Energetics and mechanics of nutritive sucking in the preterm and term neonate

Abnormal Nutritive Sucking as an Indicator of Neonatal Brain Injury

A term neonate is born with the ability to suck; this neuronal network is already formed and functional by 28 weeks gestational age and continues to evolve into adulthood. Because of the necessity of acquiring nutrition, the complexity of the neuronal network needed to suck, and neuroplasticity in infancy, the skill of sucking has the unique ability to give insight into areas of the brain that may be damaged either during or before birth. Interpretation of the behaviors during sucking shows promise in guiding therapies and how to potentially repair the damage early in life, when neuroplasticity is high. Sucking requires coordinated suck-swallow-breathe actions and is classified into two basic types, nutritive and non-nutritive. Each type of suck has particular characteristics that can be measured and used to learn about the infant's neuronal circuitry. Basic sucking and swallowing are present in embryos and further develop to incorporate breathing ex utero. Due to the rhythmic nature of the suck-swallow-breathe process, these motor functions are controlled by central pattern generators. The coordination of swallowing, breathing, and sucking is an enormously complex sensorimotor process. Because of this complexity, brain injury before birth can have an effect on these sucking patterns. Clinical assessments allow evaluators to score the oral-motor pattern, however, they remain ultimately subjective. Thus, clinicians are in need of objective measures to identify the specific area of deficit in the sucking pattern of each infant to tailor therapies to their specific needs. Therapeutic approaches involve pacifiers, cheek/chin support, tactile, oral kinesthetic, auditory, vestibular, and/or visual sensorimotor inputs. These therapies are performed to train the infant to suck appropriately using these subjective assessments along with the experience of the therapist (usually a speech therapist), but newer, more objective measures are coming along. Recent studies have correlated pathological sucking patterns with neuroimaging data to get a map of the affected brain regions to better inform therapies. The purpose of this review is to provide a broad scope synopsis of the research field of infant nutritive and non-nutritive feeding, their underlying neurophysiology, and relationship of abnormal activity with brain injury in preterm and term infants.

Sucking Performance of Babies with Cleft Conditions

Objective:

To describe the sucking performance of bottle-fed babies with cleft conditions.

Participants:

Forty 2-week-old-babies with cleft lip (CL; n = 8), cleft palate (CP; n = 22), and cleft lip and palate (CLP; n = 10) were examined.

Methods:

Suction, compression, and other sucking parameters were measured during bottle-feeding and compared to determine if they varied with cleft condition or feeding ability.

Results:

All babies with CL and one with CLP demonstrated suction. Thirteen of 22 babies with CP demonstrated suction but only three maintained regular pressure changes over time. Between-group differences in the amplitude of suction and compression were associated with cleft condition. Cleft lip participants demonstrated the greatest amplitude of suction followed by those with CP and CLP. Cleft lip and CP participants generated similar amplitudes of compression. This was greater than their counterparts with CLP. Good feeders (n = 15) generated high levels of suction, while satisfactory (n = 15) and poor feeders (n = 10) did not generate any during bottle-feeding.

Conclusion:

Between-group differences in intra-oral pressures were confirmed when babies were examined by cleft condition. Babies with smaller clefts (i.e., CL or minor soft palate clefts) were more likely to generate normal levels of suction and compression compared to their counterparts with larger clefts. Since good feeders were more likely to have smaller clefts it was not surprising that they demonstrated higher suction pressures than babies with satisfactory or poor feeding ability. Compression values were not significantly different across the feeding ability groups. These data may inform feeding management strategies.

Strategies to increase milk volume in mothers of VLBW infants

The provision of breast milk to premature VLBW infants is associated with significant health benefits. Unfortunately, the delivery of breast milk to these vulnerable infants is often limited due to insufficient maternal milk supply. Several interventions have been investigated with respect to increasing milk volume in mothers of VLBW infants but confusion exists concerning the interventions' effectiveness. The purpose of this systematic review is to critique the evidence regarding specific milk expression strategies that aim to improve milk volume in mothers of VLBW infants.Published article references, electronic databases, dissertations and theses, and select conference proceedings were searched with the goal of finding studies that target VLBW infants and milk expression techniques in which breast milk volume was an outcome. Analysis of evidence revealed an association between increased milk volume and early initiation of expression, increased frequency of expression, and provision of kangaroo care. The use of simultaneous or sequential milk expression and duration of milk expression sessions were not found to significantly improve milk volume. These results may be used to formulate specific strategies designed to increase breast milk volume in this population.

