Heart Period Variability of Intubated Very-Low-Birth-Weight Infants During Incubator Care and Maternal Holding

Monitoring lung and cerebral oxygenation using near-infrared spectroscopy in preterm infants during kangaroo mother care

Lung function has never been assessed during kangaroo mother care (KMC) in preterm infants. We measured lung (rSO2L) and cerebral (rSO2C) oxygenation by near-infrared spectroscopy (NIRS) in infants born at less than 32 weeks of gestation or weighing ≤ 1500 g during KMC. rSO2L, rSO2C, and pulmonary (FOEL) and cerebral (FOEC) tissue oxygen extraction fraction were measured in 20 preterm infants before, during, and after a 2-h period of KMC at a mean postnatal age of 36 ± 21 days of life. We found that rSO2L, rSO2C, FOEL, and FOEC did not change in our patients. After 120 min of KMC, rSO2L was lower (71.3 ± 1.4 vs. 76.7 ± 4.6%; P = 0.012) in infants with BPD (n = 6; 30%) than in infants without BPD (n = 14 = 60%), while FOEL was higher (0.26 ± 0.02 vs. 0.20 ± 0.05; P = 0.012).Conclusion: Cerebral and lung oxygenation did not change in preterm infants during KMC. A transient decrease in lung oxygenation was offset by the increase in oxygen extraction, but these changes were clinically insignificant. These results confirm the safety of KMC in preterm infants who are in stable clinical conditions. What is Known • Kangaroo mother care (KMC) is widely used to improve the care of preterm newborns since it improves their outcome. • KMC is safe as patients' vital parameters, are not negatively affected, but lung function has never been directly assessed. What is New • Cerebral and lung oxygenation measured by near-infrared spectroscopy did not change during KMC. • A transient decrease in lung oxygenation compensated for by the increase in oxygen extraction occurred only in infants with BPD, but these changes were clinically insignificant.

Impact of Kangaroo mother care on autonomic cardiovascular control in foetal-growth-restricted preterm infants

BACKGROUND

Kangaroo mother care (KMC) is WHO-recommended for low-birth-weight infants, yet its impact on autonomic cardiovascular control in preterm foetal growth-restricted (FGR) infants remains unclear. We hypothesised that KMC would promote autonomic cardiovascular control, benefiting preterm FGR infants with reduced baseline autonomic function compared to appropriate for gestational age (AGA) infants.

METHODS

Autonomic control was assessed via heart rate variability (HRV) in low frequency (LF) and high frequency (HF) bands using spectral analysis. Preterm FGR (n = 22) and AGA (n = 20) infants were assessed for 30-min before and 60-min during KMC. Comparisons were made between FGR and AGA infants; and between infants with baseline HRV below and above median.

RESULTS

Overall, no significant HRV changes were observed during KMC for FGR or AGA infants compared to baselines. Infants with low baseline HRV LF showed increased HRV during KMC (p = 0.02 and 0.05 for the entire group and FGR group, respectively). This effect was absent in the AGA group regardless of baseline HRV. Infants with high baseline HRV had decreased HRV during KMC.

CONCLUSIONS

Infants with low baseline HRV, suggesting reduced autonomic control, are more likely to benefit from KMC with increased HRV. Further, this effect is stronger in FGR than AGA infants.

IMPACT

Kangaroo mother care (KMC) is WHO-recommended for low-birth-weight infants, yet its impact on autonomic cardiovascular control in preterm foetal growth-restricted (FGR) infants is unclear. Preterm infants with low baseline heart rate variability (HRV) are more likely to benefit from KMC and increase their HRV suggesting improved autonomic control. This effect is stronger in preterm FGR infants than those with appropriate growth for age.

Pilot study shows skin-to-skin care with parents improves heart rate variability in preterm infants in the neonatal intensive care unit

Background

Skin-to-skin care in the newborn intensive care unit typically lasts for short periods of time and enhances breastfeeding, attachment, and parental self-esteem. Heart rate variability (HRV) increases with gestational age and is a measure of maturation of parasympathetic vs. sympathetic autonomic nervous system activity. HRV measurements may be useful in capturing changes in autonomic regulation in response to skin-to-skin care.

Objective

To analyze the effects of skin-to-skin care on HRV in preterm infants receiving respiratory support. We hypothesized that skin-to-skin care would result in a more mature pattern of parasympathetic activity.

