Background: In patients with COPD, oxygen therapy has been shown to improve exercise capacity and survival. Increase in barometric pressure at low altitude can serve as a simple way to improve arterial oxygenation in hypoxemic patients. We have tried to evaluate the effect of staying at low altitude on arterial oxygenation and exercise performance in patients with COPD.
Patients and method: Eleven patients with COPD (9 male, 2 female) aged 38 to 79 years (mean FEVl, 0.96 L; 36% predicted) with hypoxemia (mean PaO2, 54.2±8.9 mm Hg) at Jerusalem (altitude 800 m above sea level) were taken down to the Dead Sea area (altitude 402 m below sea level) for 3 weeks. At both locations we tested arterial blood gases, spirometry, progressive exercise, 6-minute walking distance, and sleep oximetry. The study was repeated 2 weeks after returning to Jerusalem.
Results: Spirometry results were unchanged. Mean arterial PaO2 rose from 54.2±8.9 mm Hg to 69.5±11 at the first week and to 66.6±11 at the third week of stay (p<0.001). PaCO2 rose from 43.5±9.8 mm Hg to 47.7±9 and 49.5±8.4 (p<0.006). Six-minute walking distance rose from 337±107 m to 449±73 and 507±91 in the third week (p<0.005). Maximum oxygen consumption (Vo2max) rose from 901±257 mL/min to 1,099±255 and 1,063±250 mL/min (p=0.01). Sleep oximetry showed an increase in mean sleep arterial oxygen saturation from 86.0±4.3% to 89.9±4.2% and 88.3±3.0 at 1 and 3 weeks, respectively (p<0.05). Following the return to Jerusalem, arterial gases returned to their baseline levels (PaO2, 52.9±9.4 mm Hg) but 6-min walking distance remained significantly high, 453±47 (p<0.02), and Vo2max remained high as well (1,102±357 mL/min), although it did not reach statistical significance.
Conclusions: Decline to low altitude or staying at high oxygen environment improves arterial oxygenation and exercise capacity in hypoxemic patients residing in moderate or high altitude. Low altitude (or pressurized wards) can improve pulmonary rehabilitation of hypoxemic patients with COPD.