Factors affecting survival from avalanche burial-a randomized prospective porcine pilot study
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Background and aim The majority of avalanche victims who sustain complete burial die within 35 min due to asphyxia and injuries. After 35 min, survival is possible only in the presence of a patent airway, and an accompanying air pocket around the face may improve survival. At this stage hypothermia is assumed to be an important factor for survival because rapid cooling decreases oxygen consumption; if deep hypothermia develops before cardiac arrest, hypothermia may be protective and prolong the time that cardiac arrest can be survived. The aim of the study was to investigate the combined effects of hypoxia, hypercapnia and hypothermia in a porcine model of avalanche burial. Methods Eight piglets were anaesthetised, intubated and buried under snow, randomly assigned to an air pocket (n = 5) or ambient air (n = 3) group. Results Mean cooling rates in the first 10 min of burial were −19.7 ± 4.7 °C h−1 in the air pocket group and −13.0 ± 4.4 °C h−1 in the ambient air group (P = 0.095); overall cooling rates between baseline and asystole were −4.7 ± 1.4 °C h−1 and −4.6 ± 0.2 °C h−1 (P = 0.855), respectively. In the air pocket group cardiac output (P = 0.002), arterial oxygen partial pressure (P = 0.001), arterial pH (P = 0.002) and time to asystole (P = 0.025) were lower, while arterial carbon dioxide partial pressure (P = 0.007) and serum potassium (P = 0.042) were higher compared to the ambient air group. Conclusion Our results demonstrate that hypothermia may develop in the early phase of avalanche burial and severe asphyxia may occur even in the presence of an air pocket.