Methods

In this prospective crossover study, infants <30 weeks' gestation and 1-6 weeks postnatal age had HRV recorded for 30 min before, during, and after skin-to-skin care sessions. HRV characteristics analyzed included the standard deviation of the normal-to-normal interval (SDNN), the root mean squared of successive differences of normal-to-normal intervals (RMSSD), and the standard deviation of decelerations (SDDec).

Results

10 infants between 25 5/7-29 6/7 weeks gestational age and 7-41 days postnatal age completed 22 sessions while receiving respiratory support (positive pressure ventilation or nasal cannula oxygen). Two measures of HRV (SDNN and RMSSD) were significantly decreased by the end of the skin-to-skin sessions, compared to pre-session values. SDNN decreased from a median of 10.44 ms before the session to 6.70 ms after being placed back in bed (p < 0.05), with RMSSD decreasing from a median of 6.80 ms before the session to 4.32 ms while being held at the end of 30 min (p < 0.05).

Discussion

Skin-to-skin care with a parent resulted in a more mature autonomic nervous system pattern in preterm infants receiving respiratory support, suggesting physiologic benefit for the infant. No adverse events were seen during any session.

NICU sensory experiences associated with positive outcomes: an integrative review of evidence from 2015-2020

To inform changes to the Supporting and Enhancing NICU Sensory Experiences (SENSE) program, studies investigating sensory-based interventions in the NICU with preterm infants born ≤32 weeks were identified. Studies published between October 2015 to December 2020, and with outcomes related to infant development or parent well-being, were included in this integrative review. The systematic search used databases including MEDLINE, Cumulative Index to Nursing and Allied Health Literature, the Cochrane Library, and Google Scholar. Fifty-seven articles (15 tactile, 9 auditory, 5 visual, 1 gustatory/olfactory, 5 kinesthetic, and 22 multimodal) were identified. The majority of the sensory interventions that were identified within the articles were reported in a previous integrative review (1995-2015) and already included in the SENSE program. New evidence has led to refinements of the SENSE program, notably the addition of position changes across postmenstrual age (PMA) and visual tracking starting at 34 weeks PMA.

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.

Technical Innovation for Visual Assessment of Preterm Newborns in a Neonatal Intensive Care Unit: Exploratory Study

Objective

The present study is aimed at assessing heart rate variability (HRV) and its correlation with visual acuity (VA) assessment of preterm newborns (PTNB) in neonatal intensive care units.

Method

Cross-sectional study analyzing HRV during assessment of VA with the aid of a Polar RS800CX heart rate monitor (Polar Electro Oy, Finland). HRV was analyzed according to time and frequency domains and the chaos domain used the autocorrelation coefficient and entropy. The sample consisted of hospitalized PTNB, and static analysis included simple regression diagnosis.

Results

A total of 14 PTNB were included in the sample. VA varied between 0.23 and 1.60 cpd, and only five PTNB obtained below-expected values for age. Statistical analysis demonstrated a negative correlation between VA and time domain (SDDN and SD2) and a positive correlation between frequency domain (heart rate and hertz), but in simple linear regression analysis, these variables did not influence VA.

Conclusion

The results of the study demonstrate that visual acuity was inversely correlated with SDNN and SD2 and during stimulation, showing that the higher the visual performance, the lower the autonomic modulation response.

Kangaroo Mother Care in Hospitalized Low Birth-Weight Infants on Respiratory Support: A Feasibility and Safety Study

BACKGROUND

Low birth-weight (LBW) infants on respiratory support are often deprived of kangaroo mother care (KMC) due to fear of instability. Data on safety of KMC in these infants are lacking.

PRIMARY OBJECTIVE

To determine the feasibility of KMC in LBW infants on continuous positive airway pressure or synchronized intermittent mandatory ventilation.

SECONDARY OBJECTIVES

To compare vital signs (heart rate [HR], respiration, temperature, and SpO2) and ventilatory parameters (FIO2, peak inspiratory pressure [PIP], and positive end-expiratory pressure [PEEP]) before, during, and after KMC, and assess the mother's perception of the KMC intervention.

METHODS

LBW infants stable on respiratory support were given KMC for 1 hour. Vital signs and ventilator parameters were recorded before, every 15 minutes during and after KMC. Feasibility was defined as continuation of KMC for 1 hour without interruption, with stable vital signs (HR > 100/min, SpO2 > 90%, and temperature 36.5°C-37.5°C) and ventilator parameters (no change in PIP, PEEP, or increase in FIO2 not more than 0.1) without tube dislodgement.

