What is the initial energy dose for synchronized cardioversion in unstable SVT or VT in children?

• A. 0.5-1 J/kg
• B. 1-2 J/kg
• C. 2-4 J/kg
• D. 4-6 J/kg

Answer: (A)

For unstable tachyarrhythmias in children with a pulse, use synchronized cardioversion and start with the lowest effective energy. The initial dose is 0.5–1 J/kg, delivered in a synchronized shock to the R wave. This weight-based starting point balances effectiveness with safety for the pediatric heart. If the rhythm persists, you can escalate to a higher dose (about 1–2 J/kg for the next attempt, then up to 2 J/kg or more as guided by the device and protocol, sometimes up to 4 J/kg as a maximum). The key idea is to begin with the gentlest effective energy to restore perfusion while minimizing injury; higher initial doses aren’t typically needed and increase risk on the first try.