OBJECTIVE: Gastroesophageal reflux (GER) is increased in the right compared to the left recumbent position. Esophageal acid exposure is related to the acidity at the cardia, but the effect of body position on the acidity at the cardia has not yet been investigated. We aimed to investigate the mechanisms underlying increased esophageal acid exposure in the right recumbent position. METHODS: On 2 separate days a 4-h combined esophageal and lower esophageal sphincter (LES) manometry and pH recording of esophagus, gastric cardia, and corpus was performed in the right and left recumbent position after a high fat meal in 10 healthy subjects. RESULTS: In the right recumbent position a prolonged esophageal acid exposure (7.0% vs 2.0%, p < 0.03), a higher incidence of reflux episodes (3.8 vs 0.9/h, p < 0.03), more transient LES relaxations (TLESRs) (6.5 vs 3.2/h, p < 0.03), and higher percentage TLESRs associated with reflux (57.0% vs 22.4% p < 0.03) was recorded than in the left supine position. Acidity at gastric cardia and corpus was not affected by body position. CONCLUSIONS: Increased esophageal acid exposure in the right recumbent position relative to the left recumbent position is the result of a higher incidence of GER episodes caused by an increased incidence of TLESRs and higher percentage of TLESRs associated with GER. Body position does not affect the acidity at the gastric cardia and corpus. (C) 2000 by Am. Coll. of Gastroenterology.
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