Respiratory Distress Syndrome Degrades the Fine Structure of the Non-Nutritive Suck In Preterm Infants

Oral stimulation for promoting oral feeding in preterm infants

BACKGROUND

Preterm infants (< 37 weeks' post-menstrual age (PMA)) are often delayed in attaining oral feeding. Normal oral feeding is suggested as an important outcome for the timing of discharge from the hospital and can be an early indicator of neuromotor integrity and developmental outcomes. A range of oral stimulation interventions may help infants to develop sucking and oromotor co-ordination, promoting earlier oral feeding and earlier hospital discharge. This is an update of our 2016 review.

OBJECTIVES

To determine the effectiveness of oral stimulation interventions for attainment of oral feeding in preterm infants born before 37 weeks' PMA.

SEARCH METHODS

Searches were run in March 2022 of the following databases: CENTRAL via CRS Web; MEDLINE and Embase via Ovid. We also searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-randomised trials. Searches were limited by date 2016 (the date of the search for the original review) forward. Note: Due to circumstances beyond our control (COVID and staffing shortages at the editorial base of Cochrane Neonatal), publication of this review, planned for mid 2021, was delayed. Thus, although searches were conducted in 2022 and results screened, potentially relevant studies found after September 2020 have been placed in the section, Awaiting Classification, and not incorporated into our analysis.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing a defined oral stimulation intervention with no intervention, standard care, sham treatment or non-oral intervention (e.g. body stroking protocols or gavage adjustment protocols) in preterm infants and reporting at least one of the specified outcomes.

DATA COLLECTION AND ANALYSIS

Following the updated search, two review authors screened the titles and abstracts of studies and full-text copies when needed to identify trials for inclusion in the review. The primary outcomes of interest were time (days) to exclusive oral feeding, time (days) spent in NICU, total hospital stay (days), and duration (days) of parenteral nutrition. All review and support authors contributed to independent extraction of data and analysed assigned studies for risk of bias across the five domains of bias using the Cochrane Risk of Bias assessment tool. The GRADE system was used to rate the certainty of the evidence. Studies were divided into two groups for comparison: intervention versus standard care and intervention versus other non-oral or sham intervention. We performed meta-analysis using a fixed-effect model.

MAIN RESULTS

We included 28 RCTs (1831 participants). Most trials had methodological weaknesses, particularly in relation to allocation concealment and masking of study personnel. Oral stimulation compared with standard care Following meta-analysis, it is uncertain whether oral stimulation reduces the time to transition to oral feeding compared with standard care (mean difference (MD) -4.07 days, 95% confidence interval (CI) -4.81 to -3.32 days, 6 studies, 292 infants; I2 =85%, very low-certainty evidence due to serious risk of bias and inconsistency). Time (days) spent in the neonatal intensive care unit (NICU) was not reported. It is uncertain whether oral stimulation reduces the duration of hospitalisation (MD -4.33, 95% CI -5.97 to -2.68 days, 5 studies, 249 infants; i2 =68%, very low-certainty evidence due to serious risk of bias and inconsistency). Duration (days) of parenteral nutrition was not reported. Oral stimulation compared with non-oral intervention Following meta-analysis, it is uncertain whether oral stimulation reduces the time to transition to exclusive oral feeding compared with a non-oral intervention (MD -7.17, 95% CI -8.04 to -6.29 days, 10 studies, 574 infants; I2 =80%, very low-certainty evidence due to serious risk of bias, inconsistency and precision). Time (days) spent in the NICU was not reported. Oral stimulation may reduce the duration of hospitalisation (MD -6.15, 95% CI -8.63 to -3.66 days, 10 studies, 591 infants; I2 =0%, low-certainty evidence due to serious risk of bias). Oral stimulation may have little or no effect on the duration (days) of parenteral nutrition exposure (MD -2.85, 95% CI -6.13 to 0.42, 3 studies, 268 infants; very low-certainty evidence due to serious risk of bias, inconsistency and imprecision).

