Hypoxia and hypercapnia effects on cerebral oxygen saturation in avalanche burial: A pilot human experimental study

BackgroundA sufficient supply of oxygen is crucial to avoid hypoxic cardiac arrest and brain damage within 30 min in completely-buried avalanche victims. Snow density influences levels hypoxia hypercapnia. The goal this study was investigate the effects hypercapnia on cerebral oxygenation (ScO2) humans breathing into an artificial air pocket.MethodsEach subject breathed a closed system (air-tight face mask – plastic tube snow air-pocket 4 L) up min. Each performed three tests different densities. ScO2 measured by near-infrared spectroscopy (NIRS) device. Measurements included peripheral saturation (SpO2), end-tidal carbon dioxide (ETCO2), pocket gases blood gases. assessed via standard methods micro-computed tomography. Based predetermined criteria, were classified based whether they terminated before reason for termination. categories were: completed (30 min), when SpO2 dropped ?75% that requests subjects. General linear models used compare termination groups changes ScO2, ETCO2, gases, multivariate analysis detect factor independent ScO2.ResultsScO2 decreased group which ? 75% caused decrease high In tests, increase occurred despite removal.ConclusionsOur data show determined NIRS not always impaired removal. This may indicate medium low densities can be sufficient, reflect initial stage triple H (hypothermia, hypoxia, hypercapnia) syndrome. densities, showed significant critical supply. could lead higher risk damage.