RESUMO
OBJECTIVES: To combine manometry and impedance to characterize the mechanisms of gastroesophageal reflux (GER) and to explore their relation to the rate of gastric emptying (GE) and body position. STUDY DESIGN: Ten healthy preterm infants (35 to 37 weeks' postmenstrual age) were studied with the use of a micromanometric/impedance assembly. Episodes of GER were identified by impedance, and the mechanism(s) of GER triggering and GER clearance were characterized. GE was determined with a C13Na-octanoate breath test. RESULTS: Gastroesophageal reflux episodes (n=89) were recorded, consisting of 74% liquid, 14% gas, and 12% mixed. Transient lower esophageal sphincter relaxation (TLESR) was the predominant mechanism of reflux, triggering 83% of GER. Of 92 TLESRs recorded, 27% were not associated with reflux. Infants studied in the right lateral position had significantly (P <.01) more GER, a higher proportion of liquid GER (P <.05), and faster GE (P <.005) when compared with infants studied in the left lateral position. CONCLUSIONS: In healthy preterm infants, GER is predominantly liquid in nature. Right-side positioning is associated with increased triggering of TLESR and GER despite accelerating GE.