Acute pediatric hyperammonemia: current diagnosis and management strategies

Nadia Savy,1 David Brossier,2 Catherine Brunel-Guitton,1 Laurence Ducharme-Crevier,1 Geneviève Du Pont-Thibodeau,1 Philippe Jouvet1 1Department of Pediatrics, CHU Sainte-Justine, University of Montreal, Montreal, QC, Canada; 2Department of Pediatrics, Pediatric Intensive Care Unit, CHU Caen, Caen, France Abstract: Acute hyperammonemia may induce a neurologic impairment leading to an acute life-threatening condition. Coma duration, ammonia peak level, and hyperammonemia duration are the main risk factors of hyperammonemia-related neurologic deficits and death. In children, hyperammonemia is mainly caused by severe liver failure and inborn errors of metabolism. In an acute setting, obtaining reliable plasma ammonia levels can be challenging because of the preanalytical difficulties that need to be addressed carefully. The management of hyperammonemia includes 1) identification of precipitating factors and cerebral edema presence, 2) a decrease in ammonia production by reducing protein intake and reversing catabolism, and 3) ammonia removal with pharmacologic treatment and, in the most severe cases, with extracorporeal therapies. In case of severe coma, transcranial Doppler ultrasound could be the method of choice to noninvasively monitor cerebral blood flow and titrate therapies. Keywords: pediatrics, critical care, hyperammonemia, sodium phenylacetate, sodium benzoate, hemodialysis