GASTRIC pH IN LOW BIRTH WEIGHT (LBW) INFANTS: EFFECT Of Age And Feedings

Abstract

Although maximal gastric secretory capacity of newborns is reduced, it is unclear whether gastric luminal pH is less acid. We therefore measured gastric pH in 2 groups of LBW infants assessing the impact of age and feeding type on gastric acidity. In Group I were 13 infants < 7 days BW 1716±41g. In Group II were 10 infants 7-15 days BW 1646±88g (x̄±SE). None had had theophylline, mechanical ventilation, sepsis or GI bleed. Output from a flexible pH electrode in the gastric corpus was recorded continuously for 12 hrs. Infants were fed q3hrs - one pedialyte meal(pH 4.9) and 3 cow milk formula meals(pH 6.6-6.8) of equal volume. Mean gastric pH for Grs I&II was calculated q15min. RESULTS Young infants had higher fasting gastric pH than older infants (4.6±.2 vs 3.0±.2;p<.01). Mean gastric pH of young infants remained unchanged after a pedialyte meal while after formula pH rose significantly (p<.01) to a max of 5.8±.1 and returned to fasting pH by 75 min p.c. Mean gastric pH of older infants fed pedialyte did rise significantly above fasting (p<.01) for 75 min but max pH was only 4.0. After formula mean pH rose to 5.2±.4, fell to pH 4.0 by 75 min and to fasting by 135 min p.c. The % of time gastric pH was < 4.0 was significantly greater (p<.01) in older infants after either pedialyte(61.9±7.3 vs 20.6±6.4%) or formula (42.7±8.0 vs 15.2±4.0%). Gastric pH was rarely <2.0 in either group(<2.5% monitored time). CONCLUSION Reduced gastric secretory capacity of newborns does depress fasting and post prandial gastric acidity of LBW infants during the first week of life. Thereafter adult pH patterns are found.