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Training in GI Upper Motility Techniques

Anthony Lembo and Raxitkumar Patel

Division of Gastroenterology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA

Gastrointestinal (GI) motility is defined by coordinated movements of the digestive tract resulting in transit of contents within it. A variety of motility disorders can affect the GI tract from the beginning of the GI tract (esophagus) to its end (colon and rectum) and frequently result in a significant impact on patients’ quality of life. In recent years, significant progress has been made in understanding the pathophysiology of GI motility disorders as well as methods of evaluating motility in the GI tract, including the introduction of high‐resolution motility equipment. This chapter will focus on techniques used to evaluate motility disorders of the upper GI tract with a focus on the esophagus and high‐resolution esophageal manometry as well as other motility techniques, such as Endoflip, Smart Pill, and reflux testing.

Esophageal manometry testing

Esophageal Anatomy

The esophagus is a tubular muscular structure approximately 20–25 cm in length, with sphincters at the upper and lower end. The main function of the esophagus is to deliver food to the stomach by sequential, coordinated (i.e., peristaltic) contractions that travel the length of the esophagus. The lumen of the esophagus has the ability to distend to approximately 2 cm in the anterior‐posterior dimension and up to 3 cm laterally to accommodate a swallowed bolus.

The esophagus wall is composed of striated muscle in the upper one‐third of the esophagus and smooth muscle in the lower two‐thirds of the esophagus. The musculature of the esophagus consists of an outer layer of longitudinal fibers and an inner layer of circular fibers. The longitudinal muscle is responsible for shortening the esophagus and the circular muscle generates lumen‐occluding contractions. Within the wall of the esophagus exist ganglia of the intramural myenteric (Auerbach’s plexus) and the submucosal plexus (Meissner’s plexus), which provide the intrinsic innervation of the esophagus. Auerbach’s plexus regulates contraction of the outer muscle layers, whereas Meissner’s plexus regulates secretion and the peristaltic contractions of the muscularis mucosae. The esophagus also receives extrinsic innervation from the vagal and spinal nerves that initiate and help regulate motility.

Lower esophageal sphincter

In contrast to the upper esophageal sphincter (UES), which is composed of skeletal muscles and is under voluntary control, the lower esophageal sphincter (LES) is composed of smooth muscle and is not under voluntary control. The LES is under neurohormonal influence, and relaxes with the initiation of swallowing to allow passage of food from esophagus but otherwise maintains a steady baseline tone to prevent regurgitation of food and acid from the stomach (Figure 31.1).

In addition, the diaphragm functions as an adjunctive external sphincter that raises the pressure of the LES particularly during periods of increased intra‐abdominal pressure. Because of the firm anchoring of LES and crural diaphragm by the phrenoesophageal ligament, the two structures move together with inspiration and expiration but can separate during longitudinal esophageal muscle contraction related to peristalsis and transient LES relaxation (Figures 31.2 and 31.3). The combination of the crural diaphragm and LES is known as the esophagogastric junction (EGJ).

Normal peristaltic contraction within the esophagus starts with the initiation of a swallow, which causes the LES to relax, and initiates a peristaltic wave that propels contents into the stomach (Figures 31.4–31.6). This type of contraction is known as primary peristalsis (Figures 31.4 and 31.5) and can be evaluated by esophageal manometry. Other types of peristaltic contractions include secondary peristaltic (i.e., triggered by esophageal distension from retained bolus, refluxed material, or swallowed air) and tertiary contractions (i.e., non‐peristaltic, simultaneous, isolated, dysfunctional contractions) and are not generally evaluated during manometry.

Schematic illustration of esophagus anatomy. — **Figure 31.1** Esophagus anatomy.

Schematic illustration of lower esophageal sphincter (LES) anatomy. — **Figure 31.2** Lower esophageal sphincter (LES) anatomy*.

