The central component of a defibrillator is a capacitor that stores electrical energy. In order to bring the heart muscle back into the normal beating rhythm with a targeted electrical current pulse (defibrillation), large-area electrodes are stuck to the chest of the affected person.
The current pulses of defibrillators differ slightly from manufacturer to manufacturer. The average values are as follows:
- Voltages between 1,000 and 2,000 volts (V)
- Initial currents of about 20 to 30 amperes (A)
- Energy from 150 to 360 joules (J) for adults
A modern defibrillator works biphasically (with two phases). This means that during defibrillation the voltage alternates between the two electrodes. The positive pole becomes a negative pole and vice versa. The pole change saves energy and ensures effective use of the defibrillator. A biphasic "defi" is gentle on the heart and also on the skin due to the lower electrical current.
