Final answer:
The Biphasic AED sends a shock in two directions, using a bidirectional waveform, and is distinct from monophasic and implanted defibrillators.
Step-by-step explanation:
The type of defibrillator that sends the shock first in one direction and then in the other is the Biphasic AED. A biphasic defibrillator applies a shock using a bidirectional waveform, which means the electrical current is sent to the heart in two polarities. This technology is designed to be more effective and safer, requiring lower energy levels compared to older models. In contrast, a monophasic AED sends a shock in only one direction, and an implanted defibrillator is a device that's placed inside the body. There is no such device as a triphasic defibrillator in mainstream use.Earlier models of defibrillators were manual and used monophasic waveforms. Over time, automated external defibrillators have been developed to diagnose the patient's heart rhythm automatically and administer the appropriate level of shock. These AEDs are portable and found in public places, designed for use by individuals without medical training. They can be crucial in saving lives during a cardiac emergency, such as ventricular fibrillation, before emergency services arrive. Following the instructions provided by an AED, combined with CPR, can increase the chances of survival.