Effect of Single-Use, Laser-Cut, Slow-Flow Nipples on Respiration and Milk Ingestion in Preterm Infants

Examining the Effect of Bottle Angle on Milk Drip Rate Using the Dr. Brown's® Zero-Resistance® Specialty Feeding System

ObjectiveExamine the drip rate from the Dr. Brown's® Zero-Resistance® Specialty Feeding System without compression across 8 nipple levels and 3 angles.DesignCross-sectional.SettingLaboratory.InterventionsThe drip rate of the Dr. Brown's® Zero-Resistance® Specialty Feeding System was assessed with the bottle positioned at 0°, 30°, and 45° angles across 8 bottle nipple levels: Ultra-Preemie™, Preemie Flow™, Level T, Level 1, Level 2, Level 3, Level 4, and Y-Cut.Main Outcome Measure(s)Milk volume in millimeters extracted per minute (mL/min) for each bottle nipple level and angle configuration. A one-way analysis of variance was conducted to compare the milk drip rate across 3 angles for each bottle nipple level.ResultsThe mean drip rate was 0.0 mL/min across all nipple levels when the bottle was positioned at a 0° angle. No milk drip was observed at any angle for the Y-Cut nipple. Milk drip was observed when the bottle angle increased to 30° and 45° for nipple levels Ultra-Preemie™ to Level 4 ranging from 1.3 mL/min up to 19.4 mL/min.ConclusionsMilk freely drips from the Dr. Brown's® Zero-Resistance® Specialty Feeding System when positioned at 30° and 45° angles for nipples Ultra-Preemie™ through Level 4, putting infants at risk for aspiration. Clinicians should recommend caregivers position the Specialty Feeding System at a 0° angle when infants pause to breathe.

The Impact of Varying Nipple Properties on Infant Feeding Physiology and Performance Throughout Ontogeny in a Validated Animal Model

Infant feeding requires successful interactions between infant physiology and the maternal (or bottle) nipple. Within artificial nipples, there is variation in both nipple stiffness and flow rates, as well as variation in infant physiology as they grow and mature. However, we have little understanding into how infants interact with variable nipple properties to generate suction and successfully feed. We designed nipples with two different stiffnesses and hole sizes and measured infant feeding performance through ontogeny using a pig model. We evaluated their response to nipple properties using high-speed X-Ray videofluoroscopy. Nipple properties substantially impacted sucking physiology and performance. Hole size had the most profound impact on the number of sucks infants took per swallow. Pressure generation generally increased with age, especially in nipples where milk acquisition was more difficult. However, most strikingly, in nipples with lower flow rates the relationship between suction generation and milk acquisition was disrupted. In order to design effective interventions for infants with feeding difficulties, we must consider how variation in nipple properties impacts infant physiology in a targeted manner. While reducing flow rate may reduce the frequency an infant aspirates, it may impair systems involved in sensorimotor integration.

The Effectiveness of Slightly Thick Liquids for Improving Swallowing in Bottle-Fed Children With Aerodigestive Concerns

Purpose

Strategies for facilitating safe and functional bottle feeding in children with dysphagia include selecting nipples that reduce flow rate, pacing, altered positioning, and thickening liquid consistencies. We aimed to determine the impact of slightly thick liquids on swallowing through retrospective review of a convenience sample of clinical videofluoroscopic swallowing studies (VFSS) from 60 bottle-fed children (21 boys and 39 girls, mean age of 9.9 months) referred due to suspected aspiration.

Method

Eligible VFSS exams were those in which the child swallowed both thin and slightly thick barium (40% w/v Varibar barium) using the same nipple. VFSS sequences (i.e., uninterrupted portions of the VFSS recording) were randomly assigned in duplicate for rating by trained raters; discrepancies were resolved by consensus. Parameters measured included number of swallows/sequence, sucks/swallow, swallow and sequence duration, number and timing of penetration or aspiration events, laryngeal vestibule closure integrity, and pharyngeal residue. Chi-square tests, linear mixed-model analyses of variance, and Wilcoxon signed-ranks tests identified consistency effects.

