Chicago Classification v4.0 (CCv4.0) is the updated classification scheme for esophageal motility disorders using metrics from high‐resolution manometry (HRM). Fifty‐two diverse international experts separated into seven working subgroups utilized formal validated methodologies over two‐years to develop CCv4.0. Key updates in CCv.4.0 consist of a more rigorous and expansive HRM protocol that incorporates supine and upright test positions as well as provocative testing, a refined definition of esophagogastric junction (EGJ) outflow obstruction (EGJOO), more stringent diagnostic criteria for ineffective esophageal motility and description of baseline EGJ metrics. Further, the CCv4.0 sought to define motility disorder diagnoses as conclusive and inconclusive based on associated symptoms, and findings on provocative testing as well as supportive testing with barium esophagram with tablet and/or functional lumen imaging probe. These changes attempt to minimize ambiguity in prior iterations of Chicago Classification and provide more standardized and rigorous criteria for patterns of disorders of peristalsis and obstruction at the EGJ.

Normative values for esophageal function for solids as well as liquids and in the 'physiologic', upright position will optimize the utility of HRM studies. The high level of inter-observer agreement indicates that these can be applied as reference values in clinical practice.

Background/Aims: The Chicago Classification for diagnosis of esophageal motility disorders by high-resolution manometry (HRM) is based on single water swallows (SWS).Emerging data suggest that a "Rapid Drink Challenge" (RDC) increases sensitivity for motility disorders. This study establishes normal values and diagnostic thresholds for RDC in clinical practice. Methods Results:Normal values were determined in healthy (n=95; age 37.8 ± 12) and patient controls (n=44; age 46.4 ± 15). Development and validation sets included 178 (54 ± 17 years) and 226 (53 ± 16 years) patients, respectively. Integrated relaxation pressure during RDC was higher for SWS than RDC in all groups (overall P<.001), except achalasia. Rapid Drink Challenge suppressed contractility, except in achalasia type III, spasm, and hypercontractile motility disorders (P<.001). An effective aftercontraction was present more often in health than disease (P<.001). Optimal diagnostic thresholds identified in the development set (IRP-RDC ≥12 mmHg achalasia, IRP-RDC ≥ 8mmHg "all cause" EGJ dysfunction), were confirmed in the validation set (both, sensitivity ~85%, specificity >95%). Conclusions:Rapid Drink Challenge contributes clinically relevant information to routine HRM studies, especially in patients with EGJ dysfunction. K E Y W O R D Sdiagnostic classification, esophageal motility disorders, high-resolution manometry, multiple water swallows, prospective cohort study, Rapid Drink Challenge