What is the duration of time before irreversible brain damage occurs in a cardiac arrest patient?

The correct answer highlights that irreversible brain damage can occur typically within around 10 minutes after a cardiac arrest, given that the supply of oxygen to the brain is cut off. During cardiac arrest, blood flow to the brain becomes severely limited, which leads to a rapid decline in brain function.

After approximately 4-6 minutes without oxygen, brain cells begin to die, and the longer a patient remains in a state of cardiac arrest without effective resuscitation, the greater the damage becomes. By around the 10-minute mark, significant irreversible brain damage is likely to have occurred. This timeline emphasizes the critical importance of prompt initiation of resuscitation efforts, such as CPR and defibrillation, to restore circulation and oxygenation, thereby preserving brain function and improving survival outcomes.