Deglutition apnoea as indicator of maturation of suckle feeding in bottle-fed preterm infants

Effects of Swaddling During Bottle Feeding in Preterm Infants

BACKGROUND

Preterm infants have immature oral feeding skills, affecting length of hospital stay and long-term feeding outcomes. Swaddling has positive effects on pain and stress responses, state regulation, and physiological stability in preterm infants in the neonatal intensive care unit (NICU). Swaddling during bottle feeding may support preterm infant behavioral organization and oral feeding skills. Swaddling is used inconsistently during feeding in the NICU and has not been critically examined for effects on bottle feeding performance in preterm infants.

PURPOSE

To examine the effects of swaddling on bottle feeding quality and efficiency in preterm infants.

METHODS

A convenience sample of 30 infants born before 34 weeks of gestation was selected in an urban level IV NICU. Using an experimental, randomized crossover design, each infant was swaddled for one feeding and unswaddled for one feeding. Feeding efficiency was measured by rate and volume consumed. Feeding quality was examined by the Early Feeding Skills Assessment and frequency of physiological changes. Data were analyzed using dependent t tests and Wilcoxon signed rank test.

RESULTS

When swaddled, participants demonstrated significantly better scores on all related subtests of the Early Feeding Skills Assessment ( P ≤ .001). Infants demonstrated no difference in frequency of bradycardia or oxygen desaturations greater than 4 seconds. No significant differences were found in feeding efficiency outcomes.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Swaddling can be used in the NICU to improve bottle feeding quality in preterm infants. Future investigation is needed on long-term effects of swaddling during bottle feeding on feeding performance, weight gain, and length of stay.

The Effect of Severe Intraventricular Hemorrhage on the Biorhythms of Feeding in Premature Infants

Background: Suck-swallow rhythmicity and the integration of breathing into infant feeding are developmentally regulated. Neurological injury and breathing abnormalities can both impact feeding in preterm infants. Objective: To determine the effects of neurologic injury independent of effects of disordered breathing on feeding biorhythms in premature infants. Methods: Low-risk preterm infants (LRP), infants with Grade 3-4 Intraventricular Hemorrhage (IVH), those with bronchopulmonary dysplasia (BPD), and those with both BPD and IVH (BPD+IVH) were identified. Forty-seven infants, 32-42 weeks Postmenstrual Age (PMA) were evaluated on one or more occasions (131 studies). Of these, 39 infants (81 studies) were performed at >35 weeks PMA. Coefficient of variation (COV) (=standard deviation of the inter-event (e.g., suck-suck, swallow-breath, etc.) interval divided by the mean of the interval) was used to quantify rhythmic stability. Results: To adjust for PMA, only those infants >35-42 weeks were compared. Suck-suck COV was significantly lower (more rhythmically stable) in the LRP group [COV = 0.274 ± 0.051 (S.D.)] compared to all other groups (BPD = 0.325 ± 0.066; IVH = 0.342 ± 0.072; BPD + IVH = 0.314 ± 0.069; all p < 0.05). Similarly, suck-swallow COV was significantly lower in LRP babies (0.360 ± 0.066) compared to the BPD group (0.475 ± 0.113) and the IVH cohort (0.428 ± 0.075) (p < 0.05). The BPD+IVH group (0.424 ± 0.109), while higher, was not quite statistically significant. Conclusions: Severe IVH negatively impacts suck-suck and suck-swallow rhythms. The independent effect of neurological injury in the form of IVH on feeding rhythms suggests that quantitative analysis of feeding may reflect and predict neurological sequelae.

Heart Rate Variability as a Feeding Intervention Outcome Measure in the Preterm Infant

BACKGROUND

Feeding interventions for preterm infants aim to reduce the physiologic stress of feeding to promote growth. Heart rate variability (HRV) is a potential noninvasive measure of physiologic stress that may be useful for evaluating efficacy of feeding interventions.

PURPOSE

To evaluate whether HRV is a sensitive measure of physiologic stress compared with standard physiologic outcomes in the context of a feeding intervention study.

METHODS

This was a secondary analysis of a within-subjects, cross-over design study comparing usual care feeding with a gentle, coregulated (CoReg) feeding approach in 14 infants born less than 35 weeks' postmenstrual age. HRV indices were calculated from electrocardiogram data and compared with standard physiologic outcomes, including oxygen saturation (Spo2), respiratory rate (RR), apnea, heart rate (HR), and bradycardia. Data were analyzed using linear mixed modeling.

RESULTS

Infants fed using the CoReg approach had fewer apneic events and higher RR, suggesting they were able to breathe more during feeding. No statistically significant differences were found in SpO2, HR, bradycardia, or high frequency power (the most commonly reported measure of HRV). Infants fed using the usual care approach had significantly higher SD12, a measure of HRV indicating randomness in the HR, which is a potential indicator of elevated stress.

IMPLICATIONS FOR PRACTICE

SD12 was more sensitive to stress than SpO2, HR, and bradycardia. The utility of HRV as a measure of feeding outcomes in clinical practice needs further exploration.

IMPLICATIONS FOR RESEARCH

Further exploration of HRV as an intervention outcome measure is needed, particularly evaluating nonlinear indices, such as SD12.

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

PURPOSE

Single-use, laser-cut, slow-flow nipples were evaluated for their effect on respiration and milk ingestion in 13 healthy preterm infants (32.7-37.1 weeks postmenstrual age) under nonlaboratory, clinical conditions.

METHOD

The primary outcomes of minute ventilation and overall milk transfer were measured by using integrated nasal airflow and volume-calibrated bottles during suck bursts and suck burst breaks during slow-flow and standard-flow nipple bottle feedings. Wilcoxon signed-ranks tests were used to test the effect of nipple type on both outcomes.

