Hepatic Encephalopathy and 23.4% Hypertonic Solution (HTS)

Mechanism of Action of 23.4% HTS:  functional BBB allows an osmolar gradient to develop between blood and brain parenchyma, resulting in efflux of water from brain tissue with reduction in brain volume.  This allows displaced CSF to return from spinal subarachnoid space, and intracranial compliance improves.

Indications for 23.4% HTS in hepatic encephalopathy

  1. urgent treatment of life-threatening cerebral edema or intracranial hypertension (easily arousable or localizing excludes patient)
  2. cerebral herniation syndrome or other acute neurologic deterioration in context of existing severe hepatic encephalopathy and absence of more likely explanation (sepsis, seizure, medication toxicity)
  3. as an initial form of HTS therapy or added to ongoing infusion of 3% HTS
    • 23.4% HTS 30ml bolus over 30 minutes via central venous catheter, target acute serum sodium increase of 5 mEq/L
    • check Na 1 hour later, then serum Na q6h
    • continue 3% HTS infusion to maintain steady Na levels (acute decline may lead to rebound cerebral edema)

Displacement of CSF occurs before blood or brain displacement during pathologic processes.  Can changes in CSF volume be used to evaluate severity of cerebral edema?  See reference[1] for a retrospective study that looked into this clinical question.

Note: Change in CSF volume after 23.4% is associated with the magnitude of serum Na change but not with the total mEq of Na delivered.

Invasive ICP monitoring in hepatic encephalopathy:

  1. potential for hemorrhagic complications
  2. studies have not identified a survival benefit
  3. may be associated with worse outcomes for some patients
  4. may not accurately reflect compression of brain structures (thalami / brainstem)

West Haven Criteria

The severity of hepatic encephalopathy is graded with the West Haven Criteria.

  • Grade 1 Trivial lack of awareness; euphoria or anxiety; shortened attention span; impaired performance of addition or subtraction
  • Grade 2 Lethargy or apathy; minimal disorientation for time or place; subtle personality change; inappropriate behaviour
  • Grade 3 – Somnolence to semistupor, but responsive to verbal stimuli; confusion; gross disorientation
  • Grade 4 Coma

 

References

[1] Liotta, Eric M. et al. “23.4% Saline Decreases Brain Tissue Volume In Severe Hepatic Encephalopathy As Assessed By A Quantitative CT Marker”. Critical Care Medicine 44.1 (2016): 171-179. Web.

[2] Wikipedia,. “Hepatic Encephalopathy”. N.p., 2016. Web. 19 Feb. 2016.

 

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