Results

There were no aspiration events in these recordings. Slightly thick liquids resulted in significantly fewer penetration events (p < .05), increased sucks/swallow, fewer swallows/sequence, and longer swallow and sequence durations. The number of children with ≥ 1 sequence showing pyriform sinus residue was significantly higher with slightly thick liquids.

Conclusions

Slightly thick liquids can be effective in reducing penetration in bottle-fed children with dysphagia. However, slightly thick liquids may also lead to a safety-efficiency trade-off, with increased risk of pyriform sinus residue. Thickening for children with dysphagia should be considered only when other approaches are not effective. Overthickening should be avoided to limit negative impact on swallowing efficiency.

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

Infant feeding is a critical neurological milestone in development defined by the coordination of muscles, peripheral nerves, and brainstem nuclei. In infants, milk flow rate is often limited to improve feeding performance without treating the underlying deficiencies in the sucking and swallowing processes. Modification of the neuromotor response via sensory information from the nipple during bottle feeding is an unexplored avenue for physiology-based interventions. In this study, we assessed how differences in nipple hole size and nipple stiffness affect sucking muscle activation and subsequent movement. We fabricated four bottle nipples of varying hole size and stiffness to determine how variation in nipple properties affects the sucking behavior of infant pigs. Our results demonstrate that sensory information from the nipple affects sucking motor output. Nipple hole sizes and stiffnesses with a larger milk flow rate resulted in greater muscle activity and kinematic movement. Additionally, our results suggest that sensorimotor interventions are better directed toward modulating tongue function rather than the mandible movements due to a greater response to sensory information. Understanding how sensory information influences infant feeding is instrumental in promoting effective infant feeding.

Exploring Alternative Methods to Reduce Milk Flow Rate From Infant Bottle Systems: Bottle Angle, Milk Volume, and Bottle Ventilation

PURPOSE

Modifying milk flow rate is a common pediatric dysphagia treatment. Though past investigations have demonstrated how this can be achieved using bottle nipples, little is known about the impact of other bottle modifications. The objective of this investigation is to demonstrate how bottle vent, bottle position, and volume of milk alter bottle pressures and milk flow.

METHOD

A Dr. Brown's bottle filled with formula was secured to a retort stand and inverted to allow milk to free flow from a Level 1 nipple. Milk flow rate and bottle pressures were calculated under three conditions: (a) with and without a vent in place; (b) with varying volumes of milk (1-4 oz); and (c) in horizontal, semi-inverted, and completely inverted positions. Differences between flow rates under the conditions were tested using repeated-measures analysis of variance.

RESULTS

Upon inversion, milk dripped from both vented and unvented bottles. Dripping continued throughout the 20-min testing period in the vented bottle; however, as air pressure and hydrostatic pressure declined (p < .01) in the unvented bottle, milk flow slowed and eventually ceased (p < .001). As angle of bottle inversion increased, hydrostatic pressure and milk flow rate had corresponding increases as well (p < .001). Hydrostatic pressure increased an average of 1.4 ± 0.12 mm Hg per additional ounce of formula that was added to the bottle, with corresponding increases in milk flow rate observed (p < .001).

CONCLUSIONS

Milk flow rate can be altered by feeding conditions outside of bottle nipples alone. Future work examining the clinical significance of these modifications is warranted to determine optimal interventions.

Nutrition Management of High-Risk Neonates After Discharge

Nutrition management of the high-risk infant after hospital discharge is complicated by the infant's dysfunctional or immature oral feeding skills, nutritional deficits, and the family's feeding plan. Although evidence is limited, available studies point to developing an individualized nutritional plan, which accounts for these factors; protects and prioritizes the family's plan for breastfeeding; and promotes an acceptable growth pattern. Further research is needed to identify the type and duration of posthospital discharge nutrition to optimize high-risk infant neurodevelopment and body composition. Attention to infant growth, lactation support, and safe feed preparation practices are critical in the transition to home.

