title: Mechanisms of gastroesophageal reflux in healthy premature infants.
abstract: OBJECTIVE
  The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of healthy preterm infants.
  
  
  METHODS
  Esophageal motility was recorded for 2 to 3 hours after a feeding in 24 preterm infants, 31 to 38 weeks' postmenstrual age, by using a sleeveside hole micromanometric assembly incorporating a pH probe.
  
  
  RESULTS
  Sixty acid GER episodes were recorded by pH probe, and 133 non-acid GER episodes were recorded manometrically by the presence of esophageal common cavities. Of the 193 GER episodes, 159 (82%) were associated with transient lower esophageal sphincter relaxation (TLESR). TLESRs were significantly longer in duration than single swallows (15.1 seconds vs 5.6 seconds, P < .001) and had lower nadir pressures (0.8 mm Hg vs 2.3 mm Hg, P < .001). A total of 3216 esophageal body pressure waves were analyzed; 70% of swallow-induced pressure waves were peristaltic in sequence compared with 5% of swallow-unrelated pressure waves. During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences.
  
  
  CONCLUSIONS
  In healthy preterm infants, TLESRs are the predominant mechanism underlying GER, and esophageal clearance mechanisms are well developed by at least 31 weeks' postmenstrual age.
authors.affiliation: Gastroenterology Unit, Women's and Children's Hospital, North Adelaide, Australia.
authors.forename: T I
authors.initials: TI
authors.lastname: Omari
authors.forename: C
authors.initials: C
authors.lastname: Barnett
authors.forename: A
authors.initials: A
authors.lastname: Snel
authors.forename: W
authors.initials: W
authors.lastname: Goldsworthy
authors.forename: R
authors.initials: R
authors.lastname: Haslam
authors.forename: G
authors.initials: G
authors.lastname: Davidson
authors.forename: C
authors.initials: C
authors.lastname: Kirubakaran
authors.forename: M
authors.initials: M
authors.lastname: Bakewell
authors.forename: R
authors.initials: R
authors.lastname: Fraser
authors.forename: J
authors.initials: J
authors.lastname: Dent
mesh_terms: D015331:Cohort Studies; D004943:Esophagogastric Junction / Q000503:physiopathology; D004947:Esophagus / Q000502:physiology; D005260:Female; D005744:Gastric Acid / Q000502:physiology; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D008365:Manometry; D010528:Peristalsis / Q000502:physiology