Induced hypothermia: a novel neuroprotective treatment of neonatal encephalopathy after intrapartum hypoxia-ischemia

Abstract

The current treatment approach to an infant at risk for progression to neonatal encephalopathy after intrapartum hypoxia-ischemia is threefold: 1) early identification of the infant at highest risk for evolving brain injury based on the criteria of a sentinel event during labor, prolonged depression at birth with the need for resuscitation, and evidence of severe fetal acidemia based on a cord umbilical arterial pH less than 7 and/or a base deficit more than -16 meq per L, with early clinical and/or electroencephalogram assessment of moderate to severe encephalopathy; 2) supportive therapy instituted to maintain adequate ventilation and in particular pCO2 levels in a normal range, mean arterial blood pressure within a normal range so as to avoid perturbations in cerebral perfusion, glucose in a normal range to avoid hypoglycemia, and the judicious treatment of seizures; and 3) neuroprotection--induced hypothermia is currently the only strategy that has been rigorously evaluated in two large, multicenter randomized studies. The first study used selective cooling with a cool cap to a rectal temperature at 34.5 degrees C, and the second study used total body cooling to an esophageal temperature of 33.5 degrees C, with the temperature in both studies maintained for 72 hours. No significant side effects were noted with this degree of cooling. The combined data indicate that hypothermia is associated with a reduction in the incidence of death and/or severe disability at 18 months follow-up, with the most significant effect observed in infants who at the initiation of therapy present with modest encephalopathy and/or do not exhibit electrographic seizures.