Early Intervention to Improve Sucking in Preterm Newborns: A Systematic Review of Quantitative Studies

[Latest Findings on the Suck-Swallow-Breathe Mechanism of Direct Breastfeeding From the Breast to an Infant]

A mother's breast milk is the best nourishing food for infants. No only does it provide sufficient nutrition, but it is also well suited to infants' immature digestive function, thus promoting their growth and organ maturation. A 6-month period of breastfeeding can provide infants with the necessary nutrients, energy, and fluids. The best feeding method is direct breastfeeding from the breast to an infant, yet the difficulties involved in breastfeeding should not be overlooked. Approximately 1/3 the mothers who are performing direct breastfeeding from the breast to an infant experience moderate or higher levels of feeding difficulties. Difficulties in direct breastfeeding from the breast to an infant can lead to decreased feeding efficiency, hamper the growth and development of infants, and affect the emotional communication between mothers and infants. At present, many relevant studies have focused on topics such as the mothers' psychology, family and social support, and the immature development of infants. However, little research has been done to investigate suck-swallow-breathe, a physiological mechanism that infants undertake during the process of direct breastfeeding from the breast to an infant. In this paper, we summarized published literature, research parameters, measurement instruments, and physical intervention methods of the suck-swallow-breathe mechanism in infants, aiming to facilitate the early identification of breastfeeding difficulties and the subsequently provision of early intervention measures and to promote the early identification of neurodevelopmental abnormalities and other developmental abnormalities in infants.

Quantitative non-nutritive sucking measurement as a predictor of oral feeding readiness in newborns

Background and purpose

The purpose of this study is to examine the relationship between the parameters of a silver nanowire-based flexible pressure sensor developed to measure the non-nutritive sucking (NNS) performance and predict the nutritive sucking status in preterm infants.

Methods

Preterm infants who were referred for feeding difficulty during the transition period from tubal feeding to oral feeding were enrolled in our study. A flexible pressure sensor was used to measure the non-nutritive sucking parameters of neonates. The evaluator stimulated the infants' lips and tongue with a pacifier integrated with a sucking pressure sensor, to check whether non-nutritive sucking had occurred. When the sucking reflex was induced, it was measured. The infants' sucking characteristics were subdivided into classifications according to the NOMAS criteria and full oral feeding (FOF) status. Quantitative NNS measurement according to the feeding state was compared between groups.

Results

When comparing the quantitative NNS measurement by feeding characteristics, the average sucking pressure was significantly higher in infants in the FOF capable group than those in the incomplete FOF group. In addition, the maximum and average sucking pressure was significantly higher in infants with a normal sucking pattern compared to those with a disorganized sucking pattern. The average NNS pressure was divided over the range of 0-3 kPa and the same weight was assigned to each item. When the optimal cut-off value for the sensitivity and specificity of the average NNS pressure to estimate the FOF was set, a pressure of 1.5 kPa yielded the highest sensitivity (84.62%) and specificity (67.65%) on the receiver operating characteristic (ROC) curve. The area under the curve (AUC) was 0.786, and this result was statistically significant.

Conclusions

This study presents a quantitative parameter for non-nutritive sucking in preterm infants with the use of a flexible pressure sensor. Results show possible quantitative indicators that can aid in predicting when preterm infants can transition to oral feeding and their prognosis. This will serve as a basis for future research on determining the feeding transition period of newborns with health conditions that affect oral feeding.

Oral stimulation for promoting oral feeding in preterm infants

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Direct swallowing training and oral sensorimotor stimulation in preterm infants: a randomised controlled trial

OBJECTIVE

To evaluate the effects of direct swallowing training (DST) alone and combined with oral sensorimotor stimulation (OSMS) on oral feeding ability in very preterm infants.

DESIGN

Blinded, parallel group, randomised controlled trial (1:1:1).

SETTING

Neonatal intensive care unit of a South Korean tertiary hospital.

PARTICIPANTS

Preterm infants born at <32 weeks of gestation who achieved full tube feeding.

INTERVENTIONS

Two sessions per day were provided according to the randomly assigned groups (control: two times per day sham intervention; DST: DST and sham interventions, each once a day; DST+OSMS: DST and OSMS interventions, each once a day).

PRIMARY OUTCOME

Time from start to independent oral feeding (IOF).

