The Chicago Classification defines esophageal motility disorders in high resolution manometry. This is based on individual scoring of 10 swallows performed in supine position. Disorders of esophago-gastric junction (EGJ) outflow obstruction are defined by a median integrated relaxation pressure above the limit of normal and divided into 3 achalasia subtypes and EGJ outflow obstruction. Major motility disorders (aperistalsis, distal esophageal spasm, and hypercontractile esophagus) are patterns not encountered in controls in the context of normal EGJ relaxation. Finally with the latest version of the Chicago Classification, only two minor motor disorders are considered: ineffective esophageal motility and fragmented peristalsis.

Keywords

Esophageal high-resolution manometry

Achalasia

Esophagogastric junction outflow obstruction

Aperistalsis

Distal esophageal spasm

Hypercontractile esophagus

Ineffective esophageal motility

Key points

Introduction

High-resolution manometry (HRM) is the current gold standard technique to assess esophageal motility. It uses closely spaced pressure sensors to create a dynamic representation of pressure change along the entire length of the esophagus. Data acquisition is easier than with conventional manometry and interpretation is facilitated by esophageal pressure topography (Clouse) plots.1

Along with the technological innovation, an international consensus process has evolved over recent years to define esophageal motility disorders using HRM, Clouse plots, and standardized metrics. This classification, titled the Chicago Classification, was firstly published in 20092 and was subsequently updated in 2012.3 It was intended to be applied to HRM studies performed in a supine position with 5-mL water swallows and for patients without previous esophagogastric surgery. The 2012 version of the Chicago Classification focused entirely on redefining esophageal motor disorders associated with dysphagia in HRM terms; it did not provide guidance on the assessment of the esophagogastric junction (EGJ) at rest or upper esophageal sphincter (UES) function. Since that publication, substantial further research has been presented and published, intended to improve the diagnostic accuracy and clinical utility of the Chicago Classification. In recognition of this, the international HRM Working Group met in Chicago in May 2014 in conjunction with Digestive Disease Week to discuss these new data in the context of working toward an update of the Chicago Classification (v3.0). This article presents a brief summary of these discussions and proposals to work toward the Chicago Classification 3.0; a process due to be completed in early 2015.

Metrics and swallow pattern characterization

The Chicago Classification is based on scoring of 10 5-mL water swallows performed in supine position. EGJ relaxation, esophageal contractile activity, and esophageal pressurization are evaluated for each swallow. However, a major indication for manometric studies is in the evaluation of patients for potential antireflux surgery and some description of EGJ morphology and quantification of contractility is desirable. Hence, the incorporation of simple metrics relevant to these aspects of motility will be incorporated into Chicago Classification v3.0. Proposed metrics under discussion include mean inspiratory pressure, mean expiratory pressure, the extent and variability of the separation between the lower esophageal sphincter (LES) and crural diaphragm (CD separation), and the EGJ contractile integral (CI), all of which have been used in publications. However, discrepancies exist in the details of calculation methodology for these metrics, the strength of data supporting their utility, and their normative ranges among HRM devices,4–11 all of which are important limitations meriting further consideration.