RESULTS

Prefeeding minute ventilation decreased significantly during suck bursts and returned to baseline values during suck burst breaks across both slow-flow and standard-flow nipples. No differences were found in minute ventilation (p > .40) or overall milk transfer (p = .58) between slow-flow and standard-flow nipples.

CONCLUSIONS

The lack of difference in primary outcomes between the single-use slow-flow and standard-flow nipples may reflect variability in nipple properties among nipples produced by the same manufacturer. Future investigations examining the effect of both single-use and reusable nipple products are warranted to better guide nipple selection during clinical care.

Effects of Moderate Hyperbilirubinemia on Nutritive Swallowing and Swallowing-Breathing Coordination in Preterm Lambs

BACKGROUND

Hyperbilirubinemia (HB) occurs in 90% of preterm newborns. HB induces acute neurological disorders (somnolence, abnormal tone, feeding difficulties, auditory dysfunction) and alterations in respiratory control. These findings suggest brainstem neurotoxicity that could also affect swallowing centers.

OBJECTIVE

To test the hypothesis that HB impairs nutritive swallowing (NS) and swallowing-breathing coordination.

METHODS

Two groups of preterm lambs (born 14 days prior to term), namely control (n = 6) and HB (n = 5), were studied. On day 5 of life (D0), moderate HB (150-250 µmol/l) was induced during 17 h in the HB group. Swallowing was assessed via recording of pharyngeal pressure and respiration by respiratory inductance plethysmography and pulse oximetry. The effect of HB on NS was assessed during standardized bottle-feeding. A second recording was performed 48 h after recovery from HB (D3).

RESULTS

Swallows were less frequent (p = 0.003) and of smaller volume (p = 0.01) in HB lambs while swallowing frequency was decreased (p = 0.004). These differences disappeared after HB normalization. Swallowing-breathing coordination was impaired in HB lambs, with a decrease in percent time with NS burst-related apneas/hypopneas at D0 and D3. Simultaneously, HB lambs tended to experience more severe desaturations (<80%) during bottle-feeding. Finally, following bottle-feeding, the respiratory rate was significantly lower, along with an increased apnea duration in HB lambs.

CONCLUSIONS

Swallowing and swallowing-breathing coordination are altered by acute moderate HB in preterm lambs. Decreased efficiency at bottle-feeding is accompanied by continuation of breathing during swallow bursts, which may promote lung aspiration.

Technological solutions and main indices for the assessment of newborns' nutritive sucking: a review

Nutritive Sucking (NS) is a highly organized process that is essential for infants' feeding during the first six months of their life. It requires the complex coordination of sucking, swallowing and breathing. The infant's inability to perform a safe and successful oral feeding can be an early detector of immaturity of the Central Nervous System (CNS). Even though the importance of early sucking measures has been confirmed over the years, the need for standardized instrumental assessment tools still exists. Clinicians would benefit from specifically designed devices to assess oral feeding ability in their routine clinical monitoring and decision-making process. This work is a review of the main instrumental solutions developed to assess an infant's NS behavior, with a detailed survey of the main quantities and indices measured and/or estimated to characterize sucking behavior skills and their development. The adopted sensing measuring systems will be described, and their main advantages and weaknesses will be discussed, taking into account their application to clinical practice, or to at-home monitoring as post-discharge assessment tools. Finally, the study will highlight the most suitable sensing solutions and give some prompts for further research.

Efficacy of semielevated side-lying positioning during bottle-feeding of very preterm infants: a pilot study

Very preterm (VP, ≤30 wk gestational age) infants are at risk for impaired lung function, which significantly limits their ability to eat. A semielevated side-lying (ESL) position is a feeding strategy that may improve oral feeding by supporting breathing during feeding. The study evaluated the efficacy of the ESL position compared with the semielevated supine (ESU) position on physiological stability and feeding performance of bottle-fed VP infants. Using a within-subject crossover design, 6 VP infants were bottle-fed twice on 1 day, in both the ESL and ESU positions in a random order. Physiological stability (heart rate, oxygen saturation [SaO2], and respiratory characteristics) and feeding performance (percent intake, proficiency, efficiency, and duration of feeding) were measured before and/or during feeding. Very preterm infants fed in the ESL position demonstrated significantly less variation in heart rate, less severe and fewer decreases in heart rate, respiratory rate that was closer to the prefeeding state, shorter and more regular intervals between breaths, and briefer feeding-related apneic events. No significant differences for SaO2 or feeding performance were found. The findings indicate that the ESL position may support better regulation of breathing during feeding, thereby allowing VP infants to better maintain physiological stability throughout feeding.

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.

Videofluoroscopic swallowing study findings in full-term and preterm infants with Dysphagia

OBJECTIVE

To determine the clinical characteristics and videofluoroscopic swallowing study (VFSS) findings in infants with suspected dysphagia and compare the clinical characteristics and VFSS findings between full-term and preterm infants.

METHODS

A total of 107 infants (67 full-term and 40 preterm) with suspected dysphagia who were referred for VFSS at a tertiary university hospital were enrolled in this retrospective study. Clinical characteristics and VFSS findings were reviewed by a physiatrist and an experienced speech-language pathologist. The association between the reasons of referral for VFSS and VFSS findings were analyzed.

RESULTS

Mean gestational age was 35.1±5.3 weeks, and mean birth weight was 2,381±1,026 g. The most common reason for VFSS referral was 'poor sucking' in full-term infants and 'desaturation' in preterm infants. The most common associated medical condition was 'congenital heart disease' in full-term infants and 'bronchopulmonary dysplasia' in preterm infants. Aspiration was observed in 42 infants (39.3%) and coughing was the only clinical predictor of aspiration in VFSS. However, 34 of 42 infants (81.0%) who showed aspiration exhibited silent aspiration during VFSS. There were no significant differences in the VFSS findings between the full-term and preterm infants except for 'decreased sustained sucking.'

CONCLUSION

There are some differences in the clinical manifestations and VFSS findings between full-term and preterm infants with suspected dysphagia. The present findings provide a better understanding of these differences and can help clarify the different pathophysiologic mechanisms of dysphagia in infants.

