[Pathophysiology and treatment of reflux esophagitis]

Reflux esophagitis (RE) is characterized by excessive esophageal acid exposure. The number of acid reflux episodes, the way acid comes up after reflux and the delay of acid bolus clearance cause excessive esophageal acid exposure. Transient lower esophageal sphincter relaxation (TLESR) is the major mechanism of acid reflux in both healthy subjects (HS) and in patients with RE, but there is no difference in the rate of TLESRs or in the rate of acid reflux during TLESRs above the LES between HS and patients with RE. In patients with severe RE, refluxed acid above the LES rises more easily to the proximal esophagus but it does not clear easily from the esophagus when compared with HS. To cure RE, it is necessary to normalize excessive esophageal acid exposure. In GERD guideline in Japanese Society of Gastroenterology, standard dose proton pump inhibitor (PPI) is recommended as the first-line therapy. The response to a standard dose of PPI in patients with mild RE is 90-95%, and that in patients with severe RE is 80-85%. In case that standard dose of PPI is not effective, it is possible that the change to other PPI, the change of administration method (before a meal) and double-dose PPI therapy are effective.