Prognostic Accuracy of Heart Rate Variability Analysis in Neonatal Encephalopathy: A Systematic Review

Heart Rate and Pulse Oximetry Dynamics in the First Week after Birth in Neonatal Intensive Care Unit Patients and the Risk of Cerebral Palsy

OBJECTIVE

 Infants in the neonatal intensive care unit (NICU) are at high risk of adverse neuromotor outcomes. Atypical patterns of heart rate (HR) and pulse oximetry (SpO2) may serve as biomarkers for risk assessment for cerebral palsy (CP). The purpose of this study was to determine whether atypical HR and SpO2 patterns in NICU patients add to clinical variables predicting later diagnosis of CP.

STUDY DESIGN

 This was a retrospective study including patients admitted to a level IV NICU from 2009 to 2017 with archived cardiorespiratory data in the first 7 days from birth to follow-up at >2 years of age. The mean, standard deviation (SD), skewness, kurtosis and cross-correlation of HR and SpO2 were calculated. Three predictive models were developed using least absolute shrinkage and selection operator regression (clinical, cardiorespiratory and combined model), and their performance for predicting CP was evaluated.

RESULTS

 Seventy infants with CP and 1,733 controls met inclusion criteria for a 3.8% population prevalence. Area under the receiver operating characteristic curve for CP prediction was 0.7524 for the clinical model, 0.7419 for the vital sign model, and 0.7725 for the combined model. Variables included in the combined model were lower maternal age, outborn delivery, lower 5-minute Apgar's score, lower SD of HR, and more negative skewness of HR.

CONCLUSION

 In this study including NICU patients of all gestational ages, HR but not SpO2 patterns added to clinical variables to predict the eventual diagnosis of CP. Identification of risk of CP within the first few days of life could result in improved therapy resource allocation and risk stratification in clinical trials of new therapeutics.

KEY POINTS

· SD and skewness of HR have some added predictive value of later diagnosis of CP.. · SpO2 measures do not add to CP prediction.. · Combining clinical variables with early HR measures may improve the prediction of later CP..

Autonomic Nervous System in Preterm Very Low Birth Weight Neonates with Intraventricular Hemorrhage

OBJECTIVE

 Heart rate variability (HRV) indicates cardiac autonomic nerve activity and is influenced by brain damage during the neonatal period. We aimed to determine whether a correlation exists between the HRV of extremely preterm neonates and neurodevelopmental test scores.

STUDY DESIGN

 Electrocardiogram data of neonates were assessed and HRV patterns in extremely preterm neonates with severe intraventricular hemorrhage (IVH; n = 6) and those with no/mild IVH (n = 28) were compared. We analyzed the relationship between HRV and neurodevelopmental outcomes at 18 months (n = 21) and 3 years (n = 23) in extremely preterm neonates.

RESULTS

 HRV was significantly associated with IVH severity in extremely preterm neonates (p < 0.05). Neonates with severe IVH exhibited increased HR and decreased mean R-to-R interval (NN) compared with neonates with no/mild IVH. HRV parameters significantly decreased in the severe IVH group, but not in the no/mild IVH group, suggesting that both sympathetic and parasympathetic activities decreased in neonates with severe IVH. Additionally, decreased HR and increased NN were significantly related to impaired neurodevelopmental outcomes in the no/mild IVH group at corrected ages of 18 months and 3 years, respectively (all p < 0.05).

CONCLUSION

 HRV was significantly associated with IVH severity and neurodevelopmental outcome in extremely preterm neonates. HRV can distinguish extremely preterm neonates who subsequently had severe IVH from those who had no/low-grade IVH. HRV may identify extremely preterm neonates needing adjuvant neuroprotective interventions. These findings warrant further investigation in a larger population of extremely preterm neonates.

KEY POINTS

· HRV was associated with IVH severity.. · HRV can predict subsequent severe IVH in extremely preterm neonates.. · HRV are predictive of neurodevelopmental outcomes in extremely premature neonates with low-grade IVH..

