| Acetaminophen toxicity | pH <7.3 (regardless of coma grade) or prothrombin time >100 seconds and serum creatinine >3.4 mg/dL (300 µmol/L) in patients with grade III or IV encephalopathy |
| All other causes | Prothrombin time >100 seconds (regardless of coma grade) and any three of the following: |
| Age <10 years or >40 years | |
| Liver failure caused by non-A, non-B hepatitis, halothane-induced hepatitis, or idiosyncratic drug reactions | |
| Duration of jaundice before the onset of encephalopathy >7 days | |
| Prothrombin time >50 seconds | |
| Serum bilirubin >17.5-mg/dL (300 µmol/L) |
From O’Grady JG, Gimson AES, O’Brien CJ, et al. Controlled trials of charcoal hemoperfusion and prognostic factors in fulminant hepatic failure. Gastroenterology 1988;94:1186, with permission.