Item: Avalanche victim's air-from-snow breathing device
Title: Avalanche victim's air-from-snow breathing device
Proceedings: Proceedings of the 1996 International Snow Science Workshop, Banff, Canada
Authors: Thomas J. Crowley, M.D., 11351 East Amherst Court, Aurora, Colorado 80014
Abstract: This describes a patented emergency breathing device for a person buried in snow. The device extracts air from snow, which contains some 50-90 percent air. It can be incorporated unobtrusively into a parka or vest. The person inhales through a mouthpiece in the garment's collar. The mouthpiece connects via tubing and a one-way valve to a broad, shallow inhalation chamber sewn into the front of the garment. A tough fabric membrane, permeable to air but not to snow, covers the chamber's front surface and contacts the snow. That membrane passes into the chamber (under normal respiratory pressures) enough air from the snow for normal inhalation. The buried person exhales through the same mouthpiece, which separately connects via tubes and another one-way valve to an exhalation chamber sewn into the back of the garment. The exhalation chamber also is covered by a membrane permeable to air but not to snow. The snow-contacting surface of the exhalation membrane passes exhaled air from the rear chamber to the snow. The inhalation and exhalation chambers are sufficiently far apart on the garment to minimize mixing of previously exhaled air with air that will be inhaled. In a field test of the device a person breathed easily for about 40 minutes while fully buried at a depth of about 0.8 - 0.9 m. The convenience, light weight, and mechanical simplicity of the device make it easy for a skier to carry, wear, and use. Avalanches and collapsing "tree wells" are the chief causes of snow burial. Falk et al (1994) estimate 150 avalanche deaths annually in the Alps, and Armstrong and Williams (1992) estimate about 30 in Japan, 17 in the United States, 10-15 in Norway, and 7 in Canada. Victims include highway and railroad workers, ski patrollers, researchers, mountain residents, and recreational skiers, snowshoers, and snowmobilers. Survival data are discouraging (Armstrong, Williams 1992). Of persons totally buried in snow with no tell-tale sign to the surface such as a protruding ski, three out of four die. About two-thirds of victims die of suffocation, one-third from trauma. Suffocation is quick. Reporting that only 30 percent survive 35 minutes' burial and 3 percent survive 130 minutes, Falk et al. (1994) called for the development of "...self-help techniques to facilitate creation of a life-saving air pocket, which would give the skier a relatively safe haven..."
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Keywords: survival, suffocation, tree wells
Digital Abstract Not Available