Therapeutic hypothermia for neonatal encephalopathy: a UK survey of opinion, practice and neuro-investigation at the end of 2007

Use of EEG in neonatal hypoxic-ischemic encephalopathy: A French survey of current practice and perspective for improving health care

OBJECTIVES

Controlled therapeutic hypothermia (CTH) is a standard of care in the management of neonatal hypoxic-ischemic encephalopathy HIE in newborns after 36 weeks of gestational age (WGA) in France. The electroencephalogram (EEG) plays a major role in HIE diagnosis and follow-up. We conducted a French national survey on the current use of EEG in newborn undergoing CTH.

METHODS

Between July and October 2021, an email survey was sent to the heads of the Neonatal intensive care units (NICUs) in metropolitan and overseas French departments and territories.

RESULTS

Out of 67, 56 (83%) of NICUs responded. All of them performed CTH in children born after 36 WGA with clinical and biological criteria of moderate to severe HIE. 82% of the NICUs used conventional EEG (cEEG) before 6 h of life (H6), prior to CTH being performed, to inform decisions about its use. However, half of the 56 NICUs had limited access after regular working hours. 51 of the 56 centers (91%) used cEEG, either short-lasting or continuous monitoring during cooling, while 5 centers conducted only amplitude EEG (aEEG). Only 4 of 56 centers (7%) used cEEG systematically both prior to CTH and for continuous monitoring under CTH.

DISCUSSION

The use of cEEG in the management of neonatal HIE was widespread in NICUs, but with significant disparities when considering 24-hour access. The introduction of a centralized neurophysiological on-call system grouping several NICUs would be of major interest for most centers which do not have the facility of EEG outside working hours.

Periventricular leukomalacia: an ophthalmic perspective

Periventricular leukomalacia (PVL) is a common magnetic resonance imaging (MRI) finding in cases of hypoxic ischemic encephalopathy. PVL, in MRI, is identified by the increased signal intensity of periventricular white matter on T2-weighted sequences which is more conspicuous in the posterior cortex. It occurs because of perinatal damage to the cerebral cortex. This insult is in the form of hypoxia, metabolic insults, prematurity, seizures, or infection. Periventricular area is most prone to damage owing to its immaturity and vascular supply. PVL is proven to affect vision in children. Depending on the area and cause of affection, PVL is associated with variable ophthalmic manifestations. It is known that visual function is closely linked to the overall neurodevelopment of a child. A multidisciplinary approach is required to promote the growth and development of these children, and in the midst of multiple disabilities, visual function should not be overlooked. A comprehensive knowledge of the ophthalmological presentation in the developing world can aid us in an early and accurate diagnosis and in intervention for better therapeutic recovery and rehabilitation of these children.

Consensus protocol for EEG and amplitude-integrated EEG assessment and monitoring in neonates

The aim of this work is to establish inclusive guidelines on electroencephalography (EEG) applicable to all neonatal intensive care units (NICUs). Guidelines on ideal EEG monitoring for neonates are available, but there are significant barriers to their implementation in many centres around the world. These include barriers due to limited resources regarding the availability of equipment and technical and interpretive round-the-clock personnel. On the other hand, despite its limitations, amplitude-integrated EEG (aEEG) (previously called Cerebral Function Monitor [CFM]) is a common alternative used in NICUs. The Italian Neonatal Seizure Collaborative Network (INNESCO), working with all national scientific societies interested in the field of neonatal clinical neurophysiology, performed a systematic literature review and promoted interdisciplinary discussions among experts (neonatologists, paediatric neurologists, neurophysiologists, technicians) between 2017 and 2020 with the aim of elaborating shared recommendations. A consensus statement on videoEEG (vEEG) and aEEG for the principal neonatal indications was established. The authors propose a flexible frame of recommendations based on the complementary use of vEEG and aEEG applicable to the various neonatal units with different levels of complexity according to local resources and specific patient features. Suggestions for promoting cooperation between neonatologists, paediatric neurologists, and neurophysiologists, organisational restructuring, and teleneurophysiology implementation are provided.

