Updated July 2026 · 7 min read

Adenosine: The ICU Nurse's Guide

Part of the ICU Pharmacology Hub — browse every related guide in one place.

Adenosine is the drug that stops the heart to fix it. Given as a lightning-fast push, it interrupts a re-entrant tachycardia by briefly blocking the AV node — the monitor flatlines for a few seconds, then a normal rhythm usually resumes. It's dramatic, safe when used correctly, and almost entirely dependent on nursing technique to work.

How adenosine works

Adenosine activates receptors in the AV node, transiently blocking conduction. In AV-nodal re-entrant tachycardia (AVNRT) and AV re-entrant tachycardia (AVRT), the re-entry circuit depends on the AV node, so a momentary block breaks the loop and lets the sinus node take back over. Its extraordinarily short half-life — on the order of ten seconds — is why the effect is so brief and why technique is non-negotiable: give it slowly and it's metabolized before it reaches the heart.

The dose and the technique

The classic sequence is 6 mg rapid IV push, and if the rhythm doesn't convert within a couple of minutes, 12 mg (a second 12 mg dose may follow per protocol). But the number is only half the story — how you give it determines whether it works.

What to expect — and warn the patient about

After the push, the monitor typically shows a few seconds of pause or asystole before the rhythm resumes — this is expected, not a code. Patients often feel a brief, intense sense of chest pressure, flushing, or impending doom, so a quick warning ("you may feel a strange, uncomfortable sensation for a few seconds; it passes quickly") is part of good care. Transient facial flushing, dyspnea, and chest discomfort are common and short-lived.

Diagnostic use

Even when adenosine doesn't convert a rhythm, the transient AV block can unmask the underlying atrial activity — for instance revealing the flutter waves of atrial flutter — which helps clarify a fast, regular rhythm you couldn't quite read.

Where adenosine is the wrong choice

Interactions

Theophylline and caffeine are adenosine antagonists and blunt its effect — a patient may need a higher dose or the drug may fail. Dipyridamole potentiates adenosine and can dangerously prolong its effect, so doses are reduced. Carbamazepine may increase the degree of heart block. Always check what the patient is already on.

Bottom line

Adenosine is a fast, elegant fix for stable, regular, narrow-complex SVT — but only if you give it right. The dose is 6 then 12 mg, and the technique (closest port, instant push, immediate flush) is the drug. Expect a brief pause on the monitor, warn the patient about the strange sensation, and steer clear of it in irregular wide-complex rhythms and severe asthma. Used correctly, it's one of the most satisfying interventions in critical care: a few seconds of stillness, then a normal heartbeat.

This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols, pharmacy guidance, or a provider's orders. Always follow facility policy and verify doses independently.