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Acute Liver Failure

Authors: Dean A Kerslake / Editor: Clifford J Mann / Reviewer: Mohamed Elwakil / Code: CAP19 / Published: 10/11/2017 /Review Date: 10/11/2020

Prerequisites:

Before commencing this session you should have an understanding of the normal physiology of the liver.

EMR

Acute liver failure is a rare presentation to Emergency Departments (ED) in the UK leading to around 400 admissions per year.

Paracetamol overdose accounts for in excess of 70% of cases in the UK whereas worldwide viral hepatitis is the commonest cause [1,2].

Mortality is exceptionally high and ranges from 60-90%. Paracetamol and hepatitis A have a better prognosis compared to other causes.

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Learning Bite

Paracetamol is the commonest cause of acute liver failure in the developed world.

What is Acute Liver Failure?

The most widely accepted definition of acute liver failure is:

Evidence of coagulation abnormality (Usually an INR greater than or equal to 1.5) with any degree of mental alteration (encephalopathy) in a patient without pre-existing cirrhosis and with an illness of less than or equal to 26 weeks duration [1,2].

Acute_Liver_Failure2

Acute on chronic liver disease is decompensation of liver function in a patient with chronic liver disease often precipitated by an event such as infection or gastrointestinal (GI) bleed.

Learning Bite

It is important to differentiate acute liver failure from decompensation of chronic liver disease as prognosis and treatment differs.

Basic Science and Pathophysiology Causes and Manifestations

Acute liver failure is an inflammatory process causing massive hepatocellular necrosis.

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Whilst the numerous causes of acute liver failure are heterogenous, the clinical presentation and general management is the same.

Causes:

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Manifestations of Liver Dysfunction

Normal function Pathophysiological manifestations
Carbohydrate metabolism Hypoglycaemia
Protein metabolism Hyperammonemia and toxins causing encephalopathy
Bile secretion Hyperbilirubinaemia causing jaundice
Drug detoxification Drug toxicity
Synthesis and secretion of plasma proteins Clotting factor deficiency causing coagulopathy
Hypoalbuminaemia
Clearance of gut bacteria from portal system Systemic infections resulting in sepsis
Sodium and water balance Disruption leads to altered perception of volume status by kidneys and subsequent renal failure

History

Often there is very little history available, however it should focus mainly on:

  • Exposure to viruses, drugs or toxins but can often be non specific with symptoms of anorexia or vomiting
  • Recent GI upset can point to mushroom poisoning
  • Recent shock/arrest can point towards acute ischaemic injury
  • Breast cancer, melanoma, lymphoma and small cell cancers can give rise to malignant infiltration
  • Active malignancy can also be responsible for Budd Chiari syndrome
  • Patients with severe encephalopathy, the history may be limited or unavailable

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Examination

You should examine for encephalopathy and jaundice. Right upper quadrant pain may be present. Signs of chronic liver disease would suggest either acute on chronic liver failure or decompensated liver disease.

Signs of chronic liver disease include:

  • Clubbing
  • Leukonychia
  • Palmar erythema
  • Asterixis
  • Spider naevi
  • Scratch marks
  • Loss of secondary sexual characteristics
  • Hepato/splenomeglay
  • Ascites
  • Oedema
  • Kayser-Fleisher rings (Wilson disease),
  • Features of preeclampsia (HELLP syndrome)

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Fig 1 Someone with jaundice, a sign of chronic liver disease (Reproduced with permission from CDC/Dr. Thomas F. Sellers/Emory University)

Risk Stratification

High mortality exists amongst all patients.

Although current scoring systems do not accurately predict the outcome or need for transplantation, there are some factors associated with a poorer outcome. For example, in some patient groups less than 25% survive without transplant, compared to more than 50% in other others [1].

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Factors Associated with a poor outcome:


Aetiology
  • Mushroom poisoning
  • Drug reactions
  • Non hepatitis
  • A viral hepatitis
  • Wilsons disease
  • Autoimmune hepatitis
  • Budd-Chiari Syndrome
  • Indeterminate
Admission COMA Grade III or IV

INR
> 6.5

Prediction of the need for transplant in paracetamol as aetiology:

Admission COMA Grade III or IV
pH < 7.3 following fluid resuscitation
INR > 6.5
Creatinine > 300

The Kings College Criteria (shown above for paracetamol) have also been used as tool to predict need for transplant [1,2,3].