AUTHORS' CONCLUSIONS

There remains uncertainty about the effects of oral stimulation (versus either standard care or a non-oral intervention) on transition times to oral feeding, duration of intensive care stay, hospital stay, or exposure to parenteral nutrition for preterm infants. Although we identified 28 eligible trials in this review, only 18 provided data for meta-analyses. Methodological weaknesses, particularly in relation to allocation concealment and masking of study personnel and caregivers, inconsistency between trials in effect size estimates (heterogeneity), and imprecision of pooled estimates were the main reasons for assessing the evidence as low or very low certainty. More well-designed trials of oral stimulation interventions for preterm infants are warranted. Such trials should attempt to mask caregivers to treatment when possible, paying particular attention to blinding of outcome assessors. There are currently 32 ongoing trials. Outcome measures that reflect improvements in oral motor skill development as well as longer term outcome measures beyond six months of age need to be defined and used by researchers to capture the full impact of these interventions.

Effects of an Oral Stimulation Program on Feeding Outcomes in Preterm Infants: A Systematic Review and Meta-Analysis

AIMS

To review the literature on the effects of unimodal sensorimotor stimulation protocols on feeding outcomes in very preterm and moderate to late preterm infants (PIs).

METHODS

Five databases were searched up to April 2022. Studies comparing unimodal sensorimotor stimulation protocols based on the combination of manual oral stimulation with NNS against usual care in PIs, on-time transition to full oral feeding (FOF), feeding efficacy, length of hospital stay, and/or body weight gain.

RESULTS

Eleven studies were included. Compared to usual care, unimodal sensorimotor stimulation protocols based on manual oral stimulation combined with NNS demonstrated to be more effective in decreasing time transition to FOF (standardized mean difference [95%CI] - 1.08 [-1.74, -0.41]), improving feeding efficacy (2.15 [1.18, 3.13]) and shortening length of hospital stay (-0.35 [-0.68, -0.03]). However, the proposed intervention was not effective in improving weight gain (0.27 [-0.40, 0.95]). There were no significant differences according to gestational age (p > .05).

CONCLUSIONS

Based on fair-to-high quality evidence, unimodal sensorimotor stimulation protocols combined with NNS reduce time transition to FOF, improve feeding efficacy, and shorten the length of hospital stay; yet the proposed intervention yielded no significant effects on body weight gain when compared to usual care in PIs.

The effect of early oral stimulation with breast milk on the feeding behavior of infants after congenital cardiac surgery

OBJECTIVE

To investigate the effect of early oral stimulation with breast milk on the feeding behavior of infants after congenital cardiac surgery.

METHODS

Infants with congenital heart disease were randomly divided into the breast milk oral stimulation group (n = 23), physiological saline oral stimulation group (n = 23) and control group (n = 23). Debra Beckman's oral exercise program was used with breast milk and physiological saline in the breast milk oral stimulation group and the physiological saline oral stimulation group, respectively. The time oral feeding and total oral nutrition were started, the length of intensive care unit (ICU) stay and hospital stay, weight and the complications at discharge were recorded for each group and statistically analyzed.

RESULTS

The time oral feeding and total oral nutrition were started and the length of ICU stay and hospital stay were significantly less in the breast milk oral stimulation group and physiological saline oral stimulation group than in the control group (P < 0.05). There were no significant differences in other indicators between the breast milk oral stimulation group and the physiological saline oral stimulation group, except for the time total oral nutrition began (P < 0.05). However, there were no significant differences in weight or complications at discharge among the three groups (P > 0.05).

CONCLUSION

Early oral stimulation exercises with breast milk can help infant patients quickly recover total oral nutrition and reduce the length of ICU and hospital stay after cardiac surgery.

Preterm Neurodevelopmental Outcomes Following Orosensory Entrainment Intervention

Previous research indicates that the NTrainer, a pressurized pacifier programmed to produce pulsed pneumotactile stimulation during gavage feeds, has been found to facilitate non-nutritive suck development and shorten the length of hospital stay when used in the Neonatal Intensive Care Unit (NICU). Four groups of children, including infants of diabetic mothers (IDM), healthy controls (HI), and those with respiratory distress syndrome (RDS), or chronic lung disease (CLD), were randomly assigned to an NTrainer therapy or sham 'control' condition when in the NICU. At 30 months of age, 113/223 study participants were assessed using standardized language, motor, and cognitive assessments. No significant group differences were evident between the NTrainer and sham groups in language, motor, or cognitive functioning. The NTrainer did not improve nor adversely impact language, cognition, or motor outcomes.