Design of wireless multi-parameter monitoring system for oral feeding of premature infants

Premature infants often cannot successfully and coordinately complete their oral feeding. Mature sucking, swallowing, and respiration activities are crucial indicators for the survival of newborn infants. Due to the vulnerability and unobvious muscle activities of premature infants, current clinical care givers mainly depend on the subjective behavioral observation of infants during oral feeding. There is still lack of an integrated oral feeding monitoring system to objectively and quantifiably monitor the related physiological parameters of premature infants. In this study, a wireless multi-parameter monitoring system for oral feeding of premature infants was proposed to monitor the sucking-swallowing-respiratory activities and the heart rate variability to provide quantitative indices of oral feeding. Here, a novel sucking pressure sensing module was also developed to monitor the premature infant's sucking pressure under oral feeding to avoid the immersion influence of milk. The experimental results showed that the proposed system detected the related physiological parameters of premature infants during oral feeding effectively and may provide an objective clinical evaluation tool for oral feeding ability and safety of premature infants in the future.

Wireless Monitoring System for Oral-Feeding Evaluation of Preterm Infants

The oral feeding disorder is one of the important indicators for the high risk group of neurodevelopment delay. The procedure of oral feeding requires the coordination of sucking, swallowing, and breathing activities, and it is the most complex sensorimotor process for newborn infants. Premature infants often uneasily complete the procedure of oral feeding. However, the evaluation of the oral feeding disorders and severity are usually dependent on the subjective clinical experience of the physician. Monitoring the sucking-swallowing-breathing activities directly is difficult for preterm infants. In this study, a wireless monitoring system for oral-feeding evaluation of full term and preterm infants was proposed to objectively and quantitatively evaluate the coordination of suck-swallow-respiration function during oral feeding. Moreover, the ratios of the swallowing and breathing event numbers to the sucking event number were defined to evaluate the coordination of suck-swallow-respiration function during oral feeding. Finally, the system performance was validated and the coordination of suck-swallow-respiration function for full term and preterm infants during oral feeding was also investigated.

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.

Effect of early breast milk expression on milk volume and timing of lactogenesis stage II among mothers of very low birth weight infants: a pilot study

OBJECTIVE

The purpose of this randomized pilot study was to collect preliminary data regarding the feasibility and effects of early initiation of milk expression on the onset of lactogenesis stage II and milk volume in mothers of very low birth weight (VLBW) infants.

STUDY DESIGN

Twenty women were randomized to initiate milk expression within 60 min (group 1) or 1 to 6 h (group 2) following delivery. Milk volume and timing of lactogenesis stage II was compared between groups using Wilcoxon's rank sum tests.

RESULT

Group 1 produced statistically significantly more milk than group 2 during the first 7 days (P=0.05) and at week 3 (P=0.01). Group 1 also demonstrated a significantly earlier lactogenesis stage II (P=0.03).

CONCLUSION

Initiation of milk expression within 1 h following delivery increases milk volume and decreases time to lactogenesis stage II in mothers of VLBW 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.

Effectiveness of Cheek and Jaw Support to Improve Feeding Performance of Preterm Infants

OBJECTIVE. We examined the effects of cheek and jaw support on the feeding ability of inefficient feeders born prematurely.

METHOD. Twenty preterm infants served as their own controls. Each infant received either intervention (feeding with oral support) or control (feeding without oral support) for 2 consecutive feedings per day on 2 consecutive days.

RESULTS. Infants displayed a greater intake rate during the intervention feedings, both during the first 5 min (p = .046) and throughout the entire feeding (p = .023). The percentage of leakage during the first 5-min feeding was smaller in the intervention condition than in the control condition (p = .040). No significant differences were found between the two conditions in the sucking, physiological, and alertness variables.

CONCLUSION. Findings confirm oral support as a safe and effective strategy to improve the feeding performance of preterm infants who are poor feeders.

