Simulated Avalanche vs Tree-Well Burial Effects on Human Physiology.

IntroductionAvalanches and tree-wells (TW) are causes of snow immersion death in skiers and snowboarders. TW burials may have different victim physiology profiles and rescue considerations than avalanche-related burials due to snow density, burial position, and compensatory physiologic responses. This study aimed to compare the physiological responses between avalanche and TW burials through a prospective controlled trial of simulated avalanche burial to simulated TW burial.MethodsEleven volunteers participated in two paired 60-min snow burials: Avalanche and TW simulations, controlling for position and snowpack densities. We monitored core temperature, respiratory rate, minute ventilation, end-tidal carbon dioxide, oxygen saturation, partial pressure of inspired carbon dioxide, and heart rate.ResultsThe average cooling rate for the avalanche simulation was -0.017(Δ°C/min) versus -0.012(Δ°C/min) for the TW simulation (p = 0.014*), 1.42 times faster cooling rate than TW burial. SpO2 decreased 10.9 times faster on average in TW burial than in avalanche conditions when normalized by burial time as a rate (avalanche -0.011 vs TW -0.12 (Δ%/min), p = 0.033*). More participants requested early study termination in the TW scenario.DiscussionSimulated TW burial resulted in a statistically significant slower rate of core temperature cooling and earlier hypoxemia. Inverted body position in TW burials may lead to increased physiologic distress and contribute to earlier hypoxia. These findings may have important implications for search and rescue as well as resuscitation efforts for snow burial victims.