Trends and predictors of in-hospital mortality among babies with hypoxic ischaemic encephalopathy at a tertiary hospital in Nigeria: A retrospective cohort study

A scoping review and modelling of predictors of an abnormal Thompson score in term neonates in low-resource settings

Clinical risk scores, such as Thompson score, are useful alternatives to identify neonatal encephalopathy in low-resource settings where adequate training and equipment are often unavailable. An understanding of the clinical predictors of abnormally high Thompson score values would be beneficial to identify term neonates with suspected neonatal encephalopathy. A scoping review was conducted to identify a set of a priori neonatal and maternal variables associated with neonatal encephalopathy. Next, a prospective study of all term neonates admitted to Sally Mugabe Central Hospital in Zimbabwe between October 2020 and December 2022 was conducted to develop a predictive statistical model of abnormal (> 10) Thompson score. In total 45 articles were identified from searching Medline, Scopus and Web of Science and 10 articles were selected. Five studies were conducted in countries in Asia and five in Africa. Of 6,054 neonates who met the inclusion criteria, 4.06% (n = 246) had an abnormal Thompson score at admission with a case fatality rate of 589 per 1000 admissions. Among these neonates, 90.65% (n = 223) had a low Apgar score (p < 0.001). 40 candidate predictors were identified, of which 20 predictors were selected as the most important. Six risk factors were predictive of neonates at risk of abnormal Thompson score, including low neonatal heart rate (aOR = 0.97), temperature lower than 36.5 °C (aOR = 2.24), head swelling (aOR = 2.19), other maternal risk factors of sepsis excluding offensive liquor and premature rupture of membranes (aOR = 1.97), meconium-stained umbilicus (aOR = 1.79), and not crying at birth (aOR = 2.58). These identified risk factors should be prioritised before conducting a Thompson score assessment in resource-poor settings, and local clinical guidelines should incorporate these into the clinical management of at-risk neonates.

Sedation and Pain Management in Neonates Undergoing Therapeutic Hypothermia for Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a common cause of significant neonatal morbidity and mortality. The stronghold of the treatment for moderate-to-severe HIE is therapeutic hypothermia (TH) which provides a neuroprotective effect. However, it also is associated with pain and stress. Moreover, neonates with HIE are subjected to a significant number of painful procedures. Untreated pain during the early neonatal period may entail future challenges such as impaired brain growth and development as well as impaired pain sensitivity later in life. Hereby, the provision of adequate sedation and alleviation of pain and discomfort is essential. There are currently no universally accepted guidelines for sedation and pain management for this patient population. In this review, we highlight non-pharmacologic and pharmacologic methods currently in use to provide comfort and sedation to patients with HIE undergoing TH.

Survival Status and Predictors of Mortality Among Asphyxiated Neonates Admitted to Jimma University Medical Center, Southwest Ethiopia: A Retrospective Cohort Study

Background and Aims

Perinatal asphyxia is the second leading cause of neonatal mortality in sub-Saharan African countries, including Ethiopia. This study aimed to assess survival status and predictors of mortality among neonates admitted to Jimma University Medical Center with perinatal asphyxia.

Methods

A retrospective cohort study was conducted on 373 asphyxiated neonates admitted to Jimma University Medical Center from April 12, 2019, to May 5, 2022. Data were collected from May 18 to June 3, 2022, entered into Epidata version 3.1, and analyzed using R software version 4.2.1. On univariate Cox regression, variables with a p < 0.25 were selected for the final model. Multivariate Cox regression was used to identify significant predictors of mortality among asphyxiated neonates at a 0.05 level of significance and a corresponding 95% confidence interval of the adjusted hazard ratio.

Results

The median survival time of the participants was 20 (95% CI: 18-23) days. During 2888 days of total person-time at risk, a 29.09 (95% CI: 23.20-36.01) per 1000 person-days incidence rate of neonatal mortality was identified. The significant predictors of mortality were stage III Hypoxic ischemic encephalopathy (AHR: 3.46, 95% CI: 1.55-7.70), acute kidney injury (AHR: 2.82, 95% CI: 1.28-6.23), and stress ulcers (AHR: 2.24, 95% CI: 1.26-3.97).

Conclusion

The incidence of mortality was relatively high among the study participants. Stage III Hypoxic ischemic encephalopathy, acute kidney injury, and stress ulcers were significant predictors.