Mechanics of sucking: comparison between bottle feeding and breastfeeding

Background

There is very little evidence of the similarity of the mechanics of maternal and bottle feeding. We assessed the mechanics of sucking in exclusive breastfeeding, exclusive bottle feeding, and mixed feeding. The hypothesis established was that physiological pattern for suckling movements differ depending on the type of feeding. According to this hypothesis, babies with breastfeeding have suckling movements at the breast that are different from the movements of suckling a teat of babies fed with bottle. Children with mixed feeding mix both types of suckling movements.

Methods

Cross-sectional study of infants aged 21-28 days with only maternal feeding or bottle feeding (234 mother-infant pairs), and a randomized open cross-over field trial in newborns aged 21-28 days and babies aged 3-5 months with mixed feeding (125 mother-infant pairs). Primary outcome measures were sucks and pauses.

Results

Infants aged 21-28 days exclusively bottle-fed showed fewer sucks and the same number of pauses but of longer duration compared to breastfeeding. In mixed feeding, bottle feeding compared to breastfeeding showed the same number of sucks but fewer and shorter pauses, both at 21-28 days and at 3-5 months. The mean number of breastfeedings in a day (in the mixed feed group) was 5.83 ± 1.93 at 21-28 days and 4.42 ± 1.67 at 3-5 months. In the equivalence analysis of the mixed feed group, the 95% confidence interval for bottle feeding/breastfeeding ratio laid outside the range of equivalence, indicating 5.9-8.7% fewer suction movements, and fewer pauses, and shorter duration of them in bottle feeding compared with breastfeeding.

Conclusions

The mechanics of sucking in mixed feeding lay outside the range of equivalence comparing bottle feeding with breastfeeding, although differences were small. Children with mixed feeding would mix both types of sucking movements (breastfeeding and bottle feeding) during the learning stage and adopt their own pattern.

The preterm piglet - a model in the study of oesophageal development in preterm neonates

AIM

Preterm infants have difficulty in attaining independent oral feeding. This can ensue from inadequate sucking, swallowing and/or respiration. In impeding bolus transport, immature oesophageal motility may also be a cause. As studies on the development of oesophageal motility are invasive in preterm infants, the preterm piglet was investigated as a potential research model.

METHODS

Oesophageal motility (EM) of term (n = 6) and preterm (n = 15) piglets were monitored by manometry for 10 min immediately following bottle feeding on days 1-2 and 3-4 of life.

RESULTS

Piglets' oral feeding performance and EM were similar to those of their human counterparts. Term piglets readily completed their feeding, whereas their preterm counterparts did not. They also presented with greater peristaltic activity and propagating velocity. Peristaltic activity remained unchanged over time in preterm piglets, but an increase in synchronous and decrease in incomplete motor activity were noted. Preterm piglets that developed symptoms analogous to necrotizing enterocolitis (NEC) demonstrated uncharacteristic oesophageal activity.

CONCLUSION

Immature EM may cause oral feeding difficulties. NEC-like symptoms may adversely affect EM. The piglet is a valid research model for studying human infant oral feeding and oesophageal development.

Benefits and challenges of transitioning preterm infants to at-breast feedings

Upon hospital discharge it is not unusual for mothers of preterm infants to continue to meet all or most of their infants' nutritional needs through bottle feedings of expressed breast milk (EBM) because of infants' physiological immaturity and maternal concerns with an inadequacy of milk supply. Although for some mothers the challenge of transitioning the infant to feeding at the breast may be beyond their ability and resources, for others it appears to be based on a conscious choice. Mothers are often unaware of the advantages of breastfeeding at the breast. The purpose of this article is to examine some of the factors that may contribute to the inability and resistance of mothers to transition their preterm infants, and to report on the potential short and long-term advantages associated with feeding at the breast as opposed to feeding bottles of EBM.

Breast-feeding in women with hypertensive disorders in pregnancy

AIMS

Breast feeding is particularly important and difficult in children born prematurely, especially after hypertensive diseases in pregnancies (HDP). Therefore, we aimed to investigate breast feeding in women who developed HDP.

