P0941 HIGH-RESOLUTION ESOPHAGEAL MANOMETRY (HRM) WITH TOPOGRAPHIC PLOTTING IN PRE-TERM AND TERM NEONATES

Abstract

Introduction: HRM uses closely spaced recording sites and axial data interpolation to better visualize time and space relationships of pressure data. These techniques in adults and older children reveal that esophageal peristalsis is comprised of a chain of 3 contraction segments, 1 in striated muscle and 2 in the smooth-muscle region, that culminates in lower esophageal sphincter contraction. The 2nd segment (proximal smooth-muscle esophageal body) appears to be at least in part under cholinergic control and important in the peristaltic pump. HRM has not been applied to neonates to see if segmental contraction characteristics are seen in this group. Methods: HRM was used to study 5 full-term neonates (gestational age 37–41 wk; post-delivery age 0–7 d) and 7 pre-term neonates (gestational age 30–36 wk; age 3–24 d). Subjects were intubated with a 9-lumen (2.25 mm OD) perfused catheter with recording sites at 1-cm intervals, and data were acquired with a system designed specifically for HRM (MMS, Enschede, Holland). Small volume water swallows were used when possible. 3-dimensional topographic contour plots and cines of axial wave propagation were examined to detect peristaltic characteristics and recurring contraction segments. Results: The techniques were successful in each case, and peristaltic events were easily identified on topographic plots and cine review despite expected artefact - even if not clearly recognized on conventional tracings. In full-term neonates the 2nd segment was well developed and consistently present in all subjects; the 1st and 3rd were seen intermittently in 4 subjects. Complete peristaltic sequences were present in 47.6±15.3% of swallows. The 2nd segment was also consistently evident in pre-term neonates of >34 wks gestational development or 32 wks gestation plus >3wks age. Only fragments of peristalsis and no well-defined segments were seen in 2 subjects with 30–31 wks gestation plus 9–16 d age. These youngest subjects had no completed peristalses whereas the other pre-term subjects had 43.4±5.8% completed peristalses and resembled the full-term neonates (p=0.8). Conclusion: HRM with topographic plotting simplifies the identification of peristaltic events in neonates because of their similarity to the stereotypical chain of contraction segments in older subjects. The segments cannot be identified in subjects with <32 wks gestational development with <3 wks of post-delivery age, suggesting that the maturation of this process occurs near term. The prominent, early development of the 2nd contraction segment may reflect the importance of this region for its pro-clearance protective effects.