Therapeutic Hypothermia: How Can We Optimize This Therapy to Further Improve Outcomes?

Neonatal hypoxic-ischemic encephalopathy remains associated with considerable death and disability. In multiple randomized controlled trials, therapeutic hypothermia for neonatal moderate or severe hypoxic-ischemic encephalopathy among term infants has been shown to be safe and effective in reducing death and disability in survivors. In this article, the current status of infant and childhood outcomes following this therapy is reviewed. The clinical approaches that may help to optimize this innovative neuroprotective therapy are presented.

Role of immunoglobulin in neuronal apoptosis in a neonatal rat model of hypoxic ischemic brain injury

The objective of the present study was to evaluate the neuroprotective effects of immunoglobulin (Ig) in a neonatal hypoxic ischemic (HI) rat model. Seven-day-old rat pups were randomly assigned to control, hypoxia and hypoxia + Ig groups. The rats in the hypoxia +Ig group were intraperitoneally administered 1 g/kg Ig once, immediately after hypoxia. Saline was administered to the rats in the hypoxia group at the same time point. Eight rats from each of the Ig + hypoxia and hypoxia groups were sacrificed by decapitation 4 and 24 h following the administration of Ig or saline. The rats of the control group were sacrificed at the 4 h time-point. Caspase-3 activity, as well as IL-1β, IL-6 and TNF-α mRNA expression levels, were studied in the left ischemic hemispheres. Induction of cerebral ischemia increased the TNF-α, IL-6 and IL-1β mRNA expression levels significantly at 4 and 24 h in the left ischemic hemispheres in the hypoxia group compared with those in the control group. The systemic administration of Ig following HI encephalopathy significantly reduced the TNF-α, IL-6 and IL-1β mRNA expression levels in the ischemic tissue in the Ig + hypoxia group compared with those in the hypoxia group. In the hypoxia group, caspase-3 activity in the left half of the brain was found to be significantly increased compared with that in the control group. Caspase-3 activity in the Ig + hypoxia group was significantly lower than that in the hypoxia group. The observations of the present study indicate that Ig administration may be an efficient treatment approach for reducing cerebral apoptosis associated with hypoxic ischemia.

Therapeutic hypothermia for neonatal encephalopathy in low- and middle-income countries: a systematic review and meta-analysis

Although selective or whole body cooling combined with optimal intensive care improves outcomes following neonatal encephalopathy in high-income countries, the safety and efficacy of cooling in low-and middle-income countries is not known.

Lessons learned during implementation of therapeutic hypothermia for neonatal hypoxic ischemic encephalopathy in a regional transport program in Ontario

BACKGROUND

Therapeutic hypothermia (TH) is the first intervention to consistently show improved neurological outcomes in neonates with hypoxic ischemic encephalopathy (HIE). Since the recent introduction of TH for HIE in many centres, reviews of practices during the implementation of TH in Canada have not been published.

OBJECTIVE

To determine if eligible neonates are being offered TH and to identify any barriers to the effective implementation of TH.

METHODS

A retrospective review of neonates referred to a regional tertiary centre at a gestational age of 35 weeks or more with HIE was conducted.

RESULTS

Among 41 neonates referred, 29 (71%) were eligible for TH; among eligible patients, five were moribund and excluded, and TH was initiated in 16 (67%) of the remaining 24. Reasons for not cooling in eight eligible patients included a delay in referral (n=5, median age at referral was 14 h) and a failure to recognize the severity of HIE (n=3). Among cooled patients, median times were the following: 116 min for age at referral; 80 min for time from referral to transport team arrival; and 358 min for age at initiation of cooling. Seven (44%) patients had cooling initiated after 6 h of age.

