Short-Term Suspended Animation for Humans Is Coming Soon

A man gasps for air through deep ice, in a symbolic representation of human hibernation through induced hypothermia. (© deepspacedave/Fotolia)

At 1 a.m., Tony B. is flown to a shock trauma center of a university hospital. Five minutes earlier, he was picked up unconscious with no blood pressure, having suffered multiple gunshot wounds with severe blood loss. Standard measures alone would not have saved his life, but on the helicopter he was injected with ice-cold fluids intravenously to begin cooling him from the inside, and given special drugs to protect his heart and brain.

Suspended animation is not routine yet, but it’s going through clinical trials at the University of Maryland and the University of Pittsburgh.

A surgeon accesses Tony’s aorta, allowing his body to be flushed with larger amounts of cold fluids, thereby inducing profound hypothermia — a body temperature below 10° C (50° F). This is suspended animation, a form of human hibernation, but officially the procedure is called Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma (EPR-CAT). This chilly state, which constitutes the preservation component of Tony’s care, continues for an hour as surgeons repair injuries and connect his circulation to cardiopulmonary bypass (CPB). This allows blood to move through the brain delivering oxygen at low doses appropriate for the sharply reduced metabolic rate that comes with the hypothermia, without depending on the heart and lungs. CPB also enables controlled, gradual re-warming of Tony’s body as fluid and appropriate amounts of red blood cells are transfused into him. After another hour or so, Tony’s body temperature reaches the range of 32-34° C (~90-93° F), called mild hypothermia. Having begun the fluid resuscitation process already, the team stops warming Tony, switches his circulation from CPB to his own heart and lungs, and begins cardiac resuscitation with electrical jolts to his heart. With his blood pressure stable, his heart rate slow but appropriate for the mild hypothermia, Tony is maintained at this intermediate temperature for 24 hours; this last step is already standard practice in treatment of people who suffer cardiac arrest without blood loss trauma. The purpose is to prevent brain damage that might come with the rapid influx of too much oxygen, just as a feast would mean death to a starvation victim. After he is warmed to a normal temperature of 37° C (~99° F), Tony is awakened and ultimately recovers with no brain damage. Tony’s case is fictional; EPR-CAT is not routine yet, but it’s going through clinical trials at the University of Maryland and the University of Pittsburgh, under the direction of trauma surgeon Dr. Samuel Tisherman, who spent many years developing the procedure in dogs and pigs. In such cases, patients undergo suspended animation for a couple of hours at most, but other treatments are showing promise in laboratory animals, like the use of hydrogen sulfide gas without active cooling to induce suspended animation in mice. Such interventions could ultimately fuse with EPR-CAT, sending the new technology further into what’s still the realm of science fiction – at least for now.

Consider the scenario of a 5-year-old girl diagnosed with a progressive, incurable, terminal disease.

Experts say that extended suspended animation – cooling patients in a stable state for months or years — could be possible at some point, although no one can predict when the technology will be clinical reality, since hydrogen sulfide and other chemical tactics would have to move into clinical use in humans and prove safe and effective in combination with EPR-CAT, or with a similar cooling approach. How Could Long-Term Suspended Animation Impact Humanity? Consider the scenario of a 5-year-old girl diagnosed with a progressive, incurable, terminal disease. Since available treatments would only lengthen the projected survival by a year, she is placed into suspended animation. She is revived partially every few years, as new treatments become available that can have a major impact on her disease. After 35 years of this, she is revived completely as treatments are finally adequate to cure her condition, but biologically she has aged only a few months. Physically, she is normal now, though her parents are in their seventies, and her siblings are grown and married. Such hypothetical scenarios raise many issues: Where will the resources come from to take care of patients for that long? Who will pay? And how will patients adapt when they emerge into a completely different world? “Heavy resource utilization is a factor if you’ve got people hibernating for years or decades,” says Bradford Winters, an associate professor of anesthesiology and critical care medicine, and assistant professor of neurological surgery at Johns Hopkins. Conceivably, special high-tech facilities with robots and artificial intelligence watching over the hibernators might solve the resource issue, but even then, Winters notes that long-term hibernation would entail major disparities between the wealthy and poor. “And then there is the psychological effect of being disconnected from one’s family and society for a generation or more,” he says. “What happens to that 5-year-old waking to her retired parents and married siblings? Will her younger sister adopt her? What would that be like?” Probably better than dying is one answer.

Back on Earth, human hibernation would raise daunting policy questions that may take many years to resolve.