title: Effect of postnatal maturation on the mechanisms of esophageal propulsion in preterm human neonates: primary and secondary peristalsis.
abstract: OBJECTIVE
  The changes in esophageal propulsive characteristics during maturation are not known. Our aim was to define the effects of postnatal maturation on esophageal peristaltic characteristics in preterm human neonates. We tested the hypotheses that: (i) maturation modifies esophageal bolus propulsion characteristics, and (ii) the mechanistic characteristics differ between primary and secondary peristalsis.
  
  
  METHODS
  Esophageal motility in 10 premature neonates (mean 27.5 weeks gestational age) was evaluated twice at 33.8 weeks (time 1, earlier study) and 39.2 weeks (time 2, later study) mean postmenstrual age. Esophageal manometry waveform characteristics (amplitude and duration, peristaltic velocity, and intrabolus pressure domains) were analyzed during spontaneous primary peristalsis and infusion-induced secondary peristalsis. Repeated-measures and unstructured variance-covariance or compound symmetry matrixes were used for statistical comparison. Values stated as least squares means+/-s.e.m. or percent.
  
  
  RESULTS
  A total of 200 primary peristalsis and 227 secondary peristalsis events were evaluated. Between time 1 and time 2: (i) proximal esophageal waveform amplitude increased (P<0.02), with primary peristalsis (38+/-6 vs. 48+/-7 mm Hg) and with secondary peristalsis (34+/-6 vs. 46+/-5 mm Hg); (ii) distal esophageal waveform amplitude was similar (P=NS), with primary peristalsis (42+/-4 vs. 43+/-4 mm Hg) and secondary peristalsis (29+/-3 vs. 32+/-4 mm Hg); (iii) proximal esophageal waveform onset to peak duration decreased (P=0.02) with primary (2.6+/-0.3 vs. 1.9+/-0.1 s, P<0.003) and with secondary peristalsis (2.2+/-0.2 vs. 1.8+/-0.1 s); (iv) distal esophageal waveform onset to peak duration decreased (P=0.01) with primary (2.4+/-0.3 vs. 1.8+/-0.1 s) and with secondary peristalsis (1.9+/-0.2 vs. 1.5+/-0.1 s); (v) effects of identical stimulus volume on intrabolus pressure were similar (P=NS); however, greater infusion volumes (2 vs. 1 ml) generated higher intrabolus pressure at both time 1 and time 2 (both Ps<0.05). Between primary and secondary peristalsis (mechanistic variable): (i) no differences were noted at either period, with proximal esophageal waveform amplitudes (P=NS); (ii) differences were noted with distal esophageal waveform amplitudes at each time period (P=0.0002); (iii) no differences were noted with both esophageal waveforms duration at either period (P=NS); (iv) peristaltic velocity was faster with secondary peristalsis than with primary peristalsis at either period (at earlier study, 7.9+/-1.4 vs. 2.5+/-1.4 cm/s and at later study 6.2+/-1.6 vs. 1.2+/-1.5 cm/s, both Ps<0.01).
  
  
  CONCLUSIONS
  In preterm neonates, longitudinal maturation modulates the characteristics of primary and secondary peristalsis. Differences in proximal striated muscle and distal smooth muscle activity during peristalsis are evident. Peristaltic velocity is faster with secondary peristalsis. These findings may represent maturation of central and peripheral neuromotor properties of esophageal bolus propulsion in healthy preterm human neonates.
authors.affiliation: Center for Perinatal Research, Nationwide Children's Hospital Research Institute, Columbus, Ohio 43205, USA.
authors.forename: Alankar
authors.initials: A
authors.lastname: Gupta
authors.forename: Parul
authors.initials: P
authors.lastname: Gulati
authors.forename: Walter
authors.initials: W
authors.lastname: Kim
authors.forename: Soledad
authors.initials: S
authors.lastname: Fernandez
authors.forename: Reza
authors.initials: R
authors.lastname: Shaker
authors.forename: Sudarshan R
authors.initials: SR
authors.lastname: Jadcherla
mesh_terms: D002657:Child Development / Q000502:physiology*; D003679:Deglutition / Q000502:physiology*; D004947:Esophagus / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn / Q000254:growth & development / Q000502:physiology*; D007234:Infant, Premature / Q000254:growth & development / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male; D008365:Manometry; D010528:Peristalsis / Q000502:physiology*; D012018:Reflex / Q000502:physiology