brain dead what is the limit of minutes
Unconsciousness occurs within about 30 seconds, so it's not as if you would have very much time to contemplate what is happening. Once the brain goes unconscious, tissue begins to die after about 5 minutes of oxygen starvation. After this point, there may only be small islands of activity remaining in various brain structures. After ten to fifteen minutes, complete brain death will usually occur. One exception to this is if the brain (and body) are in a state of hypothermia. Extreme cold can induce a process called neuroprotection; metabolism is greatly reduced, and the brain can survive for much longer than it would at room temperature.