Hypothermia for hypoxic-ischemic encephalopathy

Outcomes of Infants with Mild Hypoxic Ischemic Encephalopathy Who Did Not Receive Therapeutic Hypothermia

Introduction

Accurately diagnosing and treating infants with mild forms of hypoxic ischemic encephalopathy (HIE) is important, as the majority of neonates with signs and symptoms of HIE after birth do not meet clinical criteria for moderate or severe disease. Emerging evidence, however, suggests that infants with mild HIE (mHIE) have an increased risk for neurodevelopmental impairment (NDI).

Methods

This retrospective descriptive study examined all inborn infants ≥35 week's gestational age at a single, level III neonatal intensive care unit (NICU) in California between January 1, 2012, and December 31, 2015. International Classification of Diseases codes were used as a proxy to identify neonates with mHIE but who did not receive therapeutic hypothermia (TH). Short- and long-term neurodevelopmental outcomes were documented, including abnormal (1) brain magnetic resonance imaging within 10 days of birth suggestive of HIE, (2) electroencephalogram with electrographic seizures, (3) neurologic discharge examination, or (4) NDI following NICU discharge.

Results

Over the 4-year study period, 25 infants met inclusion criteria. Eight of 25 (32%) infants demonstrated neurologic impairment, defined by an abnormality in at least one of the four categories. The remaining 17 infants were without documented evidence for adverse outcomes.

Conclusion

Our results indicate that children with mHIE are at significant risk for neurologic injury and may benefit from more aggressive interventions. Further prospective studies should be completed to determine the efficacy of TH in this specific patient population.

Medico-legal implications of hypothermic neuroprotection in the newborn

Hypoxic-ischemic encephalopathy (HIE) continues to be a significant source of long term neurological sequelae in infants born at or near term. In the past decade, selective head or whole body cooling has shown promising benefit in ameliorating some of the brain injury from intrapartum asphyxial insults and has become standard care in most developed countries. A decision to offer neuroprotective hypothermia (NPH) may engender subsequent litigation because it presupposes an acute intrapartum injury. Conversely, failing to offer cooling may be interpreted as a violation in the standard of care. In this paper, we review the clinical aspects of NPH and the medico-legal scenarios often seen after acute birth injury.

Therapeutic Hypothermia in Asphyxiated Neonates: Experience from Neonatal Intensive Care Unit of University Hospital of Marrakech

INTRODUCTION

Therapeutic hypothermia (TH) is now recommended for the treatment neonates with hypoxic-ischemic encephalopathy (HIE). This treatment protocol is applied in our department since June 2012. The aim of this study is to report the first experience with head cooling in asphyxiated neonates in Morocco.

PATIENTS AND METHODS

Prospective study of newborns admitted for HIE from July 18, 2012, to May 15, 2014, in Neonatal Intensive Care Unit (NICU) of Mohamed VI University Hospital. The results were studied by comparing a newborn group who received hypothermia to a control group.

RESULTS

Seventy-two cases of neonates with perinatal asphyxia were admitted in the unit. According to inclusion criteria thirty-eight cases were eligible for the study. Only 19 cases have received the hypothermia protocol for different reason; the arrival beyond six hours of life was the main cause accounting for 41%. Complications of asphyxia were comparable in both groups with greater pulmonary hypertension recorded in the control group. The long-term follow-up of protocol group was normal in almost half of cases.

CONCLUSION

Our first experience with the controlled TH supports its beneficial effect in newborns with HIE. This treatment must be available in all the centers involved in the neonatal care in Morocco.

