Doctors aim to save gunshot victims by freezing them in ‘suspended animation’
Researchers in Pennsylvania are testing a new technique to freeze gunshot victims in suspended animation, keeping them hovering between life and death, while doctors try to save their lives. The first human trials began in May.
The groundbreaking approach of suspended animation is actually called emergency preservation and resuscitation (EPR). “We are suspending life, but we don't like to call it suspended animation because it sounds like science fiction," Samuel Tisherman, a surgeon at the University of Pittsburgh Medical Center (UPMC) Presbyterian Hospital, who is leading the trial, told New Scientist.
Unlike in science fiction, this state of suspended animation isn’t designed to preserve life for decades into the future, like with TV show Futurama’s head jars or baseball star Ted Williams’ cryogenically frozen head and body. Instead, the doctors will freeze the gunshot victims’ bodies to “buy time” for transport and resuscitative surgery, the University of Pittsburgh said.
Tisherman’s team will do their research on patients who have suffered cardiac arrest after a traumatic injury resulting in blood loss and who are unresponsive to attempts to restart their hearts, New Scientist reported. “The patient will probably have already lost about 50 per cent of their blood and their chest will be open," Tisherman said. Their survivability rate at this point is less than 7 percent.
The doctors will quickly induce hypothermia, freezing the patient’s internal organs by removing all the blood from the body and flushing the system with a cold saline solution through the heart and into the brain, cooling the body down to 10 degrees Celsius. “At this point they will have no blood in their body, no breathing, and no brain activity. They will be clinically dead,” New Scientist reported.
Normally, when the heart stops beating, oxygen stops flowing to the brain and the brain dies after five minutes with no oxygen. But cells need less oxygen the colder they are, so the hypothermia preserves the victim’s life by slowing down the chemical reactions inside the body and preventing the brain from realizing it hasn’t received oxygen. Doctors will then have several hours to repair the trauma from the gunshot before resuscitating the patient.
The technique was developed by Dr. Peter Rhee, who successfully tested it on pigs in 2000, CNET reported. Rhee’s test required cutting the pigs’ arteries with scalpels and replacing their blood with saline to drop their body temperatures to 10 degrees Celsius, while leaving the body temperatures of a control group of pigs alone. All of the pigs in the control group died, but 90 percent of the EPR pigs survived. CNET noted that some of the pigs in the trial did have to be “given a jump start,” but that after the trial, “the pigs demonstrated no physical or cognitive impairment.”
Scientists in Boston followed up on Rhee’s research in 2006, using hydrogen sulphide gas to induce hypothermia in mice, BBC News reported at the time. Researchers found that the mice’s heart rates and respiration fell as their body temperatures fell, but their heart rates did not fall, “which tends to happen with other techniques such as lowering body temperature.” The effects of the gas on the mice “seemed to be reversible,” with the mice’s vital signs returning to normal within two hours after removing the gas.
"After we did those experiments, the definition of 'dead' changed," Rhee told New Scientist. "Every day at work I declare people dead. They have no signs of life, no heartbeat, no brain activity. I sign a piece of paper knowing in my heart that they are not actually dead. I could, right then and there, suspend them. But I have to put them in a body bag. It's frustrating to know there's a solution."
Tisherman and the doctors on his team will perform their research in hospital emergency rooms at the University of Pittsburgh and the University of Maryland, and will not be able to gain consent from their subjects. However, the study will use the US Food and Drug Administration’s “exception-from-informed-consent process,” according to New Scientist, which required the team to hold meetings with community groups, advertise in local newspapers and create an online opt-out form. So far, no one has elected to opt out in advance.
Once the team has tested the technique on 10 people, they will compare their outcomes with the outcomes of a control group of 10 people who met the same criteria but did not receive the EPR treatment. The doctors will refine the process, then test the updated version on another 10 people, until there are enough results to analyze, Tisherman told New Scientist.
"We've always assumed that you can't bring back the dead. But it's a matter of when you pickle the cells," Rhee said to New Scientist, which calls to mind the emergency room adage of dealing with hypothermia: "You're not dead until you're warm and dead."
