快猫短视频

YOU鈥橰E the first doctor at the scene of a ferry disaster. People are being
plucked from the icy sea, apparently dead. No pulse, nothing. But deep cold
protects the brain, so they may still be alive.

Yet you are in a quandary. Warming can revive people with extreme
hypothermia, but it鈥檚 risky. If their brain cells warm up before blood starts
flowing, the cells may die from lack of oxygen. Then it really is all over for
the patient. So what do you do?

According to Kyrill Ivanov of the Pavlov Institute of Physiology in St
Petersburg, the answer is an injection of a simple chemical. His treatment
kick-starts the body鈥檚 normal functions: blood starts flowing and oxygen moves
around the body while cells are still cold and the brain is dormant. 鈥淚t is
lowering the temperature limit of life,鈥� says Ivanov.

Ivanov says that the treatment revives rats and rabbits that have been
chilled until their brains are at only 16 掳C. Now he wants to test his
method on people suffering from hypothermia in real emergency situations. 鈥淭his
work could well transfer to humans,鈥� says biochemist Andy Cossins of the
University of Liverpool. 鈥淸It] really is quite exciting.鈥�

As the body cools from its normal temperature of 37 掳C, it shuts down its
essential functions one by one. Shivering stops around 30 掳C, breathing
around 25 掳C, and the heart around 23 掳C. Some people have been
successfully revived after more than an hour of such deep chill, but only in
hospitals specially equipped for a heart and lung bypass, and even then it鈥檚
risky.

Our body functions stop in the cold because calcium levels in our cells rise,
says Ivanov. Calcium continuously floods in from the bloodstream, but cells
normally keep the level inside low by pumping it out again. This process
requires lots of energy, so as the body cools and slows down, cells can鈥檛 keep
up with the influx and get swamped.

Ivanov reasoned that if he could reverse the rise in calcium, the animals鈥�
cells would start working again and they鈥檇 warm themselves. He cooled rats and
rabbits until their brain temperatures were as low as 16 掳C, which stopped
their breathing and shivering. Then he gave them injections of EDTA, a chemical
that mops up calcium in the blood, reducing the amount of calcium flooding into
cells.

The animals soon started shivering and breathing again, even though their
brains were still cold. When Ivanov removed the animals from the cold water and
left them at room temperature, they warmed up and recovered completely. None of
the animals that weren鈥檛 given EDTA survived the same cold treatment.

鈥淔or the first time we have found a way to revive without rewarming,鈥� says
Ivanov. Now he wants to try the treatment with people. 鈥淚f I am invited to help
anybody, I will do it immediately.鈥�

John McGowan, resuscitation officer at the Southern General Hospital in
Glasgow, says the research is unique. But he warns that what happens in rats
won鈥檛 necessarily work in humans. 鈥淧eople have different thermoregulatory
strategies to rats,鈥� he says. If it does work, McGowan says it could help save
patients rescued far from hospital. 鈥淩estarting shivering in itself would help
to keep the patient warm.鈥�

Mike Harrison of Britain鈥檚 Defence Evaluation and Research Agency says the
treatment could be useful for soldiers in the field. 鈥淎n injection that could
induce shivering in someone suffering from hypothermia would certainly be useful
from a military medicine point of view.鈥