Cross-System Integration of Respiration and Deglutition: Function, Treatment, and Future Directions

Swallowing occurs preferentially in the expiratory phase of the quiet breathing cycle and at mid-to-low tidal volume. This coordinative pattern imparts important biomechanical advantages to swallowing and airway protection and facilitate laryngeal elevation, laryngeal vestibular and vocal fold closure, and cricopharyngeal sphincter opening. This preferred coordinative relationship between breathing and swallowing is impaired in a variety of patient populations, including head and neck cancer survivors with dysphagia. We developed a training protocol to re-establish more optimal phasing of swallowing with breathing in these patients with striking outcomes, including reduced swallowing physiological impairments and improved airway protection. This motivated us to continue to refine and expand this training protocol and develop new assistive technologies for swallowing monitoring outside of the lab. In this review, we highlight the origins of our optimal respiratory-swallowing coordination hypothesis, describe the biomechanical advantages it provides, carefully describe our training protocol and findings, and chart a course for the next phase of this work. Our overall goal is to harness technology combined with carefully constructed learning paradigms to improve the lives of patients with impaired respiratory-swallowing coordination consequent to a variety of pathologies including head and neck cancer and degenerative neurological conditions such as Parkinson's disease.

Non-Pharmacological and Non-Surgical Feeding Interventions for Hospitalized Infants with Pediatric Feeding Disorder: A Scoping Review

Infants born prematurely or with complex medical conditions often require treatment to facilitate safe and efficient feeding. Practice is based on evidence, so frontline clinicians look to the literature to make informed clinical decisions. The aim of this scoping review was to map and describe the literature base for infant feeding and swallowing interventions and to identify areas for further research. Four electronic databases were searched from the sources' inceptions through April 2020 using a search strategy designed by a health sciences research librarian. Thirteen grey literature sources were searched and forward and backward citation chasing was performed. Inclusion criteria were English-language studies reporting non-pharmacological and non-surgical interventions for hospitalized infants. Exclusion criteria included interventions exclusively for infants with cleft lip or palate or for infants being fed exclusively though enteral feeding. Data were extracted using a form created a priori and data were reported descriptively. We reviewed 6654 abstracts: 725 were chosen for full-text review and 136 met inclusion. Most studies explored interventions for infants born prematurely (n = 128). Studies were stratified by intervention domain: bridging (n = 91) and feeding/swallowing (n = 45); intervention approach: direct (n = 72), indirect (n = 31), or combination (n = 33); and outcome: feeding performance (n = 125), physiologic stability (n = 40), and swallowing physiology (n = 12). The body of research in infant feeding has grown; however, a need remains for research focused on populations of infants with various medical complexities and for frequently used interventions that lack supporting evidence.

Milk Flow Rates From Bottle Nipples: What We Know and Why It Matters

Feeding difficulties are common in infants hospitalized in the NICU and can be a challenge to manage. The purpose of this article is to explain how and why the flow rate from the bottle nipple affects physiologic stability in infants and to describe the current evidence available on the flow rates of nipples used in the hospital and after discharge. Study results have indicated that flow rate varies widely among different types of nipples. Within the same type of nipple, there can be significant variability in flow from one nipple to another. Other factors, such as type of infant formula and thickening, also affect flow. Altering the flow rate of the bottle nipple is a relatively simple intervention that may support safe oral feeding.

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

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.

Motor Learning, Neuroplasticity, and Strength and Skill Training: Moving From Compensation to Retraining in Behavioral Management of Dysphagia

Purpose Learning a motor skill and regaining a motor skill after it is lost are key tenets to the field of speech-language pathology. Motor learning and relearning have many theoretical underpinnings that serve as a foundation for our clinical practice. This review article applies selective motor learning theories and principles to feeding and swallowing across the life span. Conclusion In reviewing these theoretical fundamentals, clinical exemplars surrounding the roles of strength, skill, experience, compensation, and retraining, and their influence on motor learning and plasticity in regard to swallowing/feeding skills throughout the life span are discussed.

To Individualize the Management Care of High-Risk Infants With Oral Feeding Challenges: What Do We Know? What Can We Do?

