Crossing Over: How Science Is Redefining Life and Death

At first it seemed like nothing more than the worst headache she’d ever had.

So Karla Pérez—22 years old, the mother of three-year-old Genesis, and five months pregnant—went into her mother’s room to lie down, hoping it would pass. But the pain got worse, and as she vomited off the side of the bed, she told her younger brother to call 911.

It was not quite midnight on Sunday, February 8, 2015. The ambulance raced Pérez from her home in Waterloo, Nebraska, to Methodist Women’s Hospital in Omaha. She began to lose consciousness in the emergency room, and doctors put a tube down her throat to keep oxygen flowing to her fetus. They ordered a CT scan, and there it was: a massive brain bleed creating severe pressure in her skull.

She had suffered a stroke, but amazingly her fetus was doing fine, the heartbeat strong and steady as if nothing were wrong. Neurologists did another CT scan at about two in the morning, and their worst fears were confirmed: Pérez’s brain had become so swollen that the whole brain stem had pushed out through a small opening at the base of her skull.

“When they saw that,” says Tifany Somer-Shely, the obstetrician who’d cared for Pérez through her pregnancy with Genesis and with this baby too, “they knew for sure that it wasn’t going to end well.”

Pérez had landed at the ragged border between life and death, with a brain that had ceased functioning and would never recover—in other words, it was dead—and a body that could be sustained mechanically, in this case for one reason only: to nurture her 22-week-old fetus until he was big enough to manage on his own. This borderland is becoming increasingly populated, as scientists explore how our existence is not a toggle—“on” for alive, “off” for dead—but a dimmer switch that can move through various shades between white and black. In the gray zone, death isn’t necessarily permanent, life can be hard to define, and some people cross over that great divide and return—sometimes describing in precise detail what they saw on the other side.

Death is “a process, not a moment,” writes critical-care physician Sam Parnia in his book Erasing Death. It’s a whole-body stroke, in which the heart stops beating but the organs don’t die immediately. In fact, he writes, they might hang on intact for quite a while, which means that “for a significant period of time after death, death is in fact fully reversible.”

How can death, the very essence of forever, be reversible? What is the nature of consciousness during that transition through the gray zone? A growing number of scientists are wrestling with such vexing questions.

In Seattle biologist Mark Roth experiments with putting animals into a chemically induced suspended animation, mixing up solutions to lower heartbeat and metabolism to near-hibernation levels. His goal is to make human patients who are having heart attacks “a little bit immortal” until they can get past the medical crisis that brought them to the brink of death.

In Baltimore and Pittsburgh trauma teams led by surgeon Sam Tisherman are conducting clinical trials in which gunshot and stabbing victims have their body temperature lowered in order to slow bleeding long enough for surgeons to close up their wounds. The medical teams are using supercooling to do what Roth wants to do with chemicals—kill their patients, temporarily, in order to save their lives.

In Arizona cryonics experts maintain more than 130 dead clients in a frozen state that’s another kind of limbo. Their hope is that sometime in the distant future, maybe centuries from now, these clients will be thawed and revived, technology having advanced to the point where they can be cured of whatever killed them.

In India neuroscientist Richard Davidson studies Buddhist monks in a state called thukdam, in which biological signs of life have ceased yet the body appears fresh and intact for a week or more. Davidson’s goal is to see if he can detect any brain activity in these monks, hoping to learn what, if anything, happens to the mind after circulation stops.

And in New York, Parnia spreads the gospel of sustained resuscitation. He says CPR works better than people realize and that under proper conditions—when the body temperature is lowered, chest compression is regulated for depth and tempo, and oxygen is reintroduced slowly to avoid injuring tissue—some patients can be brought back from the dead after hours without a heartbeat, often with no long-term consequences. Now he’s investigating one of the most mysterious aspects of crossing over: why so many people in cardiac arrest report out-of-body or near-death experiences, and what those sensations might reveal about the nature of this limbo zone and about death itself.

Oxygen plays a paradoxical role along the life-death border, according to Roth, of Seattle’s Fred Hutchinson Cancer Research Center. Ever since oxygen was discovered in the early 1770s, “scientists have recognized it as essential to life,” he says. What the 18th-century scientists didn’t know is that oxygen is essential to life in a surprisingly nonbinary way. “Yes, if you take away oxygen, you can kill the animal,” Roth says. “But if you further reduce the oxygen, the animal is alive again, but it’s suspended.”

