Increased viscosity of milk during infant feeding improves swallow safety through modifying sucking in an animal model

Abstract

Infants experiencing frequent aspiration, the entry of milk into the airway, are often prescribed thickened fluids to improve swallow safety. However, research on the outcomes of thickened milk on infant feeding have been limited to documenting rates of aspiration and the rheologic properties of milk following thickening. As a result, we have little insight into the physiologic and behavioral mechanisms driving differences in performance during feeding on high viscosity milk. Understanding the physiologic and behavioral mechanisms driving variation in performance at different viscosities is especially critical, because the structures involved in feeding respond differently to sensory stimulation. We used infant pigs, a validated animal model for infant feeding, to test how the tongue, soft palate, and hyoid respond to changes in viscosity during sucking and swallowing, in addition to measuring swallow safety and bolus size. We found that the tongue exhibited substantive changes in its movements associated with thickened fluids during sucking and swallowing, but that pharyngeal transit time as well as hyoid and soft palate movements during swallowing were unaffected. This work demonstrates the integrated nature of infant feeding and that behaviors associated with sucking are more sensitive to sensorimotor feedback associated with changes in milk viscosity than those associated with the pharyngeal swallow, likely due to its reflexive nature.

Nipple properties affect sensorimotor integration during bottle feeding in an infant pig model

“…Often, infants exhibiting feeding difficulties are prescribed nipples with lower flow rates (Mathew & Cowen, 1988; Pados et al, 2015). Alternatively, infants with feeding difficulties are often fed milk with increased viscosity, which reduces the frequency of aspiration (Cichero et al, 2013; Mayerl et al, 2021; Newman et al, 2016). One limitation of these interventions is that they do not necessarily treat the underlying etiologies that generate feeding difficulties (Mayerl et al, 2022).…”

“…Pigs received an infant pig milk replacer formula (Solustart Pig Milk Replacement; Land o' lakes, Arden Mills) for the duration of the experiments. Additional housing and feeding followed care guidelines previously outlined but are standard for this animal model (Holman et al, 2013; Mayerl et al, 2021).…”

“…The active flow rate during infant feeding results from a combination of passive flow rate and suction generation (German et al, 1997; Lau, 2015). Previous research illustrates the potential for suction generation modification depending on variation in sensation (Mayerl et al, 2021). For instance, suction generation can be modified through nipple material properties, where nipple stiffness impacts the force applied to the nipple during nutritive sucking (Adjerid et al, 2022).…”

Exploring the interaction of viscosity and nipple design on feeding performance in an infant pig model

“…Most studies related to infants and increased viscosity are concerned with the physical effects increasing viscosity has on physical properties of milk or formula such as the flow rate, rheology, and thickener compatibility (Almeida et al, 2017; Koo et al, 2019; September, 2021). But few studies have investigated the effect of changing viscosity on swallow performance or physiology in infants (German et al, 1998; Goldfield et al, 2013; Mayerl, Edmonds, et al, 2021). Goldfield et al (2013) found that infants alter the movements of the tongue and soft palate relative to each other in response to different viscosities, which they hypothesize improves the efficacy of the pumping motion.…”

Food texture and texture modification for dysphagia management

“…Dysphagia among infants has also been a major concern for a long time. Two research articles are included in this special issue to reflect new progresses on the texture modification of infant milk: Viscosity of milk during infant feeding improves swallow safety (Mayerl, Edmonds, Gould, & German, 2021) and the effect of commercially available thickening agents on ready-to-feed infant formulas (Gosa & Choquette, 2021).…”