RESULTS

Twenty LBW infants with a mean birth weight of 1390 ± 484 g were included. All infants completed 1-hour duration of KMC without interruption. No significant changes in temperature, respiratory rates, or saturations were noted. The HR and FIO2 were marginally higher during KMC than before or after (HR before 147.3 ± 11.5, during 150.8 ± 11, and after 147.3 ± 11.1, P = .04; FIO2 before 30.6 ± 8.1, during 31.8 ± 8.1, and after 30.7 ± 8.0, P = .034). No accidental extubation or dislodgement of lines occurred. Most mothers were happy.

IMPLICATIONS FOR PRACTICE

The vital signs were stable during KMC. KMC is feasible in infants receiving respiratory support.

IMPLICATIONS FOR RESEARCH

Effectiveness of early initiation and prolonged duration of KMC.

Enhancing sensory experiences for very preterm infants in the NICU: an integrative review

OBJECTIVE

Very preterm infants hospitalized in the neonatal intensive care unit (NICU) experience alterations in sensory experiences. Defining types, timing and frequency of sensory-based interventions that optimize outcomes can inform environmental modifications. The objective of this study was to conduct an integrative review on sensory-based interventions used with very preterm infants in the NICU to improve infant and parent outcomes.

STUDY DESIGN

The data sources include MEDLINE, CINAHL, Cochrane Library and Google Scholar. Studies were identified that used sensory-based interventions in the NICU with preterm infants born ⩽32 weeks gestation, were published in a peer-reviewed journal between 1995 and 2015, and measured outcomes related to infant and parent outcomes. Studies were extracted from electronic databases and hand-searched from identified reference lists.

RESULTS

Eighty-eight articles were identified (31 tactile, 12 auditory, 3 visual, 2 kinesthetic, 2 gustatory/olfactory and 37 multimodal). There was evidence to support the use of kangaroo care, music and language exposure, and multimodal interventions starting at 25 to 28 weeks postmenstrual age. These interventions were related to better infant development and lower maternal stress, but not all findings were consistent. Limitations included lack of consistent outcome measures, study quality and gaps in the literature.

CONCLUSIONS

Most research identified interventions that were done for short periods of time. It is unclear what the potential is for improving outcomes if positive sensory exposures occur consistently throughout NICU hospitalization. Until more research defines appropriate sensory-based interventions to use with infants born very preterm in the NICU, information from this review can be combined with expert opinion and parent/family values to determine best practice.

Features of Heart Rate Variability Capture Regulatory Changes During Kangaroo Care in Preterm Infants

OBJECTIVE

To determine whether heart rate variability (HRV) can serve as a surrogate measure to track regulatory changes during kangaroo care, a period of parental coregulation distinct from regulation within the incubator.

STUDY DESIGN

Nurses annotated the starting and ending times of kangaroo care for 3 months. The pre-kangaroo care, during-kangaroo care, and post-kangaroo care data were retrieved in infants with at least 10 accurately annotated kangaroo care sessions. Eight HRV features (5 in the time domain and 3 in the frequency domain) were used to visually and statistically compare the pre-kangaroo care and during-kangaroo care periods. Two of these features, capturing the percentage of heart rate decelerations and the extent of heart rate decelerations, were newly developed for preterm infants.

RESULTS

A total of 191 kangaroo care sessions were investigated in 11 preterm infants. Despite clinically irrelevant changes in vital signs, 6 of the 8 HRV features (SD of normal-to-normal intervals, root mean square of the SD, percentage of consecutive normal-to-normal intervals that differ by >50 ms, SD of heart rate decelerations, high-frequency power, and low-frequency/high-frequency ratio) showed a visible and statistically significant difference (P <.01) between stable periods of kangaroo care and pre-kangaroo care. HRV was reduced during kangaroo care owing to a decrease in the extent of transient heart rate decelerations.

CONCLUSION

HRV-based features may be clinically useful for capturing the dynamic changes in autonomic regulation in response to kangaroo care and other changes in environment and state.