CONCLUSION

A significant proportion of eligible patients were not offered TH, and in many cooled patients, initiation of cooling was delayed beyond the recommended 6 h. For eligible patients to benefit from TH, it is imperative that all birthing centres be made aware that TH is now widely available as an important treatment option, but also that TH is a time-sensitive therapy requiring rapid identification and referral. In the region studied, for eligible patients, referring hospitals should initiate passive cooling before arrival of the transport team. Referring hospitals should be prepared to provide early, yet safe initiation of passive cooling by having the appropriate equipment, and having staff trained in the use and monitoring of rectal temperatures.

Hypothermia for neonatal encephalopathy: Nationwide Survey of Clinical Practice in Japan as of August 2010

BACKGROUND

Therapeutic hypothermia is now recommended as a standard of care for neonatal encephalopathy. Although adherence to standard cooling protocols used in the phase-III trials is essential, empiric approaches have prevailed in Japan.

AIM

To elucidate the gap between the standard cooling methods and the current practice in Japan.

METHOD

In July 2010, a questionnaire regarding the practice of neonatal encephalopathy was mailed to clinical leads of registered neonatal intensive care units.

RESULT

56.2% of the units were incapable of offering therapeutic hypothermia because of the reasons such as the shortage of human/medical resources (85.1%) and limited number of cases (21.1%). Eighty-nine centres provided therapeutic hypothermia using either selective-head cooling (88.8%) or whole-body cooling (11.2%). Various target temperatures and cooling durations were used; 20.2% of the units cooled infants without using purpose-built equipments, whereas 14.6% did not continuously monitor the body temperature.

DISCUSSION

Only 43.8% of the units provided therapeutic hypothermia. Even in centres where hypothermia was offered, adherence to the standard protocols was extremely poor. To secure the safety and efficacy, further promotion of the standard cooling protocols is required; an efficient cooling centre network has to be established by optimizing the work forth distribution and transportation system.

A quantitative analysis of optimal treatment capacity for perinatal asphyxia

OBJECTIVE

In centers electing to offer therapeutic hypothermia for treating hypoxic-ischemic encephalopathy (HIE), determining the optimal number of cooling devices is not straightforward. The authors used computer-based modeling to determine the level of service as a function of local HIE caseload and number of cooling devices available.

METHODS

The authors used discrete event simulation to create a model that varied the number of HIE cases and number of cooling devices available. Outcomes of interest were percentage of HIE-affected infants not cooled, number of infants not cooled, and percentage of time that all cooling devices were in use.

RESULTS

With 1 cooling device, even the smallest perinatal center did not achieve a cooling rate of 99% of eligible infants. In contrast, 2 devices ensured 99% service in centers treating as many as 20 infants annually. In centers averaging no more than 1 HIE infant monthly, the addition of a third cooling device did not result in a substantial reduction in the number of infants who would not be cooled.

CONCLUSION

Centers electing to offer therapeutic hypothermia with only a single cooling device are at significant risk of being unable to provide treatment to eligible infants, whereas 2 devices appear to suffice for most institutions treating as many as 20 annual HIE cases. Three devices would rarely be needed given current caseloads seen at individual institutions. The quantitative nature of this analysis allows decision makers to determine the number of devices necessary to ensure adequate availability of therapeutic hypothermia given the HIE caseload of a particular institution.

Erythropoietin in neonatal brain protection: the past, the present and the future

Over the last decade, neuroprotective effects of erythropoietin (Epo) and its underlying mechanisms in terms of signal transduction pathways have been defined and there is a growing interest in the potential therapeutic use of Epo for neuroprotection. Several mechanisms by which Epo provides neuroprotection are recognized. In this review, we focused on the neuroprotective mechanisms of Epo and provide a short overview on both experimental and clinical studies, testing Epo as a neuroprotective agent in the neonatal brain injury, and the safety concerns with the clinical use of Epo treatment in neonates.

