NCLEX-RNPhysiological AdaptationHard
A client is brought to the emergency department after ingesting an unknown quantity of amitriptyline. The nurse notes a widened QRS complex on ECG. Which medication should the nurse anticipate administering first?
- AActivated charcoal
- BNaloxone IV
- CFlumazenil IV
- DSodium bicarbonate IV
Show answer & explanationAnswer & explanation
Correct answer: D. Sodium bicarbonate IV
Tricyclic antidepressant (TCA) overdose causes cardiotoxicity through sodium channel blockade, manifesting as a widened QRS complex; IV sodium bicarbonate is the priority antidote as it increases extracellular sodium concentration and alkalinizes the blood, reversing cardiac conduction abnormalities and reducing arrhythmia risk.
Why the other options are wrong
- A. Activated charcoal may be used for decontamination but does not treat life-threatening cardiotoxicity already present.
- B. Naloxone reverses opioid overdose, not TCA toxicity.
- C. Flumazenil reverses benzodiazepine overdose, not TCA toxicity, and can precipitate seizures.
TCA Overdose Cardiotoxicity
Tricyclic antidepressant overdose blocks cardiac sodium channels, causing widened QRS and arrhythmias treated with sodium bicarbonate.
- Widened QRS >100 ms indicates significant toxicity
- Sodium bicarbonate is the antidote of choice
- Also causes anticholinergic effects and seizures
- Activated charcoal used only for early GI decontamination
Memory trick: Bicarb Blocks the Blockade in TCA toxicity