Advanced Cardiovascular Life Support (ACLS) Practice Exam

What is the recommended second dose of adenosine for patients in refractory but stable narrow-complex tachycardia?

1. 6 mg

2. 12 mg

3. 18 mg

4. 24 mg

The correct answer is: 12 mg

In cases of refractory but stable narrow-complex tachycardia, the recommended second dose of adenosine is indeed 12 mg. Adenosine is utilized for the treatment of certain types of tachycardias, specifically involving reentrant pathways or ectopic foci within the heart. When a patient receives an initial dose of adenosine, typically 6 mg, there may be instances where this first dose does not successfully convert the tachycardia to a normal rhythm. In such scenarios, it is common practice to administer a second dose. The rationale behind choosing 12 mg for the second dose is based on the pharmacodynamics of adenosine, which may require a higher dosage to achieve the desired effect if the first dose was ineffective. This dosing strategy facilitates effective management of the condition, while also being mindful of the potential side effects associated with higher doses. Lower doses, such as 6 mg or even higher than 12 mg, would not align with the established protocols for managing this specific type of medical emergency. This guideline helps ensure patient safety and treatment efficacy in acute situations.