A 4-year-old boy is brought to the emergency department by his mother for vomiting and diarrhea. His mother says, "He started complaining of a stomachache after playing at the neighbor's farm, but I thought he was just hungry after playing outside all afternoon." The child subsequently had several episodes of emesis and diarrhea. His mother has also noticed that he seems to be sweating excessively and drooling. He has no medical conditions and takes no daily medications. The patient lives with his parents and uncle. His uncle has sickle cell disease, for which he takes ibuprofen and oxycodone as needed for pain crises. Temperature is 37.2 C (99 F), blood pressure is 90/60 mm Hg, pulse is 50/min, and respirations are 36/min. Pulse oximetry is 94% on room air. Physical examination shows an ill-appearing child moaning on the stretcher and clutching his abdomen. Significant diaphoresis and bilateral tearing are noted, and his pupils are constricted. Cardiac examination reveals a regular rhythm with bradycardia and no murmurs, and respiratory exam is notable for tachypnea, bilateral wheezing, and mild subcostal retractions. Oxygen via facemask is administered. Which of the following medications should also be administered?

Question

A 4-year-old boy is brought to the emergency department by his mother for vomiting and diarrhea.  His mother says, "He started complaining of a stomachache after playing at the neighbor's farm, but I thought he was just hungry after playing outside all afternoon."  The child subsequently had several episodes of emesis and diarrhea.  His mother has also noticed that he seems to be sweating excessively and drooling.  He has no medical conditions and takes no daily medications.  The patient lives with his parents and uncle.  His uncle has sickle cell disease, for which he takes ibuprofen and oxycodone as needed for pain crises.  Temperature is 37.2 C (99 F), blood pressure is 90/60 mm Hg, pulse is 50/min, and respirations are 36/min.  Pulse oximetry is 94% on room air.  Physical examination shows an ill-appearing child moaning on the stretcher and clutching his abdomen.  Significant diaphoresis and bilateral tearing are noted, and his pupils are constricted.  Cardiac examination reveals a regular rhythm with bradycardia and no murmurs, and respiratory exam is notable for tachypnea, bilateral wheezing, and mild subcostal retractions.  Oxygen via facemask is administered.  Which of the following medications should also be administered?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c018_e519_8f63_6f1583bb3865_MD0005_00 This patient has signs and symptoms of cholinergic toxicity after playing outside, which is suggestive of organophosphate poisoning. Organophosphates have historically been used in bioterrorism as nerve agents but are also used in insecticides and pesticides. Intoxication occurs after absorption via contact, inhalation, or ingestion. Organophosphates act through inhibition of acetylcholinesterase, the enzyme that breaks down acetylcholine. This inhibition leads to excessive acetylcholine activity at the neuromuscular junction, thereby causing cholinergic toxicity. Classic symptoms of cholinergic toxicity are characterized by exaggerated muscarinic stimulation; they include vomiting, diarrhea, tearing, miosis, and bradycardia. In addition, muscle weakness may occur due to nicotinic receptor stimulation. After initial resuscitation (eg, oxygen, fluids), atropine should be administered as it is a competitive antagonist of the acetylcholine muscarinic receptor and decreases cholinergic activity. Pralidoxime, an acetylcholinesterase reactivator, should be given concomitantly to decrease both muscarinic and nicotinic receptor stimulation. (Choice B) Naloxone is a short-acting opioid antagonist used in the treatment of opioid (eg, oxycodone, morphine) overdose. Symptoms of overdose include constricted pupils, respiratory depression, and lethargy. This patient is tachypneic and wheezing. In addition, although there are opioids in this patient's home, symptom onset occurred after time spent at the neighbor's farm. (Choice C) Pyridostigmine is an anticholinesterase used in the treatment of myasthenia gravis, an autoimmune disorder characterized by impaired activity of acetylcholine. Pyridostigmine would exacerbate this patient's cholinergic toxicity and therefore is contraindicated. (Choice D) Pyridoxine, or vitamin B₆, is a water-soluble vitamin used in conjunction with isoniazid therapy and in the treatment of isoniazid overdose to prevent peripheral neuropathy. Pyridoxine has no role in treating organophosphate poisoning. ₆ (Choice E) Succinylcholine is a depolarizing agent often used in rapid-sequence intubation. This medication is metabolized by acetylcholinesterase, the enzyme inhibited in organophosphate poisoning, and would lead to prolonged apnea and blockade at the neuromuscular junction. Educational objective: Organophosphate poisoning causes cholinergic toxicity via acetylcholinesterase inhibition. Treatment is atropine, which reverses muscarinic receptor effects, and pralidoxime, which reactivates cholinesterase. References: Clinical features of organophosphate poisoning: a review of different classification systems and approaches. (http://www.ncbi.nlm.nih.gov/pubmed/25425841) Medical treatment of acute poisoning with organophosphorus and carbamate pesticides. (http://www.ncbi.nlm.nih.gov/pubmed/19651196)

A 4-Year-Old Boy Is Brought to the Emergency Department by His