It must be recognised that whilst it has good specificity, it has relatively poor sensitivity and clinical judgement must prevail.

Learning Bite

Certain aetiologies, COMA and significantly deranged prothombin times put patients into a group more likely to require transplantation.

In the ED remember the three Rs:

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  • Recognise
  • Resuscitate
  • Refer

1. Recognise

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Prompt recognition is essential. Look out for:

  • Unexplained acidosis
  • Confusion
  • Shock
  • Hypoglycaemia
  • Coagulopathy
  • Deranged LFTs

2. Resuscitate

  1. Consider Intubation if unable to protect or maintain airway or poor oxygenation or ventilation
  2. Give oxygen to correct hypoxia
  3. Give fluids for hypotension with evidence of poor end organ perfusion
  4. Maintain normogylcaemia

Adjuncts

  • Urinary catheter
  • ABG
  • CXR

Other investigations and monitoring as required.

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3. Refer

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Involve

  • Regional transplant teams
  • Gastroenterology teams
  • Intensive care teams

Critical Care Management Overview

The aetiology should be sought and treated in all cases.

Treatment is mainly supportive and consists of end organ support until a transplant becomes available or liver function improves.

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Learning Bite

Critical care management in a specialist tertiary referral unit is recommended for most patients with acute liver failure.

Four Grades of Encephalopathy

Grade I Changes in behaviour with minimal change in level of consciousness
Grade II Gross disorientation, drowsiness, possibly asterixis, inappropriate behaviour
  • Consider listing for transplant and transfer to tertiary referral centre
  • Consider CT to rule out other causes
  • Avoid stimulation (can raise intracranial pressure) and sedatives
  • Monitor and treat any infection
  • Consider lactulose (thought to play a role in reducing ammonia load thereby preventing worsening of encephalopathy)

Grade III
Marked confusion, incoherent speech, sleeping most of the time but rousable to vocal stimuli

Grade IV
Comatose, unresponsive to pain, decorticate or decerebrate posturing
  • Intubation and sedation
  • Head elevation
  • Consider ICP monitor if listed for transplant
  • Treat seizures
  • Mannitol and hyperventilation only if herniation imminent or severe raised ICP
  • Barbiturates for refractory raised ICP

Cerebral Oedema

The following checks and treatment should be carried out:
Sepsis

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Regular surveillance and culturing for occult or frank sepsis.

Prophylactic antibiotics and antifungals do not improve outcome but may occasionally be considered.

In the highest risk for cerebral edema, the prophylactic induction of hypernatremia with hypertonic saline to a sodium level of 145-155 mEq/L is recommended

Coagulopathy

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Most centres routinely give vitamin K but give
FFP only if active bleeding and INR >1.5 or INR >7
Platelets if <10, 000 or <50 000 and needing invasive procedure or bleeding

This is used as a marker of liver function therefore should not be routinely corrected [1].

GI Bleeding

Acute_Liver_Failure15

Give prophylactic H2 blockers to all ventilated patients as evidence shows they reduce the incidence of GI bleeds [1].

Learning Bite

Critical care management in a specialist tertiary referral unit is recommended for most patients with acute liver failure.

Haemodynamic Support

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Maintain adequate intravascular volume.

Use CVVH for acute renal failure.

Systemic Vasopressors may be required to keep MAP >60-65.

Learning Bite

Critical care management in a specialist tertiary referral unit is recommended for most patients with acute liver failure.

Metabolic Concerns

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Commence early nutritional support (preferably enteral otherwise parenteral).

Correct levels for:

  • Glucose
  • Magnesium
  • Phosphate
  • Potassium

Learning Bite

Critical care management in a specialist tertiary referral unit is recommended for most patients with acute liver failure.

Transplant

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List patient early if poor prognostic factors or predicted clinical course.

Learning Bite

Critical care management in a specialist tertiary referral unit is recommended for most patients with acute liver failure.

