The effect of stiffness and hole size on nipple compression in infant suckling
During infant feeding, the nipple is an important source of sensory information that affects motor outputs, including ones dealing with compression of the nipple, suction, milk bolus movement, and swallowing. Despite known differences in behavior across commercially available nipples, little is known about the in vivo effects of nipple property variation. Here we quantify the effect of differences in nipple stiffness and hole size on an easily measured metric representing infant feeding behavior: nipple compression. We bottle-fed 7-day old infant pigs (n = 6) on four custom fabricated silicone nipples. We recorded live X-ray fluoroscopic imaging data of feeding on nipples of two levels of hardness/stiffness and two hole sizes. We tested for differences in nipple compression at the nipple's maximum compression across different nipple types using a mixed model analysis of variance. Stiffer nipples and those with smaller holes were compressed less than compliant nipples and nipples with larger holes (p < 0.001). We also estimated the force applied on the nipple during feeding and found that more force was applied to the compliant nipple with disproportionately larger strains. Our results suggest that infant pigs' nipple compression depends on material type and hole size, which is likely detected by the infant pigs' initial assessment of compressibility and flow. By isolating nipple properties, we demonstrated a relationship between properties and suckling behavior. Our results suggest that sensory information affects feeding behaviors and may also inform clinical treatment of poor feeding performance.
Khaled Adjerid
Maxwell L Johnson
Chloe E Edmonds
Kendall S Steer
Francois D H Gould
Rebecca Z German
Christopher J Mayerl
J Exp Zool A Ecol Integr Physiol
. 2023 Jan;339(1):92-100. doi: 10.1002/jez.2657. Epub 2022 Sep 19.
2022
English
Increased viscosity of milk during infant feeding improves swallow safety through modifying sucking in an animal model.
Aspiration, the entry of food or liquid into the airway, is especially prevalent in infant mammals relative to adults (Jadcherla, 2016; Stricklen, Bond, Gould, German, & Mayerl, 2020). High rates of aspiration can have detrimental health impacts, and in the most extreme cases result in aspiration pneumonia and death (Logemann, 2007; Prasse & Kikano, 2009). One of the most commonly accepted methods of reducing the occurrence of aspiration in infants is increasing the viscosity of ingested material (Cichero, Nicholson, & September, 2013; Newman, Vilardell, Clavé, & Speyer, 2016). The clinical outcomes of increased viscosity in infants are fairly well understood, and include reduced occurrence of regurgitation and aspiration, and increased weight gain (Krummrich, Kline, Krival, & Rubin, 2017; Salvatore et al., 2018). However, most research on the impact of viscosity on infant feeding has focused on the rheologic properties of the liquid, and how time, temperature, and thickening agent impact viscosity (Gosa & Dodrill, 2017; September, Nicholson, & Cichero, 2014; Yoon & Yoo, 2017). As a result, we have very little insight into the physiologic mechanisms driving differences in performance due to changes in viscosity.
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.
Mayerl CJ; Edmonds CE; Gould FDH; German RZ
Journal Of Texture Studies
2021
2021-03-30
Journal Article
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Increased viscosity of milk during infant feeding improves swallow safety through modifying sucking in an animal model.
physiology; dysphagia; infant; animal model; suckling; viscosity
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.
Mayerl CJ; Edmonds CE; Gould FDH; German RZ
Journal Of Texture Studies
2021
2021-03-30
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