METHODS

Data on breast-feeding was collected within a nationwide research project on psychosocial factors in HDP. A self-administered questionnaire was given to 2600 women with a suspected history of HDP and 1233 controls. After matching and confirming diagnosis according to ISSHP criteria, 877 women with HDP and 623 controls were included into the study.

RESULTS

Control women initiated (48.9/39.2%; P<0.001) and continued (42.2/37.2%; P<0.005) breast-feeding significantly more often than women with HDP. This holds particularly for women who developed HELLP syndrome (48.9/34.7%; P<0.0001, 42.2/33.5%; P<0.0001). A delivery before the 32(nd) gestational week (19.5/81.8%; P<0.0001) and a birth weight of less than 1500 g (18.8/75%; P<0.0001) were associated with the decision not to breast-feed.

CONCLUSIONS

Women affected by HDP breast fed significantly less often than control women. This effect is at least partly caused by the increased rate of prematurity. Encouraging and supporting these women in breast-feeding is important to improve neonatal physical and mental development.

Does the choice of bottle nipple affect the oral feeding performance of very-low-birthweight (VLBW) infants?

BACKGROUND

There is a continuous debate regarding the best bottle nipple to be used to enhance the bottle-feeding performance of a preterm infant.

AIM

To verify that feeding performance can be improved by using the bottle nipple with the physical characteristics that enhance infants' sucking skills.

METHODS

Ten "healthy" VLBW infants (941+/-273 g) were recruited. Feeding performance was monitored at two time periods, when taking 1-2 and 6-8 oral feedings/d. At each time and within 24 h, performance was monitored using three different bottle nipples offered in a randomized order. Rate of milk transfer (ml/min) was the primary outcome measure. The sucking skills monitored comprised stage of sucking, suction amplitude, and duration of the generated negative intraoral suction pressure.

RESULTS

At both times, infants demonstrated a similar rate of milk transfer among all three nipples. However, the stage of sucking, suction amplitude, and duration of the generated suction were significantly different between nipples at 1-2, but not 6-8 oral feedings/d.

CONCLUSION

We did not identify a particular bottle nipple that enhanced bottle feeding in healthy VLBW infants. Based on the notion that afferent sensory feedback may allow infants to adapt to changing conditions, we speculate that infants can modify their sucking skills in order to maintain a rate of milk transfer that is appropriate with the level of suck-swallow-breathe coordination achieved at a particular time. Therefore, it is proposed that caretakers should be more concerned over monitoring the coordination of suck-swallow-breathe than over the selection of bottle nipples.

Does the choice of bottle nipple affect the oral feeding performance of very-low-birthweight (VLBW) infants?

BACKGROUND

There is a continuous debate regarding the best bottle nipple to be used to enhance the bottle-feeding performance of a preterm infant.

AIM

To verify that feeding performance can be improved by using the bottle nipple with the physical characteristics that enhance infants' sucking skills.

METHODS

Ten "healthy" VLBW infants (941+/-273 g) were recruited. Feeding performance was monitored at two time periods, when taking 1-2 and 6-8 oral feedings/d. At each time and within 24 h, performance was monitored using three different bottle nipples offered in a randomized order. Rate of milk transfer (ml/min) was the primary outcome measure. The sucking skills monitored comprised stage of sucking, suction amplitude, and duration of the generated negative intraoral suction pressure.

RESULTS

At both times, infants demonstrated a similar rate of milk transfer among all three nipples. However, the stage of sucking, suction amplitude, and duration of the generated suction were significantly different between nipples at 1-2, but not 6-8 oral feedings/d.

CONCLUSION

We did not identify a particular bottle nipple that enhanced bottle feeding in healthy VLBW infants. Based on the notion that afferent sensory feedback may allow infants to adapt to changing conditions, we speculate that infants can modify their sucking skills in order to maintain a rate of milk transfer that is appropriate with the level of suck-swallow-breathe coordination achieved at a particular time. Therefore, it is proposed that caretakers should be more concerned over monitoring the coordination of suck-swallow-breathe than over the selection of bottle nipples.

