When should defibrillation be applied?

Defibrillation should be applied as soon as possible once an Automated External Defibrillator (AED) is available and the patient is in cardiac arrest because timely defibrillation is critical for survival in cases of certain heart rhythms, such as ventricular fibrillation and pulseless ventricular tachycardia. The effectiveness of defibrillation decreases significantly with time; therefore, every moment counts.

Immediate use of an AED can restore a normal heart rhythm and increase the chances of survival. Quick application is part of the chain of survival for cardiac arrest, which emphasizes the importance of rapid response by calling emergency services, performing CPR, and using an AED as soon as it is available.

In contrast, waiting to check for a pulse or to perform CPR for a specific duration prior to defibrillation could delay the delivery of vital care. Similarly, waiting until the patient becomes responsive would be inappropriate, as responsiveness typically indicates that defibrillation is unnecessary and could lead to further complications.