Oxygen supplementation during air travel in patients with chronic obstructive lung disease

The objective of this study was to quantitate the effects of O₂ supplementation by nasal cannula (NC) and Venturi mask (VM) on PaO₂ in patients with chronic obstructive pulmonary disease (COPD) during acute hypobaric exposure, simulating a commercial jet aircraft cabin. We conducted a crossover intervention trial in which subjects served as their own controls in an ambulatory outpatient pulmonary disease service of a tertiary care military medical center and a hypobaric research facility. The subjects were a volunteer sample of 18 men with stable severe COPD, not requiring long-term O₂ therapy, and uncomplicated by hypercapnea or cardiac disease. Mean age was 68 years, and mean FEV₁ was 0.97 L (31.3 percent predicted). We exposed patients to conditions equivalent to 8,000 feet in a hypobaric chamber. Radial artery catheters provided blood samples at ground level and 8,000 feet. O₂ was sequentially administered at 8,000 feet by NC at 4 L/min and 24 percent or 28 percent VM. We describe changes in blood gas data from baseline values and between interventions. O₂ at 4 L/min NC flow at 8,000 feet caused PaO₂ to increase from 47.4 ± 6.3 mm Hg to 82.3 ± 14 mm Hg (n = 18), an increase of 34.9 ± 14.8 mm Hg. Supplementation of O₂ by 24 percent VM caused PaO₂ at 8,000 feet to increase by 12.7 ± 3.8 mm Hg. Twenty-eight percent VM caused PaO₂ at 8,000 feet to increase by 19.7 ± 8.2 mm Hg. Changes in PaO₂ with 4 L/min NC were greater than those with either VM. The increase with 28 percent VM was greater than that caused by 24 percent VM (P<0.05). Compared with ground level, 4 L/min NC increased mean PaO₂ by 9.9 ± 12.6 mm Hg; 24 percent and 28 percent VM did not cause mean PaO₂ to increase above ground level values. We describe a range of capability of familiar O₂ therapy devices to increase PaO₂ to levels that will maintain tissue oxygenation of patients during acute altitude exposure.