The Effect of Exercise on Oxygen Content in Anemic Patients With Chronic Obstructive Pulmonary Disease

Background: Anemia is reported in one-third of the patients with chronic obstructive pulmonary disease (COPD). Anemia, by decreasing oxygen content, can be a contributing factor for hypoxemia. We determined to find whether anemia causes more prominent hypoxia by decreasing the total oxygen content after exercise in anemic patients with COPD.

Methods: Stable moderate-to-severe COPD patients with and without anemia were recruited. Arterial blood gas analyses were performed on room air before and after a 6-minute walking test (6MWT). Walking distance, oxygen saturation, and heart rate were recorded in each case before and after the 6MWT. Pulmonary function test measurements and other data were obtained from the chart. The mean and standard deviations were calculated for continuous variables. The independent t-test and Kruskal-Wallis test were performed for numerical covariate and univariate analyses. The paired t-test was used for the analyses of data before and after exercise.

Results: A total of 24 male patients were included in the study; 12 of which were anemic. The oxygen content was decreased in the anemic group (15.22 ± 1.28 vs 15.07 ± 1.22) after exercise, but it was not significant. In the non-anemic group, no oxygen content decrease was observed after exercise (18.83 ± 1.41 vs 18.9 ± 1.37). Interestingly, the Spo₂, but not Sao₂, was significantly lower after exercise in anemic patients with COPD (93.46% ± 5.06% vs 88.20% ± 6.35% before and after exercise, respectively).

Conclusions: Anemia does not cause more prominent hypoxemia after exercise in patients with COPD. However, the recorded Spo₂ levels were significantly lower after exercise in the anemic patients with COPD.