Manual external defibrillators are standard medical devices utilized in advanced life support to deliver therapeutic shocks that terminate lethal shockable rhythms such as ventricular fibrillation, thereby restoring an organized heart rhythm.
The retrieved literature consistently supports the role of defibrillation (both automated and manual) as a cornerstone treatment for cardiac arrest involving shockable rhythms like ventricular fibrillation or pulseless ventricular tachycardia. While the prompt specifies 'manual external defibrillators', the consensus across resuscitation guidelines (AHA, ILCOR, ESC) is that delivering electrical shocks via defibrillators is the key intervention to stop lethal arrhythmias and restore perfusion, making the claim well-supported.