Volunteers agreed to be buried face-down in the snow, for science

When a person is trapped in an avalanche, there is very little time before their oxygen supply runs out. A new safety device that channels air to the buried person’s face may extend survival and increase the chance of a successful rescue, a clinical trial suggests.

Participants were buried face-down under at least 50 centimeters — about a foot and a half — of snow at a field site in northern Italy. The goal was to remain there safely for 35 minutes. No one in the group wearing a functioning safety device needed to be removed early due to low blood oxygen levels, researchers report October 8 in the Journal of the American Medical Association.

Minutes after an avalanche burial, blood levels of oxygen begin to drop and those of carbon dioxide climb. The chance of survival decreases starting at 10 minutes. Around two-thirds of people whose head and chest are trapped under snow will die of insufficient oxygen within 35 minutes. The safety device, integrated into a backpack, has a fan that draws air from the surrounding snow and directs it to the face from outlets in the shoulder straps. Called the Safeback SBX, the battery-operated device weighs a little over 500 grams, or about a pound.

In the trial, researchers monitored participants’ oxygen levels, heart and respiratory rates and other health measures during burial, which ended if anyone’s blood oxygen level became dangerously low, below 80 percent. This did not happen for the 12 people in the safety device group. Eleven remained buried for the full 35 minutes, while one asked to be removed early due to unexpected skin irritation.

In contrast, seven of the 12 using a sham device had to stop prematurely because they fell below the blood oxygen cutoff. Another four requested an early end: Three felt short of breath and one had a panic attack. The length of time the sham device group remained buried largely ranged from five to 13 minutes. Only one person in that group stayed under the snow for the full 35 minutes.

Avalanches kill an average of 100 people in Europe each year, including skiers and mountain climbers. Avalanche deaths in the last several years in the United States have ranged from roughly one dozen to several dozen.