The line between life and death is fuzzy.
The line between life and death is fuzzy.

Image: John Moore/Getty Images

When are we no longer considered alive? When, exactly, do we cross into the land of the dead?

The answer may not be as clear-cut as we previously thought, a new paper suggests.

Doctors in a Canadian intensive care unit said they witnessed a strange event after withdrawing life support from four critically ill patients. 

In three of the patients, their brain activity ceased first, followed by their heartbeat and blood pressure. A person is typically considered “clinically dead” when they stop breathing and their blood circulation ends.

But the fourth patient had the opposite experience. The person still showed persistent brain activity for up to 10 minutes after the final heartbeat, researchers wrote in a study published this week in the Canadian Journal of Neurological Sciences. 

A vital signs monitor.

A vital signs monitor.

Image: Kimmo Mantyla/REX/Shutterstock

Patient No. 4’s brain continued to fire off bursts of delta waves even after the person was declared dead, Loretta Norton and her colleagues of the University of Western Ontario found. 

The researchers said they can’t really explain what happened. Perhaps there was a human or equipment error that falsely simulated brain activity at the time of recording — though there’s no sign that either a person or machine messed up.

“It is difficult to posit a physiological basis for this EEG [electroencephalographic] activity, given that it occurs after a prolonged loss of circulation,” Norton and her team wrote.

The study is the latest effort by doctors to better understand what happens to our bodies after life support is withdrawn, which is an important question for organ donation.

Without a firm explanation, and given the tiny sample size — one patient — the doctors couldn’t make any definitive conclusions about what their findings mean, except to say that more research is required.

“Further study of the [EEG] during the withdrawal of life-sustaining therapies will add clarity to medical, ethical and legal concerns for donation after circulatory determined death,” they said.

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