CURRENT Essentials of Critical Care.pdf

Chapter 16 Toxicology 225■■■Acetaminophen OverdoseEssentials of Diagnosis• Minimal symptoms in first 24 hours; possible nausea, vomiting,diaphoresis, and lethargy• 24–48 hours postingestion, onset of hepatic AST, ALT elevation• 3–4 days postingestion: progressive hepatic damage, nausea,vomiting, jaundice, right upper-quadrant pain, asterixis, bleeding,lethargy, coma• In adults, 125 mg/kg rarely produce toxicity; 125–250 mg/kgvariably cause toxicity; doses 250 mg/kg high risk for liverfailure; patients with liver disease more susceptible to toxicity• Acetaminophen-containing combination medications should beconsidered in all overdose patientsDifferential Diagnosis• Severe viral or alcoholic hepatitis• Cyclopeptide toxicity from mushroom ingestionTreatment• Acetaminophen level 4 hours postingestion 150 g/mLtoxic; use nomogram to ascertain risk for other time points• Gastric lavage if within 2–4 hours of ingestion• Give N-acetylcysteine to patients with suspected or known ingestionof toxic dose or who have toxic levels by nomogram;most effective if given within 8 hours of ingestion• N-acetylcysteine dose 140 mg/kg orally followed by 70 mg/kgorally every 4 hours for 17 doses• Intravenous N-acetylcysteine can be given (not approved in US)if cannot tolerate oral• Supportive care for consequences of hepatic failure: vitamin Kfor coagulopathy, lactulose for encephalopathy• Liver transplantation should be considered in appropriate patientswho are refractory to treatment■ PearlLaboratories may use different units for acetaminophen level, as itcan be reported in g/mL (toxic 150 g/mL at 4 h), mol/L (toxic1000 mol/L at 4 h), or mg% (15 mg% 150 g/mL).ReferenceMokhlesi B et al: Adult toxicology in critical care: Part II: specific poisonings.Chest 2003;123:897. [PMID: 12628894]