Infant emotion regulation in the context of stress: Effects of heart rate variability and temperament

Stressful events are inherently emotional. As a result, the ability to regulate emotions is critical in responding effectively to stressors. Differential abilities in the management of stress appear very early in life, compelling a need to better understand factors that may shape the capacity for emotion regulation (ER). Variations in both biologic and behavioural characteristics are thought to influence individual differences in ER development. We sought to determine the differential contributions of temperament and heart rate variability (HRV; an indicator of autonomic nervous system function) to infant resting state emotionality and emotional reactivity in response to a stressor at 6 months of age. Participants included 108 mother-infant dyads. Mothers completed a measure of infant temperament at 6 months postnatal. Mother and infant also participated in a standardized stressor (the Repeated Still Face Paradigm) at that time. Electrocardiographic data were acquired from the infant during a baseline resting state and throughout the stressor. Fast Fourier Transformation was used to analyse the high frequency (HF) domain of HRV, a measure of parasympathetic nervous system activity. Infant ER was measured via standardized coding of emotional distress behaviours from video-records at baseline and throughout the stressor. Severity of mothers' depressive symptoms was included as a covariate in analyses. Results of linear regression indicate that neither temperament nor HRV were associated significantly with an infant's emotional resting state, although a small effect size was found for the relationship between infant negative affectivity and greater emotional distress (β = 0.23, p = 0.08) prior to the stressor. Higher HF-HRV (suggesting parasympathetic dominance) was related to greater emotional distress in response to the stressor (β = 0.34, p = 0.009). This greater emotional reactivity may reflect a more robust capacity to mount an emotional response to the stressor when infants encounter it from a bedrock of parasympathetic activation. Findings may inform eventual markers for assessment of ER in infancy and areas for intervention to enhance infant management of emotions, especially during stressful events.

Heart rate patterns predicting cerebral palsy in preterm infants

BACKGROUND

Heart rate (HR) patterns can inform on central nervous system dysfunction. We previously used highly comparative time series analysis (HCTSA) to identify HR patterns predicting mortality among patients in the neonatal intensive care unit (NICU) and now use this methodology to discover patterns predicting cerebral palsy (CP) in preterm infants.

METHOD

We studied NICU patients <37 weeks' gestation with archived every-2-s HR data throughout the NICU stay and with or without later diagnosis of CP (n = 57 CP and 1119 no CP). We performed HCTSA of >2000 HR metrics and identified 24 metrics analyzed on HR data from two 7-day periods: week 1 and 37 weeks' postmenstrual age (week 1, week 37). Multivariate modeling was used to optimize a parsimonious prediction model.

RESULTS

Week 1 HR metrics with maximum AUC for CP prediction reflected low variability, including "RobustSD" (AUC 0.826; 0.772-0.870). At week 37, high values of a novel HR metric, "LongSD3," the cubed value of the difference in HR values 100 s apart, were added to week 1 HR metrics for CP prediction. A combined birthweight + early and late HR model had AUC 0.853 (0.805-0.892).

CONCLUSIONS

Using HCTSA, we discovered novel HR metrics and created a parsimonious model for CP prediction in preterm NICU patients.

IMPACT

We discovered new heart rate characteristics predicting CP in preterm infants. Using every-2-s HR from two 7-day periods and highly comparative time series analysis, we found a measure of low variability HR week 1 after birth and a pattern of recurrent acceleration in HR at term corrected age that predicted CP. Combined clinical and early and late HR features had AUC 0.853 for CP prediction.

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.

Heart rate variability analysis for the prediction of EEG grade in infants with hypoxic ischaemic encephalopathy within the first 12 h of birth

Background and aims

Heart rate variability (HRV) has previously been assessed as a biomarker for brain injury and prognosis in neonates. The aim of this cohort study was to use HRV to predict the electroencephalography (EEG) grade in neonatal hypoxic-ischaemic encephalopathy (HIE) within the first 12 h.

Methods

We included 120 infants with HIE recruited as part of two European multi-centre studies, with electrocardiography (ECG) and EEG monitoring performed before 12 h of age. HRV features and EEG background were assessed using the earliest 1 h epoch of ECG-EEG monitoring. HRV was expressed in time, frequency and complexity features. EEG background was graded from 0-normal, 1-mild, 2-moderate, 3-major abnormalities to 4-inactive. Clinical parameters known within 6 h of birth were collected (intrapartum complications, foetal distress, gestational age, mode of delivery, gender, birth weight, Apgar at 1 and 5, assisted ventilation at 10 min). Using logistic regression analysis, prediction models for EEG severity were developed for HRV features and clinical parameters, separately and combined. Multivariable model analysis included 101 infants without missing data.

Results

Of 120 infants included, 54 (45%) had normal-mild and 66 (55%) had moderate-severe EEG grade. The performance of HRV model was AUROC 0.837 (95% CI: 0.759-0.914) and clinical model was AUROC 0.836 (95% CI: 0.759-0.914). The HRV and clinical model combined had an AUROC of 0.895 (95% CI: 0.832-0.958). Therapeutic hypothermia and anti-seizure medication did not affect the model performance.

