Hyperammonaemia in Neonatal Transport: A Retrospective Statewide Review of Neonates Retrieved With Elevated Ammonia
Jessica Sabljak, Michael Stewart, Gregory Woodhead, Rosalynn PszczolaABSTRACT
Aims
To characterise the aetiology, retrieval characteristics and outcomes of neonatal hyperammonaemia in a statewide neonatal retrieval service.
Methods
Retrospective chart review of all neonates (aged ≤ 8 weeks) retrieved by the statewide Paediatric Infant Perinatal Emergency Retrieval (PIPER) service to the Royal Children's Hospital (RCH), Melbourne, Australia, between April 2016 and February 2025, with a pre‐transport plasma ammonia > 100 μmol/L.
Results
Twenty‐one neonates met inclusion criteria. Median gestation was 38 weeks (IQR: 38–39) and median age at retrieval referral was 59 h (IQR: 48–84). A confirmed inborn error of metabolism (IEM) was identified in 16 of 21 neonates (76%), with urea cycle disorders accounting for 12 of the 16 confirmed IEMs (75%). Twelve patients (57%) required continuous veno‐venous haemofiltration (CVVHF). Compared with those managed without haemofiltration, the CVVHF group had higher peak ammonia (median 854 vs. 378 μmol/L) and a higher rate of confirmed IEM (92% vs. 56%). Twelve retrievals (57%) were classified as time‐critical, and metabolic medication was administered during transport in nine cases (43%). Median time from decision to retrieve to team dispatch was 20 min (IQR: 13–26) and to specialist hospital arrival 152 min (IQR: 97–229). Seventeen neonates (81%) survived to hospital discharge.
Conclusions
Neonatal hyperammonaemia requiring retrieval is predominantly caused by an IEM and frequently requires CVVHF, with low occurrence of spurious elevation. These findings support early retrieval to a quaternary centre with haemofiltration capability and provide benchmarking data for retrieval services managing this rare, high‐acuity condition.