Keywords: adenosine, medication side effects (PubMed Search)
Adenosine is everyone's favorite drug for SVTs, and it is often even used as a diagnostic maneuver in some tachydysrhythmias of uncertain origin. BUT there are some definite cautions of which we must all be wary:
1. Adenosine CAN convert some types of ventricular tachycardia to sinus rhythm. This "adenosine sensitive VT" is very well reported in the cardiology literature. Don't use adenosine as a diagnostic method of distinguishing VT from SVT (with aberrant conduction).
2. Atrial fibrillation with WPW can sometimes mimic SVT if one doesn't look closely and notice the irregularity. If you misdiagnose these patients as having SVT and give adenosine, you will likely induce VFib. Not good, Mav, not good!
3. Adenosine causes some histamine release (thus the flushing and hot sensation that patients report). That's bad for patients that have reactive airway disease (RAD). Adenosine should be avoided in patients with severe RAD by history (asthma, COPD) or if patients have active wheezing.
4. Concurrent use of adenosine in patients on digoxin or patients that have received digoxin or verapamil has been reported to cause VFib in rare cases.
5. The effects of adenosine appear to be potentiated by dipyridamole and carbamazepine. Lower the dose of adenosine in patients that take these medications.
6. The effects of adenosine are antagonized by methylxanthines such as caffeine or theophylline. You will probably need higher doses of adenosine in these patients.
7. There are rare cases of adenosine inducing atrial fibrillation. I'm not sure what to say about this, except don't be surprised if your patients goes from SVT into atrial fibrillation. Rare, fortunately.
8. And finally...always remember to push adenosine very quickly and follow immediately with saline BOLUS flush (don't just open up the IVF...you must PUSH 10-20cc of NS); and warn your patient that for ~10 seconds they are going to feel like they are about to die while the adenosine takes effect. If you don't warn them, they will never trust you or the drug again.
9. And finally finally...always have your code cart ready to go when you are using potent cardiac drugs such as adenosine. Don't let yourself be unprepared for a side effect.
Bad luck only happens when you are unprepared!