Final answer:
Automated external defibrillators (AED) are life-saving tools in cardiac emergencies, providing a shock to correct arrhythmias and restore normal heart rhythm. They are easily accessible in public areas and ambulances, designed for use by non-professionals and often accompanied by verbal instructions.
Step-by-step explanation:
In medical emergencies involving cardiac arrest, automated external defibrillators (AED) can be crucial for saving lives. These portable devices deliver a large charge in a short burst to help regulate a person's heart rhythm during an arrhythmia, such as ventricular fibrillation. A heart attack might trigger such an arrhythmia, which can then be corrected by the AED's controlled electrical shock, allowing the body's natural pacemaker to restore a normal rhythm.
In addition to being common equipment in ambulances, AEDs are also found in many public places, providing accessibility for laypersons to act in a cardiac emergency. The built-in electrocardiogram in the AED helps analyze the patient's heart rhythm and apply a shock with the appropriate energy and waveform when needed. These devices often come with verbal instructions to assist the user, and it is recommended to perform CPR before utilizing the AED if necessary.
For instance, during open-heart surgery, a defibrillator can be essential when a patient goes into cardiac arrest. The precisely calculated application of voltage, considering the path's resistance, aids in restoring normal heart function.