A 24-year-old woman has a regular narrow-complex tachycardia at 190 per minute with a palpable pulse and mild chest discomfort. Vagal manoeuvres fail to terminate the arrhythmia. The correct next step is:
- A Adenosine 12 mg rapid IV push through a large-bore cannula
- B Adenosine 6 mg given as an infusion over 20 minutes
- C Adenosine 6 mg rapid IV push through a large-bore cannula followed by a saline flush ✓
- D Immediate synchronised cardioversion at 100 J
Correct answer: C. Adenosine 6 mg rapid IV push through a large-bore cannula followed by a saline flush
Explanation
For stable regular narrow-complex tachycardia unresponsive to vagal manoeuvres, adenosine 6 mg is given as a rapid bolus into a large proximal vein followed immediately by a saline flush because its half-life is about 10 seconds. The 12 mg dose is the second dose if 6 mg fails. Slow infusion renders it ineffective. Cardioversion is reserved for instability, which mild symptoms do not establish.
Reference: AHA ACLS Provider Manual, 2020 guidelines ed.
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Written and medically reviewed by the StethoPrep medical team.