Xenon augmented hypothermia reduces early lactate/N-acetylaspartate and cell death in perinatal asphyxia

OBJECTIVE

Additional treatments for therapeutic hypothermia are required to maximize neuroprotection for perinatal asphyxial encephalopathy. We assessed neuroprotective effects of combining inhaled xenon with therapeutic hypothermia after transient cerebral hypoxia-ischemia in a piglet model of perinatal asphyxia using magnetic resonance spectroscopy (MRS) biomarkers supported by immunohistochemistry.

METHODS

Thirty-six newborn piglets were randomized (all groups n = 9), with intervention from 2 to 26 hours, to: (1) normothermia; (2) normothermia + 24 hours 50% inhaled xenon; (3) 24 hours hypothermia (33.5°C); or (4) 24 hours hypothermia (33.5°C) + 24 hours 50% inhaled xenon. Serial MRS was acquired before, during, and up to 48 hours after hypoxia-ischemia.

RESULTS

Mean arterial blood pressure was lower in all treatment groups compared with normothermia (p < 0.01) (although >40mmHg); the combined therapy group required more fluid boluses (p < 0.05) and inotropes (p < 0.001). Compared with no intervention, both hypothermia and xenon-augmented hypothermia reduced the temporal regression slope magnitudes for phosphorus-MRS inorganic phosphate/exchangeable phosphate pool (EPP) and phosphocreatine/EPP (both p < 0.05); for lactate/N-acetylaspartate (NAA), only xenon-augmented hypothermia reduced the slope (p < 0.01). Xenon-augmented hypothermia also reduced transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)(+) nuclei and caspase 3 immunoreactive cells in parasagittal cortex and putamen and increased microglial ramification in midtemporal cortex compared with the no treatment group (p < 0.05). Compared with hypothermia, however, combination treatment did not reach statistical significance for any measure. Lactate/NAA showed a strong positive correlation with TUNEL; nucleotide triphosphate/EPP showed a strong negative correlation with microglial ramification (both p < 0.01).

INTERPRETATION

Compared with no treatment, xenon-augmented hypothermia reduced cerebral MRS abnormalities and cell death markers in some brain regions. Compared with hypothermia, xenon-augmented hypothermia did not reach statistical significance for any measure. The safety and possible improved efficacy support phase II trials.

Pilot randomized trial of therapeutic hypothermia with serial cranial ultrasound and 18-22 month follow-up for neonatal encephalopathy in a low resource hospital setting in Uganda: study protocol

Background

There is now convincing evidence that in industrialized countries therapeutic hypothermia for perinatal asphyxial encephalopathy increases survival with normal neurological function. However, the greatest burden of perinatal asphyxia falls in low and mid-resource settings where it is unclear whether therapeutic hypothermia is safe and effective.

Aims

Under the UCL Uganda Women's Health Initiative, a pilot randomized controlled trial in infants with perinatal asphyxia was set up in the special care baby unit in Mulago Hospital, a large public hospital with ~20,000 births in Kampala, Uganda to determine:

(i) The feasibility of achieving consent, neurological assessment, randomization and whole body cooling to a core temperature 33-34°C using water bottles

(ii) The temperature profile of encephalopathic infants with standard care

(iii) The pattern, severity and evolution of brain tissue injury as seen on cranial ultrasound and relation with outcome

(iv) The feasibility of neurodevelopmental follow-up at 18-22 months of age

Methods/Design

Ethical approval was obtained from Makerere University and Mulago Hospital. All infants were in-born. Parental consent for entry into the trial was obtained. Thirty-six infants were randomized either to standard care plus cooling (target rectal temperature of 33-34°C for 72 hrs, started within 3 h of birth) or standard care alone. All other aspects of management were the same. Cooling was performed using water bottles filled with tepid tap water (25°C). Rectal, axillary, ambient and surface water bottle temperatures were monitored continuously for the first 80 h. Encephalopathy scoring was performed on days 1-4, a structured, scorable neurological examination and head circumference were performed on days 7 and 17. Cranial ultrasound was performed on days 1, 3 and 7 and scored. Griffiths developmental quotient, head circumference, neurological examination and assessment of gross motor function were obtained at 18-22 months.