RESULTS

Analyses were conducted in 186 participants based on modified intention-to-treat (63 control; 63 DST; 60 DST+OSMS). The mean time from start to IOF differed significantly between the control, DST and DST+OSMS groups (21.1, 17.2 and 14.8 days, respectively, p=0.02). Compared with non-intervention, DST+OSMS significantly shortened the time from start to IOF (effect size: -0.49; 95% CI: -0.86 to -0.14; p=0.02), whereas DST did not. The proportion of feeding volume taken during the initial 5 min, an index of infants' actual feeding ability when fatigue is minimal, increased earlier in the DST+OSMS than in the DST.

CONCLUSIONS

In very preterm infants, DST+OSMS led to the accelerated attainment of IOF compared with non-intervention, whereas DST alone did not. The effect of DST+OSMS on oral feeding ability appeared earlier than that of DST alone.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT02508571).

Influence of taste stimulation on sucking pressure in newborn infants at term

PURPOSE

To verify the influence of a taste stimulus on the suction pressure, during the non-nutritive sucking (SNN), in newborns, healthy and with weight appropriate to the gestational age.

METHODS

Quasi-experimental study of the non-randomized clinical trial type with a convenience sample of 60 newborns (NB), 30 allocated in the study group (EG) and 30 in the control group (CG). The NB were evaluated for sucking pressure during the SNN in a pacifier. For the EG, a gustatory stimulus was added to the pacifier, moistened with colostrum. The CG did not receive any stimulus, other than the pacifier itself. The average, minimum and maximum pressures were measured with the equipment S-Flex®.

RESULTS

The SG presented mean and maximum sucking pressure significantly higher than the CG. In addition, there was a statistically significant difference between the groups for the second measurement of mean sucking pressure.

CONCLUSION

The results showed that the NB of the SG presented sucking pressures, average and maximum, significantly higher, when compared to the CG. The use of a taste stimulus associated with SNN modified the sucking pressure and seems to enhance oral skills.

Supporting Premature Infants’ Oral Feeding in the NICU—A Qualitative Study of Nurses’ Perspectives

One major task in the neonatal intensive care unit (NICU) involves ensuring adequate nutrition and supporting the provision of human milk. The aim of this study was to explore nurses’ experiences of the oral feeding process in the NICU when the infant is born extremely or very preterm. We used a qualitative inductive approach. Nine nurses from three family-centered NICUs were interviewed face-to-face. The interviews were transcribed verbatim and analyzed using content analysis. Five sub-categories and two generic categories formed the main category: ‘A complex and long-lasting collaboration.’ The nurses wished to contribute to the parents’ understanding of the feeding process and their own role as parents in this process. The nurses’ intention was to guide and support parents to be autonomous in this process. They saw the family as a team in which the preterm infant was the leader whose needs and development directed the feeding and the parents’ actions in this process. Written and verbal communication, seeing all family members as important members of a team and early identification of the most vulnerable families to direct the emotional and practical feeding support accordingly can strengthen the feeding process in the NICU.

Cardio-Respiratory Events and Food Autonomy Responses to Early Uni-Modal Orofacial Stimulation in Very Premature Babies: A Randomized, Controlled Study

Uni-modal orofacial stimulation (OFS) for preventing very preterm infants’ oral disorders is highly controversial. Our study sought to demonstrate that OFS reduced cardio-respiratory events and improved food autonomy in a population of very preterm infants. Our study was randomized, controlled, prospective, and unicentric. The preterm included were born between 26–29 weeks gestational age (GA) with a corrected postnatal age <33 weeks GA. They were randomized into two groups: the experimental group underwent OFS, according to a protocol established, over 10 consecutive days, and the control group underwent no OFS. The primary outcome was the number of cardiorespiratory events: apnea–bradycardia (with or without desaturations) or number of isolated desaturations, which were evaluated at four separate times. Measurements occurred during the first, fourth and eighth independent feedings. Seventeen patients were included in the experimental group and 18 in the control group. The number of cardiorespiratory events for all independent feeding times was significantly reduced in the OFS group (p = 0.003) with univariate analysis, but not with multivariable analysis. The quantity of milk ingested during the first autonomous feeding was higher in the experimental group. The acquisition of food autonomy and the duration of hospitalization were similar in the two groups. While our study does not affirm that an early unimodal OFS improves premature infants’ cardiorespiratory evolution and/or the acquisition of food autonomy, it does indicate an improved food efficiency during their first autonomous feedings.

