Brain death is a condition where the blood that carries oxygen cannot reach the brain or the brain stem, which controls the heart rate and the breathing. Head trauma or bleeding in the brain from aneurysm or stroke can limit oxygen supply to the brain and cause the brain tissue to swell.

Just like any other injuries, our body parts swell but the brain, being in a skull, it has no room to swell. When the brain swell it increases the pressure in the skull and this will affect the flow of the blood carrying oxygen to the brain.

Without oxygen, it would ultimately lead to brain death. 

Brain dead patients do not have any response and cannot breathe on their own. The heart beats because the ventilator is pushing in the oxygen. Before time the patient is relying on the ventilation and medication to supply blood to all the organs, which will later fail, and in the end even with assistance, the heart will eventually stop.

When a patient is declared as brain dead by two authorized and experienced specialist in two separate tests, as legally dead, the ventilation machine will be switched off.

The tests conducted to determine brain dead are done following the standard procedures accepted all over the world and the specialist who announces brain death cannot have anything to do with organ transplantation.

Organ & Tissue That Can Be Donated By Brain Death Donor