Abstract 1630 Poster Session III, Monday, 5/3 (poster 79)

INTRODUCTION: Esophageal motor function in extremely premature infants with birth weights under 1000g and post-menstrual ages (PMA) less than 30 weeks has not been characterized. The aim of this study was to utilize micromanometric intraluminal recording techniques to characterize esophageal motor function and mechanisms of gastroesophageal reflux in these babies.

METHODS: Twelve premature infants of 26-31 weeks PMA (mean 27 weeks) with body weights of 610-1360g (mean 960g) were studied. Esophageal motility was recorded for 30min post-prandially using a perfused micro-manometric feeding assembly (od 2.0mm). Manometric recording side holes recorded pressures in the pharynx (air perfused at 2ml/min), esophageal body, lower esophageal sphincter (LES) (sleeve) and stomach. Esophageal and gastric side holes were perfused at a rate of 0.005-0.04ml/min dependent of allowable fluid infusion volumes. The patterning of esophageal body pressure wave sequences (peristaltic, synchronous, incomplete and retrograde), resting LES pressure and characteristics of swallow-related LES relaxations and transient LES relaxations (TLESRs) were assessed and compared.

RESULTS: Swallow-induced esophageal pressure waves were predominantly (84%) peristaltic in sequence. All infants exhibited a competent LES, mean resting LES pressure for each infant ranged from 5.1(4.1 mmHg to 20.0(4.8mmHg (mean overall of 13.6(4.2mmHg). LES relaxation occurred appropriately with pharyngeal swallow (onset of LES relaxation within 2sec before to 3sec after swallow). Transient LES relaxations occurred on average 2.6(1.6 times per study; 86% of these were associated with esophageal body common cavities indicative of flow into the esophagus from the stomach. Compared to swallow-related LES relaxations, TLESRs were longer in duration (5.8(3.0 vs 21.7(8.7sec, respectively, p<0.001) and had lower nadir pressures (1.8(2.6 vs 0.1(1.8mmHg, respectively, p<0.001).

CONCLUSION: In these extremely premature infants esophageal motor function appears well developed; LES tone is sufficient to maintain esophago-gastric competence, pharyngeal swallow is well coordinated with peristalsis and LES relaxation and TLESR may to be an important mechanism of gastroesophageal reflux.