Effects of Oral Stimulation and Supplemental Nursing System on the Transition Time to Full Breast of Mother and Sucking Success in Preterm Infants: A Randomized Controlled Trial

This study aimed to investigate the effect of oral stimulation and a supplemental nursing system on the time to full maternal breastfeeding and sucking success in preterm infants. The sample consisted of 70 preterm babies. Oral motor stimulation and a supplemental nursing system were applied to the preterm infants in the experimental group, while no intervention was applied to those in the control group. Significant differences were found between the two groups concerning transition time to oral feeding, transition weight, transition time to full maternal breast, discharge age, duration, and weight, LATCH mean scores, continuing to suck in the first month after discharge, and weight averages. Oral stimulation and a supplemental nursing system shortened the transition period to oral feeding and full breastfeeding, increased breastfeeding rates and the sustainability of breastfeeding, and did not affect the period of discharge and vital signs during feeding in preterm babies.

Effectiveness of Oral Sensory-Motor Stimulation in Premature Infants in the Neonatal Intensive Care Unit (NICU) Systematic Review

The aim of this study was to identify and to assess the best evidence currently available on the effectiveness of oral sensory-motor stimulation in preterm infants in the neonatal intensive care unit. We performed a systematic review following the Preferred Reporting Items for Systematic Reviews (PRISMA) statements. The search was conducted using the Pubmed, Web of Science (WOS), PEDro and Scopus databases. Clinical trials were reviewed and PEDro rating scale was used to assess the methodological quality of these studies. Results: 1267 studies were found and 11 were relevant and included in this review. Improvements were obtained in achieving independent feeding, maturation of the sucking pattern, transition to full feeding, motor function and length of hospital stay in most studies. Conclusions: there is evidence to support the benefits of the use of oral sensorimotor stimulation to achieve independent oral feeding in preterm infants, thereby reducing their stay in the Neonatal Intensive Care Unit.

Effectiveness of the Premature Infant Oral Motor Intervention on Feeding Performance, Duration of Hospital Stay, and Weight of Preterm Neonates in Neonatal Intensive Care Unit: Results From a Randomized Controlled Trial

BACKGROUND

Most preterm neonates are unable to achieve independent oral feeding and are fed using tubes. Premature infant oral motor intervention (PIOMI) is effective in initiating early oral feeding and reducing hospital stays.

OBJECTIVE

This study aimed to evaluate the effectiveness of PIOMI on feeding performance, duration of hospital stay, and weight of preterm neonates in the neonatal intensive care unit (NICU).

METHODS

This was a parallel randomized controlled trial conducted in Egypt. Sixty preterm neonates born between 30 and 34 weeks of gestation were randomly selected (30 in the study group and 30 in the control group). The study was conducted at the NICU in Sohag, Egypt, over 3 months from October to December 2019. Two tools were used: demographic data of preterm neonates according to gestational age, sex, weight, and diagnosis, and PIOMI.

RESULTS

Among the preterm neonates in the study group, full oral feeding was achieved significantly earlier (P = .03), milk leakage decreased significantly (P = .001), weight was significantly higher (P = .018), and the duration of hospital stay was significantly lower (P = .014) than that in the control group.

CONCLUSION

Premature infant oral motor intervention was effective in improving preterm neonates' feeding performance, reducing the duration of hospital stay, and increasing their weight. This study recommended that a training program for nurses in the NICU about PIOMI for preterm neonates be conducted, along with training of the parents to use PIOMI and the implementation of policies in the NICU to conduct PIOMI as a part of daily routine preterm neonatal care.

[Effect of oral motor intervention in improving brain function development in preterm infants: a randomized controlled trial]

OBJECTIVE

To study the effect of oral motor intervention (OMI) on brain function development in preterm infants.

METHODS

A total of 112 preterm infants were stratified into small-gestational-age (30-31⁺⁶ weeks) and large-gestational-age (32-33⁺⁶ weeks) according to gestational age at birth. The preterm infants were randomly divided into a control group and an intervention group, with 56 infants in each group. The infants in the control group were given routine treatment and nursing, while those in the intervention group were given OMI in addition to the treatment and nursing in the control group. Amplitude-integrated EEG (aEEG) and Neonatal Behavioral Neurological Assessment (NBNA) were performed on days 1, 7, and 14 of enrollment, and the level of brain function development was compared before and after intervention.