Understanding the Full Spectrum of Organ Injury Following Intrapartum Asphyxia

Birth asphyxia is a significant global health problem, responsible for ~1.2 million neonatal deaths each year worldwide. Those who survive often suffer from a range of health issues including brain damage-manifesting as cerebral palsy (CP)-respiratory insufficiency, cardiovascular collapse, and renal dysfunction, to name a few. Although the majority of research is directed toward reducing the brain injury that results from intrapartum birth asphyxia, the multi-organ injury observed in surviving neonates is of equal importance. Despite the advent of hypothermia therapy for the treatment of hypoxic-ischemic encephalopathy (HIE), treatment options following asphyxia at birth remain limited, particularly in low-resource settings where the incidence of birth asphyxia is highest. Furthermore, although cooling of the neonate results in improved neurological outcomes for a small proportion of treated infants, it does not provide any benefit to the other organ systems affected by asphyxia at birth. The aim of this review is to summarize the current knowledge of the multi-organ effects of intrapartum asphyxia, with particular reference to the findings from our laboratory using the precocial spiny mouse to model birth asphyxia. Furthermore, we reviewed the current treatments available for neonates who have undergone intrapartum asphyxia, and highlight the emergence of maternal dietary creatine supplementation as a preventative therapy, which has been shown to provide multi-organ protection from birth asphyxia-induced injury in our preclinical studies. This cheap and effective nutritional supplement may be the key to reducing birth asphyxia-induced death and disability, particularly in low-resource settings where current treatments are unavailable.

Hyperglycemia is associated with poor outcome in newborn infants undergoing therapeutic hypothermia for hypoxic ischemic encephalopathy

BACKGROUND

Therapeutic hypothermia (TH) improves survival and neurodevelopmental outcome in neonatal hypoxic ischemic encephalopathy (HIE). Both, hypoglycemia and hyperglycemia are common in infants with HIE. The relationship between hypoglycemia and hyperglycemia, and immediate outcome has not been well described.

METHODS

A retrospective analysis of newborn infants with HIE (N = 56) was conducted. Blood glucose concentrations recorded during the first 96 hours were noted. Glucose levels of infants who underwent TH (TH group, N = 20) were compared with those that did not undergo TH (No-TH group, N = 36). The relationship between blood glucose and mortality and/or moderate/severe disability was determined.

RESULTS

Mean ± SD blood glucose concentration during the first 24 hours of age was significantly higher in the TH group (148 ± 65 mg/dl), compared with the No-TH group (113 ± 50 mg/dl; p = 0.02), despite a lower glucose infusion rate in the former (4.05 ± 1.77 mg/kg/hr vs. 5.36 ± 2.51 mg/kg/hr; p = 0.04). One hundred percent of infants (n = 9) in the TH group with blood glucose levels >200 mg/dl during the first 24 hours of age died or had moderate/severe disability, compared with 54.5% of those with blood glucose <200 mg/dl in this group (p = 0.03). A similar effect was not present in the No-TH group.

CONCLUSION

Hyperglycemia on the first day portends poor outcome in newborn infants undergoing TH for HIE.

Serum Lactate, Brain Magnetic Resonance Imaging and Outcome of Neonatal Hypoxic Ischemic Encephalopathy after Therapeutic Hypothermia

BACKGROUND

Serum lactate was used to predict the severity and outcome of neonatal hypoxic ischemic encephalopathy (HIE) before the era of therapeutic hypothermia (TH). There is no report on neurodevelopment (ND) outcome of neonates with HIE treated with TH in Taiwan.

METHODS

Between April 2011 and December 2012, newborn infants admitted to Chang Gung Memorial Hospital (CGMH), with gestational age > 35 weeks and birth weight ≥ 1800 g, who had acute perinatal events, evidence of significant fetal compromise, and ongoing clinical encephalopathy were prospectively enrolled for TH. Whole body cooling method was used to maintain the affected neonate's esophageal temperature at 33.5 ± 0.5 °C for 72 hours. Demographic data were recorded and hemogram, biochemical parameters, serum lactate, and creatine kinase (CK) were measured as well. Brain magnetic resonance imaging (MRI) was performed between 7 and 14 days of life. ND outcome of infants was evaluated by Bayley Scales of Infant Development, third edition (BSID-III) at 24 months of corrected age. Poor ND (PND) outcome was defined as infants surviving with either disability or ND delay.

