Hypothermia jab 'could help warming'

Immersion in icy water can lead to hypothermia

Extremely cold patients may benefit from an injection which may reduce some of the dangers associated with warming them up.

Patients can survive, even if their bodies have been deeply chilled for some time.

If the body's cells are very cold, they may not need oxygen to survive, so it is not necessarily fatal if the end if the patient's breathing has stopped.

But severe hypothermia is a difficult condition to treat - the instinct of the first aider may be to warm up the unconscious patient, but this could be fatal.

It is lowering the temperature limit of life

Kyrill Ivanov

If the body is reheated unevenly, then cells may "wake up" before blood flow has been properly restored, and then die because there is not enough oxygen to supply them.

Normal practice with severely chilled patients is to connect them to a heart bypass machine, which takes the blood out of the body, warms it gently and then feeds it back in, gradually increasing the temperature from the core outwards.

But even this system holds immense risks for the patient, and if the patient's temperature has fallen below 30 degrees - 37 is normal - the chances of recovery fall quickly.

Shivering reflex

The new technique, from Kyrill Ivanov of the Pavlov Institute of Physiology in St Petersburg, involves injecting a chemical, called EDTA, which can start the shivering reflex when the body is in theory far too cold to shiver.

Ivanov injected the chemical into chilled rabbits and rats, and found that both breathing and shivering re-started, even though their brains were still very cold.

Then, when left at room temperature, the EDTA animals warmed up and recovered, whereas none of the animals given no EDTA survived.

Ivanov told New Scientist: "For the first time we have found a way to revive without rewarming. It is lowering the temperature limit of life."

Adrian Evans, a consultant in A&E medicine from Leicester Royal Infirmary, said that restarting shivering might not rewarm the body in an ideal way.

Safe method

He said: "What you need to do is rewarm from the core of the body. If you rewarm unequally, it can cause problems."

Dr John McGowan, a resuscitation officer at the Southern General Hospital in Glasgow, said that restarting shivering could provide a safe way of rewarming without having to use invasive procedures such as a bypass machine.

But he said that the chemical could conceivably increase the risk of dangerously abnormal heart rhythms during rewarming, as it reduced the level of the mineral magnesium in the cells.

And he added: "This study deals with anaesthetised animals in the lab - we deal with humans who have fallen off a mountain. It's not the same."

The correct way to give first aid to an unconscious and hypothermic patient was to insulate them to prevent further heat loss, he said, and get them to hospital.

Placing them in a hot room could actually hasten their death.