His small size will have helped him to survive the 100 minutes he spent buried alive by promoting the rapid cooling that is essential to avoid suffocation.
Doctors say few people can last more than 15 minutes beneath the snow because of the lack of oxygen. As the body cools, its need for oxygen falls and if that happens fast enough the victim can avoid suffocation. Children have a better chance of survival than adults because they have a greater surface area relative to their weight and so lose heat quicker.
The boy was found after almost two hours under the deep layer of snow that swept into the village of Valzur on Wednesday. Rescuers at first thought he was dead because he appeared not to be breathing and they were unable to find a pulse.
But after strenuous attempts to resuscitate him, he began to show signs of life.
Dr Michael Tipton, a specialist in thermal physiology at the University of Portsmouth, said the cold would have cast the boy's body into a state of suspended animation, which would be almost indistinguishable from death.
"You see this when people are rescued from the bottom of a freezing river after an hour when you would normally expect them to drown in minutes. It is very easy to mistake the profoundly hypothermic for the dead.
"Their hearts beat very slowly, their breathing is very low, their pupils are fixed and dilated and their tendon reflexes are absent."
Once dug out of the snow, the boy was wrapped in thermal blankets and flown by helicopter down the valley to Galtur before being transferred to hospital at Zams,where he was still recovering yesterday.
As rapid cooling of a living human takes place, the body shuts down because the cells require less oxygen. The cooling of the brain stem also has a direct effect, suppressing the organs' activity.
Dr Tipton, who is also head of the environmental medicine unit at the Institute of Naval Medicine, Haslar Hospital, Portsmouth, said: "For a person who falls into freezing water the question is whether the cooling effect occurs quickly enough so that the oxygen conservation effect on the body prevents suffocation. If you cool quickly the oxygen you already have on board will last a lot longer.
"Some adults have survived in this way but those that fare best tend to be children, who cool rapidly due to their greater surface area to weight ratio. I would guess that something similar happened in this case."Reuse content