Heart rate variability of transported critically ill neonates

Determining heart rate variability (HRV) in infants is a useful measure of physiological stability. Transport of ill neonates imposes a measurable degree of stress. A prospective observational study on 58 critically ill neonates, transported to an intensive care unit (ICU) was performed. HRV during the 24-h period before, during and after transport, heart rate (HR), mean arterial pressure and transport risk index of physiologic stability (TRIPS) score were observed. The median HRV total power value of 40.80 ms(2) was set as the cutoff value, and neonates with values below this were designated as the low-HRV group (l-HRV; n=29), and those above this as the high-HRV group (h-HRV; n=29). The h-HRV group had a significantly lower HR at retrieval and 1 h after admission and a significant 2- and 4-day shorter duration of mechanical ventilation and ICU treatment compared to the l-HRV group. Spearman's correlations between total power and duration of mechanical ventilation (ρ=-0.346; P<0.01) and ICU treatment (ρ=-0.346; P<0.01) were significant. Transported neonates were also tested for differences in HRV and other physiological and demographic parameters between the transport mode and time. No differences were found, except that the nighttime ambulance group had a statistically higher HRV compared to the daytime ambulance group.

CONCLUSION

Higher HRV of group of neonates, who did not differ in illness severity TRIPS score from the lower HRV group, is associated with a faster and significant decrease in HR after transport and a 2- and 4-day shorter duration of mechanical ventilation and ICU treatment.

Pain assessment and measurement in neonates: an updated review

Pain assessment and measurement are the cornerstones of pain management. Pain assessment connotes a comprehensive multidimensional description. Conversely, pain measurement provides a numeric quantitative description of each factor illustrating pain qualities. Pain scales provide a composite score used to guide practice and research. The type of infant pain instrument chosen is a significant factor in guiding pain management practice. The purpose of this review was to summarize current infant pain measures by introducing a conceptual framework for pain measurement. Although more than 40 infant pain instruments exist, many were devised solely for research purposes; several of the newly developed instruments largely overlap with existing instruments. Integration of pain management into daily practice remains problematic. Understanding how each instrument measures infant pain allows clinicians to make better decisions about what instrument to use with which infant and in what circumstances. In addition, novel new measurement techniques need further testing.

The effect of massage on heart rate variability in preterm infants

OBJECTIVE

To test the hypothesis that massage would improve autonomic nervous system (ANS) function as measured by heart rate variability (HRV) in preterm infants.

STUDY DESIGN

Medically stable, 29- to 32-week preterm infants (17 massage, 20 control) were enrolled in a masked, randomized longitudinal study. Licensed massage therapists provided the massage or control condition twice a day for 4 weeks. Weekly HRV, a measure of ANS development and function, was analyzed using SPSS generalized estimating equations.

RESULTS

Infant characteristics were similar between groups. HRV improved in massaged infants but not in the control infants (P<0.05). Massaged males had a greater improvement in HRV than females (P<0.05). HRV in massaged infants was on a trajectory comparable to term-born infants by study completion.

CONCLUSION

Massage-improved HRV in a homogeneous sample of hospitalized, medically stable, preterm male infants and may improve infant response to exogenous stressors. We speculate that massage improves ANS function in these infants.

Safety of Kangaroo Mother Care in intubated neonates under 1500 g

Kangaroo Mother Care (KMC) has been used as a technique to promote mother-child bonding. It has been discussed of its use for preterm under mechanical ventilation. The objective of this study is to assess the vital signs of preterm infants with a birth weight lower than 1500 g who are under intubation and hemodynamically stable in KMC. Forty-three preterm infants with a mean gestational age at birth of 29.1 ± 1.6 weeks and a mean birth weight of 1.1334 ± 2318 g. The preterm infants were longitudinally assessed for 90 min (15 min before, 60 min in KMC and 15 min after). These periods were compared, and the dependent variables heart rate, oxygen saturation (SpO(2)), axilary temperature and mean arterial blood pressure were statistically significant (p < 0.05). Clinically, however, the results were not significantly different. The results show that KMC is a safe method under the study conditions presented here.

Kangaroo Care modifies preterm infant heart rate variability in response to heel stick pain: pilot study

BACKGROUND

Heel stick is the most common painful procedure for preterm infants in neonatal intensive care units. Resultant pain causes adverse physiological effects in major organ systems. Kangaroo Care (KC), involving mother-infant skin-to-skin contact is a promising analgesic for infant pain; however, the effect of KC on the autonomic nervous system's response to pain is unknown.

AIM

To determine if KC results in improved balance in autonomic responses to heel stick pain than the standard method where infants remain in an incubator care (IC) for the heel stick.

