Avalung: A saviour in avalanche

Dear Editor,

Troops deployment at high altitude areas (HAAs) varies between 2743 m (9000 ft) to 7010 m (23,000 ft) both in northern and eastern sectors. These HAA are snow covered throughout the year and are avalanche prone. Every year many soldiers are at risk of getting trapped in these avalanches. Asphyxiation (75%) is commonest cause of death during avalanche burial as was seen during the management of eight avalanche burial victims who came to our peripheral government hospital.

We describe how the use of a simple breathing device ‘AVALUNG’ increases the chances of survival during avalanche burial. Fully buried avalanche victims survival depends upon the rapidity of extraction as survival chances drop from 90% (extracted within 15 min) to less than 30% (extracted after 35 min).² This rapid decrease in survival chances is due to asphyxiation resulting from rebreathing of expired air which is rich in carbondioxide and poor in oxygen. Rate of oxygen desaturation when buried under the avalanche depends solely upon the presence of air pocket. Brugger et al. had observed that time to asphyxia increased from 15 min (absence of air pocket) to 30 min (presence of air pocket).¹ The air pocket helped in diffusion of expired air into the snowpack and diffusion of fresh air from the snowpack into the air pocket, thus delaying asphyxiation. Radwin et al. observed that survival time increased to 90 min when snow burial subjects were breathing directly from snowpack through a two-way non-breathing valve attached to a respiratory tubing which diverted all expired gases to surface of snowpack.³ Based on the aforementioned principle, Avalung™ was introduced by Black Diamond Equipment, Ltd., Salt Lake City, Utah. Avalung consists of a mouth piece, one-way inspiratory valve, one-way expiratory valve, respiratory tube, and mesh-protected harness [Fig. 1]. Grissom et al. demonstrated increase in survival time from 10 min (breathing without Avalung) to 58 min (breathing with Avalung) from 500 ml of air pocket created during burial under dense snow.⁴ During snow burial, Avalung extracts air from snow thus enabling victims to breathe while rescue efforts for their extraction are being made. It also minimizes ‘Ice Mask’ formation around the face and tracheal packing with snow thus helping in maintaining a patent airway.⁵ Ice masking occurs when exhaled air which is warm and humidified, freezes in front of face on the surface of snow forming a barrier that is impermeable to diffusion of air. Avalung has been shown to work equally well in deep powder snow as well as densely consolidated avalanche debris.

Fig. 1.

(A) The subject inhales and exhales through the mouth piece. White arrow denotes the inspired air and dark arrow denotes the expired air. (B) Inspired air enters thorough the one-way inspiratory valve. (C) Expired air passes through a one-way expiratory valve. (D) Harness which normally covers the one-way inspiratory and one-way expiratory valve. (E) Expired air travels through respiratory tubing and comes out at the back.

This device has now become the integral part of HAA kit issued to every individual getting inducted to HAA. So, the need of the hour is to sensitize more and more people and educate them about the correct use of Avalung. It is imperative that it should become part of preinduction training whether it is at training school before induction into glacier, other HAA training schools or at unit level, and it should be ensured that everyone learns the correct way to use this device. Local commanders should ensure that all personnel should be wearing Avalung while moving in an avalanche prone area, and this will help in improving the survivability during the event of an avalanche.

Disclosure of competing interest

The authors have none to declare.