How long can the brain survive without a constant supply of oxygen before damage begins to occur?

The brain is highly sensitive to the availability of oxygen, and it can start to sustain damage within a very short period when deprived of this essential resource. After approximately four to six minutes without a constant supply of oxygen, irreversible damage to brain cells begins to occur. This critical time frame is primarily due to the brain’s high metabolic demands and its reliance on aerobic metabolism for energy.

If oxygen-rich blood flow is interrupted, the brain's cells begin to die, which can lead to significant cognitive impairments, loss of function, or even death. This time span emphasizes the importance of immediate action in emergencies where a person may not be breathing or has a severely impaired airway. Recognizing the urgency in such situations can guide first responders to act quickly and efficiently, highlighting the significance of proper first aid training.