Acute neonatal hyperammonemia is associated with poor neurological outcomes and high mortality. A user-friendly and widely applicable algorithm - based on kinetics - to tailor the treatment of acute neonatal hyperammonemia. A single compartmental model was calibrated assuming a distribution volume equal to the patient's total body water (V), as calculated using Wells' formula, and dialyzer clearance as derived from the measured ammonia time-concentration curves during 11 dialysis sessions in four patients (3.2 +/- 0.4 kg). Based on these kinetic simulations, dialysis protocols could be derived for clinical use with different body weights, start concentrations, dialysis machines/dialyzers and dialysis settings (e.g., blood flow QB). By a single measurement of ammonia concentration at the dialyzer inlet and outlet, dialyzer clearance (K) can be calculated as K = QB[(Cinlet - Coutlet)/Cinlet]. The time (T) needed to decrease the ammonia concentration from a predialysis start concentration Cstart to a desired target concentration Ctarget is then equal to T = (-V/K)LN(Ctarget/Cstart). By implementing these formulae in a simple spreadsheet, medical staff can draw an institution-specific flowchart for patient-tailored treatment of hyperammonemia.

The aim of this study is to validate these formula with a prospective study.

Inclusion Criteria:

• severe acute neonatal hyperammonaemia for which acute hemodialysis is indicated
• inborn error of metabolism
• below 1 year of age

Exclusion Criteria:

• older than 1 year

infants presenting with acute neonatale hyperammonaemia