• Hermann Brugger, Günther Sumann, Roland Meister, Liselotte Adler-Kastner, Peter Mair, Hanns Christian Gunga, Wolfgang Schobersberger, and Markus Falk.
• Mountain Rescue Service provided by the South Tyrolean Alpine Association, International Commission for Mountain Emergency Medicine, Europastrasse 17, I-39031 Bruneck, Italy. brugger.med@pass.dnet.it
• Resuscitation. 2003 Jul 1; 58 (1): 81-8.

AbstractSnow avalanche case reports have documented the survival of skiers apparently without permanent hypoxic sequelae, after prolonged complete burial despite there being only a small air pocket on extrication. We investigated the underlying pathophysiological changes in a prospective, randomised 2 x 2 crossover study in 12 volunteers (28 tests) breathing into an artificial air pocket (1- or 2-l volume) in snow. Peripheral SpO(2), ETCO(2), arterialised capillary blood variables, air pocket O(2) and CO(2), snow density, and snow conditions at the inner surface of the air pocket were determined. SpO(2) decreased from a median of 99% (93-100%) to 88% (71-94%; P<0.001) within 4 min of breathing into the air pocket; the reduction was greater at 1 l, than 2 l, volume air pocket (P=0.013, intention to treat P=0.003) and correlated to snow density (r=0.50, P=0.021, partial correlation coefficient). ETCO(2) rose simultaneously from median 5.07 kPa (3.47-6.93 kPa) to 6.8 kPa (5.87-8.27 kPa; P<0.001), with consequent respiratory acidosis. Despite premature interruption due to hypoxia (SpO(2)

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