A nurse is caring for a client who has a cardiopulmonary arrest. The nurse anticipates the emergency response team will administer which of the following medications if the client's restored rhythm is symptomatic bradycardia?

This scenario requires applying advanced cardiac life support protocols for post-arrest arrhythmias. Knowledge of autonomic nervous system pharmacology is essential to identify the specific medication that increases heart rate by blocking parasympathetic vagal inhibition on the sinoatrial node during symptomatic bradycardia. Choice A rationale Magnesium sulfate is primarily utilized to treat torsades de pointes or hypomagnesemia. It acts as a calcium channel blocker in myocardial cells but does not specifically increase heart rate for bradycardia when normal sinus rhythm has already been restored. Choice B rationale Sodium bicarbonate is administered to treat specific metabolic acidosis or certain drug toxicities during prolonged arrest. It does not possess chronotropic properties and will not increase the heart rate in a client suffering from a symptomatic slow rhythm. Choice C rationale Atropine is an anticholinergic drug that inhibits the vagus nerve, effectively increasing the firing rate of the sinoatrial node. It is the first-line medication for symptomatic bradycardia to improve cardiac output and maintain adequate systemic tissue perfusion. Choice D rationale Epinephrine is a potent vasopressor and inotrope used primarily during active pulseless arrest. While it increases heart rate, atropine is specifically indicated first for a restored rhythm that remains slow and symptomatic before progressing to more powerful infusions.