EFFECT OF NATURAL OXYGEN ENRICHMENT AT LOW-ALTITUDE ON OXYGEN-DEPENDENT PATIENTS WITH END-STAGE LUNG-DISEASE

Objective: To assess the effect of lowering altitude to that of the lo west place on earth (Dead Sea) on arterial oxygenation and exercise pe rformance in patients with hypoxemia and end-stage lung disease. Desig n: A cohort of 10 patients. Setting: Pulmonary function laboratories i n Jerusalem, Israel, and at the Dead Sea. Patients: 10 patients with e nd-stage lung disease who were receiving long-term oxygen therapy. The 4 males and 6 females were 12 to 77 years old. Four patients had chro nic obstructive pulmonary disease; 2 had cystic fibrosis; 3 had pulmon ary fibrosis; and 1 had pulmonary hypertension (thromboembolic). Mean forced vital capacity was 1.54 L (54% of predicted value) and mean for ced expiratory volume in 1 second was 0.85 L (35% of predicted value). Measurements: Spirometry, blood gas analysis, progressive exercise te sting, and sleep oximetry were done in Jerusalem (altitude, 800 m abov e sea level; barometric pressure, 696 mm Hg); the same measurements we re done 6 days after arrival at the Dead Sea (altitude, 402 m below se a level; barometric pressure, 800 mm Hg) and then 7 to 14 days later i n Jerusalem. Results: Arterial oxygenation increased from a median par tial pressure of arterial oxygen of 51.6 mm Hg in Jerusalem to 67.0 mm Hg at the Dead Sea, an increase of 15.2 mm Hg (95% CI of paired diffe rence, 4.1 to 20.4 mm Hg; P = 0.001). Partial pressure of arterial car bon dioxide increased from a median of 43.2 to 45.9 mm Hg, an increase of 2.7 mm Hg (CI, 0.5 to 6.4 mm Hg; P = 0.004), with a borderline sig nificant change in the alveolar-arterial gradient. Arterial oxygen sat uration increased from a median of 87.7% to 92.8%, a change of 4.8% (C I, 1.9% to 9.8%; P = 0.003). Exercise performance also improved as max imum oxygen uptake increased from a median of 827 mL/min to 1056 mL/mi n, an increase of 203 mL/min (CI, 54 to 388 mL/min; P = 0.006). Sleep oximetry also improved as median arterial oxygen saturation measured d uring sleep increased from 85% to 90%, a change of 5% (CI, 2% to 7%; P = 0.005), and percentage of sleep time with an oxygen saturation rate of 90% or more increased from a median of 24% to 73%, a change of 49% (CI, 20% to 87%; P = 0.02). No change in spirometry was noted. All pa tients felt less dyspneic and reported improved functional capacity wi th reduced need for oxygen. Conclusion: Descent to low altitude can im prove arterial oxygenation, exercise performance, and sleep oximetry a nd consequently the quality of life in patients with hypoxemia and adv anced lung disease.