Lung-injury depresses glutamatergic synaptic transmission in the nucleus tractus solitarii via discrete age-dependent mechanisms in neonatal rats

Transition periods (TPs) are brief stages in CNS development where neural circuits can exhibit heightened vulnerability to pathologic conditions such as injury or infection. This susceptibility is due in part to specialized mechanisms of synaptic plasticity, which may become activated by inflammatory mediators released under pathologic conditions. Thus, we hypothesized that the immune response to lung injury (LI) mediated synaptic changes through plasticity-like mechanisms that depended on whether LI occurred just before or after a TP. We studied the impact of LI on brainstem 2nd-order viscerosensory neurons located in the nucleus tractus solitarii (nTS) during a TP for respiratory control spanning (postnatal day (P) 11-15). We injured the lungs of Sprague-Dawley rats by intratracheal instillation of Bleomycin (or saline) just before (P9-11) or after (P17-19) the TP. A week later, we prepared horizontal slices of the medulla and recorded spontaneous and evoked excitatory postsynaptic currents (sEPSCs/eEPSCs) in vitro from neurons in the nTS that received monosynaptic glutamatergic input from the tractus solitarii (TS). In rats injured before the TP (pre-TP), neurons exhibited blunted sEPSCs and TS-eEPSCs compared to controls. The decreased TS-eEPSCs were mediated by differences in postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic-acid receptors (AMPAR). Specifically, compared to controls, LI rats had more Ca2+-impermeable AMPARs (CI-AMPARs) as indicated by: 1) the absence of current-rectification, 2) decreased sensitivity to polyamine, 1-Naphthyl-acetyl-spermine-trihydrochloride (NASPM) and 3) augmented immunoreactive staining for the CI-AMPAR GluA2. Thus, pre-TP-LI acts postsynaptically to blunt glutamatergic transmission. The neuroimmune response to pre-TP-LI included microglia hyper-ramification throughout the nTS. Daily intraperitoneal administration of minocycline, an inhibitor of microglial/macrophage function prevented hyper-ramification and abolished the pre-TP-LI evoked synaptic changes. In contrast, rat-pups injured after the TP (post-TP) exhibited microglia hypo-ramification in the nTS and had increased sEPSC amplitudes/frequencies, and decreased TS-eEPSC amplitudes compared to controls. These synaptic changes were not associated with changes in CI-AMPARs, and instead involved greater TS-evoked use-dependent depression (reduced paired pulse ratio), which is a hallmark of presynaptic plasticity. Thus we conclude that LI regulates the efficacy of TS → nTS synapses through discrete plasticity-like mechanisms that are immune-mediated and depend on whether the injury occurs before or after the TP for respiratory control.

Somatosensory Modulation of Salivary Gene Expression and Oral Feeding in Preterm Infants: Randomized Controlled Trial

Background

Despite numerous medical advances in the care of at-risk preterm neonates, oral feeding still represents one of the first and most advanced neurological challenges facing this delicate population. Objective, quantitative, and noninvasive assessment tools, as well as neurotherapeutic strategies, are greatly needed in order to improve feeding and developmental outcomes. Pulsed pneumatic orocutaneous stimulation has been shown to improve nonnutritive sucking (NNS) skills in preterm infants who exhibit delayed or disordered nipple feeding behaviors. Separately, the study of the salivary transcriptome in neonates has helped identify biomarkers directly linked to successful neonatal oral feeding behavior. The combination of noninvasive treatment strategies and transcriptomic analysis represents an integrative approach to oral feeding in which rapid technological advances and personalized transcriptomics can safely and noninvasively be brought to the bedside to inform medical care decisions and improve care and outcomes.

Objective

The study aimed to conduct a multicenter randomized control trial (RCT) to combine molecular and behavioral methods in an experimental conceptualization approach to map the effects of PULSED somatosensory stimulation on salivary gene expression in the context of the acquisition of oral feeding habits in high-risk human neonates. The aims of this study represent the first attempt to combine noninvasive treatment strategies and transcriptomic assessments of high-risk extremely preterm infants (EPI) to (1) improve oral feeding behavior and skills, (2) further our understanding of the gene ontology of biologically diverse pathways related to oral feeding, (3) use gene expression data to personalize neonatal care and individualize treatment strategies and timing interventions, and (4) improve long-term developmental outcomes.

