Supplemental oxygen increases arterial stiffness in chronic obstructive pulmonary disease

Study objectives: Recently, we demonstrated significantly improved baroreflex sensitivity (BRS) and autonomic balance after 31% supplemental oxygen (S_uppO₂) in resting patients with chronic obstructive pulmonary disease (COPD). In order to investigate whether peripheral arterial stiffness changes may play a role, we evaluated changes in peripheral arterial stiffness and BRS after S_uppO₂. Design: Single blinded crossover design. Setting: Pulmonary exercise testing laboratory. Participants: Seventy subjects with moderate to severe COPD. Interventions: We measured arterial vascular stiffness using the augmentation index via contour analysis of the radial pulse obtained from applanation tonometry. BRS was derived using the sequence method before and after treatments with compressed air (CA) and 30% S_uppO₂ in 70 individuals with COPD via a counterbalanced crossover design. Results: Paired t-tests indicated significant differences in oxygen saturation (SaO₂) following S_uppO₂ when compared to CA (x̄ 96.0±2.0% S_uppO₂ versus x̄ 92.6±3.6% CA, P<0.001). BRS was significantly greater following S_uppO₂ compared to CA (x̄ 3.5±2.3 ms/mmHg S_uppO₂ versus x̄ 3.1±2.1 CA ms/mmHg, P<0.03). Vascular stiffness was significantly increased with S_uppO₂ when compared with CA (x̄ 13.3±6.1% S_uppO₂ versus x̄ 10.8±4.9% CA, P<0.001). Conclusions: Our findings indicate that oxygen supplementation ameliorates BRS by changes in vasomotor activity. The amelioration of the BRS into a more normal range is a move towards the restoration of more normal physiology.