A recent study has found that the brain still functions for some time even after a person’s heart stops, and if circulation is restored quickly enough, it’s possible to revive them.
Published in the journal Annals of Neurology, the study discusses an event called “spreading depolarization” and the critical timeline that a person has until the brain completely shuts down and death is irreversible.
For the study, the researchers attached electrodes to nine patients, both in Berlin and Ohio, who were dying from a fatal brain injury and who had requested not to be resuscitated.
The electrodes allowed the researchers to examine brain activity leading up to and after someone’s death.
In eight of the patients, the researchers observed an increase in electrical activity in the brain. This wave of spreading depolarization started two to five minutes after blood flow radically slowed down and stopped.
The electrical activity was a response to the brain losing oxygen and energy, and the neurons function on reserves in the brain for a brief time until the brain eventually permanently shut down.
The results show that that brain is still “conscious” even after the heart stops, and that there may be a small window of time after circulation is cut off from the brain that a person can still be revived.
“After circulatory arrest, spreading depolarization marks the loss of stored electrochemical energy in brain cells and the onset of toxic processes that eventually lead to death,” said Jens Dreier told the Daily Mail. “’Importantly, it is reversible – up to a point – when the circulation is restored.”
Although the researchers are not sure how long a person has until the brain shuts down completely, the results could impact future research examining the traditional markers of death and how to handle patients before declaring a time of death.