Methods

A total of 180 extremely preterm infants from three neonatal intensive care units (NICUs) will be randomized to receive either PULSED or SHAM (non-pulsing) orocutaneous intervention simultaneous with tube feedings 3 times per day for 4 weeks, beginning at 30 weeks postconceptional age. Infants will also be assessed 3 times per week for NNS performance, and multiple saliva samples will be obtained each week for transcriptomic analysis, until infants have achieved full oral feeding status. At 18 months corrected age (CA), infants will undergo neurodevelopmental follow-up testing, the results of which will be correlated with feeding outcomes in the neo-and post-natal period and with gene expression data and intervention status.

Results

The ongoing National Institutes of Health funded randomized controlled trial R01HD086088 is actively recruiting participants. The expected completion date of the study is 2021.

Conclusions

Differential salivary gene expression profiles in response to orosensory entrainment intervention are expected to lead to the development of individualized interventions for the diagnosis and management of oral feeding in preterm infants.

Trial Registration

ClinicalTrials.gov NCT02696343; https://clinicaltrials.gov/ct2/show/NCT02696343 (Archived by WebCite at http://www.webcitation.org/6r5NbJ9Ym)

Oral stimulation for promoting oral feeding in preterm infants

BACKGROUND

Preterm infants (< 37 weeks' postmenstrual age) are often delayed in attaining oral feeding. Normal oral feeding is suggested as an important outcome for the timing of discharge from the hospital and can be an early indicator of neuromotor integrity and developmental outcomes. A range of oral stimulation interventions may help infants to develop sucking and oromotor co-ordination, promoting earlier oral feeding and earlier hospital discharge.

OBJECTIVES

To determine the effectiveness of oral stimulation interventions for attainment of oral feeding in preterm infants born before 37 weeks' postmenstrual age (PMA).To conduct subgroup analyses for the following prespecified subgroups.• Extremely preterm infants born at < 28 weeks' PMA.• Very preterm infants born from 28 to < 32 weeks' PMA.• Infants breast-fed exclusively.• Infants bottle-fed exclusively.• Infants who were both breast-fed and bottle-fed.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via PubMed (1966 to 25 February 2016), Embase (1980 to 25 February 2016) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 25 February 2016). We searched clinical trials databases, conference proceedings and the reference lists of retrieved articles.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing a defined oral stimulation intervention with no intervention, standard care, sham treatment or non-oral intervention in preterm infants and reporting at least one of the specified outcomes.

DATA COLLECTION AND ANALYSIS

One review author searched the databases and identified studies for screening. Two review authors screened the abstracts of these studies and full-text copies when needed to identify trials for inclusion in the review. All review authors independently extracted the data and analysed each study for risk of bias across the five domains of bias. All review authors discussed and analysed the data and used the GRADE system to rate the quality of the evidence. Review authors divided studies into two groups for comparison: intervention versus standard care and intervention versus other non-oral or sham intervention. We performed meta-analysis using a fixed-effect model.

MAIN RESULTS

This review included 19 randomised trials with a total of 823 participants. Almost all included trials had several methodological weaknesses. Meta-analysis showed that oral stimulation reduced the time to transition to oral feeding compared with standard care (mean difference (MD) -4.81, 95% confidence interval (CI) -5.56 to -4.06 days) and compared with another non-oral intervention (MD -9.01, 95% CI -10.30 to -7.71 days), as well as the duration of initial hospitalisation compared with standard care (MD -5.26, 95% CI -7.34 to -3.19 days) and compared with another non-oral intervention (MD -9.01, 95% CI -10.30 to -7.71 days).Investigators reported shorter duration of parenteral nutrition for infants compared with standard care (MD -5.30, 95% CI -9.73 to -0.87 days) and compared with another non-oral intervention (MD -8.70, 95% CI -15.46 to -1.94 days). They could identify no effect on breast-feeding outcomes nor on weight gain.

