What distinguishes a biphasic defibrillator from a monophasic defibrillator?

A biphasic defibrillator is distinguished from a monophasic defibrillator primarily by the direction in which it delivers electrical current. A monophasic defibrillator delivers a single shock where the electrical current flows in one direction, typically from one pad to another. In contrast, a biphasic defibrillator sends the current first in one direction and then reverses it to flow in the opposite direction. This two-directional flow of current in biphasic defibrillation allows for potentially more efficient defibrillation of the heart during a cardiac arrest, increasing the chances of restoring a normal heart rhythm.

The effectiveness of biphasic defibrillation over monophasic is rooted in both the physics of electrical current and the physiological responses of cardiac tissue. Biphasic shocks can provide a higher degree of success with lower energy levels, which can also result in less damage to heart tissue compared to higher energy monophasic shocks.

Other options presented do not accurately describe the core differences between biphasic and monophasic defibrillators. Therefore, the defining characteristic that sets biphasic defibrillators apart is indeed the way they deliver electrical current in two phases, enhancing their overall effectiveness in defibrillation scenarios.