Suspended animation is the slowing of life processes by
external means without termination. Breathing, heartbeat, and other
involuntary functions may still occur, but they can only be detected by
artificial means. Extreme cold can be used to precipitate the slowing of
an individual's functions; use of this process has led to the
developing
science of
cryonics. Cryonics is another method of life preservation but it
cryopreserves
organisms using liquid nitrogen that will preserve the organism until
reanimation. Laina Beasley was kept in suspended animation as a
two-celled
embryo for 13 years.
Placing
astronauts
in suspended animation has been proposed as one way for an individual
to reach the end of an interstellar or intergalactic journey, avoiding
the necessity for a gigantic
generation ship;
occasionally the two concepts have been combined, with generations of
"caretakers" supervising a large population of frozen passengers.
Since the 1970s,
induced hypothermia has been performed for some
open-heart surgeries as an alternative to
heart-lung machines.
Hypothermia, however, provides only a limited amount of time in which
to operate and there is a risk of tissue and brain damage for prolonged
periods.
Experiments
Temperature-induced
In June 2005 scientists at the
University of Pittsburgh's Safar Center for Resuscitation Research announced they had managed to place
dogs in suspended animation and bring them back to life, most of them without
brain damage, by draining the
blood out of the dogs' bodies and injecting a low temperature solution into their
circulatory systems, which in turn keeps the bodies alive in stasis. After three hours of being
clinically dead, the dogs' blood was returned to their circulatory systems, and the animals were revived by delivering an
electric shock to their hearts. The heart started pumping the blood around the frozen body, and the dogs were brought back to life.
While most of the dogs were fine, a few of the revived dogs had
severe nervous and movement coordination damage, causing them to be
mentally disabled, and demonstrating behavior that was deemed "
zombie" like. This has been pushed further by the media which named them "zombie dogs". There is concern that using this technique on humans could result in
brain damage similar to that suffered by some of the dogs in the
experiment. In extreme cases, doctors can now use
induced hypothermia which reduces brain and heart activity to a minimum. This gives doctors more time to heal or diagnose a patient.
On 20 January 2006, doctors from the
Massachusetts General Hospital in
Boston announced they had placed
pigs in suspended animation with a similar technique. The pigs were
anaesthetised
and major blood loss was induced. After the pigs lost about half their
blood the remaining blood was replaced with a chilled saline solution.
As the body temperature reached
10 °C (50 °F) the damaged blood vessel was repaired and the blood was returned. The method was tested 200 times with a 90% success rate.
Chemically induced
An article in the 22 April 2005 issue of the scientific journal
Science reports success towards inducing suspended animation-like
hypothermia in
mice. The findings are significant, as mice do not hibernate in nature. The laboratory of Mark B. Roth at the
Fred Hutchinson Cancer Research Center in
Seattle, Washington, placed the mice in a chamber containing 80
ppm hydrogen sulfide for a duration of 6 hours. The core body temperature of the mice dropped to 13 degrees Celsius and
metabolism, as assayed by
carbon dioxide production and
oxygen use, decreased 10-fold.
They also induced
hypoxia on
nematode embryos and
zebrafish
embryos, placing them in suspended animation for hours, and then
re-animating them simply by returning the oxygen to the embryos.
Massachusetts General Hospital in
Boston announced they had been able to hibernate
mice
using the same method. Their heart rate was slowed down from 500 to 200
beats per minute, respiration fell from 120 to 25 breaths per minute
and body temperature dropped to 30°C (natural: 39°C). After 2 hours of
breathing air without hydrogen sulfide the mice returned to normal.
Further studies are needed to see if the gas had damaging effects on the
brain, considering the effect of hydrogen sulfide on the body is
similar to hydrogen cyanide; it does not slow the metabolic rate but
rather inhibits the transfer of energy within the cell via ATP ("It
forms a complex bond with iron in the mitochondrial cytochrome enzymes,
thus preventing cellular respiration." quoted from 'Hydrogen sulfide' -
Wikipedia).
Experiments on sedated sheep
and partially ventilated anesthetized pigs
have been unsuccessful, suggesting that application to large mammals may not be feasible.
Hibernation
There are many research projects currently investigating how to achieve "induced
hibernation" in humans.
This ability to hibernate humans would be useful for a number of
reasons, such as saving the lives of seriously ill or injured people by
temporarily putting them in a state of hibernation until treatment can
be given.
There are cases of accidental human hibernation. The most recent is
the case of Mitsutaka Uchikoshi, a Japanese man who survived the cold
for 24 days in 2006 without food or water when he fell into a
hypothermic state similar to hibernation
{Source:
http://en.wikipedia.org/wiki/Suspended_animation }
For more information on this subject, or near-death expriences check the following links:
http://en.wikipedia.org/wiki/Lazarus_syndrome
http://en.wikipedia.org/wiki/Near_death_experience
http://en.wikipedia.org/wiki/Life_review
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