Oral-motor function and feeding intervention

This article presents the elements of the Oral Motor Intervention section of the Infant Care Path for Physical Therapy in the Neonatal Intensive Care Unit (NICU). The types of physical therapy interventions presented in this path are evidence based as well as infant driven and family focused. In the context of anticipated maturation of suck-swallow-breathe coordination, the timing and methods for initiation of oral feedings and transition from gavage to full breast or bottle-feedings are presented with supporting evidence.

Effects of nasal continuous positive-airway pressure on nutritive swallowing in lambs

Current knowledge suggests that, to be successful, oral feeding in preterm infants should be initiated as soon as possible, often at an age where immature respiration still requires ventilatory support in the form of nasal continuous positive airway pressure (nCPAP). While some neonatologist teams claim great success with initiation of oral feeding in immature infants with nCPAP, others strictly wait for this ventilatory support to be no longer necessary before any attempt at oral feeding, fearing laryngeal penetration and tracheal aspiration. Therefore, the aim of the present study was to provide a first assessment of the effect of various levels of nCPAP on bottle-feeding in a neonatal ovine model, including feeding safety, feeding efficiency, and nutritive swallowing-breathing coordination. Eight lambs born at term were surgically instrumented 48 h after birth to collect recordings of electrical activity of laryngeal constrictor muscle, electrocardiography, and arterial blood gases. Two days after surgery, lambs were bottle-fed under five randomized nCPAP conditions, including without any nCPAP or nasal mask and nCPAP of 0, 4, 7, and 10 cmH(2)O. Results revealed that application of nCPAP in the full-term lamb had no deleterious effect on feeding safety and efficiency or on nutritive swallowing-breathing coordination. The present study provides a first and unique insight on the effect of nCPAP on oral feeding, demonstrating its safety in newborn lambs born at term. These results open the way for further research in preterm lambs to better mimic the problems encountered in neonatology.

Eating as a neurodevelopmental process for high-risk newborns

Many high-risk and preterm infants have difficulty with successful feeding and subsequent optimal growth during their stay in the neonatal intensive care unit as well as in the months after discharge. Environmental, procedural, and medical issues necessary for treatment of the hospitalized infant present challenges for the development of successful eating skills. Emerging data describe eating as a predictable neurodevelopmental process that depends on the infant's organization of physiologic processes, motor tone and movement, level of arousal, and ability to simultaneously regulate these processes.

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.

Coordination of respiration and swallowing: functional pattern and relevance of vocal folds closure

CONTEXT: Breathing and swallowing coordination, despite the expressive number of study, remain as theme deserving further research. OBJECTIVE: To identify a coordination pattern between swallowing and the natural breathing pause that occur in association with it (swallowing apnea) and also the relevance of the vocal folds closure in this process. METHODS: Sixty-six adults, male and female, including normal health people, post-laryngectomy individuals and patients with digestive complaints without dysphagia were analyzed. The respiratory air flux interruptions produced by wet requested swallows and dry, requested and spontaneous swallows, were registered using thermo and piezoelectric receptors coupled to synectics medical manometry equipment, using Polygram upper 4.21 software. The results were analyzed with the Chi-square (3×2) and (2×2) nonparametric independency test with P = 0.05. RESULTS: Swallowing apnea is a preventive breathing stop that start just before and stay present during all deglutition pharyngeal phase. It is a well coordinated phenomena that occur as pattern in association with low elastic resistance of the lung, on the expiratory final phase until inspiration initial phase. This breathing stoppage it is usually followed by a short expiraton preceding a new breathing cycle. The swallow apnea and vocal folds closure are both independents mechanisms. CONCLUSION: It is possible to suppose that in the subconscious condition, swallowing apnea is integrated under coordination of the same control mechanism that also involves the elastic resistance of the lung.

Prediction for developmental delay on Neonatal Oral Motor Assessment Scale in preterm infants without brain lesion

BACKGROUND

Preterm infants often have difficulty in achieving a coordinated sucking pattern. To analyze the correlation between preterm infants with disorganized sucking and future development, weekly studies were performed of 27 preterm infants from initiation of bottle feeding until a normal sucking pattern was recognized.

METHODS

A total of 27 preterm infants without brain lesion participated in the present study. Neonatal Oral Motor Assessment Scale (NOMAS) was utilized to evaluate the sucking pattern. Infants who were initially assessed as having disorganized sucking on NOMAS and regained a normal sucking pattern by 37 weeks old were assigned to group I; infants with a persistent disorganized sucking pattern after 37 weeks were assigned to group II. The mental (MDI) and psychomotor (PDI) developmental indices of Bayley Scales of Infant Development, second edition were used for follow-up tests to demonstrate neurodevelopment at 6 months and 12 months of corrected age.

RESULTS

At 6 months follow up, subjects in group I had a significantly higher PDI score than group II infants (P= 0.04). At 12 months follow up, group I subjects had a significantly higher score on MDI (P= 0.03) and PDI (P= 0.04). There was also a higher rate for development delay in group II at 6 months (P= 0.05).

CONCLUSION

NOMAS-based assessment for neonatal feeding performance could be a helpful tool to predict neurodevelopmental outcome at 6 and 12 months. Close follow up and early intervention may be necessary for infants who present with a disorganized sucking pattern after 37 weeks post-conceptional age.

Central pattern generation involved in oral and respiratory control for feeding in the term infant

PURPOSE OF REVIEW

Drinking and eating are essential skills for survival and benefit from the coordination of several pattern generating networks and their musculoskeletal effectors to achieve safe swallows. Oralpharyngoesophageal motility develops during infancy and early childhood, and is influenced by various factors, including neuromuscular maturation, dietary and postural habits, arousal state, ongoing illnesses, congenital anomalies, and the effects of medical or surgical interventions. Gastroesophageal reflux is frequent in neonates and infants, and its role in neonatal morbidity including dysphagia, chronic lung disease, or apparent life-threatening events is not well understood. This review highlights recent studies aimed at understanding the development of oral feeding skills, and cross-system interactions among the brainstem, spinal, and cerebral networks involved in feeding.

