Detection and correction of hypoxemia associated with air travel

Hypoxemia occurs during air travel because the pressure in aircraft cabins is not maintained equal to barometric pressure at sea level. Identification of patients who will develop significant arterial hypoxemia is most conveniently achieved by exposing these individuals to inspired oxygen tensions similar to those experienced during air travel. We utilized commercial Venturi devices with nitrogen as a source gas to lower inspired oxygen tensions (114 and 99 mm Hg) to simulate exposure to altitude (6,700 and 10,000 feet) that occurs with air travel. Oxygen was administered by nasal cannulas to correct the induced hypoxemia. Eleven normal subjects had baseline oxygen saturations of 97.3% as determined by ear oximetry. Exposure to reduced oxygen tensions for 20 min using 35 and 40% Venturi devices caused minimal O2 desaturation (94.8 and 93.8%, respectively). Mean baseline arterial oxygen saturation was 93.2% in 11 patients with chronic obstructive lung disease. Oxygen saturation fell to 89.5 and 87.5%, respectively, with exposure to the two levels of reduced oxygen tensions. Hypoxemia was corrected with administration of O2 by nasal cannulas at rates of 1.2 and 1.5 L/min, respectively. We conclude that individual patients can be evaluated conveniently for possible development of hypoxemia associated with air travel using available Venturi devices. This approach also permits determination of the oxygen therapy needed to correct hypoxemia.