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

Biobehavioral Efficacy of the Elevated Side-Lying Position for Feeding Preterm Infants: Study Protocol

AIM

Present a study protocol investigating the biobehavioral efficacy of side-lying vs. supine positions on physiologic and behavioural responses of preterm infants during their transition from tube to full oral feeding, and identify associated infant characteristics.

DESIGN

Within-subject cross-over design.

METHODS

Sixty preterm infants born at ≤35 weeks gestational age (GA) from a level 3 NICU are observed during their transition to full oral feeding. Each undergoes two feedings within 24 h: One in the supine position and one in the side-lying position. Continuous physiologic and video data are collected 30 min before and after feeding. Physiologic measures include heart rate, respiratory rate, oxygen saturation, and autonomic nervous system regulation (heart rate variability and splanchnic-cerebral oxygen ratio). Behavioural responses are assessed via microanalysis of the sucking and breathing waveforms and videotaped feedings (Suck-breathe coordination and Early Feeding Skills assessment tool). Data are analysed using linear mixed-effects models. IRB was obtained in September 2021, with funding awarded by the National Institute of Nursing Research in July 2021.

CONCLUSION

This study will enhance our understanding of the effects of the side-lying position on preterm infant feeding, providing guidance for its clinical use as a feeding strategy.

IMPLICATIONS

Provides vital knowledge to guide evidence-based practices in enhancing oral feeding in preterm infants and inform future pivotal efficacy trials.

IMPACT

If effective, this intervention could significantly enhance the management of feeding challenges in preterm infants across neonatal care settings.

REPORTING METHOD

Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) 2013.

PATIENT OR PUBLIC CONTRIBUTION

While direct parent involvement was not documented in our protocol, informal feedback on data collection procedures from parents was incorporated. Additionally, extensive engagement with healthcare professionals during study design addressed patient safety, logistical challenges, and ethical standards in NICU settings.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04942106; registered on 28 June 2021. Available at: https://clinicaltrials.gov/ct2/show/NCT04942106.

Methods for analyzing infant heart rate variability: A preliminary study

Heart rate (HR) and heart rate variability (HRV) reflect autonomic development in infants. To better understand the autonomic response in infants, reliable HRV recordings are vital, yet no protocol exists. The purpose of this paper is to present reliability of a common procedure for analysis from two different file types. In the procedure, continuous electrocardiograph recordings of 5-10 min are obtained at rest in infants at 1 month of age by using a Hexoskin Shirt-Junior's (Carre Technologies Inc., Montreal, QC, Canada). Electrocardiograph (ECG; .wav) and R-R interval (RRi; .csv) files are extracted. The RRi of the ECG signal is generated by VivoSense (Great Lakes NeuroTechnologies, Independence, OH). Two MATLAB (The MathWorks, Inc., Natick, MA) scripts converted files for analysis with Kubios HRV Premium (Kubios Oy, Kuopio, Finland). A comparison was made between RRi and ECG files for HR and HRV parameters, and then tested with t tests and correlations via SPSS. There are significant differences in root mean squared successive differences between recording types, with only HR and low-frequency measures significantly correlated together. Recording with Hexoskin and analysis with MATLAB and Kubios enable infant HRV analysis. Differences in outcomes exist between procedures, and standard methodology for infant HR analysis is needed.

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

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

Cue-based feeding and short-term health outcomes of premature infants in newborn intensive care units: a non-randomized trial

BACKGROUND

Feedings based on behavioral cues is a method relying on infants' behavioral expressions of readiness to feed. The objective of this interventional study was to determine the effect of cue-based feeding on the short-term health outcomes of preterm infants.

METHODS

This quasi-experimental study utilized a historical or phase lag design. It involved 60 preterm infants admitted to an Iranian referral hospital's Level III-Newborn Intensive Care Unit (NICU) from April 2017 until January 2018. The experimental group (n = 30) received a three-step intervention of offering behavioral-cue-based oral (BCBO) feedings: Step 1 - One BCBO feeding every 12 hours for 3 days; Step 2 - Two BCBO feedings every 12 h for 3 days; and Step 3 - All feedings as BCBO feedings for 3 days. The control group received standard care feedings. Group difference data were analyzed with SPSS version 16 using descriptive and inferential statistics.

