Optimizing Adenosine Delivery in Supraventricular Tachycardia: Comparison of Double- and Single-Syringe Methods

Supraventricular tachycardia (SVT) is one of the most common tachyarrhythmias seen in young adults and accounts for over 50,000 emergency department visits each year. Currently, adenosine remains the first-line treatment for managing SVT that is unresponsive to vagal maneuvers in hemodynamically stable patients. Adenosine’s quick onset and short half-life of less than 10 seconds make it an ideal agent for rapid cardioversion. However, its unique pharmacokinetics also raise concerns about administering it properly to ensure adequate delivery to the myocardium. Traditionally, this was done using the double-syringe (DS) method. The DS method incorporates a three-way stopcock to enable fast administration of adenosine, immediately followed by a 20 mL normal saline flush. Although SVT is common in the emergency department, nursing familiarity with three-way stopcocks can vary. Additionally, due to different brands of stopcocks available, even experienced nurses may require reorientation to these devices when patients present. To improve adenosine administration, the single-syringe (SS) method was developed by diluting the adenosine dose in 15-20 mL of normal saline in one syringe. It was first described in the literature in a 2003 cohort study showing a non-statistically significant increase in cardioversion success rates. More recent studies, including a meta-analysis of three randomized controlled trials, have demonstrated significant improvements in success rates on the first and subsequent doses with the SS method. Moreover, the SS method has been associated with significantly shorter administration times compared to the DS method. Overall, the single-syringe method offers a simpler, faster, and more reliable approach to adenosine administration, potentially enhancing cardioversion success while reducing technical complexity and variability in emergency department practice.