Can the upper esophageal sphincter contractile integral help classify achalasia?

BACKGROUND: The use of high-resolution manometry (HRM) in achalasia patients has revealed abnormal findings concerning upper esophageal sphincter (UES) function. The introduction of the UES contractile integral (UES-CI), as with the distal contractile integral (DCI), may complement the interpretation of the manometric study of achalasia subtypes, defined by the Chicago Classification v3.0. METHODS: Patients were classified into achalasia subtypes based on HRM. UES length (cm), UES resting pressure (mmHg), and UES residual pressure (mmHg) were recorded. UES-CI (mmHg·sec·cm) was calculated in a manner similar to that used for the DCI measurement at rest (landmark CI), corrected for respiration, and its relation to achalasia subtypes was evaluated. RESULTS: Twenty-four achalasia patients with mean age 55.29 years were included. Of these, 16.6% (n=4) were diagnosed with achalasia type I, 58.3% (n=14) with type II, and 25% (n=6) with type III. The landmark UES-CI, mean UES-CI, UES-CI corrected for respiration, and UES resting pressure were found to be significantly higher among patients with achalasia type II compared to the other types (1768.9 vs. 677.1, P=0.03; 1827.1 vs. 3555.1, P=0.036; 174.2 vs. 72.8, P=0.027; and 108.1 vs. 55.8, P=0.009, respectively). CONCLUSIONS: We introduce the CI index as a tool for the manometric evaluation of the UES in achalasia. UES resting pressure, landmark UES-CI and mean UES-CI were significantly higher in achalasia patients with panesophageal pressurization compared to types I and III. This finding may reflect a protective reaction against the risk of aspiration in this group, but further studying and clinical correlation is required.