As a medical professional with expertise in neurology and critical care, I can provide insight into the complex issue of brain death and its impact on bodily functions, including respiration. When a person is declared brain dead, it means that all functions of the entire brain, including the brainstem, have ceased irreversibly. The brainstem is a crucial part of the brain that controls many essential life-sustaining functions, including breathing. When the brainstem is no longer functioning, the individual will not be able to breathe without mechanical ventilation. However, it is important to note that the heart can continue to beat for a period of time after the brain has died, as long as artificial breathing is maintained. This is because the heart can continue to function with the support of the respiratory system, even though it is not entirely dependent on the brain for its operation. In summary, a brain dead person cannot breathe on their own and requires mechanical support to maintain respiration. The heart may continue to beat for some time after the brain has ceased functioning, but this is not a sustainable situation without ongoing medical intervention. read more >>

When the breathing machine is turned off, a patient who is brain dead will not breathe. The heart will beat for some time after the brain dies as long as breathing is artificially maintained because heart function is not entirely dependant on the brain.read more >>