End expiration is more accurate than mid respiration in measuring lower esophageal sphincter pressure

Two ways popularly used to measure lower esophageal sphincter pressure are the mid-respiratory and end-expiratory methods. The aim of this study was to compare the suitability of these methods in the manometric assessment of patients with endoscopically documented esophagitis.

Manometry was performed on 22 consecutive patients to determine whether medical therapy or surgery was the more appropriate treatment strategy. Lower esophageal sphincter pressure was measured during a slow station pull-through. End-expiratory lower esophageal sphincter pressure was assessed by measuring the highest trough which coincided with end expiration. Mid-respiratory lower esophageal sphincter pressure was assessed by bracketing the highest pressure over >/=3 respiratory cycles and measuring the mid point.

Mid-respiratory lower esophageal sphincter pressure (25.6 mm Hg) was higher (p < 0.0001) than end-expiratory lower esophageal sphincter pressure (15.7 mm Hg). Nine (41%) end-expiratory lower esophageal sphincter pressures were abnormally low (i.e., <10 mm Hg), whereas three (14%) mid-respiratory lower esophageal sphincter pressures were abnormally low (i.e., <14 mm Hg; p = 0.042). CONCLUSIONS Mid-respiratory lower esophageal sphincter pressure measurement includes respiratory artifact and does not accurately measure lower esophageal sphincter pressure. End-expiratory sphincter pressure better identifies potential surgical candidates.