A comparison of adenosine and verapamil for the treatment of supraventricular tachycardia in the prehospital setting.

STUDY OBJECTIVE

To compare the efficacy and base hospital physician use of adenosine with that of verapamil in the prehospital treatment of supraventricular tachycardia (SVT).

DESIGN

A 12-month prospective chart review of adenosine administration and a 12-month retrospective chart review of verapamil administration.

SETTING

A single-tier advanced life support emergency medical service system.

PARTICIPANTS

Prehospital adult patients presenting with narrow-complex SVT.

INTERVENTIONS

Field paramedics identified SVT. They then administered verapamil or adenosine under on-line physician medical control. Paramedics administered up to two i.v. doses of verapamil, 2.5 mg and 5 mg, or up to two i.v. doses of adenosine, 6 mg and 12 mg. They recorded ECG readings; blood pressure; pulse; respirations; and symptoms before, during, and after drug administration.

RESULTS

During the verapamil period, paramedics identified 102 cases of SVT and administered verapamil to 17 patients. Review by a cardiologist revealed 6 of the 17 patients to have been in atrial fibrillation, atrial tachycardia, or sinus tachycardia. Of the remaining 11 patients, 7 (64%) converted from SVT to sinus rhythm. During the adenosine period, paramedics identified 89 cases of SVT, and they administered adenosine to 64 patients. Eight patients had no review because prehospital rhythm strips were lost. Of the remaining 56 patients, 24 were later determined to have been in atrial fibrillation, atrial tachycardia, sinus tachycardia, atrial flutter, or ventricular tachycardia. Of the remaining 32 patients who were in SVT, adenosine converted 25 (78%) to sinus rhythm. An important incidental finding was the misinterpretation of tachydysrhythmias in 30 of 73 patients by paramedics and base hospital physicians.

CONCLUSION

Our study showed no difference in conversion rates between verapamil and adenosine. Base hospital physicians were more likely to order adenosine than verapamil. Paramedics and base hospital physicians often misinterpret tachydysrhythmias.