The infants were evaluated for reflux while impedance and manometry probes were in place. Each infant was tested twice in a cross-over design. The 2 testing approaches were: left side down (left lateral position [LLP]) first for 1 hour after feed, then changed to right side down (RLP) for up to 225 minutes; or, the reverse, RLP for 1 hour after feed, then changing to LLP for the duration of monitoring.
Van Wijk and colleagues reviewed familiar aspects of infant feeding: gastroesophageal reflux (GER) is common in premature infants, reflux immediately after a meal is only weakly acidic, and reflux becomes more acidic as time passes after a meal. More acidic reflux is thought to produce more problematic symptoms in infants. Transient lower esophageal sphincter relaxation (TLESR) allows reflux of gastric content into the esophagus. TLESR triggers are different in different individuals and also depend upon how much time has passed after a meal.
The researchers sought to determine relationships between infant position after a meal and the frequency of TLESR and GER episodes, as well as whether amount of time after a meal could be a factor. The authors also evaluated gastric emptying.
The study included 10 infants (median age, 23 days), each tested twice. Their median gestational age was 31.5 weeks, and their median weight was 2415 g.
The authors then compared differences in rates of outcomes and overall reflux between the 2 placement-order approaches. For the study feeding, the infants were gavage-fed a median of 67 mL of formula or breast milk (whichever the infant was already taking). RLP position first was associated with more TLESRs and overall GER episodes. For example, RLP-first sessions produced 11.5 mean GER episodes compared with 7.0 mean GER episodes when infants began LLP first. The quality of GER episodes was very different depending on positioning. The RLP-first approach produced a greater proportion of liquid reflux and lower proportions of gas or mixed reflux episodes.
When these infants were turned to LLP for the remainder of the session, the episodes of liquid GER were reduced greatly and were replaced by gaseous GER episodes. In addition, the RLP-first approach was associated with faster gastric emptying and fewer episodes of all reflux later in the postprandial period when the reflux was more acidic.
The authors concluded that a positioning approach of placing infants in RLP for the first hour after a feed and then turning to LLP thereafter can improve gastric emptying. The particular benefit offered by this approach is a reduction in late (after feeding) liquid reflux episodes, which are the most acidic.
The authors are cautious and suggest that this approach requires additional testing, but their study does help lay the groundwork for future research.
Van Wijk MP, Benninga MA, Dent J, et al
J Pediatr. 2007