The increase in preterm infants' survival over the last 30 years has shed light over their inability to feed by mouth safely and efficiently. With adverse events such as increased risks for oxygen desaturation, bradycardia, penetration/aspiration, infants' hospitalization in neonatal intensive care units (NICUs) are understandably prolonged. Unfortunately, this leads to delayed mother-infant reunion, maternal stress, breastfeeding obstacles, and increased medical costs. Such impediments have stimulated clinicians and researchers to better understand the underlying causes and develop evidence-based solutions to assist these infants. However, it is notable that the research-to-practice translation of this knowledge has been limited as there are still no validated guidelines or protocols as how to best diagnose and care for these infants. This report revisits the immature physiologic functions at the root of these infants' oral feeding difficulties, the current practices, and the recent availability of evidence-based efficacious tools and interventions. Taking advantage of the latter, it presents a renewed perspective of how management strategies can be tailored to the specific needs of individual patients.

Swallow Safety is Determined by Bolus Volume During Infant Feeding in an Animal Model

Feeding difficulties are especially prevalent in preterm infants, although the mechanisms driving these difficulties are poorly understood due to a lack of data on healthy infants. One potential mechanism of dysphagia in adults is correlated with bolus volume. Yet, whether and how bolus volume impacts swallow safety in infant feeding is unknown. A further complication for safe infant swallowing is recurrent laryngeal nerve (RLN) injury due to patent ductus arteriosus surgery, which exacerbates the issues that preterm infants face and can increase the risk of dysphagia. Here, we used a validated animal model feeding freely to test the effect of preterm birth, postnatal maturation and RLN lesion and their interactions on swallow safety. We also tested whether bolus size differed with lesion or birth status, and the relationship between bolus size and swallow safety. We found very little effect of lesion on swallow safety, and preterm infants did not experience more penetration or aspiration than term infants. However, term infants swallowed larger boluses than preterm infants, even after correcting for body size. Bolus size was the primary predictor of penetration or aspiration, with larger boluses being more likely to result in greater degrees of dysphagia irrespective of age or lesion status. These results highlight that penetration and aspiration are likely normal occurrences in infant feeding. Further, when comorbidities, such as RLN lesion or preterm birth are present, limiting bolus size may be an effective means to reduce incidences of penetration and aspiration.

Capturing infant swallow impairment on videofluoroscopy: timing matters

BACKGROUND

Infant videofluoroscopic swallow studies (VFSSs) require clinicians to make determinations about swallowing deficits based on a limited number of fluoroscopically observed swallows. Although airway protection is known to decline throughout a bottle-feed, the paucity of data regarding the timing of this degradation has limited the development of procedural protocols that maximize diagnostic validity.

OBJECTIVE

We tested the stability of key components of swallow physiology and airway protection at four standardized timepoints throughout the VFSS.

MATERIALS AND METHODS

Thirty bottle-fed infants with clinical signs of swallow dysfunction underwent VFSS. Fluoroscopy was turned on to allow visualization of five swallows at 0:00, 0:30, 1:30 and 2:30 (minutes:seconds [min:s]). We evaluated swallows for components of swallow physiology (oral bolus hold, initiation of pharyngeal swallow, timing of swallow initiation) and airway protection (penetration, aspiration). We used model-based linear contrasts to test differences in the percentage of swallows with low function component attributes.

RESULTS

All components of swallow physiology exhibited a change throughout the VFSS (P≤0.0005). Changes were characterized by an increase in the number of sucks per swallow (P<0.0001), percentage of swallows with incomplete bolus hold (P=0.0005), delayed initiation of pharyngeal swallow (P<0.0001), delayed timing of swallow initiation (P=0.0004) and bolus airway entry (P<0.0001). These findings demonstrate that infants with dysphagia exhibit a change in swallow physiology throughout the videofluoroscopic swallow exam.

CONCLUSION

Fluoroscopic visualization that is confined to the initial swallows of the bottle feed limit the exam's diagnostic validity. Developing evidence-based procedural guidelines for infant VFSS execution is crucial for maximizing the exam's diagnostic and treatment yield.

