A 2-year-old child who received atropine as premedication before surgery is found flushed, with hot dry skin and a temperature of 40 degrees C. The mechanism of this 'atropine fever' is:

• A Blockade of sympathetic cholinergic innervation of eccrine sweat glands ✓
• B Increased metabolic heat production in brown adipose tissue
• C Resetting of the hypothalamic thermostat set point
• D Peripheral vasoconstriction from unopposed alpha-adrenergic tone

Explanation

Sweat glands receive sympathetic fibres that release acetylcholine acting on muscarinic receptors. Atropine blocks these, abolishing evaporative heat loss, so temperature rises especially when ambient heat or a fever load exists. The tempting distractor is option C, but antimuscarinics do not reset the hypothalamic set point like prostaglandins do; they impair heat dissipation, not regulation.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.