Correlation between intraoral pressures and tongue movements in the suckling pig

The objective was to clarify the relationship between tongue movements during suckling and the pressures in different parts of the oral cavity. A modified teat allowed a miniature pressure transducer to be passed through into the mouth. Intraoral pressures were recorded in piglets suckling on the teat attached (1) to a non-vented bottle or (2) to an automated milk delivery system. The movements of the tongue, of the milk and the transducer position were recorded by cine-radiography. In both modes of feeding, waves of elevation on the tongue moved in a pharyngeal direction and rose to contact the mid-posterior palate. Each wave corresponded to a jaw (suck) cycle in which milk was moved into and through the oral cavity. After each wave passed the transducer in the anterior part of the mouth, cyclical negative pressures were recorded. In bottle feeding, the intraoral pressure fluctuations (+/-2 mmHg) occurred against a background of a gradually developing negative pressure but, when feeding on the automatic delivery system, the same or smaller fluctuations occurred as changes from atmospheric pressure. Where the elevations contacted the mid-posterior palate in each cycle, a seal was formed (contact pressure >40 mmHg), so producing two functional antero-posterior compartments within the mouth; in these compartments pressures were generated independently. With the transducer in the valleculae, no general increase in pressure was recorded as milk accumulated there in each suck cycle but large positive pressures were recorded during the less frequent cycles when the vallecular space was emptied.

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.

Breastfeeding: making the difference in the development, health and nutrition of term and preterm newborns

Breastfeeding is the natural and safe way of feeding small infants, providing nutritional, immunological, psychological and economic recognized and unquestionable advantages. These qualities are especially important in premature infants, because of their vulnerability. Despite highly desirable, there is, in general, little success in breastfeeding preterm infants, especially in special care neonatal units. There are evidences that a high supportive hospital environment, with an interdisciplinary team, makes possible to these infants to be breastfed. In this article, the authors present an up-to-date review about the components of human milk and its unique characteristics, as well as describes aspects that make the breast milk particularly suitable for feeding the premature newborn.

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.

Breastfeeding twins: guidelines for success

BACKGROUND

Although the frequency of twin births has increased in Japan, little information is available about breastfeeding twins. An intervention of breastfeeding support was implemented to promote breastfeeding for mothers of twins and to compare the factors related to breastfed and formula-fed twins.

METHODS

Eleven Japanese twins-mother pairs received breastfeeding support according to a breastfeeding protocol for twins, and a control group of seven pairs received routine care. Perinatal data were obtained from clinical records for analysis.

RESULTS

No significant differences were evident between the two groups in terms of maternal age, gestational age, birthweight, the age at which breastfeeding was initiated, amount of supplementary feeding in hospital, infants' age at discharge, or duration of mothers' hospital stay. At age 3 months, 13 infants in the intervention group were being exclusively breastfed and 9 were almost exclusively breastfed. In the control group 4 infants were almost exclusively and 10 were exclusively formula-fed. The mothers in the intervention group breastfed and expressed milk significantly more frequently than the mothers in the control group during their hospital stay.

CONCLUSIONS

Mothers of twins face many obstacles in breastfeeding, and health care professionals should offer individualized care and support.

Is suckling behaviour a useful predictor of milk intake? A review

In studies on mammalian parental investment, time spent suckling is often used as a predictor of the milk transferred from mother to infant. It is assumed that the rate of milk transfer is positively correlated with the time spent suckling. However, this assumption has not been tested and empirical studies show conflicting results. Nevertheless, in species in which suckling can readily be observed, time spent suckling is still used to measure milk transfer, although an increasing number of workers recognize that the measure is potentially inaccurate. A meta-analysis on studies that have correlated measures of time spent suckling with milk intake estimates based on weight gain revealed a weak positive relationship and significant heterogeneity between studies. Isotope-labelling techniques for the measurement of milk transfer independent of behaviour have been in use since the 1970s, particularly in studies of species in which suckling is difficult to observe. Only one study has attempted to correlate behavioural measures with independent isotope measures, and it found no relationship between the two measures. I suggest that researchers have avoided such a test as it is unlikely that a strong relationship will be found between milk transfer and suckling behaviour, and I discuss the various factors that confound the relationship and contribute to high heterogeneity between studies. Consequently, the assumption that milk transfer can be measured by time spent suckling has inadequate empirical foundation, and needs to be tested using isotope-labelling methods. Copyright 1998 The Association for the Study of Animal Behaviour

Feeding responses to free-flow formula in term and preterm infants

OBJECTIVES

Although introducing freely flowing formula into the infant's mouth is a common feeding practice, its effect on feeding behavior is largely unknown. We evaluated the effects of free flow of formula from the nipple on infant feeding activity (sucking, swallowing, ingestion rate) and documented potential adverse behaviors such as cough, restless behavior, drooling, apnea, and bradycardia.