AUTHORS' CONCLUSIONS

Although the included studies suggest that oral stimulation shortens hospital stay, days to exclusive oral feeding and duration of parenteral nutrition, one must interpret results of these studies with caution, as risk of bias and poor methodological quality are high overall. Well-designed trials of oral stimulation interventions for preterm infants are warranted. Such trials should use reliable methods of randomisation while concealing treatment allocation, blinding caregivers to treatment when possible and paying particular attention to blinding of outcome assessors.

Effect of co-morbidities on the development of oral feeding ability in pre-term infants: a retrospective study

Pre-term infants frequently experience difficulties in attaining independent oral feeding, thus delaying the achievement of an adequate nutritional status and hospital discharge. The aim of this retrospective, single-centre, observational study was to investigate the effect of co-morbidities on the timing of the achievement of full oral feeding in pre-term infants. The neonatal and feeding data of 84 infants born at a gestational age of <32 weeks were collected, and the effect of co-morbidities on the achievement of feeding independence was evaluated using multiple linear regression analysis. The mean postmenstrual age at the time of the achievement of full oral feeding was 36.7 ± 3.68 weeks (range 33–53) weeks. The multiple linear regression analysis showed that a low birth weight, the occurrence of bronchopulmonary dysplasia, and the need for gastrointestinal surgical procedures were independently associated with a higher postmenstrual age at achievement of full oral feedings.

Oral Motor Intervention Improved the Oral Feeding in Preterm Infants: Evidence Based on a Meta-Analysis With Trial Sequential Analysis

Oral feeding for preterm infants has been a thorny problem worldwide. To improve the efficacy of oral feeding in preterm infants, oral motor intervention (OMI), which consists of nonnutritive sucking, oral stimulation, and oral support, was developed. Published studies demonstrated that OMI may be as an alternative treatment to solve this problem; however, these results remain controversial. We conducted a meta-analysis with trial sequential analysis (TSA) to objectively evaluate the potential of OMI for improving the current status of oral feeding in preterm infants.A search of PubMed, EMBASE, Web of Science, the Cochrane Library, and China National Knowledge Infrastructure was performed to capture relevant citations until at the end of October, 2014. Lists of references of eligible studies and reviews were also hand-checked to include any latent studies. Two independent investigators screened literature, extracted data, and assessed the methodology, and then a meta-analysis and TSA was performed by using Reviewer Manager (RevMan) 5.3 and TSA 0.9 beta, respectively.A total of 11 randomized controlled trials (RCTs), which included 855 participants, were incorporated into our meta-analysis. The meta-analyses suggested that OMI is associated with the reduced transition time (ie, the time needed from tube feeding to totally oral feeding) (mean difference [MD], -4.03; 95% confidence interval [CI], -5.22 to -2.84), shorten hospital stays (MD, -3.64; 95% CI, -5.57 to -1.71), increased feeding efficiency (MD, 0.08; 95% CI, 0.36-1.27), and intake of milk (MD, 0.14; 95% CI, 0.06-0.21) rather than weight gain. Results of TSA for each outcomes of interest confirmed these pooled results.With present evidences, OMI can be as an alternative to improve the condition of transition time, length of hospital stays, feeding efficiency, and intake of milk in preterm infants. However, the pooled results may be impaired due to low quality included, and thus, well-designed and large RCTs were needed to further established effects.

Effects of Oral Stimulus Frequency Spectra on the Development of Non-nutritive Suck in Preterm Infants with Respiratory Distress Syndrome or Chronic Lung Disease, and Preterm Infants of Diabetic Mothers

