Relationship between oxygen consumption kinetics and BODE Index in COPD patients

Abstract

Audrey Borghi-Silva,1 Thomas Beltrame,1,2 Michel Silva Reis,1 Luciana Maria Malosá Sampaio,3 Aparecida Maria Catai,1 Ross Arena,4 Dirceu Costa31Cardiopulmonary Physiotherapy Laboratory, Nucleus of Research in Physical Exercise, Federal University of São Carlos, São Carlos, SP, Brazil; 2Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada; 3Rehabilitation Sciences Master’s Program, Universidade Nove de Julho, Sao Paulo, SP, Brazil; 4Division of Physical Therapy, Department of Orthopedics, Division of Cardiology, Department of Internal Medicine, and Latin American and Iberian Institute, University of New Mexico, Albuquerque, NM, USABackground and objective: Patients with chronic obstructive pulmonary disease (COPD) present with reduced exercise capacity due to impaired oxygen consumption (VO2), caused primarily by pulmonary dysfunction and deleterious peripheral adaptations. Assuming that COPD patients present with slower VO2 and heart rate (HR) on-kinetics, we hypothesized that this finding is related to disease severity as measured by the BODE Index. In this context, the present study intends to evaluate the relationship between VO2 uptake on-kinetics during high-intensity exercise and the BODE Index in patients with COPD.Methods: Twenty males with moderate-to-severe stable COPD and 13 healthy control subjects matched by age and sex were evaluated. COPD patients were screened by the BODE Index and then underwent an incremental cardiopulmonary exercise test and a constant speed treadmill session at 70% of maximal intensity for 6 minutes. The onset of the exercise (first 360 seconds) response for O2 uptake and HR was modeled according to a monoexponential fit.Results: Oxygen consumption and HR on-kinetics were slower in the COPD group compared with controls. Additionally, VO2 on-kinetic parameters revealed a strong positive correlation (r = 0.77, P < 0.05) with BODE scores and a moderate negative correlation with walking distance (r = −0.45, P < 0.05).Conclusion: Our data show that moderate-to-severe COPD is related to impaired oxygen delivery and utilization during the onset of intense exercise.Keywords: COPD, VO2 on-kinetics, heart rate, BODE Index