Standard values of 24-h multichannel intraluminal impedance–pH monitoring for the Japanese

Background Combined multichannel intraluminal impedance and pH monitoring (MII–pH) is the gold standard for diagnosing gastroesophageal reflux (GER), but there are no concrete data for a Japanese population. The aim of this study is to determine the standard values of MII–pH for a Japanese population. Methods Twenty healthy Japanese volunteers without symptoms of GER were recruited through the homepage of the Department of Surgery at The Jikei University School of Medicine. Their mean age was 29.0 ± 3.0 years (range 24–36) and three of the volunteers were women (15 % of the total number of volunteers). The volunteers underwent MII–pH measurements at 6 sites. These sites were centered at 3, 5, 7, 9, 15, and 17 cm higher than the lower esophageal sphincter (LES) and a pH-monitoring device was placed 5 cm above the upper border of the LES. GER events were detected and divided into acid or non-acid reflux by pH and liquid acid or liquid non-acid reflux by impedance. Results The normal values of MII–pH for the Japanese population were as follows: a pH below 4 holding time of less than 2.5 %, less than 2.1 total number of reflux events longer than 5 min, duration of the longest reflux event less than 12.7, and DeMeester Score less than 11.0. The total number of liquid reflux events was less than 80. The total number of liquid acid reflux events and liquid non-acid reflux events was less than 49 and 58, respectively. Conclusions We provided the standard values of MII–pH for a Japanese population.