Systemic hypothermia after neonatal encephalopathy: outcomes of neo.nEURO.network RCT.

OBJECTIVE: Mild hypothermia after perinatal hypoxic-ischemic encephalopathy (HIE) reduces neurologic sequelae without significant adverse effects, but studies are needed to determine the most-efficacious methods.

METHODS: In the neo.nEURO.network trial, term neonates with clinical and electrophysiological evidence of HIE were assigned randomly to either a control group, with a rectal temperature of 37°C (range: 36.5-37.5°C), or a hypothermia group, cooled and maintained at a rectal temperature of 33.5°C (range: 33-34°C) with a cooling blanket for 72 hours, followed by slow rewarming. All infants received morphine (0.1 mg/kg) every 4 hours or an equivalent dose of fentanyl. Neurodevelopmental outcomes were assessed at the age of 18 to 21 months. The primary outcome was death or severe disability.

RESULTS: A total of 129 newborn infants were enrolled, and 111 infants were evaluated at 18 to 21 months (53 in the hypothermia group and 58 in the normothermia group). The rates of death or severe disability were 51% in the hypothermia group and 83% in the normothermia group (P=.001; odds ratio: 0.21 [95% confidence interval [CI]: 0.09-0.54]; number needed to treat: 4 [95% CI: 3-9]). Hypothermia also had a statistically significant protective effect in the group with severe HIE (n=77; P=.005; odds ratio: 0.17 [95% CI: 0.05-0.57]). Rates of adverse events during the intervention were similar in the 2 groups except for fewer clinical seizures in the hypothermia group.

CONCLUSION: Systemic hypothermia in the neo.nEURO.network trial showed a strong neuroprotective effect and was effective in the severe HIE group.