Conclusions

Early HRV and clinical information accurately predicted EEG grade in HIE within the first 12 h of birth. This might be beneficial when EEG monitoring is not available in the early postnatal period and for referral centres who may want some objective information on HIE severity.

Optimal neuromonitoring techniques in neonates with hypoxic ischemic encephalopathy

Neonates with hypoxic ischemic encephalopathy (HIE) are at significant risk for adverse outcomes including death and neurodevelopmental impairment. Neuromonitoring provides critical diagnostic and prognostic information for these infants. Modalities providing continuous monitoring include continuous electroencephalography (cEEG), amplitude-integrated electroencephalography (aEEG), near-infrared spectroscopy (NIRS), and heart rate variability. Serial bedside neuromonitoring techniques include cranial ultrasound and somatic and visual evoked potentials but may be limited by discrete time points of assessment. EEG, aEEG, and NIRS provide distinct and complementary information about cerebral function and oxygen utilization. Integrated use of these neuromonitoring modalities in addition to other potential techniques such as heart rate variability may best predict imaging outcomes and longer-term neurodevelopment. This review examines available bedside neuromonitoring techniques for the neonate with HIE in the context of therapeutic hypothermia.

Early neonatal heart rate variability patterns in different subtypes of perinatal hypoxic-ischemic brain injury

BACKGROUND

This study aims to compare the longitudinal changes in heart rate variability (HRV) during therapeutic hypothermia in neonates with different subtypes of hypoxic-ischemic brain injury.

METHODS

HRV was computed from 1 hour time-epochs q6 hours for the first 48 hours. Primary outcome was brain-injury pattern on MRI at 4(3-5) days. We fitted linear mixed-effect regression models with HRV metric, brain injury subtype and postnatal age.

RESULTS

Among 89 term neonates, 40 neonates had abnormal brain MRI (focal infarct 15 (38%), basal-ganglia predominant 8 (20%), watershed-predominant 5 (13%), and mixed pattern 12 (30%)). There was no significant difference in the HRV metrics between neonates with normal MRI, focal infarcts and basal ganglia pattern. At any given postnatal age, the degree of HRV suppression (HRV measure in the brain-injury subtype group/HRV measure in Normal MRI group) was significant in neonates with watershed pattern (SDNN(0.63, p = 0.08), RMSSD(0.74, p = 0.04)) and mixed pattern injury (SDNN (0.64, p < 0.001), RMSSD (0.75, p = 0.02)). HRV suppression was most profound at the postnatal age of 24-30 h in all brain injury subtypes.

CONCLUSION

Neonates with underlying watershed injury with or without basal-ganglia injury demonstrates significant HRV suppression during first 48 hour of hypothermia therapy.

IMPACT

Our study suggests that suppression of heart rate variability in neonates during therapeutic hypothermia varies according to the pattern of underlying hypoxic-ischemic brain injury. Neonates with watershed predominant pattern and mixed pattern of brain injury have the most severe suppression of heart rate variability measures. Heart rate variability monitoring may provide early insights into the pattern of hypoxic-ischemic brain injury in neonates undergoing therapeutic hypothermia earlier than routine clinical MRI.

Hypothermia and heart rate variability in a healthy newborn piglet model

Decreased heart rate variability (HRV) may be a biomarker of brain injury severity in neonatal hypoxic-ischemic encephalopathy for which therapeutic hypothermia is standard treatment. While therapeutic hypothermia may influence the degree of brain injury; hypothermia may also affect HRV per se and obscure a potential association between HRV and hypoxic-ischemic encephalopathy. Previous results are conflicting. This study aimed to investigate the effect of hypothermia on HRV in healthy, anaesthetised, newborn piglets. Six healthy newborn piglets were anaesthetised. Three piglets were first kept normothermic (38.5-39.0 °C) for 3 h, then exposed to hypothermia (33.5-34.5 °C) for 3 h. Three piglets were first exposed to hypothermia for 3 h, then rewarmed to normothermia for 3 h. Temperature and ECG were recorded continuously. HRV was calculated from the ECG in 5 min epochs and included time domain and frequency domain variables. The HRV variables were compared between hypothermia and normothermia. All assessed HRV variables were higher during hypothermia compared to normothermia. Heart rate was lower during hypothermia compared to normothermia and all HRV variables correlated with heart rate. Hypothermia was associated with an increase in HRV; this could be mediated by bradycardia during hypothermia.

