"improving intensive care in Scotland"

Liver failure

Hepatic encephalopathy (HE)

Ammonia, produced by urea-splitting intestinal bacteria, is central to the pathogenesis. Decreased hepatic metabolic capacity and porto-systemic shunting allow systemic hyperammonaemia. Ammonia causes cerebral oedema and changes in neurotransmission.

Portosystemic shunting (pathogenic or iatrogenic) worsens HE. Treatment of chronic encephalopathy usually involves lactulose. Non-absorbable antibiotics (neomycin) are now not used frequently, and flumazenil has limited clinical use. GCS less than 8 mandates intubation and ventilation.

Grading of encephalopathy, table 4, is recognised as imprecise. Therefore, GCS may be a more useful “common language” over the telephone.

Grade 1

Euphoria
Mild confusion
Maybe shaky (asterixis)

Liver grade 1

Grade 2

Lethargy
Moderate confusion
Shaky

Liver grade 2

Grade 3

Rousable
Very Confused
Shaky

Liver grade 3

Grade 4

Coma

Liver grade 4

Table 4. Grades of hepatic encephalopathy.

 

Intracranial hypertension

Intracranial hypertension

Raised intracranial pressure (ICP) is a common cause of death in patients with AHF. It is due to cerebral oedema and intracranial hyperaemia.

ICP may be monitored. Suitable treatment targets would be ICP < 20 mmHg, cerebral perfusion pressure (CPP) >60 mmHg. (CPP = MAP - ICP - CVP).

Acute rises in ICP may cause pupillary dilation, bradycardia, hypertension and opisthotonos.

Treatment

Treatment modalities are:

  • Improving venous drainage - 20° head up tilt, no neck restrictions.
  • Optimisation of cardiovascular status using fluid, inotrope or vasoconstrictor as appropriate.
  • Hyperventilation – used to ameliorate acute rises in ICP.
  • Hyperosmolar treatment – boluses of 100 ml 20% mannitol as required, while maintaining serum osmolarity < 320 mosmol/l. Plasma volume reduction using haemofiltration will be required if the patient is anuric.
  • Cooling – to core temperature of 33°C. Used if the patient is not responding to mannitol, or osmolarity is limiting hyperosmolar treatment. Now used early as cerebral hyperaemia is recognised as important.
  • Thiopentone coma.

 

 

Page 4

Backwards Button Forward Button