The precocial nature of orofacial sensorimotor control underscores the biological importance of establishing ororythmic activity in human infants. The purpose of this study was to assess the effects of comparable doses of three forms of orosensory experience, including a low-velocity spectrally reduced orocutaneous stimulus (NT1), a high-velocity broad spectrum orocutaneous stimulus (NT2), and a SHAM stimulus consisting of a blind pacifier. Each orosensory experience condition was paired with gavage feedings 3x/day for 10 days in the neonatal intensive care unit (NICU). Four groups of preterm infants (N=214), including those with respiratory distress syndrome (RDS), chronic lung disease (CLD), infants of diabetic mothers (IDM), and healthy controls (HI) were randomized to the type of orosensory condition. Mixed modeling, adjusted for gender, gestational age, postmenstrual age, and birth weight, demonstrated the most significant gains in non-nutritive suck (NNS) development among CLD infants who were treated with the NT2 stimulus, with smaller gains realized among RDS and IDM infants. The broader spectrum of the NT2 stimulus maps closely to known response properties of mechanoreceptors in lip, tongue, and oral mucosa and is more effective in promoting NNS development among preterm infants with impaired oromotor function compared to the low-velocity, spectrally reduced NT1 orosensory stimulus.

Effects of pre-feeding oral stimulation on oral feeding in preterm infants: a randomized clinical trial

OBJECTIVE

To evaluate the effect of early oral stimulation before the introduction of oral feeding, over the duration of concomitant tube feeding ("transition period"), the length of hospital stay and the breastfeeding rates upon discharge in preterm infants.

STUDY DESIGN

Preterm infants born between 26 and 33 weeks gestational age (n=86), were randomized into an intervention and control group. Infants in the intervention group received an oral stimulation program consisting in stimulation of the oral structures for 15 min at least for 10 days, before introduction of oral feeding. Oral feeding was introduced at 34 weeks GA in both groups.

RESULTS

Breastfeeding rates upon discharge were significantly higher in the intervention than in the control group (70% versus 45.6%, p=0.02). There was no statistical difference between the two groups in terms of the length of the transition period or the length of the hospital stay. The need for prolonged CPAP support (HR=0.937, p=0.030) and small size for gestational age at birth (HR=0.338, p=0.016) were shown to be risk factors for a prolonged transition period.

CONCLUSION

A pre-feeding oral stimulation program improves breastfeeding rates in preterm infants. The study results suggest that oral stimulation, as used in our specific population, does not shorten the transition period to full oral feeding neither the length of hospital stay.

Frequency-modulated orocutaneous stimulation promotes non-nutritive suck development in preterm infants with respiratory distress syndrome or chronic lung disease

OBJECTIVE

For the premature infant, extrauterine life is a pathological condition, which greatly amplifies the challenges to the brain in establishing functional oromotor behaviors. The extent to which suck can be entrained using a synthetically patterned orocutaneous input to promote its development in preterm infants who manifest chronic lung disease (CLD) is unknown. The objective of this study was to evaluate the effects of a frequency-modulated (FM) orocutaneous pulse train delivered through a pneumatically charged pacifier capable of enhancing non-nutritive suck (NNS) activity in tube-fed premature infants.

STUDY DESIGN

A randomized trial to evaluate the efficacy of pneumatic orocutaneous stimulation 3 × per day on NNS development and length of stay (LOS) in the neonatal intensive care unit among 160 newborn infants distributed among three sub-populations, including healthy preterm infants, respiratory distress syndrome (RDS) and CLD. Study infants received a regimen of orocutaneous pulse trains through a PULSED pressurized silicone pacifier or a SHAM control (blind pacifier) during gavage feeds for up to 10 days.

RESULT

Mixed modeling, adjusted for the infant's gender, gestational age, postmenstrual age and birth weight, was used to handle interdependency among repeated measures within subjects. A significant main effect for stimulation mode (SHAM pacifier vs PULSED orosensory) was found among preterm infants for NNS bursts per min (P=0.003), NNS events per min (P=0.033) and for total oral compressions per min (NNS+nonNNS) (P=0.016). Pairwise comparison of adjusted means using Bonferroni adjustment indicated RDS and CLD infants showed the most significant gains on these NNS performance indices. CLD infants in the treatment group showed significantly shorter LOS by an average of 2.5 days.

CONCLUSION

FM PULSED orocutaneous pulse train stimuli delivered through a silicone pacifier are effective in facilitating NNS burst development in tube-fed RDS and CLD preterm infants, with an added benefit of reduced LOS for CLD infants.

