Just as a birth certificate signifies our entry into the world, a death certificate signifies our exit from it. However, this practice merely reflects traditional views of life and death as a binary concept. We exist until the switch is flipped off, like a light bulb, after which we are no longer present. Although this understanding is widely accepted, there is growing evidence suggesting that it is an outdated social construct. In reality, dying is a process that lacks clear boundaries and offers no return.
Scientists and medical professionals have increasingly embraced this more nuanced view of death. If society were to adopt this understanding, the effects on the living could be significant. “Many people could be resuscitated,” explains Sam Parnia, director of critical care and resuscitation research at NYU Langone Health.
This text was published in issue 4/2024 of MIT Technology Review. In this issue, we explore ways to better prepare for disasters. You can order TR 4/2024 here.
For instance, neuroscientists have found that the brain can endure remarkable levels of oxygen deprivation. This discovery could someday extend the timeframe available for doctors to reverse the dying process. Additionally, other organs seem to be able to be restored for much longer than current medical practices typically allow, which could expand the availability of organ donations.
Knowledgeable about death: Sam Parnia is the director of critical care and resuscitation research at NYU Langone Health.
Photo: Elliot Goldstein / NYU Langone Health
Reconceptualizing Life and Death
However, to achieve this, we need to rethink our perspectives on life and death. Instead of viewing death as an event that is irreversible, it should be considered a temporary state of oxygen deprivation, according to Parnia. This state can become irreversible if it persists for too long or if medical interventions fail. If we adopt this perspective, “suddenly everyone will say, ‘Let’s treat this person.'”
Legal and biological definitions of death typically refer to the “irreversible cessation” of life-supporting functions in the heart, lungs, and brain. The heart is the most common point of failure. For most of human history, once the heart halted, there was no returning. This changed around 1960 with the introduction of cardiopulmonary resuscitation (CPR). Before this development, reviving a stopped heart was deemed miraculous.
Now, modern medicine has made this feasible. CPR prompted a significant reevaluation of death as a fundamental concept. The term “cardiac arrest” became commonly used, creating a clear semantic distinction between the temporary cessation of cardiac function and the permanent end of life.
Between Cardiac Arrest and Permanent Death
Around the same timeframe, mechanical positive-pressure ventilators emerged, enabling air supply to the lungs. These machines allowed individuals with severe brain injuries—from gunshot wounds to the head, significant strokes, or car accidents—to continue breathing. However, researchers discovered during autopsies of such patients that, in some instances, the brain had sustained so much damage that the tissue began to liquefy. In those cases, the ventilators had effectively turned patients into “cadavers with a beating heart,” notes Christof Koch, a neuroscientist at the Allen Institute in Seattle.
Christof Koch is the chief scientist and president of the Allen Institute for Brain Science in Seattle and studies the neurology of consciousness.
Photo: Allen Institute
These observations led to the concept of brain death, initiating medical, ethical, and legal discussions regarding whether patients could be declared dead prior to the stoppage of their heart. Many countries eventually adopted some form of this new definition. Regardless of whether it is termed brain death or biological death, the scientific complexities behind these processes are not entirely understood. “The better we can characterize the dying brain, the more questions we have,” states Charlotte Martial, a neuroscientist at the University of Liège in Belgium. “It is a very, very complex phenomenon.”
Until now, medicine has held that the brain suffers irreversible damage if deprived of oxygen for just a few minutes. This remains a common belief, according to Jimo Borjigin, a neuroscientist at the University of Michigan, but one must question “why our brains are designed to be so susceptible.”
Recent studies indicate that this might not be the case. In 2019, scientists reported in the journal Nature that they observed several functions in the brains of 32 pigs that were restored four hours after their heads were severed in a slaughterhouse. The researchers managed to restart blood circulation and cellular activity in the brains by supplying them with oxygen-rich artificial blood combined with a cocktail of protective drugs. They also administered drugs to inhibit neuronal firing, thus preventing the pigs’ brains from regaining consciousness. They maintained the brains in this state for up to 36 hours before terminating the experiment. “Our work demonstrates that much more damage caused by oxygen deprivation is likely reversible than previously thought,” says study co-author Stephen Latham, a bioethicist at Yale University.
