Characterisation of relaxation of the lower oesophageal sphincter in healthy premature infants.

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Abstract
BACKGROUND: Gastro-oesophageal reflux disease causes significant morbidity in premature infants, but the role of dysfunction of the lower oesophageal sphincter (LOS) in this condition is unclear. METHODS: Oesophageal manometry was performed after gavage feeding in 13 healthy preterm neonates (postmenstrual age > or = 33 weeks) with a perfused sleeve with side hole assembly. Swallow related (both single and multiple) and transient LOS relaxations (TLOSRs) were identified and the characteristics of these events defined. Reflux was identified with manometric criteria (common cavity episodes). RESULTS: Five hundred and eleven relaxation of the LOS were observed, 55% related to single swallows, 23% related to multiple swallows, and 22% TLOSRs. The time to maximal LOS relaxation was longer for TLOSRs than for single or multiple swallows (mean (SEM) 5.0 (0.3) s v 3.0 (0.1) s and 3.3 (0.1) s, p < 0.0001 and p < 0.005). The durations of multiple swallows and TLOSRs were longer than single swallows (12.2 (0.5) s and 11.2 (0.4) s v 5.3 (0.2) s, p < 0.0001). Most of the oesophageal body common cavity episodes (94%) occurred during TLOSRs. CONCLUSIONS: In healthy preterm infants (postmenstrual age > or = 33 weeks) the motor events associated with LOS relaxation were similar to those seen in healthy adults. TLOSRs may be an important mechanism of reflux in premature infants.