Modulation of Pharyngoesophageal Motility Characteristics During Concurrent Oral Feeding in Infants: Novel Pilot Observations

Abstract

Effect of interventions or diseases on the mechanisms of swallowing difficulties, and indications to change nipples, flows, or formula thickness in high-risk infants remains unclear. We evaluated and compared the effects of nipple flows and/or formula thickness on pharyngoesophageal timing and amplitude characteristics during oral milk challenge (OMC). A total of 48 OMC trials were undertaken in 12 infants [born at 36.4 ± 3.8 weeks gestation, studied at 48.0 ± 5.6 weeks postmenstrual age (PMA)] concurrent with high resolution pharyngoesophageal manometry (HRPM). We evaluated timing and amplitude of swallowing characteristics (pharyngeal and esophageal contractile strength, duration, activity, pharyngeal peak interval variability, bursts, and rhythm) and volume intakes. We compared within and between the entities: un-thickened formula vs. thickened formula and slower- vs. faster flow nipple. OMC durations averaged 71 ± 31 s and did not differ between interventions (p > 0.05). Pharyngeal swallow rhythms (timing) and contractile characteristics were dependent on the interaction between nipple flow rates and formula thickness (p < 0.05). Thickness decreased overall contractility and modified distal pharyngeal contractile activity (p < 0.05), which is critical to opening the upper esophageal sphincter. A structural equation model was developed that revealed the influence of PMA, respiratory status, volume extracted, nipple flow rate, and thickener presence on pharyngeal swallowing frequency with a comparative fit index of 0.83. Oropharyngeal stimulus-types trigger, integrate, and modify brainstem mediated oral and pharyngeal rhythms and modulate contractility and airway protection mechanisms. Effects of therapies, maturation and diagnoses are measurable using these novel approaches at crib-side.

Keywords: Deglutition; Infant feeding difficulties; Nipple flow; Pharyngoesophageal motility; Swallowing; Thickener.