Esophageal pressure topography or Clouse plot (left image) and the corresponding line plot (right image) from a normal swallow in HRM. The dotted white line indicates the start of the swallow at the beginning of UES relaxation. The contraction of the S1 striated muscle segment is followed by contraction of the S2 and S3 smooth muscle segments. The transition from striated to smooth muscle is indicated by the transition zone (TZ). Darker hues represent higher pressures and cooler hues represent lower pressures. The distal contractile integral (DCI) is a measure of esophageal smooth muscle vigor and is calculated from the TZ to the proximal margin of the LES. The contractile deceleration point (CDP) is defined as the inflection point within 3 cm of the proximal margin of the LES. Distal latency (DL) is the interval between UES relaxation and the CDP. IRP is defined as the mean of the 4 s of maximal deglutitive relaxation in the 10-s window, which need not be consecutive, beginning at UES relaxation
High-resolution manometry simplifies the manometric procedure and its interpretation, providing “at-a-glance” assessment of the esophagus and both sphincters and precluding the need for technical requirements such as station pull-through, reducing the time needed for the test . Compared with line tracings , HRM allows for easier identification of anatomic landmarks such as the UES and LES , and pattern recognition of motor patterns such as achalasia, jackhammer esophagus, or absent contractility, and is particularly suited for identification of esophageal outflow obstruction . These aspects support the advantage of HRM over alternative recording techniques. A randomized control trial has demonstrated that compared to conventional manometry , HRM improves the diagnostic yield of esophageal motility disorders in patients with dysphagia .
Complete HRM systems consisting of the manometric catheter and recording software are available from several companies (Sandhill Scientific, Sierra Scientific/Given, and MMS). The “Chicago Classification ” (Table 18.1) is an evolving analysis paradigm in its third iteration that takes advantage of the increased detail and accuracy afforded by HRM to classify esophageal motor disorders. It is endorsed by the American Neurogastroenterology and Motility Society and European Society of Neurogastroenterology and Motility and is increasingly used in the interpretation of HRM findings in motility labs . Values that inform the Chicago Classification are derived from water swallows using the Sierra Scientific/Given adult version 36-channel circumferential (sensors 1 cm apart) solid-state HRM catheter (4.2 mm) and software . Normative values have also been established for other systems as well as for solid boluses.
The Chicago Classification of esophageal motility V. 3
Achalasia and EGJ outflow obstruction
Type I achalasia (classic achalasia)
Elevated median IRP (>15 mmHga), 100% failed peristalsis (DCI <100 mmHg s cm)
Premature contractions with DCI values less than 450 mmHg s cm satisfy criteria for failed peristalsis
Type II achalasia (with esophageal compression)
Elevated median IRP (>15 mmHga), 100% failed peristalsis, pan-esophageal pressurization with ≥20% of swallows
Contractions may be masked by esophageal pressurization and DCI should not be calculated
Type III achalasia (spastic achalasia)
Elevated median IRP (>15 mmHga), no normal peristalsis, premature (spastic) contractions with DCI >450 mmHg s cm with ≥20% of swallows
May be mixed with pan-esophageal pressurization
EGJ outflow obstruction
Elevated median IRP (>15 mmHga), sufficient evidence of peristalsis such that criteria for types I–III achalasia are not metb
Major disorders of peristalsis
(Not encountered in normal subjects)
Normal median IRP, 100% failed peristalsis
Achalasia should be considered when IRP values are borderline and when there is evidence of esophageal pressurization
Premature contractions with DCI values less than 450 mmHg s cm meet criteria for failed peristalsis
Distal esophageal spasm
Normal median IRP, ≥20% premature contractions with DCI >450 mmHg s cma. Some normal peristalsis may be present
Hypercontractile esophagus (jackhammer)
At least two swallows with DCI >8000 mmHg s cma,c
Hypercontractility may involve, or even be localized to, the LES
Minor disorders of peristalsis
(Characterized by contractile vigor and contraction pattern)
Ineffective esophageal motility (IEM)
≥50% ineffective swallows
Ineffective swallows can be failed or weak (DCI<450 mmHg s cm)
Multiple repetitive swallow assessment may be helpful in determining peristaltic reserve
≥50% fragmented contractions with DCI >450 mmHg s cm
Normal esophageal motility
Not fulfilling any of the above classifications
Although software algorithm-based computerized analyses provide an overall interpretation of HRM data according to accepted metrics, each test swallow should be reviewed by the interpreting physician to ensure that anatomic landmarks and measurement parameters are properly identified to avoid misleading diagnoses based on automated analysis. Normal and abnormal esophageal motor patterns, however, can often be recognized quickly without detailed analysis.
