What every Intensivist should know about ... Ammonia in liver failure

• Published in: Journal of critical care Vol. 81; p. 154456
• Main Authors: Duarte, Tiago, Fidalgo, Pedro, Karvellas, Constantine J., Cardoso, Filipe S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-06-2024; Elsevier Limited
• Subjects: Acute-On-Chronic Liver Failure - therapy; Ammonia; Apheresis; Bacteria; Brain Edema; Critical care; Edema; End-stage liver disease; Failure; Hemodialysis; Hepatic Encephalopathy; Humans; Hyperammonemia; Hyperammonemia - complications; Hypertension; Infections; Kidneys; Laxatives; Liver cirrhosis; Liver transplant; Medical prognosis; Metabolism; Mortality; Nitrogen; Plasma; Polyethylene glycol; Renal replacement therapy; Sarcopenia; Transplants & implants; Writing; ACLF; IHD; Hyperammonemia; End-stage liver disease; Liver transplant; Critical care; ALF; LOLA; HE; CRRT
• ISSN: 0883-9441; 1557-8615; 1557-8615
• DOI: 10.1016/j.jcrc.2023.154456

Acute liver failure (ALF) or acute-on-chronic liver failure (ACLF) patients have high short-term mortality and morbidity. In the context of liver failure, increased serum ammonia is associated with worse neurological outcomes, including high-grade hepatic encephalopathy (HE), cerebral edema, and intracranial hypertension. Besides its neurotoxicity, hyperammonemia may contribute to immune dysfunction and the risk of infection, a frequent trigger for multi-organ failure in these patients.
We performed a literature-based narrative review. Publications available in PubMed® up to June 2023 were considered.
In the ICU management of liver failure patients, serum ammonia may play an important role. Accordingly, in this review, we focus on recent insights about ammonia metabolism, serum ammonia measurement strategies, hyperammonemia prognostic value, and ammonia-targeted therapeutic strategies.
Serum ammonia may have prognostic value in liver failure. Effective ammonia targeted therapeutic strategies are available, such as laxatives, rifaximin, L-ornithine-l-aspartate, and continuous renal replacement therapy.
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•In liver failure, hyperammonemia is associated with worse neurological outcomes.•Serial arterial ammonia may help to follow the risk of neurological complications.•Laxatives, rifaximin, L-ornithine-l-aspartate, and continuous renal replacement therapy decrease serum ammonia.