Multipoint measurement of intragastric pH in healthy preterm infants.

BACKGROUND The diagnostic use of 24 hour oesophageal pH monitoring in infants is controversial because of the impact of feed buffering of gastric acidity. AIM To re-evaluate the effect of feeding on gastric pH and reflux using multipoint pH measurements. SUBJECTS Fifteen healthy premature infants fed every four hours. METHODS Oesophageal pH and intragastric pH at 3, 6, and 9 cm below the lower oesophageal sphincter were simultaneously measured using a four channel pH probe for four hours after bolus feeding. Parameters of pH were compared for the different levels within the stomach. During reflux episodes, the nadir pH was compared with intragastric pH at all levels. RESULTS The proximal stomach was more significantly buffered by feeding and slower to re-acidify postprandially than the mid and distal stomach (42.2% of the time at pH < 4 compared with 58.7% and 55.7% respectively). During 27 of 62 gastro-oesophageal reflux episodes, nadir oesophageal pH was lower than the pH of the proximal stomach but always equal to or higher than the pH of the distal stomach. CONCLUSIONS These data indicate that previous studies may have overestimated the effect of feeding on gastric acidity and reflux.