Preterm birth disrupts the development of feeding and breathing coordination

All mammals must breathe and breathe continuously from birth. Similarly, all mammals, including infants, have high functional demands for feeding. However, the pathway that food takes through the pharynx interrupts respiration. The coordination between swallowing and breathing is therefore critical for all infant mammals. Clinically, this coordination differs between term and preterm infants. However, the neurological mechanisms underlying this coordination and how it matures as infants grow are poorly understood. Here, we integrate high-resolution data from multiple physiologic processes across a longitudinal time frame to study suck-swallow-breathe dynamics in a preterm animal model, the infant pig. In doing so, we test the hypothesis that preterm birth will have an impact on some, but not all, behaviors associated with suck-swallow-breath performance. We hypothesize that coordination will be disrupted, reflecting incomplete connections in the brainstem. We found that preterm pigs became rhythmic and mature in sucking and swallowing behaviors, suggesting substantial postnatal maturation in the coordination of these behaviors. However, their ability to coordinate swallowing and breathing never developed. These results have implications for the nature of clinical care of human infants, as well as for how feeding processes develop in mammals. Clinically, they provide a foundation for developing interventions for preterm infants. Additionally, these results suggest that the lack of coordination between swallowing and breathing may be a significant factor in determining the minimum gestation time across mammals. NEW & NOTEWORTHY Preterm infants face a variety of challenges associated with safe feeding, but obtaining high-resolution longitudinal data to understand these challenges in humans is challenging. We used a pig model to acquire high-speed videofluoroscopic and respiratory inductance plethysmograph data throughout the nursing period to show that preterm birth does not have substantial impacts on the ability of infants to perform isolated behaviors. However, it does decrease the ability of preterm infants to coordinate among behaviors during feeding.

Know the Flow: Milk Flow Rates From Bottle Nipples Used in the Hospital and After Discharge

BACKGROUND

Milk flow rate may play an important role in an infant's ability to safely and efficiently coordinate sucking, swallowing, and breathing during feeding.

PURPOSE

To test milk flow rates from bottle nipples used in the hospital and after discharge.

METHODS

Bottle nipples used in hospitals (10 unique types) and available nationwide at major retailers (15 unique types) were identified. For each of the 25 nipple types, 15 nipples of that type were tested by measuring the amount of infant formula extracted in 1 minute by a breast pump. Mean milk flow rate (mL/min) and coefficient of variation (CV) were calculated for each nipple type. Comparisons between nipple types were made within brand and within category (eg, Slow, Standard). A cluster analysis was conducted to identify nipples of comparable flow.

RESULTS

A total of 375 individual nipples were tested. Milk flow rates varied widely, from 0.86 to 37.61 mL/min. There was also a wide range of CVs, from 0.03 to 0.35. Packing information did not accurately reflect the flow rates of bottle nipples. The cluster analysis revealed 5 clusters of nipples, with flow rates from Extra Slow to Very Fast.

IMPLICATIONS FOR PRACTICE

These data can be used to guide decisions regarding nipples to use for feeding infants with medical complexity in the hospital and after discharge.

IMPLICATIONS FOR RESEARCH

Research on infant feeding should consider the flow rate and variability of nipples used, as these factors may impact findings.

Not All Pacifiers Are Created Equal: A Mechanical Examination of Pacifiers and Their Influence on Suck Patterning

PURPOSE

Many pacifier companies advertise that their product is the "best choice" to support proper sucking, feeding, and dental development; however, very little evidence exists to support these claims. As the primary differences across pacifiers are structural and mechanical, the goals of this study were to measure such properties of commercially available pacifiers and to examine how these properties alter suck patterning in healthy, full-term infants.

METHOD

Seven commonly utilized pacifiers were mechanically tested for pull and compression stiffness levels and categorized into nipple shape types based on their aspect ratio. Next, 3 pacifiers (Soothie, GumDrop, and Freeflow) with the most salient differences in pull stiffness levels with 2 different pacifier nipple types were tested clinically on 16 full-term infants (≤ 6 months old) while measuring non-nutritive suck (NNS).

RESULTS

A repeated measures analysis of variance revealed significant differences between NNS burst duration (p = .002), NNS cycles per burst (p = .002), and NNS cycles per minute (p = .006) and pacifier type. With each significant dependent measure, pairwise comparisons showed that the GumDrop and Freeflow pacifiers differed significantly on these measures.

CONCLUSIONS

Pacifier compression, pull stiffness, and nipple shape type yield different NNS dynamics. These findings motivate further investigation into pacifier properties and suck patterning in young infants.