Background
Aetiology
- Paracetamol toxicity 50%.
- Other drugs (esp. NSAIDs, anticonvulsants).
- Acute viral hepatitis (incl. Hep A).
- Acute deterioration in liver function (often previously normal) leading to encephalopathy and encephalopathy
- 50 % die or need transplant (less if acute on chronic dysfunction)
- Most develop SIRS (early treatment significantly improves prognosis)
- Very rapid progress (time jaundice to encephalopathy < 8 days) relatively better prognosis (if no cerebral oedema)
Initial assessment
Differential DDx hepatic dysfunction and antlered mentation
- Acutely decompensated chronic liver disease.
- Sepsis.
N-acetylcysteine?
- Immediately indicate if ANY chance paracetamol toxicity.
- Helps with repletion of hepatic glutathione and O2 delivery to cells.
- Probably Indicated in most cases, irrespective of aetiology.
Transfer to liver unit?
- Discuss potential cases early
- Beware INR > 2 or encephalopathy
- Extremes of age
- Early transplant being considered
- Beware HYPOGLYCAEMIA (continue 5% dextrose)
- Beware airway (consider RSI and ETT in all) if encephalopathy
King’s College criteria for Liver Transplant in ALF
Paracetamol toxicity
- Lactate > 3.5 4 hrs after resuscitation.
or
- pH< 7.30 or lactate > 3.0 12 hrs after resusc.
or
- INR > 6.5 (PT > 100 sec).
- Creat > 3.4 mg/dl
- Stage 3 or 4 encephalopathy
Non-paracetamol causes
- Lactate > 3.5 4 hrs after resuscitation.
or
- INR > 6.5 (PT > 100 sec).
or
- any 3 of the following:
- INR > 3.5 (PT > 50 sec).
- Age <10 or > 40 years.
- Serum bilirubin > 17.5 mg/dl.
- Duration of jaundice > 7 days.
- Aetiology: drug reaction.
Complications
- SIRS and multiorgan failure often triggered by sepsis
- Immunocompromise (side effect ALF)
- Invasive lines, chest (bacterial or fungal), UTI (catheter)
- Clinical signs sepsis may be lacking
- Prophylactic antibiotics indicated in most ALF
- Beware subtle, progressive airway compromise
- ARDS occurs in 1/3
- 1/4 develop cerebral oedema (? ammonia trigger)
Cerebral oedema
SIRS
Temp >38 °C or <36 °C
WCC >12 or <4 × 109/l
Pulse rate >90 bpm
- Oedema more common in hyper-acute ALF
- Consider ICP monitoring
- Nurse 30° head up
- Prophylactic Lactulose & antibiotics to reduce ammonia
- Opiate sedation relatively safe
- Actively treat pyrexia
- Monitor for and avoid hyponatraemia
- Mannitol (1 g/kg body weight) if worse confusion, serum osmolality is <320 mOsm/l, or high osmolar gap
- Seizures (atypical) very common in encephalopathy, Phenytoin unproven
Other complications
- Vasodilation and hypoperfusion treated a per sepsis (response to crystalloid challenge ± early inotropes)
- Beware adrenal failure
- Despite coagulation factor deficit and thrombocytopenia, bleeding only really with invasive procedures
- Prophylactic PPI (e.g. Zoton Fastab - MADE IN IRELAND). Variceal haemorrhage rare!
- Acute renal failure (acute tubular necrosis +/or hepatorenal synd.) common (50%), esp. in paracetamol poisoning
- Renal replacement therapy indicated for azotemia, volume overload, acidosis and electrolyte problems
- All above aggressively treated to try to prevent cerebral oedema