Red Book - Acute Liver Failure

Question 1

Define acute liver failure

Answer 1

Rare life threatening illness in patients without pre existing liver disease

A triad of Jaundice
Encephalopathy
Coagulatopathy

Question 2

How is ALF classified

Answer 2

O Grady System

Timing is based on interval from jaundice to enceph

Hyperacute - <1 week
Acte 1-4 week
Sub acute 4-12 weeks

Question 3

Causes of ALF

Answer 3

Infections - Heps A-E, HSV, CMV, EBV, VZV

Malignancy

Vascular - Budd Chiairi (hep vein thrombus)
Ischaemic hepatitits

Pregnancy - HELLP, acute fatty liver

Metabolic - Wilsons

Other - Auto immune

Mushroom poisoning

DRUGS - Paracetamol, phenytoin, isoniazid, St Johns Wort, ectasy, amphet, chemo

Question 4

What are the King’s College Criteria

Answer 4

Prognostic tool for patietns with liver failure
Identify who has a high risk for mortality and
Asceratin suitability for transplant

Divided in PARACETAMOL and NON PARACETAMOL

Question 5

Kings Criteria - Paracetamol

Answer 5

pH < 7.3 (after 24 hours fluid resus)

OR

Hepatic enceph grade 3-4
PT > 100 seconds
Cr > 300umol

OR

Lacate >3.5 at 4 hours OR 3 at 12 hours *after fluid resus

Question 6

Non paracetamol kings criteria

Answer 6

PT > 100 seconds

OR

3 of:

PT >50s
Bili >300
Non Hep A/B aetiology
Age <10 or >40
Onset from jaundice to enceph > 7 days

Question 7

How does ALF present

Answer 7

General - malaise, nausea, jaundice

Encephalopathy

High Cardiac output state, reduced SVR

Vasoplegia from inflammatory cascade, AKI and oedema

Question 8

Grading of Enceph

Answer 8

West-Haven Criteria
Grades 1-4 (some books say 0)

1 - lack of awareness, eurphora, anxiety, short attention

2 - Lethargy, disorientation, inapproriate

3 - Somnolence, semi-stupour, confusion, grossly disorientated

4 - coma

Question 9

Mechanism of renal failure in ALF

Answer 9

1) ATN from hypovolaemia, hypotension, hypoperfusion and nephrotoxins
2) Underlying disease - glomerularlynephritis in HBV/C
3) Ascites cause intra ab hypertension
4) HRS

Question 10

Management of ALF by system

Answer 10

Resp - Grade 3/4 enceph –> I&V
Avoid excess PEEP (increases hepativ venous pressure and ICP)

Renal - RRT early in the face of fluid overload and met acidosis

Neuro - Protective measures - Head up, loose ties, MAP 75 (CPP 60-80)
Avoid hypoxia/hypercapnoea, fever
Sugars at 4-10mmol/L

CVS - low SVR, fluid resus, vasopressors

Coag - If bleeding replace approrpirately with factors
HOWEVER routine correction not advised - PT is a prognostic marker

Question 11

The liver makes all factors except?

Answer 11

Factor 8

Question 12

Mechanism of paracetamol overdose

Answer 12

Normal - paracetamol is glucornidated and suphated by liver.

Small amount made by cp450 system –> makes NAPQI

NAPQI then detoxed by glutathione

OD - gluc/sulph is overwhelmed and saturated
More and more cp450 —> more NAPQI
Glutathoine stores depleted

NAPQI causes cellular damage

Question 13

Risk factors of paracetamol toxicity

Answer 13

Cytochrome enzyme induction AND Glutathione depletion

Cyto - Chronic alcoholism
Enzyme inducers - st johns, carbamazepine, rifampicin, isnoniazind

Glutathion - malnutrition, eating disorder
other liver injury - viral hep, alcohol hep

Question 14

Treatment of paracetmaol OD

Answer 14

NAC - precursor to glutathione and replenishes stores.

Effective within 8 hours

Measure serum paracetamol and plot on Rumack Matthew Nomogram