Esophageal motility studies

Esophageal manometry assesses the functional integrity of esophagus by measuring pressures, peristalsis pattern, and flow of content from the lumen of the esophagus into the stomach. While there are other techniques to assess the motor function of the esophagus (i.e., barium swallow, Endoflip), manometry remains the gold standard.

Esophageal manometry testing has been used since the 1960s [2]. The initial manometry catheter used either water perfusion or solid‐state sensors to assess esophageal pressures, typically with four to eight sensors spaced 4–5 cm apart, with line tracings of pressure versus time generated by each sensor. More recently, high‐resolution manometry (HRM) catheters have become the norm. HRM catheters generally have 36 pressure sensors spaced 1 cm apart, thereby generating better functional imaging of the contractions within the esophagus. HRM data are displayed via esophageal pressure topography, which produces dynamic, colorful, spatiotemporal (Figures 31.4 and 31.6) topography plots to depict pressure changes along length and time. Due to the presence of more closely positioned sensors, it allows for detailed evaluation of the sphincters, particularly during swallowing and breathing, as well as evaluation of small hiatal hernias. Diagnostic accuracy is greater for HRM compared to conventional line tracing [3–7].

Procedure and patient protocols

HRM is performed with the patient in the supine AND semi‐upright position in a fasting state [8]. The esophageal manometry catheter is passed through one of the nostrils, through the oropharynx, and into the stomach. After the patient has adjusted to the placement of the catheter, a 30 seconds baseline assessment (i.e., Landmark period) is obtained to measure a baseline pressure of the UES and LES without swallowing. The patient then is asked to swallow 5 mL of water followed by recordings of 30 seconds before the next wet swallow. This time allows the LES to return to its basal state, and prevents deglutition inhibition from impacting subsequent swallows. A minimum of 10 such wet swallows are obtained. Provocative testing, including multiple rapid swallows and rapid drink challenge can be used to identify clinically relevant motility disorders.

Analysis of HRM

Baseline assessment (Landmark)

The Landmark period consists of a 30 second period without swallows after patient has adjusted to the placement of the catheter. During the Landmark period, resting pressures of the UES and LES are obtained. The UES and LES are usually easily identified (Figure 31.7) as two areas of distinct high‐pressure zones that relax with swallows. A gastric marker is normally positioned 2 cm below the distal border of the LES (Figure 31.7).

Schematic illustration of normal primary peristalsis as assessed by high-resolution manometry with spatiotemporal topography. — **Figure 31.4** Normal primary peristalsis as assessed by high‐resolution manometry with spatiotemporal topography. Contractile segment (CS), upper esophageal sphincter (UES), lower esophageal sphincter (LES), esophageal gastric junction (EGJ).

Schematic illustration of conventional line plots esophageal manometry. — **Figure 31.5** Conventional line plots esophageal manometry.

The transition point where positive pressure generated by intra‐abdominal cavity to the negative pressure generated by intrathoracic cavity is known as the pressure inversion point (PIP). The PIP indicates the division point between intrathoracic and intra‐abdominal cavity by the crural diaphragm (Figure 31.8). The PIP is normally located immediately above the proximal edge of the lower esophageal sphincter. Displacement of the PIP typically indicates the presence of a hiatal hernia.

Based on the location of the PIP relative to the LES, three different subtypes of EGJ morphology can be identified [9], which allow for assessment of whether a hiatal hernia is present, its size, and pressurization pattern.

Analysis of swallows

Motility in the body of the esophagus is measured during 10 swallows with 5 cc of water 30 seconds apart [10]. Normally, a swallow begins with relaxation of the UES and deglutitive relaxation of the LES, with contraction along the length of the esophagus, and then restoration of the baseline LES pressure.

Schematic illustration of typical swallow pressure topography, also known as Clouse plots in honor of Ray E. Clouse (1951–2007), spanning from the pharynx to stomach of a normal subject with normal peristalsis and normal EGJ relaxation. — **Figure 31.6** Typical swallow pressure topography, also known as Clouse plots in honor of Ray E. Clouse (1951–2007), spanning from the pharynx to stomach of a normal subject with normal peristalsis and normal EGJ relaxation [33].