METHODS

We studied 13 preterm and 7 term infants. During a feeding, bottle pressure was adjusted every 2 to 3 minutes to increase or decrease free flow from the nipple.

RESULTS

Increase in free flow of formula from the nipple caused rapid increases in suck and swallow frequency in term and preterm infants and increased ingestion rate. The response was reversed by decreasing flow and was repeatable throughout the feeding. Peak suck and swallow rates were highest in term infants. Although drooling increased with increased milk flow, no effect of flow on coughing, restless behavior, or apnea was observed.

CONCLUSIONS

Free-flow formula is a potent stimulus for feeding activity in both preterm and term infants and is not associated with increased apnea or other adverse behaviors. The ability of the infant to divert excess formula flow by drooling is an efficient airway protective behavior. Reduced maximum suck and swallow frequency may be a primary basis for slow feeding in preterm infants.

Calibrated-orifice nipples for measurement of infant nutritive sucking

To measure infant nutritive sucking reproducibly, nipple flow resistance must be controlled. Previous investigators have accomplished this with flow-limiting venturis, which has two limitations: flow resistance is highly dependent on fluid viscosity and older infants often reject the venturi nipple. This report describes the validation of calibrated-orifice nipples for the measurement of infant nutritive sucking. The flow characteristics of two infant formulas and water through these nipples were not different; those through venturi nipples were (analysis of variance; p < 0.0001). Flow characteristics did not differ among calibrated-orifice nipples constructed from three commercial nipple styles, indicating that the calibrated-orifice design is applicable to different types of baby bottle nipples. Among 3-month-old infants using calibrated-orifice nipples, acceptability was high, and sucking accounted for 85% of the variance in fluid intake during a feeding. We conclude that calibrated-orifice nipples are a valid and acceptable tool for the measurement of infant nutritive sucking.

Mechanics and energetics of nutritive sucking: a functional comparison of commercially available nipples

The purpose of this study was to compare the mechanics of sucking for 48 term infants with four different nipple units: Gerber Newborn (Gerber Products Company, Fremont, Mich.), Playtex (Playtex Products, Westport, Conn.), Evenflo (Evenflo Products Co., Canton, Ga.), and Gerber NUK. At 24 hours after birth, infants were assigned randomly to one of the nipple units and were studied twice with that nipple unit. A customized data acquisition system was used to measure and record the following variables: intraoral suction, sucking frequency, work, power, milk flow, milk volume per suck, and oxygen saturation. Although no statistically significant differences among the nipple units were noted for intraoral suction, sucking frequency, power, and oxygen saturation, the data revealed that the Playtex nipple unit was accompanied by higher peak milk flow and greater volume of milk per suck (p < 0.05). Infants fed differently with the Playtex nipple than they did with the other nipples. Our findings indicate that the Playtex nipple permits a greater milk flow in response to similar amounts of suction, work, and power when compared with others. The mean total work per such was significantly lower in the Gerber NUK group compared with the Playtex group. In addition, the total number of sucks per volume ingested was higher, and the total time to ingest a specific quantity of milk was longer for the Gerber NUK nipple.

