A 22-year-old man is brought to the emergency department by his family for cough and shortness of breath. The patient was found an hour ago in a barn on the family's property. He was observed to have severe, frequent coughing episodes with copious sputum production. The patient also vomited several times with no visible blood. He reports feeling severely short of breath but has no fever, pain, headache, or confusion. He has a history of major depression treated with paroxetine. Family members reveal that the patient recently ended a long-term relationship with his girlfriend. He does not have a history of using tobacco, alcohol, or illicit drugs, although his younger brother, who lives nearby, uses heroin. The patient and his parents work in agriculture. Temperature is 36.6 C (97.9 F), blood pressure is 105/65 mm Hg, pulse is 48/min, and respirations are 28/min. Pulse oximetry shows 87% while breathing ambient air. Physical examination reveals an alert, diaphoretic patient in respiratory distress. Mucous membranes are moist and pupils are pinpoint bilaterally. Coarse breath sounds with bilateral wheezing are heard on lung auscultation, and heart sounds are normal. The patient's clothes are soiled with stool and urine. He is intubated for progressive respiratory distress, and his soiled clothes are removed. Copious airway secretions are noted as mechanical ventilation is initiated. Laboratory studies and imaging are ordered. Which of the following is the most likely mechanism of this patient's condition?

Question

A 22-year-old man is brought to the emergency department by his family for cough and shortness of breath.  The patient was found an hour ago in a barn on the family's property.  He was observed to have severe, frequent coughing episodes with copious sputum production.  The patient also vomited several times with no visible blood.  He reports feeling severely short of breath but has no fever, pain, headache, or confusion.  He has a history of major depression treated with paroxetine.  Family members reveal that the patient recently ended a long-term relationship with his girlfriend.  He does not have a history of using tobacco, alcohol, or illicit drugs, although his younger brother, who lives nearby, uses heroin.  The patient and his parents work in agriculture.  Temperature is 36.6 C (97.9 F), blood pressure is 105/65 mm Hg, pulse is 48/min, and respirations are 28/min.  Pulse oximetry shows 87% while breathing ambient air.  Physical examination reveals an alert, diaphoretic patient in respiratory distress.  Mucous membranes are moist and pupils are pinpoint bilaterally.  Coarse breath sounds with bilateral wheezing are heard on lung auscultation, and heart sounds are normal.  The patient's clothes are soiled with stool and urine.  He is intubated for progressive respiratory distress, and his soiled clothes are removed.  Copious airway secretions are noted as mechanical ventilation is initiated.  Laboratory studies and imaging are ordered.  Which of the following is the most likely mechanism of this patient's condition?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c19b_8d11_8f63_0536851e820d_MD0005_00 This man with diaphoresis, bowel and bladder incontinence, bronchospasm with copious sputum production, and hypoxemic respiratory failure has signs of cholinergic toxicity suggestive of organophosphate exposure. Organophosphate toxicity typically occurs after exposure to or ingestion of agricultural pesticides; organophosphates are unfortunately also used as chemical warfare agents (eg, sarin). Organophosphates are potent acetylcholinesterase (AChE) inhibitors, allowing for excessive buildup of acetylcholine within the synapses, which leads to cholinergic toxicity. Patients classically develop diarrhea, urination, miosis, bradycardia, emesis, lacrimation (tearing), and salivation (DUMBELS: muscarinic effects). Nicotinic activation leads to muscle weakness and paralysis. Patients may develop central nervous system depression which, in conjunction with bronchospasm and bronchorrhea, often leads to respiratory failure requiring intubation. Sudden onset of symptoms and garlic-like odor from clothing (possibly due to the composition of the organophosphate or the petroleum base used) are also characteristic. Treatment includes resuscitation (fluids, oxygen), intubation as needed for respiratory failure, decontamination (eg, removal of clothing), and administration of atropine (a competitive inhibitor of acetylcholine) and pralidoxime (a cholinesterase-reactivating agent) as reversal agents. (Choice A) An overdose of paroxetine (which has anticholinergic activity) or excess atropine (a competitive inhibitor of acetylcholine at muscarinic receptors) would cause anticholinergic toxicity. This is characterized by dry mucous membranes, flushing, mydriasis, urinary retention, and decreased bowel motility, the opposite of which is noted in this patient. (Choice B) Asthma exacerbations and anaphylactic reactions are due to IgE antibody-mediated mast cell activation leading to bronchoconstriction. These patients would not be expected to have bowel or bladder incontinence, emesis, or bradycardia. (Choice D) Hypersensitivity pneumonitis is caused by pulmonary immune system activation in response to an inhaled antigen (eg, poultry, mold); it may cause shortness of breath and cough, but would not cause bowel/bladder incontinence, emesis, bradycardia, or pinpoint pupils. (Choice E) Heroin toxicity is due to stimulation of opioid receptors in the central and peripheral nervous system and can cause pinpoint pupils and respiratory depression; however, it does not cause excessive bowel and bladder output, cough, secretions, or diaphoresis. Educational objective: Organophosphate poisoning typically occurs after exposure to or ingestion of agricultural pesticides; acetylcholinesterase inhibition causes a cholinergic toxidrome. Treatment includes resuscitation, decontamination, and administration of atropine and pralidoxime as reversal agents.

A 22-Year-Old Man Is Brought to the Emergency Department by His