Post-Asphyxial Aftercare and Management of Neonates in Low- and Middle-Income Countries: A Systematic Evidence Synthesis

INTRODUCTION

Effective post-resuscitation care is crucial for improving outcomes in neonates post-asphyxia. This review aimed to provide a comprehensive overview of post-asphyxial aftercare strategies and forms part of a supplement describing an extensive synthesis of effective newborn interventions in low- and middle-income countries (LMICs).

METHODS

Evidence was generated by performing de novo reviews, updates to reviews via systematic searches, and reanalyses of studies conducted in LMICs from existing reviews.

RESULTS

Sixty-one trials recruiting 5,046 term infants post-asphyxia were included across all intervention domains. Limited studies were available from LMICs related to fluid restriction, antiseizure medications, and early interventions to improve developmental outcomes. Our reanalysis of whole-body cooling trials in LMICs found effects on neonatal mortality and mortality or neurological disability in infancy differed significantly based on the care center and type of cooling device used. Pharmacological therapies for neuroprotection evaluated in 27 trials in middle-income countries had varied effects in neonates with encephalopathy. Majority of the trials (60%) focused on magnesium sulfate therapy and showed significant improvements in short-term mortality and morbidities.

CONCLUSION

The sample sizes of included trials were relatively small, and the certainty of evidence ranged from very low to moderate. Evidence on long-term survival and neurodevelopmental outcomes was limited. Further research on promising neuroprotective therapies and factors affecting their implementation in low-resource contexts is required. To reduce the high burden related to asphyxia in LMICs, this review underscores the need for a paradigm shift toward prevention, and strategies that emphasize improving antenatal and obstetric care.

INTRODUCTION

Effective post-resuscitation care is crucial for improving outcomes in neonates post-asphyxia. This review aimed to provide a comprehensive overview of post-asphyxial aftercare strategies and forms part of a supplement describing an extensive synthesis of effective newborn interventions in low- and middle-income countries (LMICs).

METHODS

Evidence was generated by performing de novo reviews, updates to reviews via systematic searches, and reanalyses of studies conducted in LMICs from existing reviews.

RESULTS

Sixty-one trials recruiting 5,046 term infants post-asphyxia were included across all intervention domains. Limited studies were available from LMICs related to fluid restriction, antiseizure medications, and early interventions to improve developmental outcomes. Our reanalysis of whole-body cooling trials in LMICs found effects on neonatal mortality and mortality or neurological disability in infancy differed significantly based on the care center and type of cooling device used. Pharmacological therapies for neuroprotection evaluated in 27 trials in middle-income countries had varied effects in neonates with encephalopathy. Majority of the trials (60%) focused on magnesium sulfate therapy and showed significant improvements in short-term mortality and morbidities.

CONCLUSION

The sample sizes of included trials were relatively small, and the certainty of evidence ranged from very low to moderate. Evidence on long-term survival and neurodevelopmental outcomes was limited. Further research on promising neuroprotective therapies and factors affecting their implementation in low-resource contexts is required. To reduce the high burden related to asphyxia in LMICs, this review underscores the need for a paradigm shift toward prevention, and strategies that emphasize improving antenatal and obstetric care.

Risk Factors and Predictors of Outcomes in Hypoxic-Ischemic Encephalopathy in Neonates

Background Hypoxic-ischemic encephalopathy (HIE) in neonates results from oxygen deprivation at birth, often leading to long-term neurological issues like cerebral palsy. Early detection is key to improving outcomes, but HIE remains a significant cause of neonatal complications. Here we aim to study the risk factors and predictors of outcome in moderate to severe HIE in inborn Term babies in the neonatal intensive care unit (NICU) Methods This prospective observational study was conducted in the NICU at a tertiary care center between August 2022 and July 2024. Forty term neonates diagnosed with moderate to severe HIE based on clinical and MRI findings were included. The study recorded antepartum, intrapartum, and postnatal risk factors, and neonatal outcomes were followed up.  Results In this study of 40 term neonates with HIE, 27 (67.5%) were male, 30 (75%) had a birth weight <2.5 kg, and 27 (67.5%) were delivered by cesarean section. Socioeconomic analysis revealed that 17 (42.5%) were from poor backgrounds. Of the mothers, 12 (30%) were over 30 years old and 19 (47.5%) used medications. Intrapartum factors included oligohydramnios in 13 (32.5%) and pregnancy-induced hypertension in 10 (25%). Postnatally, 28 (70%) required resuscitation, and 32 (80%) had a cord blood pH ≤7.0. MRI patterns showed 18 (45%) with basal ganglia/thalamus involvement and 22 (55%) with watershed lesions. At discharge, 39 (97.5%) were sent home, with 5 (12.5%) needing anti-seizure medications. No significant associations were found between MRI patterns and muscle tone or seizure activity. Conclusion This study highlights the complex interplay of maternal, intrapartum, and neonatal factors in the development of HIE. Identifying early risk factors is crucial for developing preventive and therapeutic strategies to reduce the burden of HIE-associated disabilities.