Signal Processing of Heart Rate for Predicting Sepsis in Premature Neonates

The heart rate characteristic (HeRO score) is a figure derived from the analysis of premature neonate's electrocardiogram signals, and can be used to detect infection before the onset of clinical symptoms. The United States and Europe accept this diagnostic technique, but we require more tests to prove its efficacy. This method is not accepted in other developed countries so far. The present study aimed to investigate changes in the heart characteristics of two neonates in Akbar Abadi Hospital in Tehran. Experts chose one newborn as a sepsis case, and the other neonate was healthy. The results were analyzed and compared with previous studies. In this research, a group of five neonates was selected randomly from the neonatal intensive care unit, and cardiac leads were attached to them for recording heart rates. We selected two neonates from the five cases, as a case (proven sepsis) and control, to analyze heart rate variability (HRV). Then, we compared the differences in the heart rate of both neonates. Analysis of HRV of these two neonates showed that the pattern of HRV is compatible with reports from US studies. Considering the results of this study, heart rates and their analysis can provide useful indicators for mathematical modeling before the onset of clinical symptoms in newborns.

Heart rate variability as possible marker of brain damage in neonates with hypoxic ischemic encephalopathy: a systematic review

Heart rate variability (HRV) is currently considered the most valuable non-invasive test to investigate the autonomic nervous system function, based on the fact that fast fluctuations might specifically reflect changes of sympathetic and vagal activity. An association between abnormal values of HRV and brain impairment has been reported in the perinatal period, although data are still fragmentary. Considering such association, HRV has been suggested as a possible marker of brain damage also in case of hypoxic-ischemic encephalopathy following perinatal asphyxia. The aim of the present manuscript was to review systematically the current knowledge about the use of HRV as marker of cerebral injury in neonates suffering from hypoxic-ischemic encephalopathy. Findings reported in this paper were based on qualitative analysis of the reviewed data. Conclusion: A growing body of research supports the use of HRV as non-invasive, bedside tool for the monitoring of hypoxic-ischemic encephalopathy. The currently available data about the role of HRV as prognostic tool in case of hypoxic ischemic encephalopathy are promising but require further validation by future studies. What is Known: • Heart rate variability (HRV) is a non-invasive monitoring technique to assess the autonomic nervous system activity. • A correlation between abnormal HRV and cerebral injury has been reported in the perinatal period, and HRV has been suggested as possible marker of brain damage in case of hypoxic-ischemic encephalopathy. What is New: • HRV might provide precocious information about the entity of brain injury in asphyxiated neonates and be of help to design early, specific, and personalized treatments according to severity. • Further investigations are required to confirm these preliminary data.

Emerging therapies and management for neonatal encephalopathy-controversies and current approaches

Neonatal encephalopathy (NE) continues to have a major impact on newborn survival and neurodevelopmental outcomes worldwide. In high-income settings, therapeutic hypothermia is the only established standard treatment for neonates with moderate-to-severe NE, with compelling evidence that cooling reduces mortality and major neurodevelopmental impairment in survivors. Despite therapeutic hypothermia, a significant proportion of cooled infants continue to suffer long-term disability from brain injury. Innovative therapies offer the possibility of further improving neurodevelopmental outcomes by working synergistically with therapeutic hypothermia to decrease hypoxia-ischemia-induced excitotoxicity, prevent progression to secondary energy failure, and in some cases, promote neuroregeneration in the developing neonatal brain. This review discusses emerging NE therapies currently under investigation, offers insight into controversies surrounding various approaches to clinical care during therapeutic hypothermia, and identifies ongoing knowledge deficits that hinder attainment of optimal outcomes for neonates with NE.