STUDY DESIGN

A randomized cross-over trial.

SUBJECTS

Fourteen preterm infants, 30-32 weeks gestational age and less than 9 days postnatal age.

OUTCOME MEASURES

Infant behavioral state, heart rate, heart rate variability (HRV) indices including low frequency (LF) and high frequency (HF) power, and the LF/HF ratio measured over Baseline, Heel Warming, Heel Stick, and Recovery periods in KC and IC conditions.

RESULTS

HRV differences between KC and IC were that LF was higher in KC at Baseline (p<.01) and at Heel Stick (p<.001), and HF was higher in KC at Baseline than in the IC condition (p<.05). The LF/HF ratio had less fluctuation across the periods in KC than in IC condition and was significantly lower during Recovery in KC than in IC (p<.001).

CONCLUSIONS

Infants experienced better balance in response in KC than IC condition as shown by more autonomic stability during heel stick. KC may be helpful in mediating physiologic response to painful procedures in preterm infants.

Coregulation in Salivary Cortisol During Maternal Holding of Premature Infants

Purpose: The purpose of this study was to examine coregulation between mothers and preterm infants in hypothalamic-pituitary-adrenocortical (HPA) system activity, as indicated by salivary cortisol levels, while mothers held their infants. The research questions were (a) does mother—infant coregulation in HPA activity occur during holding? and (b) if mother— infant coregulation in HPA activity exists during holding, do type of holding, antenatal steroids, sound level, and maternal touch influence this coregulation? Sample: The sample consisted of 20 mother— infant dyads with infants at a mean postconceptional age of 34.7 weeks (+0.7) and average postnatal age of 15 days (+9) at the time of cortisol sampling. Design: The design was exploratory using convenience sampling. Maternal and infant cortisol levels were obtained at Time 1 (baseline) and Time 2 (end of holding); at each time, the absolute differences in levels between mother and infant were determined. Coregulation was operationalized as less difference between maternal-infant cortisol levels immediately after holding (Time 2) as compared to before holding (Time 1). Results: The two variables with the highest correlation with the Time 1/Time 2 difference score included antenatal steroids and ambient sound level, which were entered into a linear regression equation as predictor variables. A coregulatory relationship in cortisol levels existed between mothers and infants during holding, which was moderated by sound levels. Nurses in the neonatal intensive care unit (NICU) can facilitate the mother—infant relationship, as reflected in coregulatory measures, by promoting a quiet environment, particularly around mothers who are holding their infants.

Cerebral oxygenation responses during kangaroo care in low birth weight infants

Background

Kangaroo care (KC) has been widely using to improve the care of low birth weight infants. However, very little is known about cerebral hemodynamics responses in low birth weight infants during KC intervention. The objective of this study was to elucidate the response of cerebral hemodynamics during KC in low birth weight infants.

Methods

Near infrared spectroscopy measured regional cerebral oxygenation (rSO₂), heart rate (HR), respiration rate (RR) measured by electrocardiogram, and percentages of oxygen saturation (SpO₂) measured by pulse oxymetry was monitored in 16 preterm infants (< 1600 g) in three sessions: before, during, and after KC. Using power spectral analysis, total power (TP), low-frequency (LF, 0.02–0.20 Hz) and high-frequency (HF, 0.20–0.50 Hz) bands, the ratio of LF/HF were calculated and normalized as %LF or %HF = LF or HF/TP × 100 (%).

Results

Significant differences were not observed in the mean rSO₂, HR, and SpO₂ throughout sessions; however, the TP of these parameters was significantly decreased during KC and increased after KC (p < 0.001). The %LF of LrSO₂ and RrSO₂ was decreased during KC (p < 0.05) with decreased %HF in RrSO₂ (p < 0.05). The %LF of HR was significantly increased during KC while %HF was decreased (p < 0.05). Mean and TP of RR was increased during KC (p < 0.01 respectively) with the increase of quiet sleep state (p < 0.05) and decreased after KC (p < 0.01). The %LF of RR was increased after KC (p < 0.05) with decreased %HF (p < 0.05); however, significant changes were not observed during KC.

Conclusion

KC intervention appears to have influence on cerebral hemodynamics as well as cardiorespiratory parameters. The results of rSO₂ and HR might be associated with quiet sleep states. The results of this study may indicate the contribution of KC intervention to the activation of central nervous system and brain function. Further study is needed to determine the underlying physiology responsible for these differences.