Embedding the 'CoolCuddle' intervention for infants undergoing therapeutic hypothermia for hypoxic-ischaemic encephalopathy in NICU: an evaluation using normalisation process theory

OBJECTIVES

Newborn infants exposed to lack of oxygen and blood flow to the brain around birth may develop brain dysfunction (hypoxic-ischaemic encephalopathy-HIE). These infants undergo 72 hours of cooling therapy and most are not held by their parents in the UK. We examined the implementation of 'CoolCuddle', identifying factors that impact embedding of this complex intervention in neonatal intensive care units (NICUs) across England.

DESIGN

Process evaluation and qualitative study using a standard questionnaire and interviews. Normalisation Process Theory (NPT) core constructs were used to assess relevant issues to staff embedding 'CoolCuddle', to discern change over time and different settings. Qualitative interviews provided valuable contextual exploration of implementation.

SETTING AND PARTICIPANTS

Six tertiary NICUs in England. Thirty-seven families with a newborn baby undergoing cooling therapy for HIE were recruited from September 2022 to August 2023; 17 NICU staff Normalisation MeAsure Development (NoMADs) at six NICUs over 6 months were included; 14 neonatal/research nurses from three participating NICUs were interviewed.

INTERVENTION

The family-centred intervention 'CoolCuddle' was developed to enable parents to hold their infant during cooling, without affecting the cooling therapy or intensive care.

OUTCOME MEASURES

NoMAD questionnaires at three timepoints over 6 months and NPT informed qualitative interviews.

RESULTS

NoMAD questionnaires at baseline showed more variation between units, for intervention acceptability, than those at 3 and 6 months. Qualitative data highlighted that staff understood the benefits of CoolCuddle but were apprehensive due to perceived risks involved in moving cooling babies. A rigorous standard operating procedure was flexible enough to incorporate the use of local processes and equipment and provided the relevant procedural knowledge to deliver CoolCuddle safely.

CONCLUSIONS

The CoolCuddle intervention can be implemented safely under the supervision of standard neonatal teams as part of usual practice in diverse NICU settings in England. The importance of having a rigorous standard operating procedure, which can be adapted to support local settings, is highlighted.

TRIAL REGISTRATION NUMBER

ISRCTN10018542; Results: registered on 30 August 2022.

Intranasal therapies for neonatal hypoxic-ischemic encephalopathy: Systematic review, synthesis, and implications for global accessibility to care

Neonatal hypoxic-ischemic encephalopathy (HIE) is the leading cause of neurodevelopmental morbidity in term infants worldwide. Incidence of HIE is highest in low and middle-income communities with minimal access to neonatal intensive care and an underdeveloped infrastructure for advanced neurologic interventions. Moreover, therapeutic hypothermia, standard of care for HIE in high resourced settings, is shown to be ineffective in low and middle-income communities. With their low cost, ease of administration, and capacity to potently target the central nervous system, intranasal therapies pose a unique opportunity to be a more globally accessible treatment for neonatal HIE. Intranasal experimental therapeutics have been studied in both rodent and piglet models, but no intranasal therapeutics for neonatal HIE have undergone human clinical trials. Additional research must be done to expand the array of treatments available for use as intranasal therapies for neonatal HIE thus improving the neurologic outcomes of infants worldwide.

Effectiveness and Safety of Dexmedetomidine in Neonates With Hypoxic Ischemic Encephalopathy Undergoing Therapeutic Hypothermia

OBJECTIVE

The objective of this study was to evaluate and compare the effectiveness and safety of dexmedetomidine as monotherapy between neonates with mild hypoxic ischemic encephalopathy (HIE) and moderate to severe HIE treated with therapeutic hypothermia (TH).