He has shown that this works in soil nematodes, which are alive in air with as little as 0.5 percent oxygen and are dead if you reduce the oxygen to 0.1 percent. But if you then proceed quickly to a much lower level of oxygen—0.001 percent or even less—the worms enter a state of suspension where they need significantly less oxygen to survive. It’s their way of preserving themselves during extreme deprivation, a bit like animals hibernating in winter. These oxygen-starved, suspended organisms appear to be dead but not permanently so, like a gas cooktop with only the pilot light on.

Roth is trying to get to this pilot-light state by infusing experimental animals with an “elemental reducing agent,” such as iodide, that greatly decreases their oxygen needs. Soon he’ll try it in humans too. The goal is to minimize the damage that can occur from treatments after heart attacks. If iodide slows oxygen metabolism, the thinking is, it might help avoid the blowout injury that sometimes comes with treatments like balloon angioplasty. At this lower setting the damaged heart can just sip the oxygen coming in through the repaired vessel, rather than get flooded by it.

Life and death are all about motion, according to Roth: In biology the less something moves, the longer it tends to live. Seeds and spores can have life spans of hundreds of thousands of years—in other words, they’re practically immortal. Roth imagines a day when using an agent such as iodide, a technique that will soon be studied in early clinical trials in Australia, can give people that immortality “for a moment”—the moment they most need it, when their heart is in serious trouble.

Such an approach would not have helped Pérez, whose heart never stopped beating. The day after her devastating CT scan, her obstetrician, Somer-Shely, tried to explain to Pérez’s stunned and frightened parents, Berta and Modesto Jimenez, that their beautiful daughter—the lively young woman with sparkly eyes who adored her little girl, had a passel of friends, and loved to dance—was brain-dead.

There was a language barrier. The Jimenezes’ first language is Spanish, and everything the doctor said had to be filtered through a translator. But the real barrier wasn’t language. It was the concept of brain death itself. The term dates to the late 1960s, when two medical developments coincided: high-tech, life-sustaining machinery, which blurred the border between life and death, and organ transplantation, which made clarifying that border especially urgent. No longer could death be defined in the traditional way, as cessation of breath and heartbeat, since ventilators could provide both indefinitely. Is a patient on a ventilator dead or alive? If you remove the ventilator, when can you ethically retrieve the organs to transplant into someone else? If a transplanted heart starts beating again in a new chest, was the heart donor really dead in the first place?

To address such thorny questions, a Harvard panel met in 1968 to define death in two ways: the traditional way, by cardiopulmonary criteria, and a new way, by neurological ones. The neurological criteria, which are now used to determine “brain death,” involved three cardinal benchmarks: coma or unresponsiveness, apnea or the inability to breathe without a ventilator, and the absence of brain-stem reflexes, measured by bedside exams such as flushing the ears with cold water to see if the eyes move, poking the nail bed to see if the face grimaces, or swabbing the throat and suctioning the bronchia to try to stimulate a cough.

It’s all quite straightforward, yet also counterintuitive. “Brain-dead patients do not appear dead,” wrote James Bernat, a neurologist at Dartmouth’s medical school in New Hampshire, in the American Journal of Bioethicsin 2014. “It is contrary to experience to call a patient dead who continues to have heartbeat, circulation, and visceral organ functioning.” His article, meant to clarify and defend the concept of brain death, appeared just as two controversial patients were making headlines: Jahi McMath, a California teenager whose parents refused to accept the diagnosis after the girl experienced a catastrophic loss of oxygen during a tonsillectomy, and Marlise Muñoz, a brain-dead pregnant woman whose case differed from Pérez’s in a significant way. Muñoz’s family didn’t want anything done to sustain her body, but hospital staff overruled them, because they thought Texas law required them to keep the fetus alive. (A judge eventually ruled against the hospital.)

Two days after Pérez’s stroke the Jimenez family, along with the father of the unborn baby boy, found themselves in a crowded conference room at Methodist Hospital, still reeling from the tragic twists of Pérez’s pregnancy. There to meet with them were 26 hospital staff members, including neurologists, palliative-care specialists, nurses, chaplains, ethicists, and social workers. The parents listened intently as the translator explained that the doctors’ tests had revealed their daughter’s lack of brain function. They heard the team offer “somatic support” to Pérez until the fetus was at least 24 weeks old, which is when he would have a fifty-fifty chance of surviving outside the womb. If they were lucky, the doctors said, they could keep Pérez’s body functioning even longer, improving the baby’s survival odds with each passing week.

