Stage I (0-24 hours) – relatively non-specific with nausea, vomiting, malaise and diaphoresis, though some patients may be asymptomatic. Uncommonly may have CNS depression
Stage II (24-72 hours) – resolution of initial Stage I symptoms with subsequent development of RUQ pain and hepatic enlargement. Uptrending LFT’s.
Stage III (72-96 hours) – Peak LFT derangement with manifestations of liver failure (jaundice, hepatic encephalopathy, coagulopathy). Most people who die from their overdose will die in this stage from multi-organ failure
Stage IV(Days 4-7) – Symptoms resolve and patients recover, usually by day 7. Those who have had large overdoses or who were severely ill may have more protracted recoveries past a week
Paracetamol Overdose Normogram
Take serum paracetamol level at least 4 hours post-ingestion (earlier levels will be inaccurate)
If the level lies above the line on the normogram, commence NAC infusion
If the level is greater than double the line on the normogram, commence a high dose NAC infusion instead
An extended NAC infusion should be commenced if ALT > 50 or paracetamol level >10 on repeat bloods, 2 hours prior to cessation of original NAC infusion
NAC infusion can then cease when paracetamol level < 10, ALT is downtrending and INR <2.
N.B. If the patient has ingested a toxic dose of paracetamol (>10g) and presents >8 hours post-ingestion, commence NAC infusion before paracetamol level returns.
Standard NAC Infusion:
200mg/kg of NAC in 500ml’s over 4 hours, and then the 2nd bag with 100mg/kg in 1L over 16 hours
Higher Dose NAC Infusion:
200mg/kg of NAC in 500ml’s over 4 hours, and the 2nd bag contains 200mg/kg in 1L over 16 hours