METHODS

This retrospective study included neonates of gestational age ≥36 weeks with a diagnosis of HIE and undergoing TH between January 2014 and December 2021. Patients were included if they received at least 6 hours of continuous sedation with dexmedetomidine. Baseline characteristics, dose and duration of medication, adverse events, liver and kidney function tests, and hospital course were reviewed.

RESULTS

Of the 97 neonates included, 46 had mild, 42 had moderate, and 9 had severe HIE. Dexmedetomidine was initiated at a median 5 hours of life, and the median infusion duration was 77 (46-87) hours. Fifty-two (53.6%) required at least 1 breakthrough opioid or sedative during the first 24 hours of dexmedetomidine infusion. Overall, 40 patients (41.2%) had at least 1 bradycardia episode with heart rate <80 beats/min and 14 patients (14.4%) had heart rate <70 beats/min. Hypotension was experienced by 7 patients (7.2%). Fifty-two patients (53.6%) were intubated in the delivery room and 33/52 (63.5%) were extubated on day of life 1 during dexmedetomidine infusion.

CONCLUSIONS

Dexmedetomidine as monotherapy was effective and safe sedation for infants with HIE undergoing hypothermia. The most common side effect of dexmedetomidine was bradycardia. -Dexmedetomidine may be considered as first and single agent for neonates with HIE undergoing TH.

Gross and Histologic Placental Abnormalities Associated With Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVE

To elucidate particular placental pathology findings that are associated with hypoxic ischemic encephalopathy (HIE) and determine which patterns are associated with adverse fetal/neonatal outcomes.

STUDY DESIGN

Multi-institutional retrospective case-control study of newborns with HIE (2002-2022) and controls. Four perinatal pathologists performed gross and histologic evaluation of placentas of cases and controls.

RESULTS

A total of 265 placentas of neonates with HIE and 122 controls were examined. Infants with HIE were more likely to have anatomic umbilical cord abnormalities (19.7% vs 7.4%, P = .003), fetal inflammatory response in the setting of amniotic fluid infection (27.7% vs 13.9%, P = .004), and fetal vascular malperfusion (30.6% vs 9.0%, P = <.001) versus controls. Fetal vascular malperfusion with maternal vascular malperfusion was more common in those who died of disease (P = .01).

CONCLUSION

Placental pathology examination of neonates with HIE may improve our understanding of this disorder and its adverse outcomes.

N6-methyladenosine demethylase FTO regulates synaptic and cognitive impairment by destabilizing PTEN mRNA in hypoxic-ischemic neonatal rats

Hypoxic-ischemic brain damage (HIBD) can result in significant global rates of neonatal death or permanent neurological disability. N6-methyladenosine (m6A) modification of RNA influences fundamental aspects of RNA metabolism, and m6A dysregulation is implicated in various neurological diseases. However, the biological roles and clinical significance of m6A in HIBD remain unclear. We currently evaluated the effect of HIBD on cerebral m6A methylation in RNAs in neonatal rats. The m6A dot blot assay showed a global augmentation in RNA m6A methylation post-HI. Herein, we also report on demethylase FTO, which is markedly downregulated in the hippocampus and is the main factor involved with aberrant m6A modification following HI. By conducting a comprehensive analysis of RNA-seq data and m6A microarray results, we found that transcripts with m6A modifications were more highly expressed overall than transcripts without m6A modifications. The overexpression of FTO resulted in the promotion of Akt/mTOR pathway hyperactivation, while simultaneously inhibiting autophagic function. This is carried out by the demethylation activity of FTO, which selectively demethylates transcripts of phosphatase and tensin homolog (PTEN), thus promoting its degradation and reduced protein expression after HI. Moreover, the synaptic and neurocognitive disorders induced by HI were effectively reversed through the overexpression of FTO in the hippocampus. Cumulatively, these findings demonstrate the functional importance of FTO-dependent hippocampal m6A methylome in cognitive function and provides novel mechanistic insights into the therapeutic potentials of FTO in neonatal HIBD.