Neurologic and metabolic issues in moderately preterm, late preterm, and early term infants

Common neurologic morbidities encountered in very preterm and extremely preterm infants (intracranial hemorrhage, white matter injury and periventricular leukomalacia, and apnea of prematurity) are much less common in moderately preterm and late preterm infants. The frequency of germinal matrix hemorrhage-intraventricular hemorrhage and white matter injury are reported to be low, but selection bias in neuroimaging surveillance prevents ascertainment of precise frequencies. The major neurologic morbidity of moderately and late preterm infants is feeding difficulty reflecting developmental integration of suck, swallow, and breathing.

Short-Term Effects of Pacifier Texture on NNS in Neurotypical Infants

The dense representation of trigeminal mechanosensitive afferents in the lip vermilion, anterior tongue, intraoral mucosa, and temporomandibular joint allows the infant's orofacial system to encode a wide range of somatosensory experiences during the critical period associated with feed development. Our understanding of how this complex sensorium processes texture is very limited in adults, and the putative role of texture encoding in the infant is unknown. The purpose of this study was to examine the short-term effects of a novel textured pacifier experience in healthy term infants (N = 28). Nonnutritive suck (NNS) compression pressure waveforms were digitized in real time using a variety of custom-molded textured pacifiers varying in spatial array density of touch domes. MANCOVA, adjusted for postmenstrual age at test and sex, revealed that infants exhibited an increase in NNS burst attempts at the expense of a degraded suck burst structure with the textured pacifiers, suggesting that the suck central pattern generator (sCPG) is significantly disrupted and reorganized by this novel orocutaneous experience. The current findings provide new insight into oromotor control as a function of the oral somatosensory environment in neurotypically developing infants.

Frequency Modulation and Spatiotemporal Stability of the sCPG in Preterm Infants with RDS

The nonnutritive suck (NNS) is an observable and accessible motor behavior which is often used to make inference about brain development and pre-feeding skill in preterm and term infants. The purpose of this study was to model NNS burst compression pressure dynamics in the frequency and time domain among two groups of preterm infants, including those with respiratory distress syndrome (RDS, N = 15) and 17 healthy controls. Digitized samples of NNS compression pressure waveforms recorded at a 1-week interval were collected 15 minutes prior to a scheduled feed. Regression analysis and ANOVA revealed that healthy preterm infants produced longer NNS bursts and the mean burst initiation cycle frequencies were higher when compared to the RDS group. Moreover, the initial 5 cycles of the NNS burst manifest a frequency modulated (FM) segment which is a significant feature of the suck central pattern generator (sCPG), and differentially expressed in healthy and RDS infants. The NNS burst structure revealed significantly lower spatiotemporal index values for control versus RDS preterm infants during FM, and provides additional information on the microstructure of the sCPG which may be used to gauge the developmental status and progression of oromotor control systems among these fragile infants.

Feeding Difficulties in Preterm Infants

Preterm infants often display difficulty establishing oral feeding in the weeks following birth. This article aims to provide an overview of the literature investigating the development of feeding skills in preterm infants, as well as of interventions aimed at assisting preterm infants to develop their feeding skills. Available research suggests that preterm infants born at a lower gestational age and/or with a greater degree of morbidity are most at risk of early feeding difficulties. Respiratory disease was identified as a particular risk factor. Mechanisms for feeding difficulty identified in the literature include immature or dysfunctional sucking skills and poor suck–swallow–breath coordination. Available evidence provides some support for therapy interventions aimed at improving feeding skills, as well as the use of restricted milk flow to assist with maintaining appropriate ventilation during feeds. Further research is needed to confirm these findings, as well as to answer remaining clinical questions.

Oral and respiratory control for preterm feeding

PURPOSE OF REVIEW

Feeding competency is a frequent and serious challenge to the neonatal intensive care unit survivors and to the physician-provider-parent teams. The urgency of effective assessment and intervention techniques is obviated to promote safe swallow, as attainment of oral feeding for the preterm infant/newborn is one of the prerequisites for hospital discharge. If left unresolved, feeding problems may persist into early childhood and may require management by pediatric gastroenterologists and feeding therapists. This review highlights studies aimed at understanding the motor control and development of nonnutritive and nutritive suck, swallow, and coordination with respiration in preterm populations.

