Over the years, defibrillation has saved millions of lives. Initially, defibrillation was monophasic, but biphasic defibrillators became the norm as technology evolved. The main purpose of this article is to compare the differences between these devices.Is Monophasic defibrillator better than biphasic? Read on to learn more.

Biphasic Defibrillators Display:

How to identify monophasic and biphasic defibrillators

Based on the defibrillation waveform, there are two types of modern defibrillators: monophasic and biphasic. Monophasic currents move in a single direction, while biphasic currents are bi-directional. Compared to the monophasic technology used in monophasic wave defibrillators, biphasic waveforms exhibit superior defibrillation characteristics due to their low peak currents and long effective current durations, resulting in high defibrillation success rates and minimal cardiac damage. Most AEDs on the market today use biphasic defibrillation.

Monophasic defibrillator

Monophasic defibrillators emit a current from a single electrode (direction of the current). The height of the capacitor voltage during charging determines the amount of energy subsequently released by the electrode pads. The waveform associated with monophasic defibrillation has a peak, which is critical in determining the success of defibrillation. Sufficient current needs to reach the heart to terminate a fatal rhythm or fibrillation. At the same time, avoiding a peak current that is too high or may damage the patient’s heart is important. In single-phase machines, the current released is high, which is why these machines are usually large.

Biphasic defibrillator

A Biphasic defibrillator is a device that utilizes a bi-directional current. Unlike the monophasic defibrillator, where the current flows in one direction, the pulse of the Biphasic defibrillator consists of positive and negative peaks. During the positive peak, the current moves from electrode A to electrode B, while during the negative peak, it moves from B to A. The Biphasic defibrillator adjusts the patient’s impedance through the different characteristics of the waveform to ensure that patients with high impedance and those with low impedance have the same chance of survival.

Monophasic vs Biphasic defibrillator: which is better?

The earliest defibrillators were monophasic defibrillators, and as technology evolved, biphasic defibrillators were developed. Although monophasic defibrillators are still in use, biphasic defibrillators have become more common.
Often, Biphasic defibrillators can achieve higher efficacy but deliver the same or even less energy. Also, they are less damaging to heart function.
Another advantage of Biphasic defibrillators is that they usually do not produce other negative effects, such as skin burns. In addition, because less energy is required to produce the same effect, Biphasic defibrillators are typically lighter, smaller, have lower battery requirements, and are less expensive to maintain than monophasic defibrillators.

How to tell if a defibrillator is monophasic or biphasic

Monophasic defibrillators generally have a maximum discharge energy of 360J, while biphasic defibrillators generally have a maximum charge of 200J.
Initial defibrillation: 360J for monophasic defibrillation, 120-200J for biphasic defibrillation.
Subsequent shock energies: 360 J for monophasic defibrillation and the same or higher energy for biphasic defibrillation.

Conclusion

Although monophasic and biphasic defibrillators can successfully defibrillate, the latter is considered the better choice. They are more convenient, accurate, effective, less costly, and prevent further damage to the heart.