The TOBY Study. Whole body hypothermia for the treatment of perinatal asphyxial encephalopathy: a randomised controlled trial

Collaborative pediatric critical care research network: looking back and moving forward

OBJECTIVE

To update the pediatric critical care community on the progress of the Collaborative Pediatric Critical Care Research Network and plans for the future.

SETTING

The six sites, seven hospitals of the Collaborative Pediatric Critical Care Research Network.

RESULTS

From the time of its inception in August 2005, the Network has engaged in a number of observational and interventional trials, several of which are ongoing. Additional studies are in the planning stages. To date, these studies have resulted in the publication of six manuscripts and five abstracts, with five additional manuscripts accepted and in press.

CONCLUSION

The Network remains committed to its stated goal "to initiate a multicentered program designed to investigate the safety and efficacy of treatment and management strategies to care for critically ill children, as well as the pathophysiologic basis of critical illness and injury in childhood."

Neonatal seizures: an update on mechanisms and management

The lifespan risk of seizures is highest in the neonatal period. Current therapies have limited efficacy. Although the treatment of neonatal seizures has not changed significantly in the last several decades, there has been substantial progress in understanding developmental mechanisms that influence seizure generation and responsiveness to anticonvulsants. This article provides an overview of current approaches to the diagnosis and treatment of neonatal seizures, and some of the recent insights about the pathophysiology of neonatal seizures that may provide the foundation for better treatment are identified.

Postcardiac arrest syndrome: focus on the brain

PURPOSE OF REVIEW

The field of pediatric cardiac arrest experienced recent advances secondary to multicenter collaborations. This review summarizes developments during the last year and identifies areas for further research.

RECENT FINDINGS

A large retrospective review demonstrated important differences in cause, severity, and outcome of in-hospital vs. out-of-hospital pediatric cardiac arrest. This distinction is relevant to interpretation of retrospective studies that may not distinguish between these entities, and in planning therapeutic clinical trials. Hypothermia was further evaluated as a treatment strategy after neonatal hypoxia and leaders in the field of neonatology recommend universal use of hypothermia in term neonates at risk. In infants and children after cardiac arrest, there are inadequate data to make a specific recommendation. Two retrospective studies evaluating hypothermia in children after cardiac arrest found that it tended to be administered more frequently to sicker patients. However, similar or worse outcomes of patients treated with hypothermia were observed. Use of extracorporeal membrane oxygenation is another emerging area of research in pediatric cardiac arrest, and surprisingly good outcomes have been seen with this modality in some cases.

SUMMARY

Therapeutic hypothermia and extracorporeal membrane oxygenation continue to be the only treatment modalities over and above conventional care for pediatric cardiac arrest. New approaches to monitoring, treatment, and rehabilitation after cardiac arrest remain to be explored.

Cortical visual impairment: new directions

Cortical visual impairment is the leading cause of bilateral low vision in children in the U.S., yet very little research is being performed to find new diagnostic measures and treatments. Dr. Velma Dobson pioneering work on visual assessments of developmentally delayed children stands out as highly significant in this field. Future research will assess new diagnostic measures, including advanced imaging techniques. In addition, research will evaluate methods to prevent, treat, and rehabilitate infants and children afflicted with this condition.

Hypothermia for hypoxic ischemic encephalopathy in infants > or =36 weeks

Hypoxic ischemic encephalopathy is a serious condition affecting infants which can result in death and disability. This is a summary of pathogenesis of HIE, animal studies of cooling for hypoxic and ischemic models, human hypothermia trials, and the American Academy of Pediatrics publication on hypothermia for HIE. Hypothermia for neonatal HIE is continuing to evolve as a therapy. Studies, gaps in knowledge and opportunities for research are presented herein.

Neonatal resuscitation in low-resource settings: what, who, and how to overcome challenges to scale up?

BACKGROUND

Each year approximately 10 million babies do not breathe immediately at birth, of which about 6 million require basic neonatal resuscitation. The major burden is in low-income settings, where health system capacity to provide neonatal resuscitation is inadequate.

OBJECTIVE

To systematically review the evidence for neonatal resuscitation content, training and competency, equipment and supplies, cost, and key program considerations, specifically for resource-constrained settings.

