Let’s define a few terms:
Energy: A joule (J) is the unit of work associated with one amp of current passed through one ohm of resistance for one second.
When we express it in a formula, it is generally stated as follows:
Joules (Energy) = Voltage X Current X Time
Joules have become a surrogate for current in modern defibrillator language.
Current: Current is what actually defibrillates the heart. It is also expressed as Voltage/Impedance (resistance).
Impedance: Resistance to Flow; there is resistance in the electrical circuit itself as well as in the patient. The amount of impedance in a patient is difficult to determine as it relates to body mass, temperature, diaphoresis quality of the contact with paddles or pads. Impedance is expressed in ohms.
3 major components of a defibrillator: