A lifesaver

People buried in avalanches will have a better chance of survival thanks to a simple breathing device

Published: Saturday 15 May 1999

 Skiers trapped in avalanches< it is not easy by any chance to survive burial in an avalanche. About one-third of the people caught in an avalanche are killed by injuries from rocks, trees, debris or the force of snow itself. For the remaining two-thirds who manage to remain alive by the time the snow settles, the only chance of survival is a quick rescue. There is a 90 per cent chance of survival after 15 minutes. However, suffocation kills 70 per cent of the people buried alive after 35 minutes. Now, the good news: a simple device called AvaLung, which extracts air from the snow itself, can help the victims survive for up to an hour, giving rescuers the crucial extra time ( New Scientist , Vol 161, No 2169).

People buried in an avalanche rapidly use up the oxygen available in the typically small pocket of air that they have to breathe. Oxygen is fast replaced by carbon dioxide. Moreover, exhaled air also contains moisture. This condenses into water and then freezes into a suffocating 'ice mask' on the victim's face. But even the debris of an avalanche contains 40-60 per cent air. In light, powdered snow, the figure can be up to 90 per cent. Yet it is difficult to breathe. Why? Because the human mouth and nose do not provide a surface area large enough to extract the air from the snow.

This is where Thomas Crowley, an occasional skier and medical professor at the University of Colorado in Denver, usa , has made a difference. Crowley realised that what was needed in the situation was a wider surface to breathe. This led him to conceive a device with a broad, hollow chamber covered by a filter, sewn into the front of a jacket, and attached to a breathing tube. Exhaled air is directed through one-way valves to a chamber on the victim's back, where it is vented. This keeps the level of carbon dioxide low.

Using plastic tubing and a pair of nylon tights, Crowley put together his prototype. The results were encouraging. After making a workable model, he licensed the technology to Black Diamond Equipment, a company that makes mountaineering equipment in Salt Lake City, Utah. The result has been AvaLung. Crowley and the company tested the device on three men who volunteered to be buried in snow on Mount Hood in Oregon in August 1998. Oxygen levels remained above 90 per cent of saturation for two of the volunteers after they had been buried for an hour. The level fell to 81 per cent after 45 minutes in the case of the third volunteer, but that was attributed to a faulty valve.

Subsequent tests carried out by Black Diamond have revealed that volunteers maintain oxygen and carbon dioxide concentrations, blood pressure and heart rhythms at "acceptable levels" for up to an hour when using AvaLung in conditions designed to simulate an avalanche.

However, AvaLung is no substitute for shovels, probes, beacons and training, warn rescue experts. Says Don Bachman, executive director of the American Association of Avalanche Professionals: "I am afraid that people think that the more they festoon themselves with safety devices, the safer they will be." On his part, Crowley says, "By no means is this a cure-all for this horrendous force. But we think it gives a person a snowball's chance."

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