Suspended Animation: Fact or fiction?

Erica Nordby, a toddler in Edmonton Canada had wandered out alone into the frigid night. Before she was resuscitated her heart had stopped beating for two hours and her body temperature had dropped to 61 degrees Fahrenheit. She was brought back to life and has no lasting effects from the experience.

Erica Nordby, a toddler in Edmonton Canada had wandered out alone into the frigid night. Before she was resuscitated her heart had stopped beating for two hours and her body temperature had dropped to 61 degrees Fahrenheit. She was brought back to life and has no lasting effects from the experience.

In October 2006, a Japanese man, Mitsutaka Uchikoshi, fell asleep on a snowy mountain and was found unconscious by rescuers 23 days later; doctors who treated him believed his temperature had fallen to 71 degrees Fahrenheit during that period.

Medical science defines hypothermia as being present within an organism when it's temperature drops to a point at which normal functions are impaired. Typically, hypothermia results in a decrease in metabolism and cellular activity ultimately causing cell death. In addition, there is a significant decrease in blood flow and oxygen levels which causes the muscles, organs and brain to malfunction.

Chilling stories like these intrigued Dr. Mark Roth, an investigator at the Fred Hutchinson Cancer Research Center. After reading accounts of people being revived after long periods in the cold, he became interested in the idea that humans may have metabolic flexibility and be able to decrease their respiration and heartbeat and, in effect, "turn themselves off" in response to physical or environmental stress. These stories may provide clues about our capacity to briefly suspend our vital functions when environmental conditions get rough.

Metabolic flexibility has been around for many years and is observed in mammals that hibernate. During hibernation, there is a decrease in respiration, heart rate and body temperature allowing mammals to survive the cold winter and conserve energy sources.

Additionally, many invertebrates can hibernate for days, months, and even years before reanimating.

Roth was interested in harnessing the effect that cold had on the ability of humans to 'turn themselves off' and then reanimate.

The Art of hibernation on-demand

After watching a documentary about underground caves on PBS, Roth got an idea about how to induce metabolic flexibility in humans. The television show explained how cave explorers risk encountering the gas hydrogen sulfide, which in high concentrations can immediately render a person unconscious.

Hydrogen sulfide is toxic flammable gas found not only in caves but is produced by volcanoes, hot springs, and bacterial break down of organic matter in swamps and sewers. One of its most notable features is the foul odor of rotten eggs.

Hydrogen sulfide binds with iron in cytochrome enzymes, disrupting a critical step in a process called oxidative phosphorylation, in which oxygen is burned to produce energy in the form of a substance called ATP. By blocking oxygen from binding to the iron, hydrogen sulfide stops cellular respiration and energy production completely. When energy production is inhibited, body temperature and metabolic rate are severely reduced.

Enzymes exist in the body that can detoxify hydrogen sulfide by oxidation to (harmless) sulfate. As a result, low levels of sulfide may be tolerated indefinitely. However, at higher levels it can poison several systems in the body although the nervous system is the most affected.

Roth hypothesized that perhaps he could prevent death in low oxygen situations by adding agents such as hydrogen sulfide that decrease metabolic activity by inhibiting oxygen utilization and induce suspended animation. Suspended animation refers to the state where all observable life processes are stopped but the animal can later resume its normal function.

How did Roth investigate his theory?