RESULTS

On day 7 of OMI, the small-gestational-age intervention group had lower upper bounds of voltage and bandwidth and a higher aEEG score than the small-gestational-age control group (P < 0.05). Compared with the small-gestational-age control group, the small-gestational-age intervention group had higher upper bound of voltage, percentage of mature sleep-wake cycle, aEEG score, and NBNA score and a lower narrow bandwidth on day 14 of OMI (P < 0.05). Compared with the large-gestational-age control group, the large-gestational-age intervention group had lower upper voltage and voltage difference and higher lower bound of voltage and aEEG score on days 7 and 14 of OMI (P < 0.05). On day 7 of OMI, the large-gestational-age intervention group had a higher NBNA score than the large-gestational-age control group (P < 0.05).

CONCLUSIONS

OMI can promote the maturation of aEEG background activities, improve neurobehavioral manifestations, and accelerate brain function development in preterm infants.

[Effectiveness of 2 interventions for independent oral feeding in pre-terms]

INTRODUCTION

Oral feeding of pre-term newborns (PTNB) is hampered by their immaturity and intercurrent diseases, which can prolong their hospital stay. The objective of this study was to assess the effectiveness of a program that combines tactile, kinesthetic and oral stimulation (T+K+OS) compared to another intervention based on exclusively oral stimulation (OS), in the time necessary to achieve independent feeding and hospital discharge.

PATIENTS AND METHODS

A clinical study of 2 randomized groups (OS vs. T+K+OS) was carried out on 42 PTNB with gestational age between 27-32 weeks and birth weight>900g. The stimulation programs were carried out in sessions of 15min, for 10 days.

RESULTS

The PTNBs in the T+K+OS group achieved independent oral feeding earlier, compared to the OS group (24.9±10.1 vs. 34.1±15.6 days, P=.02). An analysis of covariance was performed, which confirmed that the birth weight and gestational age covariates had significant effects on time to reach suction feeding (birth weight: F[1, 38]=5.79; P=.021; gestational age: F[1, 38]=14.12; P=.001) and that once its effect was controlled, the intervention continued to have a significant effect (F[1, 38]=6.07; P=.018). The T+K+OS group, compared to the OS group, achieved an earlier hospital discharge (39±15 vs. 45±18 days), although the differences were not significant (P=.21).

CONCLUSIONS

Combined therapies that include T+K+OS are more effective than OS alone, in order to achieve independent oral feeding in PTNBs.

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.

Feeding and Swallowing Difficulties in Neonates: Developmental Physiology and Pathophysiology

Development of enteral and oral feeding milestones in infants is intricately linked to physiologic maturation of the gastrointestinal tract and its complex interplay with cardiorespiratory and central nervous system control and coordination. Assessment of an infant's developmental skills and maturation can guide us with targeted management approaches and prediction of feeding outcomes. In this article, we review and summarize the developmental aspects of oral feeding and swallowing physiology, and current understanding of the pathophysiological changes associated with feeding difficulties in infants.

Premature birth impacts bolus size and shape through nursing in infant pigs

BACKGROUND

The formation of a bolus of food is critical for proper feeding function, and there is substantial variation in the size and shape of a bolus prior to a swallow. Preterm infants exhibit decreased abilities to acquire and process food, but how that relates to their bolus size and shape is unknown. Here, we test two hypotheses: (1) that bolus size and shape will differ between term and preterm infants, and (2) bolus size and shape will change longitudinally through development in both term and preterm infants.

METHODS

To test these hypotheses, we measured bolus size and shape in preterm and term infant pigs longitudinally through nursing using high-speed videofluoroscopy.

RESULTS

Preterm infant pigs swallowed smaller volumes of milk. Although term infants increased the amount of milk per swallow as they aged, preterm infants did not. These changes in bolus volume were also correlated with changes in bolus shape; larger boluses became more elongate as they better filled the available anatomical space of the valleculae.

CONCLUSIONS

These results suggest that preterm birth reduces the ability of preterm pigs to increase bolus size as they grow, affecting development in this fragile population. These results highlight that studies on term infant feeding may not translate to preterm infants.