Defibrillator: Defibrillator is a device used to deliver high voltage direct current (DC) shock to the chest through a pair of electrode patches or paddles to restart the heart which has suffered a cardiac arrest. Usually the voltage is above 2000 volts. A high voltage capacitor is used in the device to store the energy at high voltage just before delivery. The energy used in a biphasic device is 150 – 200 Joules while that in a monophasic device could be as high as 360 Joules. Biphasic devices are more efficient than monophasic devices, which are being phased out.