A 24-year-old woman brought to the emergency department says that she ingested about twenty 500-mg acetaminophen tablets 2 hours ago after an intense argument with her husband. She currently has no symptoms. The patient does not smoke but drinks alcohol on weekends. She is alert and oriented. Her temperature is 37.2 C (99 F), blood pressure is 110/60 mm Hg, pulse is 90/min, and respirations are 16/min. Examination shows no abnormalities. Complete blood count, coagulation studies (prothrombin time/International Normalized Ratio), and serum chemistries, including liver functions tests, are within normal limits. Which of the following is the most appropriate next step in management of this patient?

Question

A 24-year-old woman brought to the emergency department says that she ingested about twenty 500-mg acetaminophen tablets 2 hours ago after an intense argument with her husband.  She currently has no symptoms.  The patient does not smoke but drinks alcohol on weekends.  She is alert and oriented.  Her temperature is 37.2 C (99 F), blood pressure is 110/60 mm Hg, pulse is 90/min, and respirations are 16/min.  Examination shows no abnormalities.  Complete blood count, coagulation studies (prothrombin time/International Normalized Ratio), and serum chemistries, including liver functions tests, are within normal limits.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d1c5_a350_bc81_b5943b101afb_MD0003_00 This patient was brought to the emergency department ~2 hours after ingesting a potentially toxic dose (single dose of >7.5 g [= 20 tablets × 0.5 g/tablet]) of acetaminophen. Patients at this early stage of acetaminophen intoxication can be asymptomatic (first 24 hours) or may have only nonspecific symptoms such as nausea, vomiting, and anorexia. After 24 hours, patients may develop severe liver injury. The initial management should be focused on gastric decontamination with activated charcoal if the patient presents within 4 hours of ingestion. Although activated charcoal is traditionally thought to have the most effect within the first hour, studies suggest lower rates of liver injury among patients with toxic acetaminophen ingestion who received activated charcoal later. Acetaminophen levels should be obtained at the same time. The Rumack-Matthew nomogram, which provides the likelihood of hepatotoxic effects of acetaminophen overdose after a single ingestion (based on plasma acetaminophen level and hours since ingestion), is used to guide N-acetylcysteine (NAC) administration in patients with dangerous acetaminophen levels. Although the first data point begins at 4 hours (ie, an acetaminophen level may not be predictive of hepatotoxicity prior to that point), obtaining a level at presentation because the exact timing or dosage may be unclear and an acetaminophen concentration >10 µg/mL with an unknown time of ingestion is an indication for NAC administration. If the level is not within the toxic range by the nomogram, it should be repeated in 2 hours (ie, at 4 hours) based on the patient's history of ingestion. There is debate regarding the best timing and duration of NAC administration protocols. (Choices B and C) It would be inappropriate to discharge the patient or place her in observation only before obtaining a current and 4-hour acetaminophen level as the reported ingestion places her at risk for hepatotoxicity. (Choice D) A psychiatry consultation may be required but is less urgent than medical stabilization. (Choice E) Aspirin overdoses are associated with an increased risk of arrhythmias, but acetaminophen overdoses usually do not have primary cardiac manifestations; ECG is less helpful in assessing toxicity. (Choice F) Patients at risk for fulminant hepatic failure should be evaluated for potential liver transplantation. However, this patient has no signs of toxicity and was seen soon after ingestion, making the likelihood of need for transplantation relatively low. Educational objective: For patients who present soon after a single, potentially toxic ingestion (>7.5 g) of acetaminophen, the first step in management is gastric decontamination and measurement of acetaminophen levels. Patients can be asymptomatic during the first 24 hours after ingestion. References: A review of acetaminophen poisoning. (http://www.ncbi.nlm.nih.gov/pubmed/22998987) Acetaminophen poisoning: an update for the intensivist. (http://www.ncbi.nlm.nih.gov/pubmed/11983032)

A 24-Year-Old Woman Brought to the Emergency Department Says That