Discussion

We will highlight differences in neonatal care and infrastructure that need to be taken into account when considering a large safety and efficacy RCT of therapeutic hypothermia in low and mid resource settings in the future.

Trial registration

Current controlled trials ISRCTN92213707

Techniques for therapeutic hypothermia during transport and in hospital for perinatal asphyxial encephalopathy

Over the past 10 years, several randomised clinical trials of therapeutic hypothermia for perinatal asphyxial encephalopathy have demonstrated both safety and efficacy of therapeutic hypothermia in improving neurological outcome. Today cooling is increasingly used in tertiary level units throughout the developed world. Therapeutic hypothermia (cooling to a rectal or core temperature of 33-34 degrees C for 72 h) is easier to achieve in newborn infants than in adults. There is a natural tendency for the core temperature of infants who suffered birth asphyxia to fall and remain lower than non-asphyxiated infants for up to 16 h after birth. A variety of high- and low-tech surface cooling methods have been used in neonates - newer systems are servo-controlled and provide very stable temperature control. It is well accepted that to be most effective, cooling needs to be initiated as soon as possible after birth and, thus, needs to be commenced prior to the transfer of infants to cooling centres. We describe our experience of passive cooling before and during the transfer of infants with encephalopathy to cooling centres in a major city in the UK.

Ethics and hypothermia treatment

Hypothermia is the first effective neuroprotective intervention for newborns who are critically ill following a life-threatening asphyxial insult. It is not surprising that it has raised complex and controversial ethical dilemmas for investigators and clinicians. Given the history of iatrogenic disasters in neonatology, there has been an understandable reluctance to incorporate hypothermia into routine clinical practice until there is persuasive evidence from high quality randomised trials. This article reviews ethical issues that arose during the design of the original clinical trials, the implications of accumulating evidence of safety and efficacy, and the problems of ensuring informed parental participation in treatment decisions.

Synergistic neuroprotective therapies with hypothermia

Neuroprotection is a major health care priority, given the enormous burden of human suffering and financial cost caused by perinatal brain damage. With the advent of hypothermia as therapy for term hypoxic-ischemic encephalopathy, there is hope for repair and protection of the brain after a profound neonatal insult. However, it is clear from the published clinical trials and animal studies that hypothermia alone will not provide complete protection or stimulate the repair that is necessary for normal neurodevelopmental outcome. This review critically discusses drugs used to treat seizures after hypoxia-ischemia in the neonate with attention to evidence of possible synergies for therapy. In addition, other agents such as xenon, N-acetylcysteine, erythropoietin, melatonin and cannabinoids are discussed as future potential therapeutic agents that might augment protection from hypothermia. Finally, compounds that might damage the developing brain or counteract the neuroprotective effects of hypothermia are discussed.

Experimental treatments for hypoxic ischaemic encephalopathy

Hypoxic ischaemic encephalopathy continues to be a significant cause of death and disability worldwide. In the last 1-2 years, therapeutic hypothermia has entered clinical practice in industrialized countries and neuroprotection of the newborn has become a reality. The benefits and safety of cooling under intensive care settings have been shown consistently in trials; therapeutic hypothermia reduces death and neurological impairment at 18 months with a number needed to treat of approximately nine. Unfortunately, around half the infants who receive therapeutic hypothermia still have abnormal outcomes. Recent experimental data suggest that the addition of another agent to cooling may enhance overall protection either additively or synergistically. This review discusses agents such as inhaled xenon, N-acetylcysteine, melatonin, erythropoietin and anticonvulsants. The role of biomarkers to speed up clinical translation is discussed, in particular, the use of the cerebral magnetic resonance spectroscopy lactate/N-acetyl aspartate peak area ratios to provide early prognostic information. Finally, potential future therapies such as regeneration/repair and postconditioning are discussed.