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 lowest place on earth (Dead Sea) on arterial oxygenation and exercise performance in patients with hypoxemia and end-stage lung disease.

DESIGN

A cohort of 10 patients.

SETTING

Pulmonary function laboratories in Jerusalem, Israel, and at the Dead Sea.

PATIENTS

10 patients with end-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 chronic obstructive pulmonary disease; 2 had cystic fibrosis; 3 had pulmonary fibrosis; and 1 had pulmonary hypertension (thromboembolic). Mean forced vital capacity was 1.54 L (54% of predicted value) and mean forced expiratory volume in 1 second was 0.85 L (35% of predicted value).

MEASUREMENTS

Spirometry, blood gas analysis, progressive exercise testing, and sleep oximetry were done in Jerusalem (altitude, 800 m above sea level; barometric pressure, 696 mm Hg); the same measurements were done 6 days after arrival at the Dead Sea (altitude, 402 m below sea level; barometric pressure, 800 mm Hg) and then 7 to 14 days later in Jerusalem.

RESULTS

Arterial oxygenation increased from a median partial 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 difference, 4.1 to 20.4 mm Hg; P = 0.001). Partial pressure of arterial carbon 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 significant change in the alveolar-arterial gradient. Arterial oxygen saturation increased from a median of 87.7% to 92.8%, a change of 4.8% (CI, 1.9% to 9.8%; P = 0.003). Exercise performance also improved as maximum oxygen uptake increased from a median of 827 mL/min to 1056 mL/min, 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 during 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 patients felt less dyspneic and reported improved functional capacity with reduced need for oxygen.

CONCLUSION

Descent to low altitude can improve arterial oxygenation, exercise performance, and sleep oximetry and consequently the quality of life in patients with hypoxemia and advanced lung disease.