Putting life on hold in medical “suspended animation” has long been a dream. (The preferred scientific term for the modern-day procedure is emergency preservation and resuscitation [EPR].) Dr. Sam Tisherman and a team of surgeons at UPMC Presbyterian Hospital in Pittsburgh, Pennsylvania, have recently started human trials for a practical application of EPR. This surgical technique replaces all of a patient’s blood with a solution to cool the body down and buy time for doctors to fix injuries without losing patients to blood loss.

Dr. Peter Rhee at the University of Arizona in Tucson first started researching suspended animation when asked by the military to find a way of preserving wounded victims before they reached the hospital, and together with his colleagues developed a technique through experimenting on pigs. Dr. Tisherman of the University of Pittsburgh and his team  developed another method, which is what will be tested in the new human trials.

Hypothermia — an abnormally low body temperature — dramatically decreases the human body’s need for oxygen. This is similar to how animals hibernate. In EPR, doctors will induce hypothermia in patients by swapping their blood with very cold salt water to cool the entire body down to 10°C (50°F) in 15 minutes. Normally, we can’t survive with our blood missing — it carries the oxygen that cells need to make energy. However, when the body temperature is very low, cellular activity stops and cells survive without oxygen, thus preventing further damage to tissues and organs. It’s also important to cool the body down quickly when trauma patients are losing blood rapidly. If they don’t have any blood flow to the brain for 4 to 5 minutes, while the body is at normal temperature, there could be irreversible damage. Feel free to click through to get the details on how the procedure will be performed if you’re up for it.

How It Works: Putting Humans In Suspended Animation | Popular Science.