Modesto Jimenez might have been thinking of the conversation he’d had the night before with Somer-Shely—the only physician in the hospital who’d known Pérez as a living, breathing, laughing, loving person—when he’d taken her aside and asked, “¿Será mi hija nunca despertar?”

“No,” she’d said. “Your daughter probably will never wake up.” It was one of the hardest things she’d ever had to say.

“In my clinical mind I knew that brain death is death,” she says. “Clinically speaking, she was dead at that point.” But seeing her patient lying there in the intensive care unit, Somer-Shely found that stark fact almost as difficult to believe as the family did. Pérez looked like someone who’d just come out of surgery: Her skin was warm, her chest was rising and falling, and in her belly a fetus was still moving about, apparently healthy.

In the crowded conference room the Jimenezes nodded gravely, telling the medical team that they understood their daughter was brain-dead and would never wake up. But, they added, they would keep praying for un milagro—a miracle—just in case.

If a miracle is defined as bringing someone back from the dead, sometimes that does happen in medicine.

The Martin family believe they witnessed a miracle after their youngest son, Gardell, died last winter when he fell into an icy stream. He and his mother, father, and six older siblings live on a big rural property in central Pennsylvania that the kids love to explore. On a warm day in March 2015 two of the boys took Gardell, not quite two years old, out to play. The toddler lost his footing and fell into a stream about a hundred yards from his home. His brothers noticed that he was gone and were frantic when they couldn’t find him. By the time emergency rescuers got to Gardell—who’d been pulled out of the water by a neighbor—the boy’s heart had stopped beating for at least 35 minutes. The EMTs began chest compression, but they couldn’t get his heart to start up again. They continued CPR as they sped the ten miles to Evangelical Community, the closest hospital. He had no heartbeat, and his body temperature was 77 degrees Fahrenheit, more than 20 degrees below normal. They prepped Gardell for a helicopter ride to Geisinger Medical Center, 18 miles away in Danville. Still no heartbeat.

“He had no signs of life whatsoever,” recalls Richard Lambert, director of pediatric sedation service and a member of the pediatric critical-care team that awaited the helicopter. “He looked like a child who was … Well, he was dusky, dark colored. His lips were blue …” Lambert’s voice trails off as he remembers that dreadful moment. He knew that children who drown in ice water sometimes recover, but he’d never known of one who’d been dead for as long as Gardell had. Even worse, the boy had a shockingly low blood pH, a sign of imminent organ failure.

An emergency room resident turned to Lambert and his colleague Frank Maffei, director of pediatric critical care for Geisinger’s Janet Weis Children’s Hospital: Maybe it was time to stop trying to revive the boy? Lambert and Maffei both wanted to keep going. All the elements were as favorable as they could be in a brink-of-death story. The water was cold, the child was young, and resuscitation efforts had been started within minutes of the drowning and had continued nonstop ever since. Let’s try just a little longer, they told the team.

So they continued. Another 10 minutes, another 20 minutes, another 25. By this time Gardell had been without pulse or breath for more than an hour and a half. He was “a flaccid, cold corpse showing no signs of life,” as Lambert describes him. But team members kept pumping, pressing, monitoring. The ones doing chest compression rotated on and off every two minutes—it’s exhausting to keep doing it right, even on a tiny chest—and others inserted catheters into his femoral vein, jugular vein, stomach, and bladder, infusing warm fluids to gradually increase his body temperature. None of it seemed to be making any difference.

Rather than call off the resuscitation entirely, Lambert and Maffei decided to bring Gardell into surgery for a cardiopulmonary bypass—the most aggressive form of active rewarming, a last-ditch effort to get his heart beating. After they scrubbed up, they checked for a pulse one more time.

Incredibly, there it was: a heartbeat, faint at first, but steady, without the rhythm abnormalities that sometimes appear after a prolonged cardiac arrest. And just three and a half days later Gardell left the hospital with his prayerful family, a little wobbly on his feet but otherwise perfectly fine.

