Figure 6.

Mean pulmonary artery pressure (pap) above 30 mm hg excludes from flying without O₂ increases in all 10 copd patients exposed to a cabin pressure equivalent to an altitude of 2,500 m above sea level. All patients increased their mean PAP far more than normal subjects range. One patient had a pre-flight PAP of more than 30 mm Hg (complete vascular recruitment) and could not tolerate the altitude exposure. Residual volume correlated best with PAP, all patients fell asleep during the hypobaric exposure and showed a decrease in FEV₁ from 1.08 to 0.78 L, the FEV₁/IVC ratio diminishing from 45.7 to 40.2%. Arterial hypoxia and alveolar arterial O₂-difference did not restore pre-exposure levels or mean PAP one hour after altitude exposure. From [24].