Popular Mechanics recently re-shared an article on social media with the audacious title, “A Groundbreaking Scientific Discovery Shows that We Can Reverse Death.” Is that true?
It depends on how you understand death. In the old days, it was relatively easy to determine whether someone was dead: he stopped breathing and his pulse disappeared.
That was a useful way of determining death because breathing is necessary to get oxygen to the blood, and a beating heart is necessary to push oxygen-laded blood to the cells of the body. Without that happening, every cell in the body would die.
Of course, mistakes could be made. Someone might be breathing really shallowly, and he might have only a faint pulse, but if he really stopped breathing and his heart really stopped, he was dead. End of story.
Things got more complex in the twentieth century. Techniques became available to keep someone breathing and to restart his heart.
In the 1950s, ventilators were introduced. These are machines that act like bellows to move air in and out of the lungs.
Also in the 1950s, the first (external) mechanical hearts became available, and by 1960, cardiopulmonary resuscitation (CPR) could help keep blood moving during a cardiac arrest, adrenaline could encourage the heart to resume beating, and defibrillators could hopefully shock it back into a normal rhythm.
All this raised the question of whether people who met the previous definition of death (no breathing and no heartbeat) should be considered dead.
By the late 1960s, a new criterion was proposed: absence of brain activity. This could make sense because a functioning brain was needed to keep things like breathing and hearts going without mechanical aid.
So perhaps—some reasoned—if the brain was no longer working, if the patient was “brain dead,” you could forego artificial respiration and heart stimulation and treat the patient as dead.
This meant you could harvest his organs, if he was an organ donor—including his precious heart. The first successful heart transplant took place in 1967, so maybe someone else could use the organ if the donor was brain dead.
There has been a lively debate about whether lack of brain activity should be used to define death, and advocates of brain death as the key criterion have won a lot of converts to their view.
At the same time, there have been concerns that doctors have been defining brain death in a loosey-goosey way, such as merely being in a persistent vegetative state rather than truly and permanently lacking brain function. This would let them take more people off life-support—freeing up medical resources—and harvest organs from more people.
Personally, I am not at all convinced that the brain death criterion is adequately defined—or applied—today, and so a person who is actually still alive may be killed by the removal of their heart for a transplant. Consequently, I have not agreed to donate my organs on my driver’s license.
While the brain death debate has been going on, the concept of death has begun to be questioned on a new front: the cellular level. Hypothetically, one could argue that a person’s body isn’t fully dead unless all of the cells in it have died, and things like brain function, respiration, and heart action are just things needed to keep the cells alive.
We thus might be able to help save more people if we could intervene to keep their cells alive long enough to fix whatever is wrong with their brain, lungs, heart, or other organs.
The Popular Mechanics article discusses a team of researchers who have been working on how to support the cells of the body when critical organs are not functioning. They call this system OrganEx, and preliminary trials on pigs have been successful, though human trials are still years off.
Other advances are also being made. It turns out that, if a person’s body and brain are cooled down in the right way, they can be brought back to normal functioning as much as six hours after cardiac arrest has occurred (see Sam Parnia, Erasing Death: The Science That Is Rewriting the Boundaries Between Life and Death).
We also now have implantable artificial hearts, and—though they aren’t yet as convenient and reliable as the one the biological version of Captain Picard had on Star Trek—we’re approaching the point where not having a functioning human heart may no longer be useful as a criterion for irreversible death.
What all of these advances have done is make death—which used to look like a simple either-or state—to look more like a process, and a process that in many cases can be reversed.
As medicine continues to advance, we may expect it to become more and more reversible, which will make it more challenging to define precisely when “final” death occurs.