RESULTS

Evidence from several observational studies shows that facility-based basic neonatal resuscitation may avert 30% of intrapartum-related neonatal deaths. Very few babies require advanced resuscitation (endotracheal intubation and drugs) and these newborns may not survive without ongoing ventilation; hence, advanced neonatal resuscitation is not a priority in settings without neonatal intensive care. Of the 60 million nonfacility births, most do not have access to resuscitation. Several trials have shown that a range of community health workers can perform neonatal resuscitation with an estimated effect of a 20% reduction in intrapartum-related neonatal deaths, based on expert opinion. Case studies illustrate key considerations for scale up.

CONCLUSION

Basic resuscitation would substantially reduce intrapartum-related neonatal deaths. Where births occur in facilities, it is a priority to ensure that all birth attendants are competent in resuscitation. Strategies to address the gap for home births are urgently required. More data are required to determine the impact of neonatal resuscitation, particularly on long-term outcomes in low-income settings.

Passive induction of hypothermia during transport of asphyxiated infants: a risk of excessive cooling

BACKGROUND

Induced mild hypothermia is an emerging therapy that has been shown to reduce the combined outcome of death or severe neurodevelopmental disabilities in asphyxiated full-term infants if started within 6 h after birth.

AIM

To study the feasibility and safety of inducing hypothermia in asphyxiated infants already at the referring hospital by stopping active warming.

METHODS

Temperatures during passive induction of hypothermia were prospectively collected from transported asphyxiated infants.

RESULTS

Between December 2006 and April 2008, 37 infants of the total birth cohort of 40, 350 fulfilled the criteria for hypothermia treatment. Eighteen of 34 infants treated with induced hypothermia were outborn. The rectal temperatures of the infants were 33.0-36.4 degrees C before transport and 31.0-36.5 degrees C on arrival. Six of the infants had a sub-therapeutic (<33.0 degrees C) rectal temperature on arrival.

CONCLUSION

Passive induction of hypothermia by turning off active warming devices is possible, making an earlier start of hypothermia achievable. However, there is a substantial risk of unintended excessive cooling;therefore, continuous monitoring of the central temperature is mandatory when such a strategy is used.

Mitochondrial mechanisms of cell death and neuroprotection in pediatric ischemic and traumatic brain injury

There are several forms of acute pediatric brain injury, including neonatal asphyxia, pediatric cardiac arrest with global ischemia, and head trauma, that result in devastating, lifelong neurologic impairment. The only clinical intervention that appears neuroprotective is hypothermia initiated soon after the initial injury. Evidence indicates that oxidative stress, mitochondrial dysfunction, and impaired cerebral energy metabolism contribute to the brain cell death that is responsible for much of the poor neurologic outcome from these events. Recent results obtained from both in vitro and animal models of neuronal death in the immature brain point toward several molecular mechanisms that are either induced or promoted by oxidative modification of macromolecules, including consumption of cytosolic and mitochondrial NAD(+) by poly-ADP ribose polymerase, opening of the mitochondrial inner membrane permeability transition pore, and inactivation of key, rate-limiting metabolic enzymes, e.g., the pyruvate dehydrogenase complex. In addition, the relative abundance of pro-apoptotic proteins in immature brains and neurons, and particularly within their mitochondria, predisposes these cells to the intrinsic, mitochondrial pathway of apoptosis, mediated by Bax- or Bak-triggered release of proteins into the cytosol through the mitochondrial outer membrane. Based on these pathways of cell dysfunction and death, several approaches toward neuroprotection are being investigated that show promise toward clinical translation. These strategies include minimizing oxidative stress by avoiding unnecessary hyperoxia, promoting aerobic energy metabolism by repletion of NAD(+) and by providing alternative oxidative fuels, e.g., ketone bodies, directly interfering with apoptotic pathways at the mitochondrial level, and pharmacologic induction of antioxidant and anti-inflammatory gene expression.

[Hypothermia for intracranial hypertension]

There is a large body of experimental evidence showing benefits of deliberate mild hypothermia (33-35 degrees C) on the injured brain as well as an improvement of neurological outcome after cardiac arrest in humans. However, the clinical evidence of any benefit of hypothermia following stroke, brain trauma and neonatal asphyxia is still lacking. Controversial results have been published in patients with brain trauma or neonatal asphyxia. Hypothermia can reduce the elevation of intracranial pressure, through mechanisms not completely understood. Hypothermia-induced hypocapnia should have a role on the reduction of intracranial pressure. The temperature target is unknown but no additional benefit was found below 34 degrees C. The duration of deliberate hypothermia for the treatment of elevated intracranial pressure might be at least 48 hours, and the subsequent rewarming period must be very slow to prevent adverse effects.

