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

Abstract

Background 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. Methods High‐resolution manometry data during oral milk feeding were analyzed for pharyngeal contractile (PhCI, mm Hg cm s) and regulatory (number and frequency of pharyngeal contractions and bursts, pharyngeal activity‐to‐quiescence ratio, upper esophageal sphincter nadir pressure) characteristics in 23 preterm (<38 weeks’ gestation) and 18 full‐term‐born infants at term maturation. Mixed linear models and stepwise regression methods were used. Results 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). Conclusions 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.

Premature birth impacts bolus size and shape through nursing in infant pigs

“…Bolus size and shape may be impacted by both the oral and pharyngeal phases of feeding, as noted above, but also might relate to the mechanics, requirements and constraints of the esophageal phase of feeding. For example, both human and pig preterm infants have decreased esophageal motility compared with term infants (31,32), and human preterm infants exhibit decreased pharyngeal contractions within bursts and decreased pharyngeal activity and contraction frequency (33). This is especially relevant because clinical work suggests that the pharyngeal swallow reflex itself does not show maturational changes in preterm infants, but preterm infants do show longitudinal maturation in esophageal sphincter relaxation reflexes (34).…”

Anemia of Prematurity and Oral Feeding Milestones in Premature Infants

“…The effects of neurologic, cardiorespiratory, and aerodigestive factors on regulation of biorhythms involved with feeding safety need further longitudinal study in premature infants with evolving disease, such as neuropathology or BPD. Such studies should incorporate patient-specific bedside tools, such as highresolution manometry studies [32][33][34][35] or NIRS 12,36 to assess the compensatory mechanisms. If infants with severe AOP showing decompensation features with oral feeding attempts, effects of interventions (use of Erythropoietin and Darbepoetin), which also have neuroprotective effects, on prevention of AOP and oral feeding outcomes could be tested in future studies or as a secondary outcome in ongoing randomized trials.…”

Preterm Birth Impacts the Timing and Excursion of Oropharyngeal Structures during Infant Feeding

“…Furthermore, because of radiation concerns, past studies evaluating pharyngeal constriction have often been limited to pharyngeal manometry ( Rommel et al. 2011 ; Prabhakar et al. 2019 ).…”

“…2019 ). Preterm infants also exhibit decreased pharyngeal contractility, and thus represent an ideal population for studying pharyngeal dysfunction ( Prabhakar et al. 2019 ).…”

“…Because preterm infants have decreased pharyngeal contractility ( Prabhakar et al. 2019 ), we predicted that the excursion of the soft palate and palatopharyngeal arch of preterm pigs would be less than their term counterparts throughout infancy.…”