Gardell is too young to tell us what it was like during the 101 minutes he was dead. But sometimes people who’ve been rescued, thanks to persistent, high-quality resuscitation, come back with stories that are quite clear—and eerily similar. These survivors can be thought of as having crossed over to the other side and returned with stories that offer some insight into how it feels to die. Their tales from the gray zone have been the subject of some scientific scrutiny, most recently in a study called AWARE (AWAreness during REsuscitation), led by Sam Parnia. Beginning in 2008, Parnia, director of resuscitation research at Stony Brook University, and his colleagues looked at 2,060 cases of cardiac arrest at 15 American, British, and Austrian hospitals. Among them were 330 survivors, 140 of whom were interviewed. Fifty-five of the 140 patients said that during the time when they were being resuscitated, they perceived some kind of awareness.

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Though most couldn’t quite recall details, others mentioned sensations similar to those found in best-selling books such as Heaven Is for Real: time either speeding up or slowing down (27 people), peacefulness (22), separating from their bodies (13), joy (9), or seeing a bright light or golden flash (7). Some (the exact number wasn’t specified) said they remembered bad sensations: fear, drowning or being dragged through deep water, or in one case, seeing “men in coffins being buried upright.” The study, Parnia and his co-authors wrote in the medical journal Resuscitation, provides “further understanding of the broad mental experience that likely accompanies death after circulatory standstill.” They wrote that the next step would be to study whether and how these episodes—which most investigators call near-death experiences (NDEs), though Parnia prefers “actual death experiences”—affect survivors after recovery, either with positive influences or negative ones, such as cognitive problems and post-traumatic stress. What the AWARE team didn’t explore was a common aftereffect of NDEs: a renewed sense of purpose and meaning to one’s life. That’s the feeling you often hear about from survivors—especially those who go on to write books about it. Mary Neal, an orthopedic surgeon from Wyoming, mentioned that effect to a large audience at a 2013 New York Academy of Sciences panel discussion called Rethinking Mortality. Neal, author of To Heaven and Back, described drowning while kayaking in Chile 14 years earlier. She said she could feel her spirit peeling away from her body and rising out of the river, as her knees bent backward, breaking her bones. She remembered walking down an “incredibly beautiful pathway toward this great domed structure that I knew was the point of no return—and I could hardly wait.” She described thinking how strange the whole experience was, wondering how long she’d been underwater (later she learned it had been at least 30 minutes), finding comfort in the knowledge that her husband and children would be fine without her. Then she felt her body come out of the boat and could see the first responders doing CPR. She heard one of them calling to her, “Come back, come back!”—which she said she found “really very irritating.”

Kevin Nelson, a neurologist at the University of Kentucky, was on Neal’s panel, and he was skeptical—not of her memory, which he acknowledged was intense and valid, but of its explanation. “These are not return-from-death experiences,” he said, also contradicting Parnia’s view of what had happened. “During these experiences the brain is very much alive and very much active.” He said that what Neal went through could have been a phenomenon called REM intrusion, when the same brain activity that characterizes dreaming somehow gets turned on during other, nonsleep events, such as a sudden loss of oxygen. To him, near-death and out-of-body experiences are the result not of dying but of hypoxia—a loss of consciousness, not of life itself.

Other studies point to different physiological explanations for NDEs. At the University of Michigan a team led by neuroscientist Jimo Borjigin measured brain waves in nine rats after cardiac arrest. In all of them high-frequency gamma waves (the ones associated with meditation) became more intense after the heart stopped—more coherent and organized, in fact, than they are during ordinary wakefulness. Maybe this is what NDEs are, the investigators wrote, a “heightened conscious processing” that occurs during the limbo period before death becomes permanent.

More questions about the gray zone arise from the phenomenon of thukdam, a rare occurrence in which a monk dies but there is seemingly no physical decomposition for a week or more. Richard Davidson of the University of Wisconsin, who has spent years studying the neuroscience of meditation, has long been intrigued by this—is the person conscious or not? dead or not?—especially after he saw a monk in thukdam at the Deer Park monastery in Wisconsin in the summer of 2015.

“If I had just casually walked into the room, I would have thought he was sitting in deep meditation,” Davidson says, his voice on the phone still a little awestruck. “His skin looked totally fresh and viable, no decomposition whatsoever.” The sense of the dead man’s presence, even at close range, helped inspire Davidson to study thukdam scientifically. He has assembled some basic medical equipment, such as EEGs and stethoscopes, at two field stations in India and has trained an on-site team of 12 Tibetan physicians to test these monks—preferably beginning while they’re still alive—to see whether any brain activity continues after their death.