Evaluation of syringin's neuroprotective effect in a model of neonatal hypoxic-ischemic brain injury

BACKGROUND/AIM

A significant cause of mortality and morbidity in the neonatal era is hypoxic-ischemic encephalopathy (HIE). This study examined the histopathological analysis and neuroprotective impact of syringin (SYR) in an experimental HIE rat model.

MATERIAL AND METHODS

On the 7th postnatal day, 24 Wistar albino rats were evaluated in 3 groups using the HIE model under gas anesthesia. In the experiment, Group A received 10 mg/kg SYR plus dimethyl sulfoxide (DMSO), Group B received DMSO only, and Group C served as a sham group. Immunohistochemical techniques were used to assess apoptotic cell measurement and proinflammatory cytokines (TNF-α and IL-1β primary antibodies).

RESULTS

Rats suffering from hypoxic-ischemic brain damage had their apoptosis assessed. The SYR and sham groups had statistically fewer cells undergoing apoptosis (p < 0.001). There was no difference between the groups in terms of IL-1β and TNF-α during immunohistochemical staining. Neuronal degeneration was significantly lower in the histological evaluation of the hippocampus in the SYR group (p = 0.01). A statistically significant difference (p = 0.01) was observed between the SYR and the control groups regarding pericellular and perivascular edema.

CONCLUSION

SYR reduced apoptosis, perivascular and pericellular edema, and neuronal degeneration in rat cerebral tissue. These results raise the possibility that SYR may have a neuroprotective effect on the harm brought on by HIE. This is the first investigation of SYR's function within the HIE paradigm.

Risk factors of mortality in neonates with neonatal encephalopathy in a tertiary newborn care unit in Zimbabwe over a 12-month period

Neonatal encephalopathy (NE) accounts for ~23% of the 2.4 million annual global neonatal deaths. Approximately 99% of global neonatal deaths occur in low-resource settings, however, accurate data from these low-resource settings are scarce. We reviewed risk factors of neonatal mortality in neonates admitted with neonatal encephalopathy from a tertiary neonatal unit in Zimbabwe. A retrospective review of risk factors of short-term neonatal encephalopathy mortality was conducted at Sally Mugabe Central Hospital (SMCH) (November 2018 -October 2019). Data were gathered using a tablet-based data capture and quality improvement newborn care application (Neotree). Analyses were performed on data from all admitted neonates with a diagnosis of neonatal encephalopathy, incorporating maternal, intrapartum, and neonatal risk predictors of the primary outcome: mortality. 494/2894 neonates had neonatal encephalopathy on admission and were included. Of these, 94 died giving a neonatal encephalopathy-case fatality rate (CFR) of 190 per 1000 admitted neonates. Caesarean section (odds ratio (OR) 2.95(95% confidence interval (CI) 1.39-6.25), convulsions (OR 7.13 (1.41-36.1)), lethargy (OR 3.13 (1.24-7.91)), Thompson score "11-14" (OR 2.98 (1.08-8.22)) or "15-22" (OR 17.61 (1.74-178.0)) were significantly associated with neonatal death. No maternal risk factors were associated with mortality. Nearly 1 in 5 neonates diagnosed with neonatal encephalopathy died before discharge, similar to other low-resource settings but more than in typical high-resource centres. The Thompson score, a validated, sensitive and specific tool for diagnosing neonates with neonatal encephalopathy was an appropriate predictive clinical scoring system to identify at risk neonates in this setting. On univariable analysis time-period, specifically a period of staff shortages due to industrial action, had a significant impact on neonatal encephalopathy mortality. Emergency caesarean section was associated with increased mortality, suggesting perinatal care is likely to be a key moment for future interventions.

Trends of neonatal hypoxic-ischemic encephalopathy prevalence and associated risk factors in the United States, 2010 to 2018

BACKGROUND

Despite recent advances in perinatal care, neonatal hypoxic-ischemic encephalopathy remains one of the most common causes of neonatal morbidity and mortality. The trends for prevalence and mortality of neonatal hypoxic-ischemic encephalopathy have not been examined in the era of therapeutic hypothermia in the United States.

OBJECTIVE

This study aimed to determine (1) the overall and gestational age-specific (35-36, ≥37, and >42 weeks) trends of hypoxic-ischemic encephalopathy prevalence and use of therapeutic hypothermia, (2) the trends of mortality in association with hypoxic-ischemic encephalopathy, (3) the confounding variables associated with hypoxic-ischemic encephalopathy, and (4) the clinical outcomes of neonates with hypoxic-ischemic encephalopathy.