RECENT FINDINGS

Functional linkages between suck-swallow and swallow-respiration manifest transitional forms during late gestation through the first year of life, which can be delayed or modified by sensory experience or disease processes, or both. Relevant central pattern generator (CPG) networks and their neuromuscular targets attain functional status at different rates, which ultimately influences cross-system CPG interactions. Entrainment of trigeminal primary afferents accelerates pattern genesis for the suck CPG and transition-to-oral feed in the RDS preterm infant.

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, which optimize experience-dependent mechanisms to promote safe swallows among newborn and pediatric patients.

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.

Nutritive sucking pattern--from very low birth weight preterm to term newborn

The contribution of maturation and stimulation to the development of oral feeding was investigated, with two main objectives: (1) to analyze the nutritive sucking pattern of very-low-birth-weight newborns from their first oral feeding to the acquisition of independent oral feeding, and (2) to compare the nutritive sucking patterns of these babies, after feeding autonomy, with healthy term newborns.

METHODS

Two groups were considered for analysis. Group 1: N=15 Very-Low-Birth-Weight (VLBW), gestacional age (GA)=28.15+/-1.5, birth weight (BW)=1178.3+/-174.4. The intervention program began at 30.19+/-1.52 weeks GA. Group 2: N=25 term newborns, healthy, GA=39.04+/-1.2, BW=3370.42+/-310.76. Repeated measures of the following variables were taken (weekly for group 1): suction efficacy (SEF), rhythm of milk transfer (RMT), suctions, bursts and pauses. Group 2 was analysed only once between the 2nd and 5th day of life.

RESULTS

Group 1 has revealed a minimal suction number at 32 GA weeks (82+/-77.6) and maximal suction number at 36-37 GA weeks (162.7+/-60.7). The number of sucks seemed to be dependent of weight (p=0.005), duration of intervention (p=0.001) and chronological age (p=0.000). Significant statistical effects of gestational age were not observed (p=0.904). Sucks in bursts represented 77% at the beginning of oral feeding (32 weeks GA), and 96% at 33 weeks GA, remaining constant thereafter. The number of sucks and bursts increased with GA and weeks of feeding. The mean duration of the pauses decreased from first to fourth week of feeding (week1=14.1+/-9.1 and week4=6.4+/-1.4 s). The sucking efficacy (SEF) was better explained by weight (p=0.000), number of sucks in 5 min (p=0.025) and chronological age (p=0.044). Gestational age (p=0.051) and nutritive intervention duration (NDI) (p=0.110) did not contribute to explain SEF. Despite the observation of significant statistical differences between groups regarding GA (35.9/39.08; p=0.00), chronological age (53.3/2.5; p=0.00) and weight (1875/3360; p=0.00), the nutritive suction pattern was not statistically different between groups after feeding autonomy.

CONCLUSION

in VLBW oral feeding before 32 weeks GA allows the attainment of a mature nutritive suction pattern before term (37-40 weeks). Experience seems to be one of the influencing factors in the change of the nutritive suction pattern.

Respiratory patterns and strategies during feeding in preterm infants

Because patterns of integration of respiration into rhythmic suck-swallow efforts are highly variable, we examined the vagaries of respiratory efforts as they evolve from the first tentative attempts at integration through more complex rhythmic interactions, with a focus on several strategies in which breathing and suck-swallow are coordinated. Thirty-four preterm infants (18 males, 16 females) of 26 to 33 weeks gestational age, 32 to 40 weeks postmenstrual age (PMA), and 2 to 12 weeks postnatal age were studied weekly from initiation of bottle feeding (using breast milk or preterm formula, both fed from a bottle) until discharge, with simultaneous digital recordings of pharyngeal pressure, nasal thermistor airflow, and thoraco-abdominal strain-gauge readings. Exceptional patterns of feeding-adapted variations of respiration were noted, including breathing during swallow, alternating blocks of suck-swallow and respiration efforts, narial airflow without thoracic movement, modulation of respiratory phase relationship against swallow rhythm, and paired rhythms with swallow:breath ratios of more than 1:1. Some of these strategies were developmentally regulated. Alternating blocks of suck-swallow and respiratory efforts were only seen in the earliest (PMA 32-33 wks) studies. In contrast, coordination and phase relationships of suck-swallow and breathing stabilized over time, as did the percentage of synchronized narial and thoracic respiratory efforts, which increased significantly after 36 weeks PMA compared with synchronization at 32 to 33.9 and 34 to 35.9 weeks PMA (p<0.05). There was also a significant positive correlation between percentage synchronization and PMA (r=0.58; p<0.001). The strategies and patterns noted here further clarify the developmentally regulated coordination of suck, swallow, and respiration into mature infant feeding, and may be predictive of those infants with short- and long-term feeding or developmental difficulties.

Sucking and swallowing in infants and diagnostic tools

Preterm infants often have difficulties in learning how to suckle from the breast or how to drink from a bottle. As yet, it is unclear whether this is part of their prematurity or whether it is caused by neurological problems. Is it possible to decide on the basis of how an infant learns to suckle or drink whether it needs help and if so, what kind of help? In addition, can any predictions be made regarding the relationship between these difficulties and later neurodevelopmental outcome? We searched the literature for recent insights into the development of sucking and the factors that play a role in acquiring this skill. Our aim was to find a diagnostic tool that focuses on the readiness for feeding or that provides guidelines for interventions. At the same time, we searched for studies on the relationship between early sucking behavior and developmental outcome. It appeared that there is a great need for a reliable, user-friendly and noninvasive diagnostic tool to study sucking in preterm and full-term infants.

