Acute Liver Injury Management

Treatment Initiation and Efficacy

• For patients with unknown time of ingestion or presenting >24 hours post-ingestion, NAC should still be administered if acetaminophen toxicity is suspected, with the goal of reducing disease progression in patients with established hepatic injury, as recommended by the American College of Emergency Physicians 1
• NAC should be considered for patients with evidence of hepatotoxicity (elevated liver enzymes) but without hepatic failure, even in the absence of controlled studies demonstrating efficacy in this specific scenario, highlighting the potential benefit of NAC in reducing disease progression, as suggested by the American College of Emergency Physicians 1
• The American Society of Anesthesiologists and the American College of Emergency Physicians recommend starting N-acetylcysteine (NAC) without waiting for acetaminophen level results, along with surgical evaluation of lacerations and comprehensive psychiatric assessment with suicide risk screening 1, 2
• Obtaining an acetaminophen plasma level and plotting it on the Rumack-Matthew nomogram is necessary to determine toxicity risk, with baseline labs including liver function tests, coagulation studies, renal function, electrolytes, and blood glucose, as recommended by the American College of Emergency Physicians 1
• The Rumack-Matthew nomogram can be used to determine the risk of hepatotoxicity:

• Initiate N-acetylcysteine (NAC) treatment immediately in cases of acetaminophen overdose with a level at or above the "possible toxicity" line (≥100 mg/L) or when the time of ingestion is unknown with suspicion of overdose, as recommended by the American Academy of Clinical Toxicology 1
• NAC can be administered orally with a loading dose of 140 mg/kg (diluted to 5% solution) and a maintenance dose of 70 mg/kg every 4 hours for 17 doses, or intravenously with a loading dose of 150 mg/kg over 15-60 minutes, followed by maintenance doses of 50 mg/kg over 4 hours and 100 mg/kg over 16 hours, as recommended by the American Association for the Study of Liver Diseases 3

Monitoring and Supportive Care

• Daily monitoring of serum bilirubin, INR, serum creatinine, and serum sodium is recommended to assess liver function and guide treatment decisions in patients with acetaminophen toxicity, as suggested by the American College of Medical Toxicology 4
• Arterial ammonia levels should be monitored, with a critical threshold of 150-200 μmol/L, to guide treatment decisions in patients with acetaminophen toxicity 2
• Provide IV fluids, correction of coagulopathy, and treatment of metabolic acidosis as needed, and consider fresh frozen plasma and vitamin K for coagulopathy, as recommended by the American College of Medical Toxicology 1
• Supportive care, such as IV fluids, correction of coagulopathy, and treatment of metabolic acidosis, should be provided as needed, according to the American Academy of Clinical Toxicology 1

Special Considerations

• Patients with hepatic encephalopathy should be monitored for cerebral edema and intracranial hypertension, and those with grade 3-4 encephalopathy should be considered for intubation for airway protection, as recommended by the American Association for the Study of Liver Diseases 2
• Contact with a liver transplant center is recommended for patients with severe acute liver failure, persistent severe coagulopathy, encephalopathy, or a MELD score >30.5, as suggested by the American College of Medical Toxicology 2
• Consider fomepizole as an adjunctive treatment to inhibit further toxic metabolite formation in patients with severe acidosis not responding to standard NAC therapy, as recommended by the American Academy of Pediatrics and the American Association of Emergency Medicine 1
• Consider renal replacement therapy (hemodialysis or continuous renal replacement therapy) for severe acidosis, especially with altered mental status, according to the American Association for the Study of Liver Diseases 3

Adverse Effects and Management

• Common side effects of NAC include nausea, vomiting, skin rash (<5%), and transient bronchospasm (1-2%), as reported by the American Academy of Clinical Toxicology 2
• Monitor for hypersensitivity reactions (10-15% of patients), and be aware that common side effects include nausea, vomiting, and rare urticaria or bronchospasm, which can be managed with antihistamines and epinephrine if necessary, according to the Hepatology society 3
• The American Academy of Clinical Toxicology recommends monitoring for NAC-related adverse effects and managing them with temporary discontinuation of infusion, antihistamines, and restarting at a slower rate 1

Respiratory Support

• Provide supplemental oxygen if SpO2 < 94% (target 94-98%) unless patient has risk factors for hypercapnic respiratory failure, as recommended by the American Thoracic Society 5
• Consider intubation and mechanical ventilation for severe acidosis with altered mental status or respiratory compromise, as suggested by the Society of Critical Care Medicine 6

Transplantation Considerations

• If no response after approximately 1 week of NAC therapy, consider hepatic transplantation, as suggested by the American College of Medical Toxicology 1
• In cases of persistent severe coagulopathy and/or encephalopathy, transplantation considerations may need to begin after only 2-3 days, according to the American Academy of Clinical Toxicology 1
• Consultation with a pediatric liver transplant center should be sought for optimal management, as advised by the American Academy of Pediatrics 7