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Death “Takes Longer Than We Thought”
In 2022, Latham and his team published another article in Nature in which they successfully restored multiple functions of various organs in pigs that had been dead for an hour— including the brain and heart. They extended the experiment for six hours, during which the anesthetized, previously deceased animals had restored blood circulation and numerous vital cellular functions became active again. “These studies have demonstrated that the distinction between life and death is not as clear as we once believed,” comments lead author Nenad Sestan, a neuroscientist at Yale School of Medicine. Death “takes longer than we thought, and at least some of these processes can be halted and reversed.”
A few human studies have similarly shown that the brain can withstand oxygen deprivation better than previously assumed when the heart stops. “When the brain is deprived of oxygen, there seems to be a kind of paradoxical surge in some instances,” Koch explains. “For reasons we do not understand, the brain becomes hyperactive for at least a few minutes.” Parnia and his team are currently gathering data for a study published in Resuscitation examining the oxygen levels and brain electrical activity in 85 patients who experienced cardiac arrest. In the majority of patients, brain activity on EEG monitors initially stagnated—however, in about 40 percent, nearly normal electrical activity in the brain temporarily reappeared up to 60 minutes after resuscitation. How can this phenomenon be explained?
Life After Death
Borjigin and her team reported similar findings in a study published in May in the Proceedings of the National Academy of Sciences regarding surges of activity in the brains of two comatose patients after their ventilators were removed. Their EEG readings displayed all the characteristics of consciousness shortly before death, Borjigin stated. Although many questions remain unanswered, these results pose intriguing questions about the dying process and the mechanisms of consciousness.
The more scientists understand these mechanisms, the greater the potential to develop “more systematic rescue strategies,” asserts Borjigin. In the most optimistic scenario, this area of research “could revolutionize medical practice and save numerous lives.”
A More Detailed Understanding of the Dying Process
Of course, everyone must die at some point, and then there is no saving them. However, an improved comprehension of the dying process could enable medicine to save individuals who were previously healthy and faced an unexpectedly premature end—while their bodies remain relatively intact. This could include individuals who have suffered a heart attack, experienced significant blood loss, or drowned. The fact that many of these individuals die—and remain dead—simply indicates “a lack of adequate resources, medical expertise, or sufficient scientific advancements to resuscitate them,” explains Parnia.
Borjigin’s aspiration is to eventually understand the dying process “second by second.” Such discoveries could not only lead to medical advancements but also “transform and revolutionize our understanding of brain function.”
Sestan and his team are also conducting follow-up studies aimed at “perfecting the technology” they employed to restore metabolic functions in pig brains and other organs. This line of research could eventually produce techniques capable of reversing damage induced by oxygen deprivation in the brain and other organs—to a certain extent, of course. If successful, it could also increase the pool of available organ donors by extending the timeframe within which doctors can extract organs from deceased individuals, adds Sestan.
If these breakthroughs are to be realized, he stresses, they will necessitate many years of research. “It is crucial that we do not overextend ourselves and make unrealistic promises, but this does not imply there is no vision.” In the interim, ongoing research into the dying process will undoubtedly continue to challenge our notions of death, leading to significant changes across research and various societal domains—from theology to law. Parnia concurs: “Death is not solely the domain of neuroscience. We all play a role in it.”
This text was authored by journalist Rachel Nuwer and first appeared in the U.S. edition of MIT Technology Review.
Rethinking Life and Death: The Evolving Understanding of Mortality
Just as a birth certificate marks our entrance into the world, a death certificate signifies our departure. However, this traditional binary concept of life and death is increasingly viewed as an outdated social construct. In reality, dying is a process with no clear boundaries, and recent advancements in medical science are revealing a more complex picture of mortality.
Experts like Sam Parnia, director of critical care and resuscitation research at NYU Langone Health, argue that this evolving understanding of death could demonstrate surprising implications for resuscitation. “Many people could be resuscitated,” he states, indicating a paradigm shift in how we define and approach death.
Knows a lot about death: Sam Parnia is director of critical care and resuscitation research at NYU Langone Health.
