Which defibrillation energy delivery is described for shocks delivered by AEDs?

• A. Monophasic, fixed-energy shocks.
• B. Manual external defibrillation only.
• C. Internal cardioversion.
• D. Escalating energy, biphasic defibrillation (includes AEDs).

Answer: (C)

Shocks from AEDs use escalating energy with a biphasic waveform. Biphasic means the current flows in one direction and then reverses, which improves the chance of successful defibrillation and lowers heart muscle injury compared with older monophasic shocks. The energy is delivered in steps, starting at a lower level and increasing if the first shock doesn’t restore a normal rhythm. This approach is what modern AEDs use.

Older monophasic, fixed-energy shocks are associated with older defibrillators, and manual external defibrillation is performed by trained responders who control the energy, not a self-contained AED. Internal cardioversion involves synchronized shocks delivered via implanted or internal leads, not external AED shocks.