Doctors Place Humans in True Suspended Animation for First Time
New Scientist reports that doctors have used therapeutic suspended animation for the first time as part of a carefully designed human trial. The procedure, called Emergency Preservation and Resuscitation (EPR), is a way to try to save the lives of people with severe traumatic injuries like gunshot damage—patients who have lost the majority of their blood and gone into cardiac arrest. In the moment, these people are extremely unlikely to survive because of the tiny timeframe before their bodies are out of options.
EPR involves identifying a patient who is likely to die of reparable injuries within literally minutes and replacing their blood with “ice-cold saline,” New Scientist reports. Their body temperature is lowered to about 50 to 60 degrees Fahrenheit, far below the threshold of currently practiced therapeutic hypothermia at about 94 degrees Fahrenheit.
Instead of a gentle lowering, EPR is a drastic countershock to stop the progression of bleedout or cardiac arrest. Surgeons buy themselves a couple of hours of time to repair damage where they previously had just minutes. Without a pulse or any measurable brain activity, these patients are in true suspended animation by any measure.
From a treatment perspective, the time crunch is what prevents better outcomes most of the time, not the extent of the injuries themselves. The overall field of resuscitation science includes everything from civilian CPR to the advanced techniques used in trauma centers—the industry term for hospital facilities that are able to treat trauma injuries, which is a blanket term for everything from bullet or stab wounds to car crashes to head trauma during boxing matches.
There have been huge obstacles in this study’s way. First, not all hospitals have trauma centers—in 2002, only about 20 percent did. Trauma centers are expensive and specialized, which has left many Americans in what are called trauma deserts, defined as “any urban community that is at least five miles away from advanced trauma care.” The long drive or ambulance ride to a trauma center more than five city miles away can mean life or death for trauma injury victims.
The ethics of a human study of EPR is the other gigantic obstacle. Dr. Samuel Tisherman at the University of Maryland is in the news today for his first successful trial of the EPR technique, but he’s tried to get this specific human trial approved for at least five years as part of an entire career of research into suspended animation.
Tisherman has been a critical care surgeon since completing a specialty fellowship in 1994, and he studied under “the father of CPR,” Dr. Peter Safar. He first tried to design and conduct an EPR study at the University of Pittsburgh, where he taught for 20 years until 2014, but the patient base there just didn’t experience enough trauma injuries for him to draw significant statistics.
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From his new base in the University of Maryland medical system, Tisherman began pushing for his study in 2015. Nicola Twilley reported on Tisherman’s progress for the New Yorker and attended a 2015 EPR rehearsal. “The plan had been to do a complete run-through of the procedure, but there were so many questions about unforeseen complications that the rehearsal kept grinding to a halt,” she wrote. Tisherman was handing out information at a local mall to help drum up community support for his EPR human trial.
Because the patients he sought to treat were almost or actually clinically dead, Tisherman faced a third obstacle in bureaucratic opposition to his study. The FDA has special rules for tests like this, in emergency situations where an unconscious person can’t possibly give informed consent. Tisherman had to navigate training his colleagues on an experimental and dramatic technique while trying to get official institutional permission to study it at all. Four years have passed since Twilley attended Tisherman’s training, but Tisherman has studied delayed resuscitation for his entire career and has waited all this time.
Finally, 10 years after his lifetime achievement award from the American Heart Association, Tisherman is finally doing what he considers the culmination of his life’s work. The facilities where he works at the University of Maryland, Shock Trauma, was called “the world’s most advanced emergency room” by Baltimore magazine in 2010—a natural fit when Tisherman sought a population whose outcomes he could improve with his lifetime of trauma injury expertise. Shock Trauma is one of five trauma centers in the city of Baltimore, out of 11 total in the state of Maryland.
EPR sounds like a miracle from a sci-fi book, but it’s not without significant potential drawbacks. Patients don’t experience true freezing tissue injury like the kind that causes frostbite, but their tissues are deprived of oxygen for a long enough time that there’s a bounce-back injury called reperfusion: “the paradoxical exacerbation of cellular dysfunction and death, following restoration of blood flow,” according to the National Institutes of Health. As blood is pumped back into deprived tissues, those cells are more likely to die.
Tisherman hopes the risk of reperfusion is something he can study in detail down the road, including the possibility of drugs that will mitigate all the risks associated with EPR. “It may be possible to give people a cocktail of drugs to help minimise these injuries and extend the time in which they are suspended,” Tisherman told New Scientist.
After years of working toward the trial, this is Tisherman’s first public presentation, and just one step on a long road to any potential wide acceptance and use of EPR.
From: Popular Mechanics
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