Adenosine Dosing for Pediatric Supraventricular Tachycardia
For pediatric SVT, start with 0.1 mg/kg (100 mcg/kg) as a rapid IV bolus, followed by 0.2 mg/kg if the first dose fails, up to a maximum of 0.3 mg/kg (300 mcg/kg). 1, 2
Dosing Protocol
- Initial dose: 0.1 mg/kg (100 mcg/kg) administered as the most rapid IV push possible 1, 2
- Second dose: 0.2 mg/kg (200 mcg/kg) if the first dose is ineffective 1, 2
- Maximum dose: 0.3 mg/kg (300 mcg/kg) 1, 2
- The initial pediatric dose is substantially higher than the adult starting dose of 6 mg, reflecting the higher doses needed in children 3, 1
Critical Administration Technique
- Use a large, proximal peripheral vein (antecubital preferred) 1
- Administer as the most rapid IV push possible followed immediately by a rapid 5-10 mL saline flush 1, 2
- The rapid administration and flush are essential because adenosine has an extremely short half-life of 0.6-10 seconds 4
Expected Efficacy
- Overall cardioversion success rate: 72-88% for all SVT types 1, 5
- Success rate for AV node-dependent SVT: 79-96% 1, 5
- Adenosine is superior to digoxin (61-71% success) with approximately 90% success when used appropriately 1
- Most successful conversions occur with medium (0.1-0.2 mg/kg) to high (≥0.2 mg/kg) doses 5
When to Use Adenosine
Adenosine is the drug of choice (Class I recommendation) specifically for supraventricular tachycardia with narrow QRS complexes (<0.09 seconds). 6, 2
- Attempt vagal stimulation first (such as applying ice to the face without occluding the airway) unless the patient is hemodynamically unstable or this will unduly delay treatment 7, 2
- For hemodynamically unstable patients, proceed directly to synchronized cardioversion at 0.5-1 J/kg 7
Critical Pitfalls to Avoid
Never Use Adenosine for Wide-Complex Tachycardia
Never assume wide-complex tachycardia (QRS >0.09 seconds) is supraventricular—treat as ventricular tachycardia until proven otherwise. 6, 2
- The diagnostic use of adenosine in wide-complex tachycardia carries significant risk if the rhythm is actually VT 6
- For unstable VT, synchronized electrical cardioversion is the preferred first therapy 6
Avoid Verapamil in Infants
Never use verapamil in infants due to multiple reports of cardiovascular collapse and death. 7, 1, 2
- Verapamil (0.1-0.3 mg/kg) may be used in older children but should not be used in infants without expert consultation due to potential myocardial depression, hypotension, and cardiac arrest 7
Management of Refractory SVT
If adenosine fails to convert SVT:
- Procainamide has higher success rates than amiodarone for refractory pediatric SVT with equal adverse effects 1, 2
- Consider amiodarone 5 mg/kg IV/IO or procainamide 15 mg/kg IV/IO for SVT unresponsive to vagal maneuvers and adenosine 7
- Synchronized cardioversion is preferred for unstable patients or when pharmacologic therapy fails, starting at 0.5-1 J/kg and increasing to 2 J/kg if needed 7, 1, 2
Adverse Effects
- Adverse effects occur in approximately 22% of patients but are typically transient and mild 5
- Common effects include flushing, chest discomfort, sinus bradycardia, varying degrees of AV block, irritability, and nondistressing alterations in respiratory pattern 4, 5
- All adverse effects resolve within seconds to minutes due to adenosine's extremely short half-life 4, 8
- Reinitiation of SVT within 5 seconds occurs in approximately 13% of successfully terminated episodes, requiring consideration of prophylactic antiarrhythmic therapy 9