RESULTS

Seventeen patients were enrolled. Fifty-nine percent of babies (10/17) were born through cesarean section and 77% of babies (13/17) were transferred from outside hospitals. Six babies were moderate HIE and 11 babies were severe HIE. Among the 14 surviving patients, eight infants had PND outcome. There was no difference in demographic data between infants with and without PND. Serum level of lactate (mg/dL) after 72 hours of TH was higher (35.6 vs. 13.8, p = 0.042) in infants with PND. Neonates with abnormal brain MRI findings were also associated with PND (p = 0.01).

CONCLUSION

This is the first report on ND outcome of neonates with HIE treated with TH in Taiwan. Higher serum level of lactate following TH and abnormal results of brain MRI are associated with poor ND outcome.

Effect of therapeutic hypothermia on oxidative stress and outcome in term neonates with perinatal asphyxia: a randomized controlled trial

OBJECTIVES

To evaluate in term babies with perinatal asphyxia, the effect of therapeutic hypothermia (TH) on oxidative stress and neurological outcome at discharge.

METHODS

Babies who satisfied inclusion criteria were randomized to TH, with cooling gel packs to a target temperature of 33-34°C for 72 h or normothermia. Blood sample was collected before and after TH for oxidative stress assessment: total antioxidant status (TAS) and malondialdehyde (MDA).

RESULTS

Of 116 babies randomized, there was no statistically significant difference in the baseline TAS and MDA. After 72 h of TH, TAS was significantly higher (p = <0.001) (761.69 ± 114.01 vs. 684.16 ± 88.86) and MDA was significantly lower (p = <0.001) in TH group (1.73 ± 0.66 vs. 5.2 ± 1.06). Risk of developing deficit was lower (p < 0.001) in TH group with relative risk of 0.49 and 95 % confidence interval: 0.29-0.68.

CONCLUSION

TH reduces oxidative stress and improves neurological outcome in perinatal asphyxia.

TRIAL REGISTRATION NUMBER

CTRI/2011/12/002196.

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.

The dose-response effect of acute intravenous transplantation of human umbilical cord blood cells on brain damage and spatial memory deficits in neonatal hypoxia-ischemia

Despite the beneficial effects of cell-based therapies on brain repair shown in most studies, there has not been a consensus regarding the optimal dose of human umbilical cord blood cells (HUCBC) for neonatal hypoxia-ischemia (HI). In this study, we compared the long-term effects of intravenous administration of HUCBC at three different doses on spatial memory and brain morphological changes after HI in newborn Wistar rats. In addition, we tested whether the transplanted HUCBC migrate to the injured brain after transplantation. Seven-day-old animals underwent right carotid artery occlusion and were exposed to 8% O(2) inhalation for 2 h. After 24 h, randomly selected animals were assigned to four different experimental groups: HI rats administered with vehicle (HI+vehicle), HI rats treated with 1×10(6) (HI+low-dose), 1×10(7) (HI+medium-dose), and 1×10(8) (HI+high-dose) HUCBC into the jugular vein. A control group (sham-operated) was also included in this study. After 8 weeks of transplantation, spatial memory performance was assessed using the Morris water maze (MWM), and subsequently, the animals were euthanized for brain morphological analysis using stereological methods. In addition, we performed immunofluorescence and polymerase chain reaction (PCR) analyses to identify HUCBC in the rat brain 7 days after transplantation. The MWM test showed a significant spatial memory recovery at the highest HUCBC dose compared with HI+vehicle rats (P<0.05). Furthermore, the brain atrophy was also significantly lower in the HI+medium- and high-dose groups compared with the HI+vehicle animals (P<0.01; 0.001, respectively). In addition, HUCBC were demonstrated to be localized in host brains by immunohistochemistry and PCR analyses 7 days after intravenous administration. These results revealed that HUCBC transplantation has the dose-dependent potential to promote robust tissue repair and stable cognitive improvement after HI brain injury.