“It’s likely that in many of these practitioners, they enter a state of meditation before they die, and there is some kind of maintenance of that state afterward,” Davidson says. “Just how that occurs, and what the explanation might be, eludes our conventional understanding.” His research, though grounded in Western science, aims for a different kind of understanding, a more nuanced one that might clarify what happens not only to monks in thukdam but also to anyone traveling across the border between life and death.

Disintegration usually proceeds swiftly after a person dies. When the brain stops functioning, it loses all ability to keep the other systems in balance. So to allow Karla Pérez to continue nurturing her fetus after her brain stopped working, a team of more than a hundred doctors, nurses, and other hospital workers had to fill in as ad hoc orchestrators. They took readings continuously, around the clock, of Pérez’s blood pressure, kidney function, and electrolytes, all the while adjusting what was going into her tubes and IV lines.

But even as the team members performed the functions of Pérez’s ruined brain, they still had trouble thinking of her as dead. To a person, they treated her as though she were in a deep coma, greeting her by name when they came into the room and saying goodbye when they left.

To some extent these gestures toward Pérez’s personhood were made out of respect for the family, a courtesy to avoid seeming to treat her as an inert baby vessel. But in a way, the gestures went beyond courtesy. They reflected how the people attending to Pérez actually felt.

Todd Lovgren, co-leader of the medical team, knows the anguish of losing a daughter—he lost one too, the oldest of his five children, who would have been 12 years old had she lived. “It would have offended me not to treat Karla like a person,” he told me. “I saw a young woman with painted fingernails, her mom doing her hair, with warm hands and warm toes … Whether her brain was still functional or not, I don’t think her humanity was gone.”

Speaking as a parent rather than a clinician, Lovgren says he thought something of Pérez’s essence was still there in the bed—even though he knew, by the time of her second CT scan, that not only was her brain not functioning but large portions of it were dying off and peeling away. (Despite this, he hadn’t tested for the last of the three criteria of brain death, apnea, fearing that removing Pérez from the ventilator for even a few minutes might harm the fetus.)

On February 18, ten days after Pérez’s stroke, it became clear that her blood wasn’t clotting normally—an indication that dead brain tissue was getting into her bloodstream, one more sign to Lovgren that “she was never going to recover.” By this time the fetus was 24 weeks old, so the team transferred Pérez from the main campus back to Methodist Women’s, the maternity hospital. They managed to correct the clotting problem for the moment. But they were ready to do a C-section as soon as it became clear that it was time to let go, when even the semblance of a living person that their skills and instruments had patched together was beginning to fall apart.

To Sam Parnia, death is potentially reversible. Cells inside our bodies don’t usually die when we die, he says; some cells and organs can remain viable for hours, maybe even days. The timing of the declaration of death is sometimes a matter of personal attitude, he says. When he was in training, he notes, people would stop CPR after just five to ten minutes, assuming that any longer would mean irreparable brain damage.

But resuscitation scientists have learned ways to keep the brain and other organs from dying even after the heart stops. They know that lowering body temperature helps—which happened naturally with Gardell Martin, and which happens deliberately in some ERs that routinely chill patients before doing CPR. They know that persistence helps too, especially in hospitals that use machines to regulate chest compressions or that someday might use drugs such as iodide.

Parnia compares resuscitation science to aeronautics. It never seemed possible for people to fly, yet in 1903 the Wright brothers flew. How incredible, he says, that it took only 66 years from that first, 12-second flight to a moon landing. He thinks such advances can happen in resuscitation science too. When it comes to reversing death, Parnia believes we’re still in the Kitty Hawk era.

Yet doctors are already able to snatch life from death in stunning, inspiring ways. In Nebraska that happened on April 4, 2015, the day before Easter, when a baby boy named Angel Pérez was born by C-section at Methodist Women’s Hospital just before noon. Angel is alive today because doctors were able to keep his brain-dead mother’s body functioning for 54 days, long enough to let him grow into a small yet otherwise perfectly normal newborn, two pounds, 12.6 ounces, miraculous in his ordinariness. A baby who turned out to be the milagro his grandparents had been praying for.