Pediatric TCA Overdose: Sodium bicarbonate dose for wide QRS?

• A. 0.5 mEq/kg
• B. 1 mEq/kg
• C. 2 mEq/kg
• D. 3 mEq/kg

Answer: (B)

When a pediatric TCA overdose causes wide QRS, the curative idea is to counteract the drug’s sodium channel blockade quickly. Sodium bicarbonate helps in two ways: alkalinizing the blood makes the TCA more ionized and less able to block sodium channels, and increasing the extracellular sodium concentration helps compete with the drug at those channels, improving conduction and narrowing the QRS.

The best starting dose for a child is 1 mEq/kg given as an IV bolus of 8.4% sodium bicarbonate. This dose is aimed at rapidly achieving the desired alkalinization while providing a sodium boost. If the QRS remains widened after the first dose, a repeat bolus may be used with careful monitoring, but higher doses carry greater risk of metabolic alkalosis and sodium overload. Lower doses are generally less effective at counteracting the blockade, and higher doses increase safety concerns.