Successful treatment of profound hypothermia of the newborn

We report a case of a profoundly hypothermic newborn with a core temperature of 25 degrees C with a successful recovery and normal neurological outcome at 3 and 6 months. This term male infant had been exposed to a temperature of -3 degrees C for approximately 30 min. Slow re-warming, using external modalities was used in addition to volume expansion, heparinization, antibiotics and sedation. There is limited information available concerning the safest and most effective method of re-warming hypothermic newborns. Slow re-warming has been advocated as it replicates the normal physiological process in a neonate, which minimizes a negative therapy impact.

CONCLUSION

The most significant decision regarding treatment is the identification of the most appropriate method and speed of re-warming. This report supports recommendations for gradual re-warming of a severely hypothermic newborn. Physiological cardiovascular mechanisms seemed to be intact during slow re-warming; this might be applicable to the treatment of profound hypothermia of the newborn.

Acute brain injury and therapeutic hypothermia in the PICU: A rehabilitation perspective

Acquired brain injury from traumatic brain injury, cardiac arrest (CA), stroke, and central nervous system infection is a leading cause of morbidity and mortality in the pediatric population and reason for admission to inpatient rehabilitation. Therapeutic hypothermia is the only intervention shown to have efficacy from bench to bedside in improving neurological outcome after birth asphyxia and adult arrhythmia-induced CA, thought to be due to its multiple mechanisms of action. Research to determine if therapeutic hypothermia should be applied to other causes of brain injury and how to best apply it is underway in children and adults. Changes in clinical practice in the hospitalized brain-injured child may have effects on rehabilitation referral practices, goals and strategies of therapies offered, and may increase the degree of complex medical problems seen in children referred to inpatient rehabilitation.

Supportive care during neuroprotective hypothermia in the term newborn: adverse effects and their prevention

Hypothermia as neuroprotective treatment requires significant knowledge of how temperature affects all organ systems and interventions used in intensive care. Education and training in resuscitation, including avoidance of hyperthermia, early diagnosis of eligible infants, and initiation of early cooling followed by safe transport of cooled infants to the cooling center seems to be an optimal approach. This article suggests clinical management and shows examples of potential adverse effects of clinical hypothermia. The practical cooling recommendations suggested herein are therefore likely to develop and change over time as more experience is gained.

Cooling for newborns with hypoxic ischaemic encephalopathy

BACKGROUND

Newborn animal and human pilot studies suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae, without adverse effects.

OBJECTIVES

To determine whether therapeutic hypothermia in encephalopathic asphyxiated newborn infants reduces mortality and long-term neurodevelopmental disability, without clinically important side effects.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group as outlined in the Cochrane Library (Issue 2, 2003) was used. Randomised controlled trials evaluating therapeutic hypothermia in term newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue Issue 2, 2003), MEDLINE (1966 to July 2003), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching.

SELECTION CRITERIA

Randomised controlled trials comparing the use of therapeutic hypothermia with normothermia in encephalopathic newborn infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies were included. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

Three reviewers independently selected, assessed the quality of and extracted data from the included studies. Authors were contacted for further information. Meta-analyses were performed using relative risk and risk difference for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals.

MAIN RESULTS

Two randomised controlled trials were included in this review, comprising 50 term infants with moderate/ severe encephalopathy and evidence of intrapartum asphyxia. There was no significant effect of therapeutic hypothermia on the combined outcome of death or major neurodevelopmental disability in survivors followed. No adverse effects of hypothermia on short term medical outcomes or on some 'early' indicators of neurodevelopmental outcome were detected.

REVIEWER'S CONCLUSIONS

Although two small randomised controlled trials demonstrated neither evidence of benefit or harm, current evidence is inadequate to assess either safety or efficacy of therapeutic hypothermia in newborn infants with hypoxic ischaemic encephalopathy. Therapeutic hypothermia for encephalopathic asphyxiated newborn infants should be further evaluated in well designed randomised controlled trials.