STUDY DESIGN

This study used National Inpatient Sample datasets from 2010 to 2018. Moreover, the study included infants with a gestational age of ≥35 weeks with a documented hypoxic-ischemic encephalopathy diagnosis (mild, moderate, severe, or unspecified). We calculated trends in hypoxic-ischemic encephalopathy prevalence and the use of therapeutic hypothermia using chi-squared testing. Furthermore, this study used logistic regression models to control for confounders.

RESULTS

A total of 32,180,617 infants were included, of which 31,249,100 were term (gestational age of ≥37 weeks) and 931,517 were late preterm (gestational age of 35-36 weeks). Hypoxic-ischemic encephalopathy prevalence slightly increased from 0.093% in 2010-2012 to 0.097% in 2016-2018 (P=.01) in term infants and did not significantly change in late preterm infants (P=.20). There were 6235 term infants (20.8%) and 449 late preterm infants (21.1%) with hypoxic-ischemic encephalopathy who were managed with therapeutic hypothermia. The use of therapeutic hypothermia in both term and late preterm infants has increased over the years (P<.01). The mortality rate with hypoxic-ischemic encephalopathy decreased over time from 11.5% to 12.3% between 2010 to 2012, and from 8.3% to 10.6% betweenn 2016 to 2018 (P<.01). The factors with the strongest association with hypoxic-ischemic encephalopathy were placental infarction or insufficiency (odds ratio, 144; 95% confidence interval, 134-157), placental abruption (odds ratio, 101; 95% confidence interval, 91-112), cord prolapse (odds ratio, 74; 95% confidence interval, 65-84), and maternal anemia (odds ratio, 26; 95% confidence interval, 20-37).

CONCLUSION

Hypoxic-ischemic encephalopathy prevalence in neonates essentially remained the same at 1 per 1000 live births. The use of therapeutic hypothermia increased, and the mortality rate decreased in infants with hypoxic-ischemic encephalopathy. The identification of hypoxic-ischemic encephalopathy-associated factors should promote increased vigilance to optimize newborn outcomes.

Short-term outcome of perinatal hypoxic-ischaemic encephalopathy at Chiang Mai University Hospital, Thailand: a 15-year retrospective study

BACKGROUND

The outcome of perinatal hypoxic-ischaemic encephalopathy (HIE) in middle-to-low-income countries varies between regions.

OBJECTIVES

To determine the mortality and morbidity, and factors influencing the deaths of infants with perinatal HIE.

METHODS

A retrospective study was conducted at Chiang Mai University Hospital, Thailand. Perinatal HIE infants of >35 weeks gestation, birthweight ≥2000 g and admitted during 2005-2019 were reviewed. Baseline Characteristics, clinical course and outcome at discharge were compared between the period before and after initiation of therapeutic hypothermia (TH). Risk of death in HIE infants who underwent TH was identified.

RESULTS

A total of 162 HIE infants were included. Compared to the period before TH initiation, the mortality rate was significantly decreased in the TH period. (27% vs. 12.8%, p=0.04) Among 100 HIE infants who underwent TH, the mortality rates was 14%(14/100), of whom 2.5% (2/76) and 50% (12/24) were in the moderate and severe HIE groups. Apgar score at 5 mins ≤1, severe HIE, seizures, hypoglycaemia, organ involvement ≥ five sites, ammonia ≥100 umol/L, lactate ≥14 mmol/L, and requirement for two or more inotropic drugs were risks of death. Multivariate analysis demonstrated that severe HIE (aOR 732.8, 95% CI 4.7-114643, p=0.01) and a need for two or more inotropic drugs (aOR 45.7, 95% CI 1.5-1040, p=0.029) were significant factors for mortality.

CONCLUSION

In the period of TH, perinatal HIE infants had decreased mortality. Severe HIE and a need for two or more inotropic drugs were associated with death in the infant with HIE who underwent TH.Abbreviations: AED: anti-epileptic drug; BW, birthweight; CI: confidence interval; CMU: Chiang Mai University; EEG: electro-encephalogram; GA: gestational age; HIE: hypoxic-ischaemic encephalopathy; IQR: interquartile range; NICU: neonatal intensive care unit; SD: standard deviation; TH: therapeutic hypothermia.