Plasma Exchange in Acute Liver Failure
Primary Indication: Hyperammonemia
- The American College of Critical Care Medicine provides a conditional recommendation for plasma exchange in acute liver failure patients with hyperammonemia, defined as ammonia levels >150 μmol/L, with limited evidence quality 1, 2, 3
- Hyperammonemia independently predicts intracranial hypertension and hepatic encephalopathy in acute liver failure patients, with 55% of patients developing intracranial hypertension when ammonia exceeds 200 μmol/L 1, 2
- Acute liver failure patients are more vulnerable to cerebral edema and intracranial hypertension due to hyperammonemia, unlike those with acute-on-chronic liver failure 1, 2, 3
Specific Etiologies Where PLEX Should Be Considered
- The American Association for the Study of Liver Diseases recommends initiating plasma exchange immediately in Wilson disease-related acute liver failure as a bridge to transplantation, due to its uniformly fatal outcome without transplant 4, 5
- Plasma exchange should be considered in acute fatty liver of pregnancy, with expeditious delivery remaining the primary treatment 4, 5
Important Caveats and Limitations
- The guideline recommendation for plasma exchange is conditional with low-quality evidence, meaning clinical circumstances and resource availability should heavily influence the decision 1, 2, 3
Clinical Algorithm
- Identify acute liver failure patients with ammonia >150 μmol/L and consider plasma exchange as adjunctive therapy to standard medical management 1, 2, 3
- Initiate plasma exchange immediately for Wilson disease, regardless of ammonia level, as a bridge to transplant 4, 5
- Ensure simultaneous listing for liver transplantation in appropriate candidates, as plasma exchange is a bridge therapy, not definitive treatment 4, 5
- Weigh resource availability and expertise given the conditional nature of the recommendation 1, 2, 3
What NOT to Use
- Traditional therapies for chronic liver failure, such as lactulose and rifaximin, have not demonstrated benefit in acute liver failure and should not be relied upon 1, 2, 3
High-Volume Plasma Exchange in Acute Liver Failure
Guideline Recommendations
- The American Gastroenterological Association (AGA) recommends extracorporeal liver support systems, including plasma exchange, only within clinical trials 6, 7