When should a defibrillator be used during cardiac arrest?

A defibrillator should be used as soon as it is available after the initiation of CPR during a cardiac arrest situation because it provides an essential intervention that can significantly increase a person's chance of survival. Cardiac arrest typically involves an abnormal heart rhythm, often ventricular fibrillation or pulseless ventricular tachycardia, which can be corrected with a shock from the defibrillator.

Using the defibrillator immediately allows for a prompt return to a normal heart rhythm, ideally during the critical window before brain damage occurs. This is especially important since the effectiveness of defibrillation decreases the longer the heart remains in an abnormal rhythm without intervention. Ensuring that CPR is initiated right away helps to maintain blood flow to the brain and other vital organs while waiting for the defibrillator to arrive.

Waiting to perform CPR for a set duration or only using the defibrillator if certain conditions are met, such as consciousness returning or heart rate parameters being specific, can delay life-saving treatment, which is crucial in a cardiac emergency. Therefore, the immediate use of a defibrillator is vital whenever it is available in conjunction with ongoing CPR.