[Function of the lower esophageal sphincter in infants]

Main basal pressure and the deglutition-induced behavior of the lower esophageal sphincter (LES) in 115 infants between the ages of 6 hr and 6 mo were evaluated by continuous perfusion manometry. In comparison to the adult, higher pressures were found, especially in the first weeks and months of life. The relaxation stimulated by the deglutition reflex and the pressure increase following abdominal compression were similar to the responses observed in adults. Singificant differences between vomiting and nonvomiting infants could be determined. From these results we conclude that the vomiting often observed in early infancy results from factors other than the previously proposed hypotonia or neuromuscular underdevelopment of the LES.