After a person experiences cardiac arrest, within five to eight seconds, brain hypoxia will cause fainting!
Convulsions occur in more than fifteen seconds, and sustained coma occurs within thirty seconds; at this time, gasping-like breathing or respiratory arrest may occur.
Within a minute, the pupils dilate, leading to clinical death.
After five to six minutes, the brain enters a state of brain death due to continuous hypoxia, and at this point, there is basically no hope for recovery.
Therefore, within six minutes is the critical time for rescuing a patient who has experienced cardiac arrest.
To be precise, it should be three minutes, as after three minutes, a person's brain could suffer irreversible brain damage due to ischemia and hypoxia.
For ordinary people, when encountering a patient with cardiac arrest, the most crucial thing is to perform CPR as quickly as possible, using external force to maintain blood and respiratory circulation until rescue personnel arrive.
