Normal ranges of continuous pH monitoring in the proximal esophagus

Background: To determine normal ranges of gastroesophageal reflux (GER) in the proximal esophagus, measured with continuous pH monitoring. Normal rang es in the distal esophagus have been published. Because esophageal pH monit oring is frequently performed in children with atypical manifestations such as chronic respiratory disease, and because one of the possible pathophysi ologic mechanisms may be (micro-)aspiration, it may be relevant to establis h normal ranges in the proximal esophagus. Methods: Twenty-four-hour pH monitoring was performed in 200 children with suspected GER disease. The mean age of the patients was 4.5 months (range, 0.5-17.0 months). After initial analysis, patients were divided into three groups according to the reflux index CRI) in the distal esophagus, because it could be speculated that the amount of reflux reaching the proximal esop hagus depends on the amount of reflux in the distal esophagus: Group I(n:12 0) children had a distal RI of less than 5% and were considered normal, gro up IT (n:50) had a distal RI of 5% to 10% and was considered to have interm ediate disease, and group III (n:30) had a distal RI of more than 10% and w as regarded as pathologic. The following parameters are calculated: the RI, the total number of reflux episodes, the number of reflux episodes lasting more than 5 minutes, the duration of the longest reflux episode, and the a cid clearance time (ACT). Results: The median RI in the distal esophagus was 3.8 +/- 0.34 (standard e rror of the mean [SEMI), and in the proximal esophagus, the RI was 1.2 +/- 0.23. In,group I patients, the RT in the proximal esophagus was 0.5% +/- 0. 09%,in group II the RI increased significantly to 2.75% +/- 0.34% CP [group I compared with group III < 0.01), and in group III the RT was 6.15% +/- 0 .96% (P [II-III] < 0.01). The number of acid reflux episodes in group I was 17.0 +/- 2.27, in group II the number increased to 62.5 +/- 8.18 (P [I-II] < 0.01), and in group III it reached 102.0 +/- 23.9 (P [II-III] < 0.05). A lso the duration of the longest reflux episodes and the number of reflux ep isodes lasting more than 5 minutes increased from group I to group IT, and from group Il to group Ill. The ACT was shorter in the proximal esophagus ( group I 0.3 +/- 0.06 minutes; group II 0.48 +/- 0.07 minutes, P [I-II] = no t significant [NS]; group III 0.56 +/- 0.17 minutes P [II-III] = NS) than i n the distal esophagus (group I 0.49 +/- 0.03 minutes, P [proximal ACT comp ared with distal ACT] < 0.05; Group II 0.76 +/- 0.05 minutes, P [proximal-d istal] < 0.01; Group Ill 0.89 +/- 0.09 minutes, P [proximal-distal] = NS) s uggesting more effective esophageal clearance in the proximal esophagus. Conclusions: Protection of the proximal esophagus from acid reflux is signi ficantly related to the incidence and duration of reflux measured in the di stal esophagus. These normal ranges in the upper esophagus will be helpful in the interpretation of upper esophageal pH monitoring data.