If the initial adenosine dose for stable narrow-complex tachycardia is ineffective, what is the maximum recommended second dose?

If the initial adenosine dose for stable narrow-complex tachycardia is ineffective, what is the maximum recommended second dose?

• A. 3 mg
• B. 6 mg
• C. 12 mg
• D. 24 mg

Answer: (C)

Adenosine works by briefly blocking AV nodal conduction to interrupt reentrant circuits that cause stable narrow-complex tachycardia. Because the effect is very short, the dosing starts with a 6 mg rapid IV push and a saline flush. If there’s no conversion, the next step is to give a second, higher dose of 12 mg as a rapid IV push. This 12 mg dose is the maximum recommended amount for a second administration. If the tachycardia persists after the second dose, do not keep escalating adenosine; proceed with synchronized cardioversion. The rationale is to increase the chance of stopping the AV nodal pathway while limiting exposure to adenosine’s potential side effects, given its rapid action and transient effects.

Adenosine works by briefly blocking AV nodal conduction to interrupt reentrant circuits that cause stable narrow-complex tachycardia. Because the effect is very short, the dosing starts with a 6 mg rapid IV push and a saline flush. If there’s no conversion, the next step is to give a second, higher dose of 12 mg as a rapid IV push. This 12 mg dose is the maximum recommended amount for a second administration. If the tachycardia persists after the second dose, do not keep escalating adenosine; proceed with synchronized cardioversion. The rationale is to increase the chance of stopping the AV nodal pathway while limiting exposure to adenosine’s potential side effects, given its rapid action and transient effects.