Oral feeding in low birth weight infants

To gain a better understanding of the development of sucking behavior in low birth weight infants, the aims of this study were as follows: (1) to assess these infants' oral feeding performance when milk delivery was unrestricted, as routinely administered in nurseries, versus restricted when milk flow occurred only when the infant was sucking; (2) to determine whether the term sucking pattern of suction/ expression was necessary for feeding success; and (3) to identify clinical indicators of successful oral feeding. Infants (26 to 29 weeks of gestation) were evaluated at their first oral feeding and on achieving independent oral feeding. Bottle nipples were adapted to monitor suction and expression. To assess performance during a feeding, proficiency (percent volume transferred during the first 5 minutes of a feeding/total volume ordered), efficiency (volume transferred per unit time), and overall transfer (percent volume transferred) were calculated. Restricted milk flow enhanced all three parameters. Successful oral feeding did not require the term sucking pattern. Infants who demonstrated both a proficiency > or = 30% and efficiency > or = 1.5 ml/min at their first oral feeding were successful with that feeding and attained independent oral feeding at a significantly earlier postmenstrual age than their counterparts with lower proficiency, efficiency, or both. Thus a restricted milk flow facilitates oral feeding in infants younger than 30 weeks of gestation, the term sucking pattern is not necessary for successful oral feeding, and proficiency and efficiency together may be used as reliable indicators of early attainment of independent oral feeding in low birth weight infants.

Getting enough: mothers' concerns about breastfeeding a preterm infant after discharge

OBJECTIVE

To describe maternal concerns about breastfeeding a preterm infant in the postdischarge period and to delineate the strategies mothers used in managing these concerns.

DESIGN

Naturalistic inquiry was used.

SETTING

A semistructured interview was conducted with the mother in the home 1 month after discharge of the infant.

PARTICIPANTS

Twenty mothers of preterm infants; the infants had been in a level 3 hospital nursery, and the mothers had received individualized breastfeeding support services in the hospital.

MAIN OUTCOME MEASURES

Three categories of maternal concerns emerged from the data: adequate milk consumption by infants; milk composition; and problems with the mechanics of breastfeeding a preterm infant. Mothers identified strategies for these concerns.

RESULTS

The mothers' main concern was whether infants consumed an adequate volume of milk by breastfeeding alone. Strategies for managing concerns about getting enough included using supplemental and complemental feeding, using ongoing cues to tell that the infant is getting enough, and persevering with breastfeeding.

CONCLUSIONS

Mothers of preterm infants have unique concerns about breastfeeding in the postdischarge period and need individualized interventions.

The development of eating behavior in childhood

Eating behavior must be viewed as a complex phenomenon involving the coordination of motor, cognitive, social and emotional development, all under the regulation of both central and peripheral factors. Eating provides not only the necessary biologic substrate for human growth and normal physiologic function but is strongly involved in the full range of social interaction from the formation of the mother-infant relationship to later social interaction. Eating is associated with a variety of pleasurable and painful affective experiences. The pediatrician, working closely with the parents, can facilitate the development of healthy attitudes toward eating and healthy eating behaviors.

The analysis of sucking behaviour in newborn infants

A special video camera devised by the author and a fiberscope were used to film the neonatal sucking response of 50 low-risk full-term newborn infants on the 5th day after birth. Analysis of the sucking behaviour showed that the sucking movements consist mainly of a peristaltic tongue movement and two kinds of negative pressure; that the peristaltic tongue movements are synchronized with the jaw movements; that infants actively adapt to a varying environment; and that the sucking movements change to minimize the energy required.

Developmental patterns of normal nutritive sucking in infants

The purpose of this investigation was to quantify normal nutritive sucking, using a microcomputer-based instrument which replicated the infant's customary bottle-feeding routine. 86 feeding sessions were recorded from infants ranging between 1.5 and 11.5 months of age. Suck height, suck area and percentage of time spent sucking were unrelated to age. Volume per suck declined with age, as did intersuck interval, which corresponded to a more rapid sucking rate. This meant that volume per minute of sucking time was fairly constant. The apparatus provided an objective description of the patterns of normal nutritive sucking in infants to which abnormal sucking patterns may be compared.

Sucking efficiency of early orthopaedic plate and teats in infants with cleft lip and palate

Intraoral negative pressure during bottle feeding with two kinds of teats (a regular Nuk and a cleft Nuk) was measured in 7 infants with cleft lip and palate, 8 infants with cleft palate, 2 infants with cleft lip, 4 infants with operated cleft lip and palate and 7 normal infants. Infants with cleft lip and palate or cleft palate were unable to generate negative pressure before cleft lip and palate closure. The presence or absence of an early orthopaedic plate did not make any difference. In infants with unoperated cleft lip and with operated cleft lip and palate, peak negative pressure during feeding differed little from that of normal infants.