Continuous venovenous hemofiltration in neonates with hyperammonemia. A case series

Neonatal hyperammonemia secondary due to inborn errors of metabolism is a rare condition with a high rate of neurological sequelae and mortality. Initial medical management is often insufficient to stop the progressive increase of ammonia, with the consequent deterioration of the patient. For this reason, depurative techniques have been implemented, including peritoneal dialysis, intermittent hemodialysis and continuous renal replacement therapy (CRRT).

To describe our experience with continuous extracorporeal dialysis in severely ill neonates with hyperammonemia.

Retrospective review of clinical records of neonates with hyperammonemia due to congenital errors of metabolism undergoing CRRT admitted in our institution in the last 6 years. Demographic data, chronological and gestational age, gender, anthropometric and laboratory data (creatininemia, ammonemia), and severity index PIM-II where collected. It was analyzed the CRRT: modality, duration and complications. The stard of therapy depended on the response to medical management in the first 24 hours, progressive neurological involvement, or increased blood ammonia (> 400 qg/dl) at the time of admission. CRRTs were performed using the Prisma Flex system and M100 and/or HF20 filters.

6 neonates, 4 males, half of them with a history of prematurity, all with severe acute neurological involvement and severe ammonemias (> 1,000 qg/dl). The average age and weight at the start of the CRRT were 10 days and 2798 g, respectively, ammonia (median) 1,663 qg/dl (range 1,195 - 3,097). The PIM-II score had a median of 53 (range 13.4 - 87.4). On average, patients were 49.5 hours in continuous therapy. In four neonates, a mixed convective and diffusive technique (hemodiafiltration) was used, and only convective one (hemofiltration) in the 2 remaining. Mortality was 33%, and one of the survivors had permanent moderate neurological damage in clinical follow-up.

The results obtained in this extremely ill group of neonates encourage us to propose this dialytic therapy as an excellent alternative in the management of this type of patients.