The difference between monophasic and biphasic defibrillation

Diac Medicals sell both used monophasic- as biphasic AEDs.
But what is the actual difference between monophasic and biphasic defibrillation? In this article you will find the difference in clear and understandable words.

Administering shocks

In the course of the years, the technique of AED defibrillation has changed. Previously an AED was only able to give a monophasic shock, nowadays there are also AEDs available that give a biphasic shockwave. The real difference between monophasic and biphasic defibrillation is the way in which the shock(s) are being administered to the victim. With biphasic defibrillation it is possible to achieve the same effect as with monophasic defibrillation with a lower number of Joules.

DC Plus and switched AC

An AED is made of two capacitors, a discharge of one capacitor would cause a DC plus. In monophasic AEDs is this the case. With monophasic defibrillation the height of the voltage of the capacitor during charging determine the energy which is delivered by the pads. A biphasic AED contrast creates a short switched AC. Here, the current pulse is composed of a positive and negative peak. During the positive peak, the current flows from electrode A to electrode B, and during the negative peak from B to A. A modern AED first measure the impedance of the thorax between the electrodes and accordingly adjusts the level of the voltage of the shock(s). Some AEDs even have a child’s position plus associated smaller electrodes.