RESULTS

The infants' mean weight at time of discharge for the intervention and control groups were 1492.79 ± 21.65 g and 1395.71 ± 17.61 g (P = .003) respectively. The mean durations of achieving full oral feedings in the intervention and control groups were 17 ± 6 and 20 ± 11 days, respectively (P = .19). The mean frequencies of hypoxia were 1 ± 1.54 and 5 ± 9.31 respectively (P = .03) and of gavage feedings 725 ± 584 and 1846 ± 2097 respectively (P = .009). No apnea events were reported for the intervention group; the frequency of apnea in the control group was 1 ± 2.11 (P = .16).

CONCLUSION

The findings indicate that cue-based feeding is beneficial for preterm infants. Therefore, it is recommended that nurses employ cue-based feeding in the NICU.

TRIAL REGISTRATION

IRCTID: IRCT20170828035962N2. Registered 27 may 2018 - Retrospectively registered, https://en.irct.ir/trial/27024 .

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

Validity of stress assessment using heart-rate variability in newborns

BACKGROUND

The process of birth causes stress for neonates, but additional stressors for sick neonates are a matter of concern. As analysis of heart-rate variability (HRV), which reflects autonomic activity, has demonstrated that low-frequency (LF) activity reflects overall autonomic activity, high-frequency (HF) activity reflects parasympathetic activity, and the LF/HF ratio reflects sympathetic activity, HRV has been clinically applied as a non-invasive index of physical stress. In this study, we evaluated whether HRV is useful as a stress index for neonates by analyzing it in comparison with their salivary cortisol level.

METHODS

We measured the salivary cortisol level and HRV in 12 healthy neonates and 37 neonates born during between 2014 and 2016 and admitted to the neonatal intensive care unit. These examinations were performed at birth and after approximately 1 week. The changes in parameters with time were examined.

RESULTS

The LF and HF values in both groups exhibited significant negative correlations with the salivary cortisol level. In those admitted to the neonatal intensive care unit, the LF and HF values were correlated with gestational age and height. In the healthy neonates, a reduced salivary cortisol level and increase in the LF and HF values were observed approximately 1 week after birth compared with the values at birth, whereas the LF/HF ratio was not correlated with the salivary cortisol level and did not change over time.

CONCLUSIONS

The LF and HF values were significantly correlated with the cortisol level, suggesting their usefulness as physiological indices of stress in clinical neonatal care.

Order Through Disorder: The Characteristic Variability of Systems

Randomness characterizes many processes in nature, and therefore its importance cannot be overstated. In the present study, we investigate examples of randomness found in various fields, to underlie its fundamental processes. The fields we address include physics, chemistry, biology (biological systems from genes to whole organs), medicine, and environmental science. Through the chosen examples, we explore the seemingly paradoxical nature of life and demonstrate that randomness is preferred under specific conditions. Furthermore, under certain conditions, promoting or making use of variability-associated parameters may be necessary for improving the function of processes and systems.

Systematic Review of the Effects of Skin-to-Skin Care on Short-Term Physiologic Stress Outcomes in Preterm Infants in the Neonatal Intensive Care Unit

BACKGROUND

Infants in the neonatal intensive care unit (NICU) are exposed to many stressors. There is growing evidence that chronic stress early in life has long-term neurodevelopmental implications. Skin-to-skin care (SSC) is an intervention used to reduce stress in the NICU.

CLINICAL QUESTION

In premature infants in the NICU, what is the available evidence that SSC improves short-term physiologic stress outcomes compared with incubator care?

SEARCH STRATEGY

PubMed and CINAHL were searched for terms related to SSC, stress, physiology, and premature infants. Of 1280 unique articles, 19 were identified that reported on research studies comparing SSC with incubator care in the NICU and reported stress-related physiologic outcome measures.

RESULTS

Although there have been some mixed findings, the research supports that SSC improves short-term cardiorespiratory stress outcomes compared with incubator care. The evidence is clearer for studies reporting stress hormone outcomes, with strong evidence that SSC reduces cortisol and increases oxytocin levels in preterm infants.

IMPLICATIONS FOR PRACTICE AND RESEARCH

SSC is safe and has stress-reducing benefits. SSC should be considered an essential component to providing optimal care in the NICU. More research is needed to determine the timing of initiation, duration, and frequency of SSC to optimize the stress-reducing benefits. Future research should include the most fragile infants, who are most likely to benefit from SSC, utilize power analyses to ensure adequate sample sizes, and use sophisticated data collection and analysis techniques to more accurately evaluate the effect of SSC on infants in the NICU.