Emergency treatment of neonatal hyperammonaemic coma with mild systemic hypothermia.

An infant aged 3 days presented with hyperammonaemic coma and seizures, which were found to be a result of a urea-cycle defect. Haemofiltration, alternative pathway metabolites, and glucose and insulin failed to lower the plasma ammonia concentration below 2000 micromol/L. The infant was then cooled to a rectal temperature of 34 degrees C for 48 h and put on haemofiltration for 12 h. Plasma ammonia fell to around 100 micromol/L and remained at this concentration after haemofiltration. He roused from his coma, breathed spontaneously, and resumed bottle feeding. Hypothermia may be therapeutic in such instances of metabolic coma because it lowers the enzymatic rate of production of the toxin while non-enzymatic methods remove the toxin.