Mechanisms of gastro-oesophageal reflux in preterm and term infants with reflux disease

Abstract

Background: Transient lower oesophageal sphincter relaxation (TLOSR) is the predominant mechanism of gastro-oesophageal reflux (GOR) in healthy infants but the mechanisms of GOR in infants with GOR disease (GORD) are poorly understood.

Aims: To measure the occurrence of TLOSR, GOR, and gastric emptying (GE) rate in preterm and term infants with GORD.

Patients: Thirty six infants were studied and grouped as normals or GORD based on a routine clinical assessment and confirmation of an assessment of GORD by reflux symptom charts and oesophageal pH monitoring.

Methods: A micromanometric assembly incorporating a micro pH electrode recorded oesophageal motility and pH. GE rate was determined using the (13)C-octanoic acid breath test.

Results: TLOSR was the predominant mechanism of GOR, triggering 50-100% of GOR episodes (median 91.5%). Abdominothoracic straining significantly increased the occurrence of GOR in association with TLOSR. In infants with GORD, the number of TLOSRs overall was similar to normals but the proportion of TLOSRs accompanied by acid GOR was significantly higher than in normals (16.5% v 5.7%, respectively; p<0.001). Infants with GORD had a similar GE rate to normals.

Conclusions: In infant GORD, acid reflux associated TLOSRs are abnormally common and likely to be a major contributing factor to the pathophysiology of GORD. Infants with GORD do not have delayed GE.

Figures

Figure 1

Example tracings of transient lower oesophageal sphincter relaxations (TLOSRs) triggering (A) acid gastro-oesophageal reflux (GOR), (B) non-acid GOR, and (C) acid GOR during abdominothoracic straining. In (A) and (B), TLOSR (indicated by the horizontal black line) triggers a common cavity (cc) episode the onset of which is closely associated with the onset of the pH change (vertical dotted line). In (C), abdominothoracic straining (hatched bar) causes a sustained (>10 seconds) increase in intraluminal pressure across all channels. If LOS and gastric pressure recordings are superimposed (see insert), the occurrence of a TLOSR at the end of the straining episode can easily be identified by a prolonged equalisation LOS and gastric pressures (horizontal black line) which is associated with the onset of the GOR episode (vertical dotted line).

Figure 2

Incidence of symptoms in normal infants and patients with gastro-oesophageal reflux disease (GORD). p values for χ2 analysis are shown.

Figure 3

Occurrence of all transient lower oesophageal sphincter relaxations (TLOSRs) (lines) and TLOSRs associated with non-acid gastro-oesophageal reflux (GOR) (light shading) and acid GOR (dark shading) in infants receiving feeds at (A) four hourly, (B) three hourly, and (c) two hourly intervals. Data represent the mean number of events recorded during each one hour period of the four hour studies.