The impact of updated national guidelines for managing unintentional paediatric liquid paracetamol exposures: a retrospective poisons centre study.

Introduction: In 2015, Australia and New Zealand treatment guidelines recommended a 2 h paracetamol serum concentration for risk assessment of unintentional paracetamol liquid exposures. We assess our experience with this approach.

Methods: Retrospective case review of children <6 years-old with liquid paracetamol overdoses referred to a regional poisons information centre January 2017 to August 2022. We extracted data on the exposure and management from the poisons information centre and hospital medical records. We identified additional cases with two paracetamol concentrations obtained from September 2022 to June 2024.

Results: Of 437 paediatric poisonings, 271 were eligible for inclusion. The median age was 24 months, the median time to presentation was 120 min, and paracetamol was the sole ingestant in 92% of cases. Blood testing was recommended in 131 patients (48.3%), occurring at 2 h post-ingestion in 62 patients (47.3%). Testing at a later time was mostly due to delayed presentation, including to hospitals unable to measure paracetamol concentrations. Eighteen patients (16.7%) had repeat blood testing, and five additional cases were identified in the subsequent period. Overall, the concentration decreased in 19 patients (83%), but in three patients it increased, from 73 mg/L to 81 mg/L (0.49-0.54 mmol/L), from 154 mg/L to 179 mg/L (1.03-1.19 mmol/L), and from 56 mg/L to 115 mg/L (0.37-0.77 mmol/L). Symptomatic patients were more likely to receive a second blood test or acetylcysteine while awaiting investigations. Of 19 patients administered acetylcysteine, it was discontinued in five due to low paracetamol serum concentrations. All patients recovered.

Discussion: Guidelines were followed in >90% of patients and this testing regimen shortened length of stay. Based on these data, Australian treatment guidelines now recommend repeat testing for 2 h paracetamol serum concentrations >100 mg/L (0.67 mmol/L).

Conclusion: A paracetamol serum concentration between 2 h and 4 h post-ingestion in children <6 years-old with unintentional poisonings of paracetamol liquid can facilitate medical discharge.