Heart rate and leukocytes after air and ground transportation in artificially ventilated neonates: a prospective observational study

OBJECTIVE

To evaluate the effect of interhospital air and ground transportation of artificially ventilated neonates on heart rate and peripheral blood leukocyte counts.

DESIGN

Prospective, observational study.

SETTING

Level III multidisciplinary Neonatal and Pediatric Intensive Care Unit.

PATIENTS

Fifty-eight near-term artificially ventilated transported neonates between May 2006 and April 2007.

INTERVENTIONS

Day-helicopter, day- and night-ground transportation.

MEASUREMENTS AND RESULTS

Heart rate at retrieval, on admission to the ICU and 1 h later, and peripheral blood leukocyte counts on admission and 1 d later were compared. Fifteen neonates were transported by helicopter during the daytime (D-HEL), 20 by daytime ground and 23 by nighttime ground transportation (D-GROUND, N-GROUND). No differences in delivery mode, birth weight, gestational age, gender, primary diagnoses for transportation, response time and duration of transportation were found between the groups. Similarly, no differences in pH, pCO(2), blood pressure and skin temperature at retrieval and on admission to the ICU were found between the three groups. The mean heart rate at retrieval did not differ significantly, while on arrival in the ICU and 1 h later the D-GROUND group of patients showed a significantly higher mean heart rate compared to the D-HEL and N-GROUND groups. Moreover, leukocyte counts on arrival in the ICU showed significantly higher leukocyte counts in the D-GROUND group of patients compared to the D-HEL group of patients.

CONCLUSIONS

These results demonstrate that there is an association between daytime ground transportation and higher heart rate and peripheral blood leukocytes.

Longitudinal assessment of heart rate variability in very low birth weight infants during their NICU stay

BACKGROUND

Maturation of the autonomic nervous system has not been studied in high-risk very low birth weight (VLBW) infants in the first few weeks of life.

AIM

To characterize developmental changes in autonomic nervous system activity of high-risk VLBW infants from 23 to 38 weeks post-menstrual age by measuring heart rate variability (HRV).

STUDY DESIGN AND SUBJECTS

In this prospective cohort study 38 infants admitted to Children's Memorial Hermann Hospital NICU were longitudinally followed weekly or biweekly. Heart period data were recorded while infants were resting in active sleep.

OUTCOME MEASURES

Growth of spectral power of HRV in low-frequency (0.05-0.25 Hz) and high-frequency (0.25-1.00 Hz) bands was modeled with linear mixed-effects models. The high-frequency power provides a measure of respiratory sinus arrhythmia (RSA).

RESULTS

Low-frequency power increases with post-menstrual age, and intubated infants have lower HRV. The increase in low-frequency power is faster (0.50+/-0.12 dB/week) than the increase in RSA (0.17+/-0.09 dB/week).

CONCLUSION

This longitudinal data exhibits developmental maturation of the RSA and of the low-frequency power of HRV in high-risk VLBW infants.

Heart rate variability responses of a preterm infant to kangaroo care

OBJECTIVE

To examine the effect of kangaroo care on heart rate variability in a healthy preterm infant.

DESIGN

Case study.

SETTING

Private room on a postpartum unit.

PARTICIPANT

A mother-preterm infant dyad.

INTERVENTION

Kangaroo (skin-to-skin) care.

MAIN OUTCOME MEASURE

Heart rate variability, a noninvasive measurement of the sympathetic and parasympathetic components of the autonomic nervous system's influence on heart rate.

RESULTS

Heart rate variability, especially the parasympathetic component, was high when the infant was fussy in the open crib, indicating increased autonomic nervous system activity. With kangaroo care, the infant fell asleep, and both sympathetic and parasympathetic components of heart rate variability decreased.

CONCLUSIONS

The wide fluctuations in the parasympathetic component of heart rate variability suggest immaturity of the sympathovagal response. Overall, kangaroo care produced changes in heart rate variability that illustrate decreasing stress.

Holding the very low birth weight infant: skin-to-skin techniques

Skin-to-skin holding has been reported as a valuable intervention for preterm infants for over a decade. However, many neonatal intensive care units are not practicing this therapy and cite lack of protocols and techniques as a barrier. This article describes in detail the nursing considerations and techniques involved to successfully implement skin-to-skin holding for very low birth weight, technology-dependent infants. NICU protocols can be derived from this article.