Time is very important when an unconscious person is not breathing. Permanent brain damage begins after only 4 minutes without oxygen, and death can occur as soon as 4 to 6 minutes later.
A full recovery from severe anoxic or hypoxic brain injury is rare, but many patients with mild anoxic or hypoxic brain injuries are capable of making a full or partial recovery. Furthermore, symptoms and effects of the injury are dependent on the area(s) of the brain that was affected by the lack of oxygen.
No. Resuscitation after cardiac arrest longer than 4 to 6 minutes at normal body temperature typically results in irreversible brain injury, coma, or death. Therefore there is a popular belief that the brain “dies” after 4 to 6 minutes without oxygen.
During cardiac arrest, unconsciousness will occur rapidly once the heart stops beating, typically within 20 seconds. Deprived of the oxygen and sugars it needs to function, the brain will be unable to deliver the electrical signals needed to sustain organ function, including breathing.
This leads to asphyxiation ( death from lack of oxygen ) without the painful and traumatic feeling of suffocation (the hypercapnic alarm response, which in humans arises mostly from carbon dioxide levels rising), or the side effects of poisoning.
Bone, tendon, and skin can survive as long as 8 to 12 hours. The brain, however, appears to accumulate ischemic injury faster than any other organ. Without special treatment after circulation is restarted, full recovery of the brain after more than 3 minutes of clinical death at normal body temperature is rare.
It is possible for the brain to heal itself, with new brain cells growing to replace damaged ones, but much of the ‘recovery’ we experience is actually due to the brain ‘re-wiring’ itself and finding new pathways to bypass recently-broken connections.
Brain death (also known as brain stem death) is when a person on an artificial life support machine no longer has any brain functions. A person who’s brain dead is legally confirmed as dead. They have no chance of recovery because their body is unable to survive without artificial life support.
Unlike most other cells in the body, brain cells do not regenerate when they are destroyed. However, this does not mean that no recovery can occur. The brain is somewhat flexible and is able to reorganize itself, to an extent, in order to regain lost function.
Does an individual feel any pain or suffer after brain death is declared? No. When someone is dead, there is no feeling of pain or suffering.
Now UBC researchers have evidence that some people may still be able to hear while in an unresponsive state at the end of their life. This research, published recently in Scientific Reports, is the first to investigate hearing in humans when they are close to death.
This gives us the ability to use our senses – to see, taste, smell, hear and feel. “ Brain death” means both the upper and lower part of the brain are not functioning. That command center of the body that regulates the central nervous system is unable to perform. However, some function, such as a heartbeat, may linger.
A person who is brain dead is dead, with no chance of revival. Coma: A state of profound unresponsiveness as a result of severe illness or brain injury. Patients in a coma do not open their eyes or speak, and they do not exhibit purposeful behaviors. Some patients need ventilators while others do not.