Maturation of oral feeding skills in preterm infants

AIM

Safe and successful oral feeding requires proper maturation of sucking, swallowing and respiration. We hypothesized that oral feeding difficulties result from different temporal development of the musculatures implicated in these functions.

METHODS

Sixteen medically stable preterm infants (26 to 29 weeks gestation, GA) were recruited. Specific feeding skills were monitored as indirect markers for the maturational process of oral feeding musculatures: rate of milk intake (mL/min); percent milk leakage (lip seal); sucking stage, rate (#/s) and suction/expression ratio; suction amplitude (mmHg), rate and slope (mmHg/s); sucking/swallowing ratio; percent occurrence of swallows at specific phases of respiration. Coefficients of variation (COV) were used as indices of functional stability. Infants, born at 26/27- and 28/29-week GA, were at similar postmenstrual ages (PMA) when taking 1-2 and 6-8 oral feedings per day.

RESULTS

Over time, feeding efficiency and several skills improved, some decreased and others remained unchanged. Differences in COVs between the two GA groups demonstrated that, despite similar oral feeding outcomes, maturation levels of certain skills differed.

CONCLUSIONS

Components of sucking, swallowing, respiration and their coordinated activity matured at different times and rates. Differences in functional stability of particular outcomes confirm that maturation levels depend on infants' gestational rather than PMA.

Infants with bronchopulmonary dysplasia suckle with weak pressures to maintain breathing during feeding

OBJECTIVE

Preterm infants with bronchopulmonary dysplasia often demonstrate sucking difficulties. The aim of this study was to determine whether the severity of bronchopulmonary dysplasia affects not only coordination among suck-swallow-respiration but also sucking endurance and performance itself.

PATIENTS AND METHODS

Twenty very low birth weight infants were studied. Infants with anomalies or intraventricular hemorrhage were excluded from the evaluation. Subjects were divided into 3 groups: no bronchopulmonary dysplasia (7 infants), bronchopulmonary dysplasia without home oxygen therapy (7 infants), and bronchopulmonary dysplasia with home oxygen therapy (6 infants). In addition to sucking efficiency, pressure, frequency, duration, and duration of sucking burst, length of deglutition apnea, number of swallows per burst, and respiratory rate were also measured during bottle-feeding at 40 weeks' postmenstrual age. In addition, PCO2 and oxygen saturation were measured at rest and during bottle-feeding.

RESULTS

Infants with severe bronchopulmonary dysplasia demonstrated not only the lowest sucking pressure and sucking frequency, shortest sucking burst duration, and lowest feeding efficiency but also the lowest frequency of swallows during the run and the longest deglutition apnea. The respiratory rate was highest, and the decrease in oxygen saturation was largest, in infants with severe bronchopulmonary dysplasia.

CONCLUSIONS

Feeding problems depend on the severity of bronchopulmonary dysplasia. Infants with bronchopulmonary dysplasia demonstrated not only poor feeding coordination but also poor feeding endurance and performance.

The First Year of Human Life: Coordinating Respiration and Nutritive Swallowing

This study provides the first documented report of the maturation of breathing-swallowing coordination during feeding in ten healthy term human infants through the first year of life. A total of 15,073 swallows were obtained across ten assessments between 48 h and 12 months of age. Midexpiratory swallows represented the dominant pattern of breathing-swallowing coordination within the first 48 h (mean = 45.4%), but the prevalence of this pattern declined rapidly in the first week to 29.1% (p = 0.012). Inspiratory-expiratory swallows increased with age (p < 0.001), particularly between 9 (37.0%) and 12 months (50.4%). Between 72.6% and 75.0% of swallows were followed by expiration in the latter 6 months, which is an adult-like characteristic. These data suggest that while postswallow expiration is a robust feature of breathing-swallowing coordination from birth, two major shifts in the precise patterns occur: the first after 1 week of postnatal feeding experience and the second between 6 and 12 months, most likely due to neural and anatomical maturation.

The early impact of feeding on infant breathing-swallowing coordination

This longitudinal study assessed the coordination of nutritive and non-nutritive swallowing with breathing in 10 healthy term infants from birth to 1 year of age. Swallows were classified into five respiratory-phase categories: mid-inspiration (II), mid-expiration (EE), inspiratory-expiratory cusp (IE), expiratory-inspiratory cusp (EI), and mid-pause (P). Breathing-swallowing coordination differed markedly between the two swallowing conditions, especially between 2 weeks and 2 months. Significant condition effects were found in up to four respiratory-phase categories (II, IE, EI, and P). The condition effect was minimal from 9 months with only IE swallow proportions differing between conditions. These data suggest a 'critical period' in infantile neural response to oropharyngeal stimulation during feeding and that the impact of this on infants with neurological and/or respiratory disorders should be further investigated.

Nutritive and non-nutritive swallowing apnea duration in term infants: implications for neural control mechanisms

The impact of bolus ingestion and level of consciousness on swallowing apnea duration (SAD) in healthy term infants has not been adequately explored despite the likely contribution of swallowing apnea to upper airway protection against aspiration. SAD during wakefulness, sleep, and feeding (breast or bottle) of 10 term infants was measured 10 times from birth to 1 year of age. Nineteen thousand four hundred and two swallows were analyzed. Irrespective of age, SAD during feeding was significantly shorter than SAD of non-nutritive swallowing (during wakefulness and sleep). SAD did not change significantly within the first year of life in any of the three conditions and there was no change in the relative durations of nutritive, wake and sleep conditions with age. The absence of an age effect implies that the neural mechanisms controlling SAD are fundamentally brainstem-mediated and largely hard-wired at birth in healthy term neonates.

Sipping/lapping is a safe alternative feeding method to suckling for preterm infants

AIM

To determine whether sipping/lapping is a safe alternative to suckle bottle-feeding without any hydrostatic pressure, in terms of physiological stability and the relationship between swallowing and respiration. In addition, tongue movement was compared between sipping/lapping and suckling (bottle- and breastfeeding).

