Esophageal pH study and symptomatology of gastroesophageal reflux in newborn infants.

A retrospective study was undertaken to assess the association between esophageal pH monitoring variables and signs such as regurgitation, vomiting, apnea, bradycardia, and cyanotic episodes attributable to gastroesophageal reflux (GER) in neonates. One hundred thirty-four infants with one or more of the above-described signs underwent 24-hour distal esophageal pH monitoring in the neonatal intensive care unit, and were divided into 2 groups by gestational age. Group 1 (preterm infant group) consisted of infants aged 25 to 36 weeks of gestation ( n = 45) and group 2 (term infant group) consisted of infants aged 37 to 42 weeks gestation ( n = 89). Esophageal pH monitoring variables were compared by gestational age group and within preterm infants by theophylline treatment and, separately, by nasogastric tube using the Mann-Whitney U test. Comparisons of nominal data were made using the chi square test. Logistic regression analysis was used to assess the net effect of each independent variable on the risk of developing GER. The prevalence of GER was not influenced by gestational age. The prevalence of gastrointestinal signs did not differ between groups. Cardiorespiratory signs attributed to GER were more frequent in preterm infants than in term infants. The number of episodes with pH < 4 in 24 hours was greater in the term compared with the preterm infant groups. Logistic regression analysis failed to detect an association between acid GER and gestational age, apnea, bradycardia, cyanotic episodes, vomiting, or regurgitation. Theophylline treatment and the presence of a nasogastric tube did not significantly affect the esophageal pH monitoring variables in preterm infants. Preterm infants have a smaller number of reflux episodes compared with term infants. In addition, treatment with theophylline for apnea of prematurity and the presence of a nasogastric tube in preterm infants did not significantly affect pH-monitoring variables in preterm infants.