Exercise and oxygen inhalation in relation to prognosis of chronic obstructive pulmonary disease

We examined the relationship between prognosis and arterial blood gases during exercise and 100 percent oxygen inhalation in 54 patients randomly selected from 119 background patients with chronic obstructive pulmonary disease (COPD). Light exercise was performed and 100 percent oxygen was inhaled during clinically stable stages. By four years after these tests, 19/54 patients had died from respiratory failure. All subjects had similar physical and clinical features. Survivors had significantly higher PaO2 during air breathing than nonsurvivors; in nonsurvivors, FEV1 and MVV were significantly lower, and heart rate and RV/TLC were significantly higher. Exercise PaO2 of nonsurvivors decreased by 6.7 mm Hg, whereas that of survivors did not change. The P(A--a)O2 did not change in survivors and nonsurvivors during exercise, but in survivors it was significantly smaller. Mean PaO2 after 100 percent oxygen was significantly lower, and PaCO2 was significantly higher in nonsurvivors than in survivors, and in nonsurvivors the increase in PaO2 during 100 percent oxygen correlated positively with the time between first admission and death. These results indicate that patients with combination of resting arterial hypoxemia, worsened hypoxemia during stepped-up exercise, and lesser degree of arterial oxygenation and increased PaCO2 during 100 percent oxygen inhalation may have a poor prognosis.