Abstract
Background: The functional limitation of patients with COPD results from a respiratory impairment and a reduction in peripheral muscle extraction. Inasmuch as the circulatory system is not a limiting factor, it can serve a useful adaptive role to optimise oxygen transport.
Objective: To assess the extent to which compensatory cardiocirculatory adjustments are present when there is reduced oxygen transfer.
Methods: Using a subset (N=115) from the Canadian longitudinal COPD cohort study (CanCOLD), we compared results from continuous measurements of ventilation,VO2 and bioimpedance (Physio-Flow®) cardiac output (CO) during peak incremental cycling. Arteriovenous oxygen difference was computed using Fick equation (Da-vO2 = VO2 / CO). Subjects were grouped for disease severity : Gr. A: At Risk,ever smokers (N=51) Gr. B: GOLD1 (N=33) Gr.C:GOLD2 (N=31). There were no group differences in age, body mass index or sex ratio.
Results: The figure below shows that the CO vs Da-vO2 relationship with increasing VO2 is not different between groups A and B but the relationship is shifted up and leftward in group C indicating a compensatory increase in CO for VO2 over approximately 1000ml.
Conclusion: Severity of COPD, even moderate, negatively impacts peripheral O2 extraction. An elevation in CO is then observed which serves as partial compensation to optimize the O2 transport function.
Footnotes
Cite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 3768.
This abstract was presented at the 2020 ERS International Congress, in session “Respiratory viruses in the "pre COVID-19" era”.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2020
