Question

Organophosphate poisoning typically presents with __________.

• A. dry mouth
• B. mydriasis
• C. bronchospasm
• D. tachycardia

Hint:

Organophosphate toxicity turns the body's secretions completely "on" (wet, leaking fluids from everywhere). Bronchospasm combined with fluid in the lungs (bronchorrhea) is the leading lethal complication, managed aggressively using high-dose Atropine.

Answer 1

The Correct Option is C

Concept: Organophosphates are irreversible inhibitors of the enzyme acetylcholinesterase (AChE). When AChE is inhibited, it can no longer hydrolyze the neurotransmitter acetylcholine (ACh) into choline and acetate. This results in an accumulation of toxic levels of acetylcholine at both muscarinic and nicotinic receptors throughout the peripheral and central nervous systems, leading to a massive toxidrome known as a cholinergic crisis.

Step 1: Map the clinical signs of cholinergic excess Overstimulation of muscarinic receptors can be easily remembered using the classic mnemonic DUMBELS:
• D - Diarrhea
• U - Urination
• M - Miosis (pupillary constriction)
• B - Bradycardia, Bronchospasm, and Bronchorrhea
• E - Emesis
• L - Lacrimation
• S - Salivation

Step 2: Contrast options with expected signs
• Dry mouth: Organophosphate poisoning induces excessive salivation (sialorrhea) due to hyperstimulation of salivary glands.
• Mydriasis: Hyperstimulation causes pinpoint pupils (miosis), not pupillary dilation (mydriasis).
• Tachycardia: Muscarinic activation in the cardiac sinoatrial node predominantly induces bradycardia (slowing of heart rate).
• Bronchospasm: Acetylcholine causes constriction of bronchial smooth muscles via \(\text{M}_3\) muscarinic receptors. This leads directly to bronchospasm, accompanied by heavy mucus secretion (bronchorrhea), creating severe respiratory distress. Thus, bronchospasm is a definitive characteristic manifestation of organophosphate poisoning.