Pharyngeal contractile and regulatory characteristics are distinct during nutritive oral stimulus in preterm-born infants: Implications for clinical and research applications.

Abstract

Maturation of pharyngeal swallowing during neonatal oral feeding is unknown. Our objective was to evaluate pharyngeal functioning using high-resolution manometry (HRM) during nutritive oral stimulus and test the hypothesis that pharyngeal contractility and regulation are distinct in preterm-born infants. High-resolution manometry data during oral milk feeding were analyzed for pharyngeal contractile (PhCI, mmHgcms) and regulatory (number and frequency of pharyngeal contractions and bursts, pharyngeal activity-to-quiescence ratio, upper esophageal sphincter nadir pressure) characteristics in 23 preterm (<38weeks' gestation) and 18 full-term-born infants at term maturation. Mixed linear models and stepwise regression methods were used. Despite more oral feeding experiences (P<0.05), preterm infants (vs full-term), consumed less milk volume (P<0.001), had lesser pharyngeal contractions within bursts (P=0.04), lower pharyngeal contraction frequency (P<0.01), and lower pharyngeal activity (P=0.03), but higher PhCI per individual contraction (P=0.01). PhCI is higher for longer PMA (P<0.05), higher UES nadir pressures (P<0.05), and lower pharyngeal contraction frequency (P<0.05). Nutritive oral milk stimulus provoked pharyngeal contractility characteristics is distinct in preterm-born. Despite more oral nutritive experiences, preterm infants had underdeveloped excitatory and inhibitory rhythmic activity. Cranial nerve IX and X effects on sensory-motor responses and feedback (excitation-inhibitory rhythm regulation) remain immature among preterm-born even at full-term maturational status. We speculate the relationship between PhCI and UES regulatory activity contributes to the observed differences in preterm and full-term infants.