Femoral Artery Blood Flow During Rest and One-leg Knee Extensor Exercise in Patients With COPD

Experimental assessments of changes in skeletal muscle blood flow during exercise in humans are important for elucidating the factors that limit exercise capacity and adaptations, both in healthy humans, including athletes, as well as in various disease states with functional impairment, such as chronic obstructive pulmonary disease COPD). A classical 'gold standard' for measuring blood flow is thermodilution, and this has notably applied to provide data on femoral blood flow during exercise. Because thermodilution required invasive catheterization, many have replaced it with Doppler ultrasound, but the test-retest reliability of Doppler ultrasound in this context is unknown. However, many studies have used Doppler ultrasound to document that the femoral blood flow response to exercise is impaired in COPD, which ultimately affects oxygen uptake and thus exercise capacity, but the interpretation of these findings is currently hampered by the lack of knowledge regarding the test-retest reliability of the method in this patient group.

The investigators aim is to compare the femoral blood flow response to one-legged knee extensor exercise in patients with COPD vs. healthy participants, and to provide an estimate of the test-retest reliability the femoral blood flow measurements obtained by Doppler ultrasound.

Inclusion criteria

for COPD patients:

• Men and women
• 45-80 years
• COPD (GOLD stage I to III)
• Forced expiratory volume in 1 sec (FEV1)/forced vital capacity ratio (FVC) < 0.8, FEV1 < 90% of predicted value
• Modified Medical Research Council score (mMRC 0 - 3) Resting arterial oxygenation > 90%

Exclusion criteria

for COPD patients:

• Symptoms of ischaemic heart disease
• Known heart failure
• Claudication
• Symptoms of disease within 2 weeks prior to the study
• Participation in pulmonary rehabilitation within 6 months
• Known malignant disease
• Pregnancy
• Unstable cardiac arrhythmic disease
• Renal or liver dysfunction

Inclusion criteria

for healthy matched controls:

• Men and women
• 45-80 years
• Normal FEV1, FVC, FEV1/FVC, and single-breath diffusion capacity
• Same sex, age (± 3 years) as the COPD patients

Exclusion criteria

for healthy matched controls:

• Known chronic lung disease
• Known ischaemic heart disease
• Known heart failure
• Symptoms of disease within 2 weeks prior to the study
• Known malignant disease
• Claudication
• Pregnancy
• Unstable cardiac arrhythmic disease
• Renal or liver dysfunction