br/Defibrillators

Defibrillators

“Principles of Effective Waveform Design” — comprehensive article

Principles of Effective Waveform Design

Until recently, the way in which electrical therapy was delivered by transthoracic defibrillators was essentially the same for all manufacturers. Most commonly, the defibrillation waveforms used were monophasic. Monophasic technology was constrained by the electronics components available during the era it originated (1960s), remained largely unchanged over time, and never had substantive research to support its performance. Further, the waveforms used energy inefficiently and were not able to adjust effectively to a patient’s chest impedance.

Without effective defibrillator impedance compensation, high patient impedance degrades the waveform, a key factor in the relatively poor performance of traditional uncompensated monophasic technologies. Low impedance imposes a different set of potential problems. As will be described in greater detail later, low impedance patients may be more likely to shunt current away from the heart.