Comparison of Oxygen Delivery Devices for Reversal of Altitude-Induced Hypoxemia in Normal Subjects

This study will compare the ability of pulsed-dose oxygen from a concentrator to reverse altitude-induced hypoxemia compared to compressed gas from a standard oxygen cylinder.

Subjects will be monitored non-invasively with pulse oximetry, end-tidal carbon dioxide, tissue oxygenation and ECG. The mean seal level oxygen saturation will be recorded.Subjects exposed to an altitude of 14,000 feet will experience moderate hypobaric hypoxia. The mean oxygen saturation at this altitude is 83%. Subjects will receive oxygen from both an oxygen concentrator or a cylinder of oxygen following exposure to hypobarism. Oxygen from each source will be increased in 1 liter per minute increments until the oxygen saturation returns to the baseline sea level oxygen saturation. The oxygen requirement to return oxygen saturation to baseline values will be recorded. The flow from the concentrator and the cylinder will be compared.

Oxygen will be titrated from either an oxygen concentrator or an oxygen cylinder in liters per minute until the oxygen saturation returns to the sea level value. The flow in liters per minute is the dependent variables. Each participant will experience induced hypoxemia followed by cylinder oxygen delivery; each will also experience induced hypoxemia followed by pulse-dose oxygen from a concentrator.

Inclusion Criteria: Current altitude chamber certification Age 18 years - 60 years Exclusion Criteria: Current upper respiratory infection Current symptoms of lower respiratory infection -- productive cough