So, WTF Is Up With Putting a Human in ‘Suspended Animation?’

At least one patient has been treated with an experimental therapy that rapidly lowers their body temperature to a state of suspended animation, the trial's leader revealed to New Scientist this week.

The cold shock is meant to slow cell death in the brain that occurs when the brain’s supply of oxygen is cut off due to severe blood loss, buying time for a potentially life-saving surgery.

The patients were treated at the University of Maryland Medical Center as part of an ongoing clinical trial for emergency preservation and resuscitation (EPR) led by Samuel Tisherman, director of the center's division of critical care and trauma education. The technique has shown promise in animals, but had never been used to treat humans until now.

“These are patients that are basically dead and have nothing to lose,” said Kees Polderman, a professor of intensive care medicine at Basildon and Thurrock University Hospitals in the U.K. Polderman worked with Tisherman at the University of Pittsburgh, but he is not involved in the trial. “The idea is, I think, a very good one. I really, really hope it works.”

A University of Maryland spokesperson said that Tisherman could not comment on the progress or results of the ongoing trial, which began in 2016. He told New Scientist that he hopes to announce the full results of the trial by the end of 2020.

“The fact that the study is continuing means that they haven't at least encountered massive problems,” Polderman said.

Tisherman gave a presentation

about the procedure to The New York Academy of Sciences on Monday as part of a conference on resuscitation and consciousness. He discussed the motivation for the trial and the method by which his team can put patients into suspended animation.

“We thought the fastest way we could cool the whole body, particularly the brain and the heart, would be just to flush the body with cold fluid,” Tisherman told the audience.

The process for achieving suspended animation is detailed in a patent that was granted to Tisherman and his collaborators in 2014. The patent describes flushing a patient’s bloodstream with a saline solution between 32 and 40 degrees Fahrenheit that can cool the body from its resting temperature of 98.6 degrees to 50 degrees Fahrenheit in under 20 minutes. Surgeons can inject the solution directly into the heart or a major artery using a thin tube called a cannula.

After performing surgery, doctors can warm up the patients by placing them on a heart-lung machine that mechanically circulates and oxygenates their blood. Patients will only be in a suspended state for a few hours, according to the patent.

Studies that applied this technique to dogs and pigs offered promising results, which Tisherman and his collaborators cite in a description of the trial’s procedure published in 2017. They hope to enroll 10 people into the study who will receive the cold-shock treatment, and 10 controls.

For a patient to qualify for the trial, they must have lost a pulse within five minutes of arriving to the ER or operating room, according to publicly available study details. They must also be between the ages of 18 and 65 and have sustained a penetrative wound, like a gunshot or knife wound, that can be surgically repaired.

“We’re trying to thread that fine line between doing something to someone that’s going to do well anyway, or doing something to somebody that’s going to die no matter what we do,” Tisherman told The New York Academy of Sciences.

Suspended animation isn’t a new theory—real-life instances of humans surviving for hours after being buried in snow or drowning in icy water spurred scientists to attempt to artificially create similar conditions. Tisherman's approach isn't the only one being investigated by researchers, either.

An alternative method of suspended animation is to simulate hibernation, said Matteo Cerri, an assistant professor of physiology at the University of Bologna who studies synthetic torpor. During hibernation, a warm-blooded animal’s heart rate and breathing slows, its metabolism decreases, and its body temperature gradually lowers to that of a cold-blooded animal.

“In hibernation you have an orchestrated response of the body,” Cerri said. “Whereas for this trial, it is really really forcing the body to cool by overloading the body with cold fluid.” Hibernation would be a more effective strategy for long-term cooling but would take longer than Tisherman’s method in an emergency situation, he added.

The U.S. Department of Defense funds multiple research projects on suspended animation, including Tisherman’s trial. The DoD's interest may lie in eventually applying the technique on the battlefield: According to one study, 80 percent of soldiers killed in action in Vietnam without brain trauma had penetrating wounds that bled out quickly.

Cerri said that he is curious to see Tisherman’s full results, particularly what the long-term effects of the cold fluid are on people’s organs and blood vessels.

If the trial is successful in saving at least a few patients, Polderman said that he would consider it a success. Proving that the fundamentals of suspended animation are sound, he added, could open the door to making procedures that may sound like science fiction into reality.

“If you can prove that you can conserve the brain in that way and bring it back, it opens up a whole list of other possibilities,” Polderman said. “You can even think of things like spaceflight and cryopreservation.”

This more far-out possibility raises a host of ethical questions, said David Hoffman, a health care lawyer and clinical bioethicist.

“If you are able to put somebody into a cryogenically stabilized state for an hour or a day, fine, but if you have to do it for a week or a month…then the question becomes, how do you decide when you've provided enough therapy? And who makes decisions about what to do after the therapy is either worked or hasn't worked?” he said.

Tisherman's approach is more grounded in the present, however, and is firmly aimed at giving Earth doctors a bit more time to save a life.

“So just to be clear, I'm not going to be talking about suspended animation to send people off to Jupiter and have them wake up when they get there. I’m also not going to talk about freezing people until whatever caused them to die has now been cured 50 years later,” he told The New York Academy of Sciences. “What I’m going to talk about is just figuring out how we can buy time to save people who are dying in front of us who we just can't fix quickly enough.”