After local anesthetic injection, a 22-gauge catheter is inserted in one radial artery. Pulse oximeters are attached to fingers, ears, or flat body surfaces. Subjects are in a comfortable semi-recumbent position. Subjects then breathe air mixtures containing reduced amounts of oxygen to produce the desired level of hypoxemia. Stable, safe, and controlled hypoxia is breath-by-breath by breath respiratory gas analysis and a computer program that permits the inspired gas mixture to be adjusted to achieve a level of lung alveolar gas that will achieve the desired degree of saturation.
