A 19-year-old girl presents 8 hours after ingesting an unknown quantity of aspirin. Blood gas shows pH 7.38, PaCO2 28 mmHg, bicarbonate 16 mEq/L. Along with IV fluids, the specific measure that enhances salicylate elimination is:

• A Acetazolamide to produce acidic urine
• B Furosemide forced diuresis
• C N-acetylcysteine infusion
• D Sodium bicarbonate to alkalinise urine ✓

Explanation

Salicylate is a weak acid; alkalinising the urine with sodium bicarbonate converts it to its ionised form, which cannot be reabsorbed across renal tubular epithelium (ion trapping), markedly increasing excretion. Acetazolamide would acidify urine and worsen retention while aggravating systemic acidosis, which drives salicylate into the brain. The gas shows the classic mixed picture: respiratory alkalosis from direct medullary stimulation plus metabolic acidosis from uncoupled oxidative phosphorylation. N-acetylcysteine is the antidote for paracetamol, not salicylate.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.