Defibrillation Waveforms: Is There a Better Biphasic?

Biphasic defibrillation waveforms have been used effectively for over two decades, replacing the monophasic waveforms originally used for defibrillation and cardioversion. Not all biphasic waveforms are the same, however, and member healthcare organizations continue to ask us for guidance when selecting from among the available defibrillator models. Common questions include:

1. Is any one biphasic waveform preferable to another?

2. Is high-energy or low-energy biphasic better?

We answer these questions with the same response we gave when we first addressed the topic in 2001: There is not enough clinical literature to support the superiority of any one biphasic waveform or the superiority of high- or low-energy devices.

The terms monophasic and biphasic refer to the direction in which current flows during defibrillation. The current delivered by a monophasic waveform flows in one direction throughout delivery. In contrast, the current delivered by a biphasic waveform flows in one direction during the first phase of the shock and in the opposite direction during the second phase. Biphasic waveforms have been broadly shown to be as effective as, or more effective than, monophasic waveforms, while exposing patients to lower peak currents. The American Heart Association's (AHA) 2020 Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care(1) state that "these...