METHODS

Eighteen infants (30-35?wk of gestation at birth) were studied while sipping/lapping and suckling a bottle without any hydrostatic pressure at different feeding sessions on the same day of the first oral feeding. The postmenstrual age at the time of study was 34.6+/-0.2 wk. We evaluated the amounts ingested and administration times. The heart rate, O(2) saturation (SpO(2)), and relationship between swallowing and respiration were examined while feeding. Tongue movements were also observed by ultrasonography. Statistical analysis was performed by a paired t-test.

RESULTS

The amounts ingested and intake volume per minute were lower while sipping/lapping compared to suckling. The overall heart rate and SpO(2) showed no statistically significant difference. The frequency of swallows followed by inspiration (27.6+/-0.8% and 31.0+/-1.3%) and swallows followed by expiration (46.4+/-0.9% and 45.4+/-1.4%, sipping and suckling, respectively) also showed no difference. Tongue movements while sipping/lapping differed from those while suckling a bottle or breast.

CONCLUSION

Because physiological parameters and the relationship between swallowing and respiration while sipping/lapping are comparable to those while suckle bottle-feeding without any hydrostatic pressure, sipping/lapping is a safe alternative feeding method to suckle bottle-feeding, even in preterm infants.

The early feeding skills assessment for preterm infants

Preterm infants develop the skills necessary to begin oral feeding as their health stabilizes and as they reach a postconceptional age that supports coordination of breathing and swallowing with oral-motor functioning. The time from initiation of oral feeding to full oral feedings (with adequate intake for growth and maintenance of physiologic stability) can vary from days to months for the preterm infant. The approach to feeding the infant during this transition period must be developmentally supportive and tailored to meet the needs of the individual. To accomplish this, caregivers--notably nurses and parents--need to communicate about the specific skills that the infant has gained, about skills that are emerging, and about skills that the infant has not yet developed. The Early Feeding Skills (EFS) Assessment is a checklist for assessing infant readiness for and tolerance of feeding and for profiling the infant's developmental stage regarding specific feeding skills: the abilities to remain engaged in feeding, organize oral-motor functioning, coordinate swallowing with breathing, and maintain physiologic stability. This article introduces the EFS.

Assessment of infant oral sensorimotor and swallowing function

The development of feeding and swallowing is the result of a complex interface between the developing nervous system, various physiological systems, and the environment. The purpose of this article is to review the neurobiology, development, and assessment of feeding and swallowing during early infancy. In recent years, there have been exciting advances in our understanding of the physiology and neurological control of feeding and swallowing. These advances may prove useful in furthering our understanding of the pathophysiology of dysphagia in infancy. Progress in developing standardized, reliable, and valid measures of oral sensorimotor and swallowing function in infancy has been slow. However, there have been significant advances in the instrumental analysis of feeding and swallowing disorders in infancy, including manometric analyses of sucking and swallowing, measures of respiration during feeding, videofluoroscopic swallow evaluations, ultrasonography, and flexible endoscopic examination of swallowing. Further efforts are needed to develop clinical evaluative measures of dysphagia in infancy.

Regional neonatal oral feeding protocol: changing the ethos of feeding preterm infants

The Calgary Health Region Neonatal Oral Feeding Protocol is the culminating work of a broad range of healthcare professionals, including staff nurses, nurse practitioners, nurse educators, nurse managers, dietitians, lactation consultants, clinical nurse specialists, and occupational therapists. The protocol represents a synthesis of research evidence and expert opinion pertaining to the introduction and management of oral milk feedings for high-risk infants in the neonatal intensive care unit. This evidence-based neonatal oral feeding protocol is presented to share knowledge and skill required to create positive feeding experiences while assisting high-risk infants to achieve full oral feedings. Goals of this project include promoting consistent neonatal nursing feeding practices and changing the ethos in relation to feeding interactions between caregiver and infant in the neonatal intensive care unit. This culture change will assist nurses to identify what is unique about their professional practice, which is of particular importance given the skill mix resulting from hospital understaffing and a growing nursing workforce shortage.

State of the science: feeding readiness in the preterm infant

Finding ways to consistently prepare preterm infants and their families for more timely discharge must continue as a focus for everyone involved in the care of these infants in the neonatal intensive care unit. The gold standards for discharge from the neonatal intensive care unit are physiologic stability (especially respiratory stability), consistent weight gain, and successful oral feeding, usually from a bottle. Successful bottle-feeding is considered the most complex task of infancy. Fostering successful oral feeding in preterm infants requires consistently high levels of skilled nursing care, which must begin with accurate assessment of feeding readiness and thoughtful progression to full oral feeding. This comprehensive review of the literature provides an overview of the state of the science related to feeding readiness and progression in the preterm infant. The theoretical foundation for feeding readiness and factors that appear to affect bottle-feeding readiness, progression, and success are presented in this article.

Preterm infants' behavioural indicators of oxygen decline during bottle feeding

BACKGROUND

During the time when preterm infants' oral feeding skills are developing they often experience physiological instability and need assistance from caregivers to maintain adequate oxygenation. Assisting infants to maintain optimal oxygenation during oral feeding requires an understanding of how they express and aim to self-regulate their oxygen status.

AIM

The purpose of this study was to identify potential behavioural indicators of declining oxygenation during preterm infant early bottle-feeding.

METHOD

The design was explorative. Data were collected from a secondary analysis of 20 videotapes of preterm infant bottle feedings which included concurrent oxygen saturation data. In this analysis infant behaviours and quality of breathing were coded and compared across three periods: high oxygen saturation, immediately preceding an oxygen desaturation event, and during an oxygen desaturation event.

FINDINGS

Infants gave limited behavioural indicators of declining oxygenation. Immediately prior to a desaturation event, they had an increase in eye flutter and were typically sucking and apnoeic. During a desaturation event, they typically relaxed their arms/hands and stopped sucking.

