[Experimental and clinical studies of gastroesophageal reflux (GER) in infants]

The lower esophageal sphincter (LES) is observed as a zone with higher esophageal pressure by manometric studies and considered to save a barrier against gastric pressure. Mechanisms to prevent GER have still not been fully understood. Manometric studies and pH studies were performed in dogs and in infants. The following results were obtained: Experimental studies Increasing gastric pressure with 0.1 N HCl, LES relaxation was elicited by increased esophageal pressure after GER was detected by pH measurement. LES pressure increased with increased abdominal pressure and decreased with elevated intraesophageal pressure after intraluminal injection of normal saline. Inflation of the esophagus with air caused GER when gastric pressure elevated with 0.1 N HCl. Clinical studies Manometric studies were performed in 63 infants with or without GER. Infants with GER had higher esophageal pressure, lower LES pressure and shorter LES than infants without GER (p less than 0.001). In conclusion, these studies may indicate that relaxation of LES caused by increased intraesophageal pressure induces GER in infants.