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Hypothermia for Neonatal HIE
Pilot Study of Treatment with Whole Body Hypothermia for Neonatal Encephalopathy. Azzopardy MA, Robertson NJ, Cowan FM, et al. Pediatrics 2000; 106: 684-94.
The objectives of this study were to determine whether it would be feasible to select infants with a bad neurological prognosis and to begin hypothermic therapy within 6 hours of birth, and to observe the effect of this therapy on relavent physiologic variables. Sixteen newborn infants with clinical features of birth asphyxia were assessed by amplitude integrated encephalography (aEEG), and mild whole body hypothermia was instituted within 6 hours of birth in the 10 infants with an aEEG prognostic of a bad outcome. Rectal temperature was maintained at 33.2 +/- 0.6 degrees centigrade for 48 hours. All infants selected to receive hypothermia developed convulsions and a severe encephalopathy. During hypothermia, infants had prolonged metabolic acidosis, elevated lactate and decreased blood potassium levels, lower heart rate and higher mean blood pressure. These changes did not seem to be clinically relevant, and no significant complication from hypothermia was encountered. Blood viscosity and coagulation studies were similar during and after cooling. Unusual MRI findings were noted in 3 infants: transverse sinus thrombosis with small cerebellar infarct; probable thrombosis in the straight sinus; and hemorrhagic cerebellar infarct. Six of the 10 cooled infants had minor abnormalities only or normal follow up neurological examination, 3 infants died, and 1 had major abnormalities. None of the 6 infants with normal aEEG developed a severe neonatal encephalopathy of neurological sequel.
Comment. This was a pilot study, not a randomized clinical trial. The results appear encouraging, but do not validate either the efficacy or the safety of this experimental treatment for neonatal encephalopathy. That being said, I was impressed that this degree of whole body hypothermia was relatively easy to maintain and apparently well-tolerated (despite minor metabolic derangement). The short-term neurological outcomes were very good in 6 of 7 survivors in the treatment group, but without a control group it is difficult to know if this was significant. It also appears that a normal aEEG may be predictive of a good neurological outcome in asphyxiated neonates. We now must await the results of a large multi-center RCT of whole body hypothermia in the treatment of neonatal encephalopathy . Surely such a study will be forthcoming after the encouraging results of this pilot study.
Andrew B. Kairalla MD