Adenosine Administration for Neonatal SVT
For newborns with SVT, administer adenosine as a rapid IV bolus starting at 0.1 mg/kg (100 mcg/kg), followed by 0.2 mg/kg if the first dose fails, up to a maximum of 0.3 mg/kg (300 mcg/kg). 1
Dosing Protocol
- Initial dose: 0.1 mg/kg (100 mcg/kg) as a rapid IV bolus 1
- Second dose: 0.2 mg/kg (200 mcg/kg) if SVT persists 1
- Maximum cumulative dose: 0.3 mg/kg (300 mcg/kg) 1
- The initial pediatric dose is higher than the adult starting dose of 6 mg, reflecting the higher doses needed in children 1
Administration Technique
- Use a large, proximal peripheral vein (antecubital preferred) 1
- Administer as the most rapid IV push possible 1
- Immediately follow with a rapid 5-10 mL saline flush 2, 1
- The rapid flush is critical because adenosine has an extremely short half-life of 0.6 to 10 seconds 3
- Termination of SVT typically occurs within 12-25 seconds if effective 4
Alternative Single-Syringe Method
- Draw adenosine 0.2 mg/kg into a syringe containing 0.9% sodium chloride to a total volume of 3 mL 5
- This technique eliminates the need for a stopcock and may be easier to facilitate 5
Expected Efficacy
- Overall cardioversion success rate: 72-88% for all SVT types 1
- Success rate for AV node-dependent SVT: 79-96% 1
- Adenosine is the drug of choice (Class I recommendation) for supraventricular tachycardia 2
Monitoring Requirements
- Monitor blood pressure, electrocardiogram, respiratory status, and capillary refill before, during, and after administration 3
- Continuous rhythm monitoring during therapy is essential to evaluate the effect of interventions 2
Common Side Effects (Transient)
- Flushing 3, 6
- Nondistressing alterations in respiratory pattern 3
- Irritability 3
- Sinus bradycardia (lasting less than 40 seconds) 6
- Transient complete AV block (lasting less than 6 seconds) 6
- All adverse effects are transient due to the extremely short half-life 3
Critical Pitfalls to Avoid
- Do not use adenosine for wide-complex tachycardia (QRS >0.09 seconds) unless confirmed to be SVT, as it carries significant risk if the rhythm is actually ventricular tachycardia 7
- Adenosine will not prevent reinitiation of SVT due to its short half-life, so consider prophylactic medications if recurrence occurs 3, 6
- Reinitiation of SVT within 5 seconds occurred in 13 of 90 terminated episodes in one study 6
When Adenosine Fails
- Attempt vagal stimulation first (unless the patient is hemodynamically unstable), such as applying ice to the face without occluding the airway 2
- For refractory SVT, procainamide has higher success rates than amiodarone with equal adverse effects 1
- Synchronized cardioversion is preferred for unstable patients or when pharmacologic therapy fails 1
- Never use verapamil in infants due to multiple reports of cardiovascular collapse and death 1