A 55-year-old man presents to the emergency department and reports that he has been suffering from depression since his mother passed last year. He has no significant past medical history but reports that he has chronically consumed alcohol and smoked cigarettes since childhood. This morning approximately 8 hours ago, he ingested 30-40 pills of acetaminophen in a suicidal attempt. He denies any symptoms such as chest pain, dyspnea, nausea, vomiting, or abdominal pain but reports mild generalized weakness. On arrival to the emergency department, his vitals are within normal limits. A serum acetaminophen level shows 167 mg/L, and another serum level drawn four hours later shows 92 mg/L. Both numbers are plotted on the acetaminophen poisoning nomogram, and a decision is made to treat the patient.
C) N-acetylcysteine administration and consult a regional poison control center
Most patients who present within 24 hours after ingesting a toxic dose of acetaminophen are asymptomatic. Poisoning severity is determined by using a graph called the Rumack-Matthew nomogram. A serum concentration above the treatment line is an indication for immediate treatment with N-acetylcysteine is the antidote for acetaminophen poisoning. Other indications for treatment include an acute ingestion of greater than 150mg/kg or 7.5g total dose regardless of weight; a patient with a prior history of acetaminophen ingestion and liver injury even if current laboratory findings are within normal range; and a patient with laboratory findings of transaminitis and a history of toxic acetaminophen ingestion. Severe liver damage is rare if the antidote is administered on time prior to onset of liver injury. Poison control can provide guidance on a patient’s treatment course.
Answer choice A: Activated charcoal, is incorrect. Activated charcoal could be used for gastrointestinal decontamination; however, it is not the first line treatment. In a patient who presents within four hours of a potentially toxic ingestion of acetaminophen (single dose ≥150 mg/kg or 7.5 g), activated charcoal can be administered orally. Contraindications to charcoal include gastrointestinal obstruction or altered mental status with an unprotected airway. Endotracheal intubation should not be performed solely for the purpose of giving charcoal.
Answer choice B: Intubate the patient for airway protection, is incorrect. The patient’s status does not warrant intubation. He is alert and orientated, and he is hemodynamically stable without any signs of respiratory distress.
Answer choice D: Obtain a complete metabolic panel to evaluate for end-organ damage prior to initiating treatment, is incorrect. As mentioned above, this patient requires immediate N-acetylcysteine administration without delay with an emphasis on initiating the medication prior to any evidence of liver injury.
Answer choice E: Obtain ultrasound of the liver, is incorrect. An ultrasound of the liver can provide an idea of whether the patient has risk factors for liver injury or failure at baseline such as hepatic steatosis or cirrhosis; however, it does not change the patient’s current treatment course.
Key Learning Point
N-acetylcysteine is used for acute acetaminophen intoxication to prevent liver damage. Severe liver damage is rare if the antidote is administered on time. The Rumack-Matthew nomogram helps to guide treatment.