Hypoxic Ischemic Encephalopathy: Pathophysiology and Experimental Treatments

Hypoxic ischemic encephalopathy (HIE) is a serious birth complication affecting full term infants: 40-60% of affected infants die by 2 years of age or have severe disabilities. The majority of the underlying pathologic events of HIE are a result of impaired cerebral blood flow and oxygen delivery to the brain with resulting primary and secondary energy failure. In the past, treatment options were limited to supportive medical therapy. Currently, several experimental treatments are being explored in neonates and animal models to ameliorate the effects of secondary energy failure. This review discusses the underlying pathophysiologic effects of a hypoxic-ischemic event and experimental treatment modalities being explored to manage infants with HIE. Further research is needed to better understand if the long-term impact of the experimental treatments and whether the combinations of experimental treatments can improve outcomes in infants with HIE.

"Caution! Contents should be cold": developing a whole-body hypothermia program

Hypoxic-ischemic encephalopathy (HIE) is characterized as brain injury that results from lack of oxygen or blood flow to the brain in the perinatal period. Neonatal whole-body hypothermia and selective head cooling are becoming increasingly common care practices across the U.S. and Canada for infants with moderate-to-severe HIE because of the demonstrated ability of these approaches to reduce reperfusion injury to the brain. Health care professionals must develop a clinical care path for these fragile infants. For best results, induced hypothermia should be initiated within six hours of birth; therefore, care must be organized and provided without delay. This article provides bedside clinicians with care recommendations for infants being treated with these new interventions.

Noninvasive cerebral perfusion imaging in high-risk neonates

Advances in medical and surgical care of the high-risk neonate have led to increased survival. A significant number of these neonates suffer from neurodevelopmental delays and failure in school. The focus of clinical research has shifted to understanding events contributing to neurological morbidity in these patients. Assessing changes in cerebral oxygenation and regulation of cerebral blood flow (CBF) is important in evaluating the status of the central nervous system. Traditional CBF imaging methods fail for both ethical and logistical reasons. Optical near infrared spectroscopy (NIRS) is increasingly being used for bedside monitoring of cerebral oxygenation and blood volume in both very low birth weight infants and neonates with congenital heart disease. Although trends in CBF may be inferred from changes in cerebral oxygenation and/or blood volume, NIRS does not allow a direct measure of CBF in these populations. Two relatively new modalities, arterial spin-labeled perfusion magnetic resonance imaging and optical diffuse correlation spectroscopy, provide direct, noninvasive measures of cerebral perfusion suitable for the high-risk neonates. Herein we discuss the instrumentation, applications, and limitations of these noninvasive imaging techniques for measuring and/or monitoring CBF.

Enhancement of autophagic flux after neonatal cerebral hypoxia-ischemia and its region-specific relationship to apoptotic mechanisms

The multiplicity of cell death mechanisms induced by neonatal hypoxia-ischemia makes neuroprotective treatment against neonatal asphyxia more difficult to achieve. Whereas the roles of apoptosis and necrosis in such conditions have been studied intensively, the implication of autophagic cell death has only recently been considered. Here, we used the most clinically relevant rodent model of perinatal asphyxia to investigate the involvement of autophagy in hypoxic-ischemic brain injury. Seven-day-old rats underwent permanent ligation of the right common carotid artery, followed by 2 hours of hypoxia. This condition not only increased autophagosomal abundance (increase in microtubule-associated protein 1 light chain 3-11 level and punctuate labeling) but also lysosomal activities (cathepsin D, acid phosphatase, and beta-N-acetylhexosaminidase) in cortical and hippocampal CA3-damaged neurons at 6 and 24 hours, demonstrating an increase in the autophagic flux. In the cortex, this enhanced autophagy may be related to apoptosis since some neurons presenting a high level of autophagy also expressed apoptotic features, including cleaved caspase-3. On the other hand, enhanced autophagy in CA3 was associated with a more purely autophagic cell death phenotype. In striking contrast to CA3 neurons, those in CA1 presented only a minimal increase in autophagy but strong apoptotic characteristics. These results suggest a role of enhanced autophagy in delayed neuronal death after severe hypoxia-ischemia that is differentially linked to apoptosis according to the cerebral region.