CONCLUSIONS

Reliance on preterm infant behavioural cues will be insufficient for detection of oxygen desaturation during oral feeding. Attention to changes in breath sounds and to the pattern of sucking are potentially important intervention strategies for the prevention of and appropriate response to oxygen decline during feeding. Sucking pauses may be a time when preterm infants aim to regulate their breathing pattern and thereby increase oxygenation. Interventions that focus on detection and minimization of apnoea during feeding, and which aim to protect infant sucking pauses, may reduce the number and severity of desaturation events preterm infants experience during bottle feeding.

Occurrence of oxygen desaturation events during preterm infant bottle feeding near discharge

AIMS

The purpose of this study was to examine the occurrence, severity, pattern, and moderators of oxygen desaturation during preterm infant bottle feeding near the time of discharge from the neonatal intensive care unit (NICU) when fed by mothers.

STUDY DESIGN

Twenty-two very low birthweight (VLBW) infants [birthweight 1155+/-293 g, gestational age (GA) 28.1+/-2.0, postconceptional age (PCA) 36.5+/-1.6 weeks] were videotaped being bottle-fed by their mothers. Most infants (86%) were discharged within 6 days of the study. Oxygen saturation was continuously monitored and infant feeding behaviors were coded. Oxygen desaturation events (SpO(2)<90%) were identified and analyzed.

RESULTS

Infants averaged 10.8 events during feeding (range 1-28, S.D. 8.9) and spent, on average, 20% of their feeding time (range 0-70%, S.D. 17.98%) with oxygen levels below 90%. One hundred forty of the desaturation events (59%) were classified as mild (SpO(2) 85-89), 47 events (20%) were classified as moderate (SpO(2) 81-84), and 51 events (21%) were classified as severe (SpO(2)</=80). Events were evenly distributed across infants' feeding time. Receiving supplemental oxygen, beginning the feeding with a higher baseline SpO(2), and being of older PCA predicted lower percentage of feeding time with SpO(2) below 90% (R(2)=0.57). Receiving supplemental oxygen and beginning the feeding with a higher baseline SpO(2) predicted less number of desaturation events during the feeding (R(2)=0.44). Despite similar baseline SpO(2) levels, infants who were on supplemental oxygen had 50% less oxygen desaturation events and spent 33% less time with SpO(2) less than 90%.

CONCLUSION

VLBW infants continue to have desaturation events during feeding when fed by their mothers near the time of discharge. Further research is needed to understand the effect of hypoxemia on the preterm infant's development of oral feeding skills, to study the effects of supplemental oxygen during feeding, and to further develop interventions to minimize desaturation during feeding.

The maturation and coordination of sucking, swallowing, and respiration in preterm infants

OBJECTIVES

Our objectives were to establish normative maturational data for feeding behavior of preterm infants from 32 to 36 weeks of postconception and to evaluate how the relation between swallowing and respiration changes with maturation.

STUDY DESIGN

Twenty-four infants (28 to 31 weeks of gestation at birth) without complications or defects were studied weekly between 32 and 36 weeks after conception. During bottle feeding with milk flowing only when infants were sucking, sucking efficiency, pressure, frequency, and duration were measured and the respiratory phase in which swallowing occurs was also analyzed. Statistical analysis was performed by repeated-measures analysis of variance with post hoc analysis.

RESULTS

The sucking efficiency significantly increased between 34 and 36 weeks after conception and exceeded 7 mL/min at 35 weeks. There were significant increases in sucking pressure and frequency as well as in duration between 33 and 36 weeks. Although swallowing occurred mostly during pauses in respiration at 32 and 33 weeks, after 35 weeks swallowing usually occurred at the end of inspiration.

CONCLUSIONS

Feeding behavior in premature infants matured significantly between 33 and 36 weeks after conception, and swallowing infrequently interrupted respiration during feeding after 35 weeks after conception.

Developmental progression of feeding skills: an approach to supporting feeding in preterm infants

Infants born prematurely, with congenital or acquired medical conditions, or who have extended stays in the neonatal intensive care unit (NICU) are at higher risk of developing feeding and nutritional problems than are full-term, healthy newborns. Because of the complex nature of feeding, it is necessary to have a thorough understanding of the developmental nature of this skill. The importance of recognizing stability in the physiologic, motor and state systems and using stability to determine both readiness to begin nipple feeding and progress in feeding, is discussed. Intervention strategies to promote stability leading to successful feeding are also described. Viewing infant feeding from a developmental skill acquisition perspective can guide the caregiver in determining how challenging it is for the infant, and therefore is useful in supporting the progression of feeding.

Early introduction of oral feeding in preterm infants

OBJECTIVE

To determine whether transition from tube to all oral feeding can be accelerated by the early introduction of oral feeding in preterm infants. It is hypothesized that this shortened transition time will lead to earlier attainment of all oral feeding.

DESIGN

Twenty-nine infants (<30 weeks' gestation) were randomized to an intervention or control group. The intervention group (n = 13) was initiated to oral feeding 48 hours after achieving full tube feeding (120 kcal/kg/d), and the feeding progression followed a structured protocol. The oral feeding management of the control infants (n = 16) was left to the discretion of their attending physicians. Oral feeding progress was monitored for achievement of selected feeding milestones: achievement of first and all successful oral feedings. Feeding performance was assessed by overall transfer (percent volume transferred during a feeding/total volume offered) and rate of milk transfer (mL/min), which were measured from introduction of oral feeding to first successful oral feeding.