Heart Rate Variability in the Perinatal Period: A Critical and Conceptual Review

Neonatal intensive care units (NICUs) greatly expand the use of technology. There is a need to accurately diagnose discomfort, pain, and complications, such as sepsis, mainly before they occur. While specific treatments are possible, they are often time-consuming, invasive, or painful, with detrimental effects for the development of the infant. In the last 40 years, heart rate variability (HRV) has emerged as a non-invasive measurement to monitor newborns and infants, but it still is underused. Hence, the present paper aims to review the utility of HRV in neonatology and the instruments available to assess it, showing how HRV could be an innovative tool in the years to come. When continuously monitored, HRV could help assess the baby’s overall wellbeing and neurological development to detect stress-/pain-related behaviors or pathological conditions, such as respiratory distress syndrome and hyperbilirubinemia, to address when to perform procedures to reduce the baby’s stress/pain and interventions, such as therapeutic hypothermia, and to avoid severe complications, such as sepsis and necrotizing enterocolitis, thus reducing mortality. Based on literature and previous experiences, the first step to efficiently introduce HRV in the NICUs could consist in a monitoring system that uses photoplethysmography, which is low-cost and non-invasive, and displays one or a few metrics with good clinical utility. However, to fully harness HRV clinical potential and to greatly improve neonatal care, the monitoring systems will have to rely on modern bioinformatics (machine learning and artificial intelligence algorithms), which could easily integrate infant’s HRV metrics, vital signs, and especially past history, thus elaborating models capable to efficiently monitor and predict the infant’s clinical conditions. For this reason, hospitals and institutions will have to establish tight collaborations between the obstetric, neonatal, and pediatric departments: this way, healthcare would truly improve in every stage of the perinatal period (from conception to the first years of life), since information about patients’ health would flow freely among different professionals, and high-quality research could be performed integrating the data recorded in those departments.

Hearables: Feasibility and Validation of In-Ear Electrocardiogram

Out-of-clinic, continuous monitoring of vital signs is envisaged to become the backbone of future e-health. The emerging wrist worn devices have already proven to be a success in the measurement of pulse, however, a susceptibility to artefacts and missing data caused by regular motion in everyday activities, and the inability to continuously acquire the electrocardiogram call into question the utility of this technology in future e-Health. With this in mind, the head, and in particular the ear canals, have been investigated as possible locations for wearable devices. The ears offer a stable position relative to the vital signs during everyday activities, such as sitting, walking, running and sleeping, as well as being a practical and widely accepted base for wearable accessories. This all suggests that the ear canals are a most natural location for physiological sensing in the community. This work addresses the feasibility of recording the ECG from the ear canals, from a one-fits-all, user-friendly device. For rigour and clarity, we quantitatively compare the timings of the identified P-, QRS-, and T-waves within Ear-ECG and standard arm-ECG. Finally, to depict a future e-Health scenario for the Ear-ECG technology, a case study with an abnormal heart condition, the ventricular bigeminy, is presented. A comprehensive study over ten subjects demonstrates conclusively the possibility of in-ear cardiac monitoring in normal daily life.

Getting an Early Start in Understanding Perinatal Asphyxia Impact on the Cardiovascular System

Perinatal asphyxia (PA) is a burdening pathology with high short-term mortality and severe long-term consequences. Its incidence, reaching as high as 10 cases per 1000 live births in the less developed countries, prompts the need for better awareness and prevention of cases at risk, together with management by easily applicable protocols. PA acts first and foremost on the nervous tissue, but also on the heart, by hypoxia and subsequent ischemia-reperfusion injury. Myocardial development at birth is still incomplete and cannot adequately respond to this aggression. Cardiac dysfunction, including low ventricular output, bradycardia, and pulmonary hypertension, complicates the already compromised circulatory status of the newborn with PA. Multiorgan and especially cardiovascular failure seem to play a crucial role in the secondary phase of hypoxic-ischemic encephalopathy (HIE) and its high mortality rate. Hypothermia is an acceptable solution for HIE, but there is a fragile equilibrium between therapeutic gain and cardiovascular instability. A profound understanding of the underlying mechanisms of the nervous and cardiovascular systems and a close collaboration between the bench and bedside specialists in these domains is compulsory. More resources need to be directed toward the prevention of PA and the consecutive decrease of cardiovascular dysfunction. Not much can be done in case of an unexpected acute event that produces PA, where recognition and prompt delivery are the key factors for a positive clinical result. However, the situation is different for high-risk pregnancies or circumstances that make the fetus more vulnerable to asphyxia. Improving the outcome in these cases is possible through careful monitoring, identifying the high-risk pregnancies, and the implementation of novel prenatal strategies. Also, apart from adequately supporting the heart through the acute episode, there is a need for protocols for long-term cardiovascular follow-up. This will increase our recognition of any lasting myocardial damage and will enhance our perspective on the real impact of PA. The goal of this article is to review data on the cardiovascular consequences of PA, in the context of an immature cardiovascular system, discuss the potential contribution of cardiovascular impairment on short and long-term outcomes, and propose further directions of research in this field.

