Late Hypothermia for Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a rare, but life-threatening condition characterized by acute or subacute brain injury due to asphyxia. In most cases the underlying cause and timing of injury are unknown, but many cases are diagnosed at or shortly after birth. According to the World Health Organization, more than 722,000 children died from birth asphyxia and birth trauma worldwide in 2004. An estimated 50-75 percent of infants with severe (stage 3) HIE will die, with 55 percent of these deaths occurring in the first month. The incidence of long-term complications depends on the severity of HIE. Up to 80 percent of infants who survive stage 3 HIE develop significant long-term neurological disabilities - mental retardation, epilepsy, and cerebral palsy with hemiplegia, paraplegia, or quadriplegia; 10-20 percent develop moderately serious disabilities; and up to 10 percent are normal. Because animal data suggests that brain injury from HIE evolves over several hours to days after the initial asphyxic insult, induced hypothermia holds promise as a neuroprotective therapy. Additional trials are needed to help define the most effective cooling strategies. With this in mind, and knowing that many babies with HIE arrive at neonatal intensive care units several hours after birth, this study will evaluate the safety and efficacy of initiating hypothermia 6-24 hours after birth. Study subjects: Infants born at 36 0/7ths weeks or greater gestational age that have been diagnosed with neonatal depression, perinatal asphyxia, or encephalopathy. The goal is to enroll 168 subjects. Stratification: After informed consent is obtained, infants will be randomized to either a hypothermia arm (with a target esophageal temperature of 33.5°C) or a control arm (37.0°C) for 96 hours. Enrolled infants will be stratified by age of enrollment (≤ 12 and \> 12 hours) and stage of encephalopathy (moderate or severe). Informed Consent: Parents of eligible infants will be approached for consent to enroll in the study if the infant has a high probability of acute hemodynamic compromise, as defined above. Subsequent screening will determine whether the infant meets all inclusion criteria. Randomization: eligible and consented infants will be randomly assigned to either a hypothermia intervention group, or a non-cooled (control) group. Study Intervention: Induced whole-body hypothermia (with a target esophageal temperature of 33.5°C) or a control group (37.0°C) for 96 hours. Interim Study Interruptions: None to date. Secondary Study includes determining an association between MRI detectable injury and neurodevelopment at 18-22 months.