RESULTS

Infants in the experimental group, when compared with their control counterparts, were introduced to oral feeding significantly earlier (31.1 +/- 1.3 vs 33.7 +/- 0.9 weeks' postmenstrual age, respectively) and attained all oral feeding significantly earlier as well (34.5 +/- 1.6 vs 36.0 +/- 1.5 weeks' postmenstrual age, respectively). The transition time from full tube feeding to all oral feeding was 26.8 +/- 12.3 days for the experimental group and 38.4 +/- 14.0 days for the control group. Both groups of infants demonstrated similar increase in overall transfer and rate of milk transfer from introduction of oral feeding until achievement of first successful oral feeding.

CONCLUSIONS

Early introduction of oral feeding accelerates the transition time from tube to all oral feeding. This not only allows earlier attainment of all oral feeding, but it also provides practice opportunities that enhance the oral motor skills necessary for safe and successful feeding.

Feeding disorders in infants and children

Feeding disorders are common in infants and children. Multiple interacting behavioral, anatomic, and functional factors all can impact on the feeding process, making the evaluation and treatment of pediatric disorders complex and challenging. Knowledge of the normal process of feeding and swallowing, a careful history, observation of the patient during a feeding session, and selected tests usually provide an understanding of the underlying cause of feeding difficulties. Treatment of underlying pathology and careful balancing of the risks and benefits of oral feeding underlie the selection of an optimal management strategy.

Kangaroo mother care in the nursery

Kangaroo mother care is becoming an integral part of the care of low birth weight infants worldwide. It provides economic savings to families and health care facilities and many physiologic and psychobehavioral benefits to mothers and infants, the most important of which is the promotion of successful breastfeeding. The benefits of breastfeeding, of human milk over formula, and of feeding from the breast per se, are beyond dispute, and so KMC should be actively promoted. The full impact of KMC on breastfeeding low birth weight infants is yet to be realized.

Feeding efficiency and respiratory integration in infants with acute viral bronchiolitis

OBJECTIVE

To examine the effects of bronchiolitis on feeding efficiency and respiratory integration.

STUDY DESIGN

We studied 21 infants with bronchiolitis and 21 bottle-fed healthy infants who formed a comparison group. Repeat evaluations of half the bronchiolitis group were performed during recovery. During each feeding study we measured the duration and frequency of sucking, the frequency of single and multiple swallows, the respiratory rate, the postswallow respiratory direction, and the suck and swallow volumes.

RESULTS

The infants with bronchiolitis devoted significantly less time to sucking than their healthy peers (P <.05), and the mean suck volume was reduced. Although the frequency of swallowing was slightly higher, the volume of milk consumed per swallow was almost half the amount consumed by the comparison group (P <.01). Coordination of breathing with swallowing was also less effective (P <.01).

CONCLUSION

Although most aspects of feeding are less efficient during periods of respiratory illness, others are preserved or recover rapidly. Coordination of breathing during feeding is also significantly impaired.

The development of preterm infants' breastfeeding behavior

Extensive scientific data are available on the development of sucking in term infants, but corresponding knowledge about preterm infants has been lacking. The aim was to describe the development of preterm infants' behavior at the breast, according to postmenstrual and postnatal age. Mothers co-operated as data collectors using the Preterm Infant Breastfeeding Behavior Scale for observations. Seventy-one singletons (born after 26.7-35.9 gestational weeks) were studied prospectively. Mothers received regular advice about breastfeeding and guidance about interaction and appropriate stimulation. Breastfeeding was initiated at a postmenstrual age (PMA) of 27.9-35.9 weeks. Mothers provided 4321 records of infants' behavior, 70% of the total breastfeeding sessions during the infants' hospital stay. Irrespective of PMA, the infants responded by rooting and sucking on the first contact with the breast. Efficient rooting, areolar grasp and latching on were observed at 28 weeks, and repeated bursts of > or = 10 sucks and maximum bursts of > or = 30 sucks at 32 weeks. Nutritive sucking appeared from 30.6 weeks. Sixty-seven infants were breastfed at discharge. Fifty-seven of them established full breastfeeding at a mean PMA of 36.0 weeks (33.4-40.0 weeks). Their early sucking behavior is interpreted as the result of learning, enhanced by contingent stimuli. We therefore suggest that guidelines for initiation of breastfeeding in preterm infants should be based on cardiorespiratory stability, irrespective of current maturity, age or weight.

Assessment of sensorial oral stimulation in infants with suck feeding disabilities

A non-randomized single blind study was undertaken to determine the clinical and physiological changes in suck feeding after sensorial oral stimulation, in fourteen patients age 9 to 210 days old with sucking alterations. Patients lacked at least one of the five oral reflexes, plus two or more abnormal sucking sings or at least one abnormal sucking sign, plus two or more abnormal oral reflexes. Oral sensorial therapy was performed thrice daily for five days. The number of absent oral reflexes, number of abnormal sucking signs, volume of milk for nursing and sucking rate, were registered. Differences of medians were tested using Freidman's test and differential of proportions using Cochran's Q test. After therapy, oral reflexes were recovered (2, 0-4 vs. 5,5-5, p = 0.0000, median rank of absence oral reflexes) and the number of abnormal sucking signs decreased (6,1-9 vs. 1, 0-4; p = 0.0000). There were statistically significant improvements in patients who had lost launch up nipple ability (p = 0.005), delay at the beginning of sucking (p = 0.0022), drawing of milk from the mouth (p = 0.0001), cyanosis (p = 0.0084), weaning (p = 0.0004) and prolonged sucking (p = 0.0038). Even in patients with moderate improvement, no statistical differences were observed in nipple rooting (p = 0.09) and coughing (p = 0.09). No changes were observed in patients who had cried (p = 0.31) and spitted (p = 0.51) during feeding. At the end of therapy, volumes of consumed milk were increased at each feeding (10 ml, 0-40 vs. 50 ml, 25-60; p = 0.0001). Sucking rates also increased (22 sucks/minute, 10-35 vs. 40.5, 35-48; p = 0.0044). Oral sensorial and motor stimulation normalise oral motor reflexes, diminish the clinical abnormal sucking signs and increase milk volumes ingested for nursing.