Aetiology Speciifc Management

Aetiology specific management for the various causes of ALF is shown below:


Aetiology

Treatment

Further Action
Paracetamol poisoning Activate charcoal within 1 hour
N-acetylcysteine even if >48 hours or if paracetamol poisoning cannot be excluded. (has been shown to decrease mortality even in established hepatotoxicity)
Mushroom poisoning Penicillin G and silymarin.Consider administration of N-acetylcysteine List for transplant
Drug reactions Discontinue any possible offending drugs
Viral Hepatitis Acyclovir if HSV/VZV suspected
Wilsons disease List for transplant
Autoimmune Hepatitis Corticosteroids List for transplant
HELLP Delivery of unborn child
Acute Ischaemic injury Cardiovascular support
Budd Chiari Syndrome List for transplant if malignancy excluded
Malignant Infiltration N/A
Indeterminate N/A

There are however some hidden hazards that should be avoided:

  • Failing to differentiate between acute liver failure and decompensated chronic liver failure
  • Failing to appreciate the severity and likely clinical deterioration of patients with acute liver failure
  • Missing the subtle signs of grade I encephalopathy
  • Failing to alert the transplant and ICU teams early
  • Failing to maintain a high index of suspicion for paracetamol poisoning in all acute liver failure patients
  • Consideration to administration of N-acetylcysteine to all patients in whom paracetamol poisoning cannot be confidently ruled out

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Key Learning Points

  • Paracetamol toxicity is the commonest cause of acute liver failure in the developed world
  • Evidence of chronic liver disease suggests acute on chronic liver failure rather than acute liver failure and this has prognostic implications
  • History should focus mainly on exposure to viruses, drugs or toxins
  • Aetiology, grade III or IV encephalopathy or an INR >6.5 put patients into a higher risk group (grade III recommendation)
  • The Kings college criteria can be used to predict the need for transplant and has good specificity but poor sensitivity but clinical judgement must still prevail (grade III recommendation)
  • All patients should get a full blood count, urea and electrolytes, glucose, liver function tests, INR, Group & Save and arterial blood gases and consideration of a CT Head if encephalopathy is present
  • Further tests may include paracetamol assay, virus serology, autoimmune tests, ceruloplasmin, CT, flow imaging or biopsy
  • Early recognition, resuscitation and referral to intensive care are essential components of emergency department treatment
  • Give N-acetylcysteine to all patients if paracetamol poisoning cannot be excluded (grade II recommendation)
  • Look for signs of raised intracranial pressure, sepsis, coagulopathy, gastrointestinal bleeding, renal failure and metabolic abnormalities and treat appropriately (grade III recommendation)

Learning Objectives

  • Having completed this session you will now be able to:
  • Define acute liver failure and describe the pathophysiology
  • Elicit the likely cause of acute liver failure in a patient presenting to the ED
  • Assess the risk of morbidity and mortality in a patient presenting to the ED with acute liver failure
  • Order and interpret laboratory tests in patients with suspected acute liver failure
  • Use imaging appropriately in patients with suspected acute liver failure
  • Institute appropriate management within the ED and describe the on-going critical care management of a patient with acute liver failure
  • Revise physiology of the liver
  • Toxbase: Guidelines for the management of paracetamol toxicity (Link: http://www.toxbase.org)
  • Be aware of your regional management guidelines for acute liver failure and your referral processes
  • AASLD Position Paper: The Management of Acute Liver Failure: Update 2011, William M. Lee, Anne M. Larson, Todd Stravitz
  • Acute liver failure
  1. Polson J, Lee WM. AASLD position paper: the management of acute liver failure. Hepatology 2005;41:1179-1197.
  2. Stravitz RT, Kramer AH, Davern T. Intensive care of patients with acute liver failure:
    recommendations of the U.S. Acute Liver Failure Study Group. Crit Care Med 2007;35:2498-2508
  3. Trotter JF. Practical management of acute liver failure in the intensive care unit. Curr Opin Crit Care 2009;15:163-167

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4 Comments

  1. matsona says:

    Very good summary, given a recent case I have seen

  2. barnesch says:

    Many thanks, very informative

  3. Kavitha Dhanapalan says:

    Very informative

  4. kashinathc2929 says:

    A good, concise look at acute liver injury and its management

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