The literature describes and report neurologic intact patients surviving an avalanche several hours after they were buried. The most important factor for surviving more than 15-35 min of burial is considered to be the presence of an air-filled space around the head and neck, termed an air pocket. Little is known how the inspired air is influenced by the patients breathing and how oxygen and carbon dioxide diffuse through snow.

In a controlled and simulated avalanche scenario the investigators want to investigate how oxygen (O2) and carbon dioxide (CO2) diffuse and how rebreathing of CO2 in addition to mild hypoxia influence standardized physiological parameters in two scenarios: Fresh air and no fresh air delivered into the air pocket. The project is a field study designed to measure and document gas diffusion through snow. The outcome measures are: (1) Concentration of O2 and CO2 in the air pocket and 50 cm from the pocket. (2) Time interval for development of threshold values for concentration of O2 and CO2. The investigators will also monitor physiologic measures such as: Electrocardiogram (ECG), continuous invasive blood pressure, cerebral oximetry, continuous pulse oximetry, transthoracic impedance, and gas content in expired air. Subjective evaluation of comfort will also be scored. Twenty healthy young volunteers with written consent to participate will be used as test subjects.

The study may have a clinical consequence for better outcome, for victims of avalanches by providing additional air or oxygen close to the patient. The study will also measure specific body measures and spirometry.

Inclusion Criteria:

• Subject must be Healthy
• Subject must be non smoking
• Subject must have normal BMI

Exclusion Criteria:

• None