Early Postnatal Heart Rate Variability in Healthy Newborn Infants

Background

Despite the increasing interest in fetal and neonatal heart rate variability (HRV) analysis and its potential use as a tool for early disease stratification, no studies have previously described the normal trends of HRV in healthy babies during the first hours of postnatal life.

Methods

We prospectively recruited 150 healthy babies from the postnatal ward and continuously recorded their electrocardiogram during the first 24 h after birth. Babies were included if born in good condition and stayed with their mother. Babies requiring any medication or treatment were excluded. Five-minute segments of the electrocardiogram (non-overlapping time-windows) with more than 90% consecutive good quality beats were included in the calculation of hourly medians and interquartile ranges to describe HRV trends over the first 24 h. We used multilevel mixed effects regression with auto-regressive covariance structure for all repeated measures analysis and t-tests to compare group differences. Non-normally distributed variables were log-transformed.

Results

Nine out of 16 HRV metrics (including heart rate) changed significantly over the 24 h [Heart rate p < 0.01; Standard deviation of the NN intervals p = 0.01; Standard deviation of the Poincaré plot lengthwise p < 0.01; Cardiac sympathetic index (CSI) p < 0.01; Normalized high frequency power p = 0.03; Normalized low frequency power p < 0.01; Total power p < 0.01; HRV index p = 0.01; Parseval index p = 0.03], adjusted for relevant clinical variables. We observed an increase in several HRV metrics during the first 6 h followed by a gradual normalization by approximately 12 h of age. Between 6 and 12 h of age, only heart rate and the normalized low frequency power changed significantly, while between 12 and 18 h no metric, other than heart rate, changed significantly. Analysis with multilevel mixed effects regression analysis (multivariable) revealed that gestational age, reduced fetal movements, cardiotocography and maternal chronic or pregnancy induced illness were significant predictors of several HRV metrics.

Conclusion

Heart rate variability changes significantly during the first day of life, particularly during the first 6 h. The significant correlations between HRV and clinical risk variables support the hypothesis that HRV is a good indicator of overall wellbeing of a baby and is sensitive to detect birth-related stress and monitor its resolution over time.

Severity of hypoxic ischemic encephalopathy and heart rate variability in neonates: a systematic review

BACKGROUND

Several studies have investigated heart rate variability (HRV) as a biomarker for acute brain injury in hypoxic ischemic encephalopathy (HIE). However, the current evidence is heterogeneous and needs further reviewing to direct future studies. We aimed to systematically review whether HIE severity is associated with HRV.

METHODS

This systematic review was conducted according to the preferred reporting items for systematic review and meta analyses (PRISMA). We included studies comparing neonates with severe or moderate HIE with neonates with mild or no HIE with respect to different HRV measures within 7 days of birth. Article selection and quality assessment was independently performed by two reviewers. Risk of bias and strength of evidence was evaluated by the Newcastle-Ottawa scale (NOS) and the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

We screened 1187 studies. From these, four observational studies with 248 neonates were included. For all HRV measures, the strength of evidence was very low. Neonates with severe or moderate HIE showed a reduction in most HRV measures compared to neonates with mild or no HIE with a greater reduction in those with severe HIE.

CONCLUSIONS

Moderate and severe HIE was associated with a reduction in most HRV measures. Accordingly, HRV is a potential biomarker for HIE severity during the first week of life. However, the uncertainty calls for more studies.

[Heart rate variability in neonates with non-benign tachyarrhythmia]

OBJECTIVE

To study heart rate variability (HRV) in neonates with non-benign tachyarrhythmia (NNTA) and the role of automatic nervous system (ANS) in NNTA.

METHODS

The neonates who were admitted to the Department of Neonatology, the Second Xiangya Hospital of Central South University, from January 2010 to June 2018 and were diagnosed with NNTA were enrolled as the NNTA group, and the neonates with sinus rhythm or accidental premature beats on ambulatory electrocardiography were enrolled as the control group. Each group was further subdivided into preterm and term subgroups. A retrospective analysis was performed for their clinical data.

RESULTS

A total of 27 NNTA neonates were enrolled, accounting for 0.28% (27/9 632) of all neonates hospitalized during the same period of time, and 53 neonates were enrolled in the control group. Compared with the preterm and term control subgroups, the preterm NNTA and term NNTA subgroups had a significant increase in the standard deviation of average RR interval (P<0.05).

CONCLUSIONS

Immature and unbalanced ANS function may play an important role in the development and progression of NNTA.