A 60-year-old farmer is brought to the emergency department due to acute-onset confusion, muscle weakness, and difficulty breathing. The patient has vomited twice and has had 3 loose bowel movements over the past 2 hours. His medical history is insignificant and he currently takes no medications. Blood pressure is 110/70 mm Hg, pulse is 58/min, and respirations are 26/min. His pupils are constricted, symmetric, and reactive to light. Examination reveals excessive sweating, lacrimation, and wheezing. He is incontinent of urine. Intravenous atropine is administered. Which of the following findings is most likely to persist in this patient without additional therapy?

Question

A 60-year-old farmer is brought to the emergency department due to acute-onset confusion, muscle weakness, and difficulty breathing.  The patient has vomited twice and has had 3 loose bowel movements over the past 2 hours.  His medical history is insignificant and he currently takes no medications.  Blood pressure is 110/70 mm Hg, pulse is 58/min, and respirations are 26/min.  His pupils are constricted, symmetric, and reactive to light.  Examination reveals excessive sweating, lacrimation, and wheezing.  He is incontinent of urine.  Intravenous atropine is administered.  Which of the following findings is most likely to persist in this patient without additional therapy?

Quizplus · Accepted Answer

11ec160b_3c16_0505_9249_81e4e3dbe6f5_MD0001_00 This farmer is exhibiting multiple signs of excessive cholinergic stimulation. He has likely been exposed to an organophosphate, a cholinesterase inhibitor that is commonly used in agricultural pesticides. Organophosphates inhibit cholinesterase in both muscarinic and nicotinic cholinergic synapses, leading to decreased acetylcholine degradation. Overabundance of acetylcholine within the synaptic cleft leads to overstimulation of the corresponding receptors. This patient is currently experiencing the effects of widespread muscarinic activation, which increases visceral smooth muscle tone and glandular secretions throughout the body (DUMBELS mnemonic). Nicotinic activation leads to muscle fasciculations, weakness, and paralysis. Activation of both receptors in the central nervous system leads to seizures and coma. Atropine is a competitive inhibitor of acetylcholine at the muscarinic receptors, thereby reversing muscarinic symptoms of organophosphate poisoning. However, atropine has no effect on nicotinic receptors; patients are still at risk of muscle paralysis. Pralidoxime is a cholinesterase-reactivating agent that allows for degradation of excess acetylcholine and treats both the muscarinic and nicotinic effects of organophosphates. (Choices A, B, C, D and F) Bradycardia, bronchospasm, diarrhea, miosis, and urinary incontinence are symptoms of excessive muscarinic activation, and are reversed with atropine. Educational objective: Organophosphates inhibit cholinesterase in both muscarinic and nicotinic cholinergic synapses, leading to decreased acetylcholine degradation and overstimulation of the corresponding receptors. Atropine reverses muscarinic effects but does not prevent the development of nicotinic effects such as muscle paralysis. Pralidoxime is a cholinesterase-reactivating agent that allows for degradation of excess acetylcholine and treats both the muscarinic and nicotinic effects of organophosphates.

A 60-Year-Old Farmer Is Brought to the Emergency Department Due