AFTB Lecture Notes - Acute Liver Failure
Oct 4th, 2008 by sandnsurf
DEFINITION
- Hyperacute liver failure
- Presents within 7 days of onset. 36% survival with medical management alone (single most common cause in UK and USA is paracetamol poisoning).
- Acute liver failure
- Encephalopathy, coagulopathy and jaundice presenting within 8-28 days in patient with previously normal liver. More likely (with hyperacute group) to get cerebral oedema (80%).
- Subacute liver failure
- Presents from 29-72 days, less likely to get cerebral oedema, but more likely to have ascites. Poorer 14% survival.
AETIOLOGY
- Commonest causes:
- Viral hepatitis A, B, C, D, E, F, G, EBV, CMV, HSV, HZV.
- Drugs including paracetamol poisoning - including multiple doses, often inadvertently in children, volatile anaesthetics, idiosyncratic reactions to rifampicin / isoniasid / NSAIDs / valproate and use of Ecstasy (methylmetamphetamine).
Jalan R, Williams R, Bernuau J. Paracetamol: are therapeutic doses entirely safe? Lancet 2006; 368: 2195-6. (Editorial) [Reference]
- Rare (5% causes):
- Autoimmune CAH, Budd-Chiari, Wilson’s, fatty liver of pregnancy, pre-eclampsia (HELLP), mushrooms (Amanita phalloides).
- Malignancy, ischaemia, heat stroke, Reye’s.
MANAGEMENT
- General supportive:
- Hospitalize if INR >1.5; IPPV for Grade 3 or 4 coma or respiratory failure, invasive monitoring including ICP monitor (ICP < 25 mmHg) +/- jugular bulb O2 (NB: clinical signs/imaging unreliable to detect the earliest signs cerebral oedema), infusion 5-10% dextrose (watch for hyponatraemia), fluids and vasopressor noradrenaline therapy. GI bleeding prophylaxis.
- Specific to complications:
- Encephalopathy with cerebral oedema. Correct avoidable factors (hypoxia, sepsis, hyperthermia, hemorrhage, hypokalaemia, benzodiazepines), monitor ICP early. Give mannitol 0.5 g/kg if ICP ≥ 25 mmHg, or hypertonic saline 7.5% boluses 2.0 mL/kg. Lactulose and neomycin appear not to work, and have complications such as aspiration and nephrotoxicity, respectively.
Shawcross D, Jalan R. Dispelling myths in the treatment of hepatic encephalopathy. Lancet 2005; 365:431-3. [Reference]
- Infection. Daily surveillance for bacterial (S.aureus, S.pneumoniae and E.coli) and fungal (Candida) infections, including primary peritonitis. Empiric and or prophylactic broad-spectrum antibiotics + antifungals given.
- Microcirculatory / haemodynamic failure including acute oliguric renal failure. Epoprostenol (PGI2), angiotensin, vasopressors, NOS antagonists.
- Coagulopathy. Vit K 10 mg IV; FFP / platelets for active bleeding; recombinant Factor VIIa (rFVIIa) with FFP - use declining + many contraindications.
- N. acetylcysteine IV for paracetamol poisoning, even if ingested 48-72 hours before.
- Orthotopic liver transplantation (OLT). Note there are different referral criteria for paracetamol poisoning from all other causes eg INR >3.0 / hypoglycaemia/ acidosis pH <7.30 / encephalopathy on Day 2.- liver unit referral may show 60->80% one year survival in selected patients. If in doubt - ring and discuss early…
- Liver support systems. ‘Bridging support’ to transplantation, but no convincing outcome efficacy data yet