RECENT FINDINGS

Functional linkages between suck-swallow and swallow-respiration manifest transitional forms during late gestation and can be delayed or modified by sensory experience and/or disease processes. Moreover, brainstem central pattern generator (CPG) networks and their neuromuscular targets attain functional status at different rates, which ultimately influences cross-system interactions among individual CPGs. Entrainment of trigeminal primary afferents to activate the suck CPG is one example of a clinical intervention to prime cross-system interactions among ororhythmic pattern generating networks in the preterm and term infants.

SUMMARY

The genesis of within-system CPG control for rate and amplitude scaling matures differentially for suck, mastication, swallow, and respiration. Cross-system interactions among these CPGs represent targets of opportunity for new interventions that optimize experience-dependent mechanisms to promote robust ororhythmic patterning and safe swallows among preterm infants.

Suck Predicts Neuromotor Integrity and Developmental Outcomes

Neonatal motor behavior predicts both current neurological status and future neurodevelopmental outcomes. For speech pathologists, the earliest observable patterned oromotor behavior is suck. Suck production requires effective coordination of an infant's oral sensorimotor system and is subject to a variety of neuromodulatory inputs. Demonstration and practice of coordinated suck serves as a biomarker for oral feeding skills neural integrity and is being assessed for its relation to neurodevelopmental outcomes (speech, cognition, and learning) by research teams in the United States, Europe, Japan, and Brazil. Suck may also serve as an intervention point to prevent feeding disorders and mitigate speech-language delays and disorders.

Synthetic orocutaneous stimulation entrains preterm infants with feeding difficulties to suck

BACKGROUND

Prematurity can disrupt the development of a specialized neural circuit known as suck central pattern generator (sCPG), which often leads to poor feeding skills. The extent to which suck can be entrained using a synthetically patterned orocutaneous input to promote its development in preterm infants who lack a functional suck is unknown.

OBJECTIVE

To evaluate the effects of a new motorized 'pulsating' pacifier capable of entraining the sCPG in tube-fed premature infants who lack a functional suck and exhibit feeding disorders.

METHODS

Prospective cohort study of 31 preterm infants assigned to either the oral patterned entrainment intervention (study) or non-treated (controls) group, matched by gestational age, birth weight, oxygen supplementation history and oral feed status. Study infants received a daily regimen of orocutaneous pulse trains through a pneumatically controlled silicone pacifier concurrent with gavage feeds.

RESULTS

The patterned orocutaneous stimulus was highly effective in accelerating the development of non-nutritive suck (NNS) in preterm infants. A repeated-measure multivariate analysis of covariance revealed significant increases in minute rates for total oral compressions, NNS bursts, and NNS cycles, suck cycles per burst, and the ratiometric measure of NNS cycles as a percentage of total ororhythmic output. Moreover, study infants also manifest significantly greater success at achieving oral feeds, surpassing their control counterparts by a factor of 3.1 x (72.8% daily oral feed versus 23.3% daily oral feed, respectively).

CONCLUSION

Functional expression of the sCPG among preterm infants who lack an organized suck can be induced through the delivery of synthetically patterned orocutaneous pulse trains. The rapid emergence of NNS in treated infants is accompanied by a significant increase in the proportion of nutrient taken orally.

Pacifier Stiffness Alters the Dynamics of the Suck Central Pattern Generator

Variation in pacifier stiffness on non-nutritive suck (NNS) dynamics was examined among infants born prematurely with a history of respiratory distress syndrome. Three types of silicone pacifiers used in the NICU were tested for stiffness, revealing the Super Soothie™ nipple is 7 times stiffer than the Wee™ or Soothie™ pacifiers even though shape and displaced volume are identical. Suck dynamics among 20 preterm infants were subsequently sampled using the Soothie™ and Super Soothie™ pacifiers during follow-up at approximately 3 months of age. ANOVA revealed significant differences in NNS cycles/min, NNS amplitude, NNS cycles/burst, and NNS cycle periods as a function of pacifier stiffness. Infants modify the spatiotemporal output of their suck central pattern generator when presented with pacifiers with significantly different mechanical properties. Infants show a non-preference to suck due to high stiffness in the selected pacifier. Therefore, excessive pacifier stiffness may decrease ororhythmic patterning and impact feeding outcomes.