Photo: Elliot Goldstein / NYU Langone Health
Rethinking the Concepts of Life and Death
The need to rethink our understanding of life and death stems from emerging research. Instead of viewing death as an irreversible event, we might consider it a temporary process influenced by oxygen deprivation. Parnia suggests that if society adopts this perspective, the mindset of countless medical professionals could change, leading to more proactive treatment approaches.
Tradition has defined death largely in terms of the “irreversible cessation” of heart, lung, and brain functions. Historically, once the heart stopped beating, survival was deemed impossible. This belief was fundamentally altered in the 1960s with the emergence of cardiopulmonary resuscitation (CPR), which offered medical professionals the ability to restore heart function, effectively creating a distinction between “cardiac arrest” and “death.”
Between Cardiac Arrest and Permanent Death
Mechanical ventilators and advancements in resuscitation techniques have since allowed patients with severe brain injuries to keep breathing even when critical brain functions have diminished. Autopsy findings revealed instances where damaged brains, devoid of consciousness, persisted alongside beating hearts, prompting discussions about “brain death.”
Christof Koch is chief scientist and president of the Allen Institute for Brain Science in Seattle and researches the neurology of consciousness.
Photo: Allen Institute
The boundaries defining death are increasingly scrutinized, with recent studies suggesting the brain may endure far longer than previously thought under oxygen deprivation. This has led to compelling questions about our existing definitions of death in medicine and law.
Scientific Insights into the Dying Process
Research has shown that the brain may exhibit remarkable resilience during the dying process. A 2019 study observed brain activity in pigs that had their heads severed four hours earlier. Remarkably, blood circulation and activity resumed when rich-oxygen solutions were introduced. According to Stephen Latham, a bioethicist at Yale University, these findings indicate that “much more damage caused by oxygen deprivation is probably reversible than previously thought.”
In 2022, further studies demonstrated that various organs, including the heart and brain, could regain function even after being “dead” for up to an hour. Researchers successfully restored circulation and vital cellular processes in previously deceased pigs, noting that the line between life and death is not as clear-cut as prior thought.
Revived Consciousness: A Glimpse Beyond Death
The phenomenon of revived brain activity doesn’t solely exist in animal studies. Recent human research revealed that some patients who experienced cardiac arrest displayed bursts of brain activity—characteristics of near-consciousness—up to an hour after resuscitation attempts began. These observations offer tantalizing insights into the mechanisms of consciousness and life.
Practical Implications of New Discoveries
By transforming our understanding of death, medical professionals may be equipped to save individuals whose conditions were previously considered fatal. Many individuals who undergo traumatic events such as heart attacks or drownings might still possess viable organ function, thanks to advancements in medical knowledge and technological capabilities.
According to Parnia, the challenge often lies not in the process of dying itself, but rather in the resource limitations and medical expertise available to respond in critical moments. Enhanced awareness of the dying process could lead to improved protocols that increase survival rates in unexpected emergency scenarios.
The Future of Research on Mortality
The ongoing research aims not only to improve the management of trauma and revive victims but also to completely reassess the mechanisms underlying consciousness, paving the way for revolutionary advancements in medical practice. Borjigin emphasizes, “Understanding the dying process on a second-by-second basis could lead to breakthroughs that reshuffle our comprehension of brain function.”
Looking forward, researchers aim to perfect methods applied in animal studies to gradually translate these findings into human applications. By doing so, there exists potential to not only enhance understanding but also pragmatically improve organ donation practices and resuscitation techniques.
Key Takeaways and Insights from Ongoing Research
- Death as a Process: The understanding of mortality is evolving. Dying should be viewed as a process rather than a binary event.
- Resuscitation Potential: Many individuals previously deemed irretrievably lost may still possess viable functions, expanding possibilities for resuscitation.
- Marked Advances in Science: Research is revealing that brain functions can endure longer than previously acknowledged.
- Practical Implications: A better understanding of the dying process can lead to enhanced survival chances for patients experiencing life-threatening events.
These discoveries usher in a fundamental shift in our understanding of mortality. As research continues to advance, the reevaluation of death will not only enrich medical practice but also encourage broader societal discourse encompassing legal, ethical, and philosophical dimensions surrounding life and the process of dying.
The text was based on insights from Rachel Nuwer, as featured in the US edition of MIT Technology Review.
