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The median annual mortality from snow avalanches registered in the 17 ICAR countries from 1981 to 1998 was 146. Swiss data document a mortality rate of 52.4% in completely-buried, ver­sus 4.2% in partially-, or non-buried, persons (n=1,886). The survival probability of completely-buried victims in open areas (n=638) plummets from 91% at 18 min after bur­ial to 34% at 35 min (acute asphyxiation of victims without an air pocket), then remains fairly constant until a second drop after 90 min (the »latent phase« for victims with an air pocket). The inflection point of the survival probability curve at 35 min indicates that vic­tims completely buried under an avalanche cannot survive beyond 35 min without an air pocket. A prospective, randomised study in volunteers (28 tests) breathing into an artificial air pock­et (1 l or 2 l volume) in snow showed that peripheral oxygen saturation SpO₂ decreased from median 99% to 88% (p<0.001) within 4 min. End-tidal carbon dioxide rose from median 38 to 51 mmHg (p<0.001), with consequent respiratory acidosis. We conclude that the degree of hypoxia following avalanche burial is dependent on air pocket volume, snow density and unknown individual personal characteristics, yet long-term survival is possible with only a small air pocket. The combination of hypoxia, hypercapnia and hypothermia in persons buried by avalanches presenting an air pocket and free airways is designated as »triple H syndrome«. Standardised guidelines are introduced for the field management of avalanche victims. Strategy is primarily governed by the length of snow burial, the victim’s core temperature and the presence of an air pocket. With a burial time < 35 min, survival depends on preventing asphyx­ia by rapid extrication and immediate airway management, and cardiopulmonary resuscitation for unconscious victims without spontaneous respiration. With a burial time > 35 min, com­bating hypothermia becomes of paramount importance. Thus, gentle extrication, ECG and core temperature monitoring and body insulation are mandatory; unresponsive victims should be intubated. If obviously fatal injuries can be excluded, all pulseless hypothermic avalanche victims (core temperature < 32 °C [89.6 °F]) with an air pocket and free airways should be managed optimistically by attempted re-warming in a specialist unit with cardiopulmonary bypass facilities.