Why Do I Need an Esophageal Manometry Study?
Response to the Patient
There are several reasons why your doctor orders an esophageal manometry. The main reason is evaluation of your difficulty in swallowing (dysphagia ) for which a definitive diagnosis has not been achieved by endoscopy or radiographic studies. Other indications include evaluation of chest pain once cardiac causes or musculoskeletal pain have been excluded. Manometry is also used to definitively establish the diagnosis of achalasia , an esophageal motility disorder characterized by absent or abnormal esophageal contractions and failure of the lower esophageal sphincter to relax. Other indications include evaluation of esophageal involvement in connective tissue diseases such as scleroderma, identifying the lower esophageal sphincter location for placement of catheters that measure esophageal acid exposure, and evaluating esophageal motor function prior to anti-reflux surgery or evaluation of dysphagia after such operations.
Brief Review of Supporting Evidence
Esophageal manometry is used primarily to evaluate esophageal motility and often serves as a complementary study to upper endoscopy and barium esophagram in the assessment of bolus transit. The primary indication for esophageal manometry is evaluation of dysphagia after endoscopy or radiographic studies have not revealed a structural etiology resulting in mechanical obstruction or an inflammatory condition such as eosinophilic esophagitis. It is also used to definitively establish the diagnosis of achalasia after suggestive barium or endoscopic studies. Achalasia subtypes can also be distinguished based on manometric patterns. Symptoms such as regurgitation, heartburn, or chest pain, for which endoscopy and/or barium contrast studies have not provided a structural explanation can also be evaluated with manometry. Other indications include evaluation of esophageal involvement in connective tissue diseases such as scleroderma, identification of the lower esophageal sphincter location for placement of an ambulatory pH and pH-impedance probe, evaluation of esophageal motor function prior to fundoplication, or evaluation of dysphagia and regurgitation following foregut surgery such as fundoplication or bariatric procedures such as laparoscopic band placement  (Table 18.2).
Indications and contraindications for esophageal manometry
Suspicion of achalasia
Noncardiac chest pain
Abnormal oral-pharyngeal anatomy
Identification of LES for placement of pH or pH-impedance catheters
Infiltrating tumor or abnormal nasal passages that prevent catheter insertion
Evaluation of esophageal function prior to anti-reflux surgery
Altered mental status
Evaluation of esophageal involvement in connective tissue disorders, e.g., scleroderma
Chronic anticoagulation, the inability to swallow on command or the inability to tolerate the catheter
Absolute contraindications include esophageal obstruction from an infiltrating process such as a tumor, abnormal nasal passages preventing transnasal catheter insertion, abnormal oropharyngeal anatomy, frank aspiration with water swallows, significantly abnormal coagulation, or altered mental status. Relative contraindications include patients on chronic anticoagulation, inability to swallow on command, or inability to tolerate the catheter  (Table 18.2). In these instances, if the procedure is absolutely necessary, the catheter can sometimes be placed endoscopically. The sedation required for endoscopic placement of the manometric catheter ideally consists of propofol with monitored anesthesia and avoids the use of benzodiazepines and in particular narcotics that may alter esophageal motility . Placement of a manometry catheter in patients with esophageal varices should be approached with caution.
The HRM Manometry Report and the Clinical Implications of HRM
As more and more motility labs are using HRM technology, we will describe the HRM metrics that inform the basis of the Chicago Classification , a hierarchical algorithm for the interpretation of HRM studies and classification of esophageal motility disorders . These include disorders of esophagogastric junction (EGJ) outflow obstruction: achalasia and its variants including EGJ outflow obstruction; major disorders of peristalsis: distal esophageal spasm, jackhammer esophagus, and absent contractility; and minor peristaltic disorders: ineffective motility and fragmented peristalsis . These diagnoses may have clinical implications which are also described below.
The resting characteristics of the UES and LES are easily recognized by horizontal bands of higher pressure color in the proximal and distal sensors, respectively. Variations in pressure in the LES induced by respiration can be seen as cyclical changes in color. An electronic tool called the eSleeve is positioned to straddle the LES for 6 cm and calculates the highest pressure at each point in time during a 10-s deglutitive window which begins with relaxation of the UES. LES relaxation is then derived using a 4-s integrated relaxation pressure (IRP) algorithm that calculates the lowest mean of these pressures. IRP is defined as the mean of the 4 s of maximal deglutitive relaxation in the 10-s window, which need not be consecutive, beginning at UES relaxation .