Schematic illustration of upper esophageal sphincter (UES) and lower esophageal sphincter (LES) location at rest (Landmark). — **Figure 31.7** Upper esophageal sphincter (UES) and lower esophageal sphincter (LES) location at rest (Landmark).

Integrated relaxation pressure (IRP)

IRP is an assessment of the EGJ relaxation following swallow. IRP is the lowest mean pressure across the EGJ, continuous or non‐continuous, in the 10 seconds window beginning with the initiation of a swallow [10]. Elevated IRP values indicate increased resistance to bolus transit across EGJ [11]. Abnormal IRP could be due to a mechanical or functional process that blocks flow across the EGJ [11], such as achalasia or stricture. The IRP is referenced to intragastric pressure as determined by the gastric marker [10] (Figure 31.9).

Schematic illustration of pressure inversion point (PIP), inspiration (I), expiration (E). Thoracic pressure (blue line), abdominal pressure (green line). — **Figure 31.8** Pressure inversion point (PIP), inspiration (I), expiration (E). Thoracic pressure (blue line), abdominal pressure (green line).

Schematic illustration of different metrics of high-resolution esophageal pressure topography (EPT). — **Figure 31.9** Different metrics of high‐resolution esophageal pressure topography (EPT). Integrated relaxation pressure (IRP), contractile deceleration point (CDP), distal latency (DL), distal contractile integral (DCI), upper esophageal sphincter (UES), lower esophageal sphincter (LES).

Contractile deceleration point (CDP)

The CDP is the region in the distal esophagus where there is deceleration in the peristaltic wave prior to the LES [12–15] (Figure 31.9). The CDP defines the termination of rapid esophageal peristalsis, and the progression of slower ampullary emptying [16]. The CDP is usually associated with the point of greatest axial contraction of the esophagus [16, 17], and must be located within 3 cm of the proximal margin of the LES.

Distal latency (DL)

Time between the start of swallow‐induced UES relaxation to esophageal contraction at the CDP [10]. It is the period of deglutitive inhibition [18]. A swallow is considered premature or spastic if the DL is less than 4.5 seconds (Figures 31.9 and 31.10) [10, 16]. DL should only be assessed in a swallow with DCI values above 450 mmHg · s · cm [10].

Contraction vigor—distal contractile integral (DCI)

DCI measures the vigor of peristalsis in the distal two‐third of esophagus (i.e., between the smooth muscle transition zone in the esophagus to the most proximal aspect of EGJ). It is generated by calculating the product of the average amplitude of smooth muscle contraction, contraction duration, and length. The normal range of DCI is between 450 and 8000 mmHg · s · cm. Contractions are characterized as hypercontractile if DCI > 8,000 mmHg · s · cm (Figure 31.11d), and ineffective if DCI < 450 mmHg · s · cm. Ineffective swallows are further characterized as weak if DCI is between 100 and 450 mmHg · s · cm, and failed if DCI < 100 mmHg · s · cm [11, 19] (Figures 31.10 and 31.12).

Schematic illustration of premature contraction, distal latency less than 4.5 seconds with DCI more than 450 mmHg ∙ s ∙ cm. — **Figure 31.10** Premature contraction, distal latency less than 4.5 seconds with DCI more than 450 mmHg ∙ s ∙ cm.

Peristaltic pattern (integrity) is evaluated by the presence of spatial breaks or gaps in the 20 mmHg isobaric contour. A swallow with a peristaltic break greater than 5 cm but otherwise normal contractile vigor and distal latency is classified as a fragmented contraction [10] (Figure 31.13c).

There are two types of abnormal esophageal pressurization patterns: compartmentalized esophagus, and panesophageal pressurization (Figure 31.12).