Hemodynamic effects of altitude exposure and oxygen administration in chronic obstructive pulmonary disease

Cardiovascular events are the leading cause of death during air travel. Because patients with chronic obstructive pulmonary disease (COPD) develop severe hypoxemia at altitude, we sought to determine whether changes in systemic hemodynamics may contribute to health risks during hypobaric hypoxia.

We recorded radial artery catheter blood pressure, cardiac frequency, and cardiac ectopy in 18 men (aged 68 +/- 6 years, mean +/- SD) with severe COPD (forced expiratory volume in 1 second 0.97 L +/- 0.32 L) at sea level, after 45 minutes of steady-state hypobaric hypoxia at 2,438 m in a hypobaric chamber, and after oxygen supplementation at 2,438 m.

Mean arterial pressure (mm Hg), systolic blood pressure (SBP), diastolic blood pressure, and pulsus paradoxus during acute hypobaric exposure did not differ from baseline. During oxygen supplementation, SBP declined (p = 0.028). Decreases in pulsus paradoxus and pulse pressure were noted on oxygen (p < 0.05). We found no changes in cardiac frequency. Cardiac ectopy was uncommon; for one subject, ectopy increased with hypobaric hypoxia and decreased with oxygen administration.

Vasopressor responses to hypoxia do not add to the risk of air travel in patients with severe COPD. Supplemental oxygen may cause beneficial hemodynamic changes in patients with COPD during acute hypobaric exposure.