino JE, Schwizer W, Smout AJ, et al
. Chicago classification criteria of esophageal motility disorders defined in high resolution esophageal pressure topography. Neurogastroenterol Motil 2012;24 Suppl 1:57-65.
Bredenoord AJ, Hebbard GS. Technical aspects of clinical high-resolution manometry studies. Neurogastroenterol Motil 2012;24 Suppl 1:5-10.
Srinivas M, Jain M, Bawane P, Jayanthi V. Chicago classification normative metrics in a healthy Indian cohort for a 16-channel water-perfused high-resolution esophageal manometry system. Neurogastroenterol Motil 2018;30:e13386.
Srinivas M, Jain M, Bawane P, Jayanthi V. Normative values for esophageal motility assessed in the physiological seated position for 16-channel water perfused high-resolution esophageal manometry system and postural variations in healthy volunteers. J Neurogastroenterol Motil 2020;26:61-6.
Roman S, Kahrilas PJ, Boris L, Bidari K, Luger D, Pandolfino JE. High-resolution manometry studies are frequently imperfect but usually still interpretable. Clin Gastro Hepatol 2011;9:1050-55.
Jain M. Technical problems encountered during esophageal manometry-An audit. Tropical Gastroenterol 2018;39:147-8.
Gyawali CP, Bredenoord AJ, Conklin JL, Fox M, Pandolfino JE, Peters JH, et al
. Evaluation of esophageal motor function in clinical practice. Neurogastroenterol Motil 2013;25:99-133.
Raeside MC, Madigan D, Myers JC, Devitt PG, Jamieson GG, Thompson SK. Post-fundoplication contrast studies: Is there room for improvement? Br J Radiol 2012;85:792-9.
Jain M, Srinivas M, Jayanthi V. Chicago classification for minor peristaltic abnormalities-much ado about nothing! Indian J Gastro 2019;38:362-3.
Monrroy H, Cisternas D, Bilder C, Ditaranto A, Remes-Troche J, Meixueiro A, et al
. The Chicago classification 3.0 results in more normal findings and fewer hypotensive findings with no difference in other diagnoses. Am J Gastroenterol 2017;112:606-12.
Bogte A, Bredenoord AJ, Oors J, Siersema PD, Smout AJ. Relationship between esophageal contraction patterns and clearance of swallowed liquid and solid boluses in healthy controls and patients with dysphagia. Neurogastroenterol Motil 2012;24:e364-72.
Liang B, Yi Q, Feng Y. Association of gastroesophageal reflux disease with asthma control. Dis Esophagus 2013;26:794-8.
Jain M, Srinivas M, Bawane P, Venkataraman J. Does Chicago classification address symptom correlation with high-resolution esophageal manometry? Euroasian J Hepatogastroenterol 2017;7:122-5.
Saha AK, Roy N, Hazra SC. Role of esophageal manometry in patients with reflux symptoms, dysphagia and noncardiac chest pain. Int J Recent Scientific Res 2015;6:2599-601.
Jain M, Agrawal V. Role of esophageal manometry and 24-h pH testing in patients with refractory reflux symptoms. Indian J Gastroenterol 2020;39:165-70.
Andolfi C, Bonavina L, Kavitt RT, Konda VJ, Asti E, Patti MG. Importance of esophageal manometry and pH monitoring in the evaluation of patients with refractory gastroesophageal reflux disease: A multicenter study. J Laparoendosc Adv Surg Tech A 2016;26:548-50.
Jain M. Evaluation of noncardiac chest pain in Indian setting--can we reduce the investigation burden? Indian J Gastroenterol 2015;34:266-7.
Jain M. Normal study or minor motility disorders detected in high resolution esophageal manometry-Are they relevant? Gastroenterology Rev 2020;15:76-7.
Ravi K, Friesen L, Issaka R, Kahrilas PJ, Pandolfino JE. Long-term outcomes of patients with normal or minor motor function abnormalities detected by high-resolution esophageal manometry. Clin Gastroenterol Hepatol 2015;13:1416-23.
Herregods TV, Roman S, Kahrilas PJ, Smout AJ, Bredenoord AJ. Normative values in esophageal high-resolution manometry. Neurogastroenterol Motil 2015;27:175-87.
Bakhos CT, Petrov RV, Parkman HP, Malik Z, Abbas AE. Role and safety of fundoplication in esophageal disease and dysmotility syndromes. J Thorac Dis 2019;11:S1610-7.
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]