Passive Leg Movement (PLM) in Patients with COPD

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by limited pulmonary function, inflammation, greater free-radical levels, vascular dysfunction and subsequently a greater incidence of CVD. However, in terms of vascular function, as previous investigations have focused on the brachial artery flow mediated dilation technique, whether vascular dysfunction exists in the locomotor muscles in patients with COPD, remains unknown. PURPOSE: To determine the hemodynamic response to PLM in patients with COPD and healthy age-matched controls. METHODS: Second-by-second finger photoplethysmography measurements of heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), and femoral artery blood flow (FBF) (Doppler ultrasound) were recorded prior to and during 2 min of continuous upright PLM in patients with COPD (n=12, 64±3 yrs) and healthy age matched controls (n=12, 66±4 yrs). RESULTS: Baseline values for MAP (Controls: 85±4; COPD: 99±4 mmHg) and HR (Controls: 59±3 COPD: 74±3 bpm) were significantly different between groups (p<0.05), while FBF, femoral vascular conductance (FVC), SV, and CO were not different (p>0.05). In response to PLM, the HR (3.7±1.8 vs 5.9±1.9 Δbpm), SV (6.3±1.1 vs 12.0±3.2 Δml/beat), CO (0.5±0.1 vs 1.2±0.3 ΔL/min), and MAP (9.3±1.6 vs 9.2±0.9 ΔmmHg) responses were not different between controls and COPD, respectively (p>0.05), while FBF (482±61 vs 344±53 Δml/min) and FVC (5.3±0.5 vs 3.2±0.6 Δml/min/mmHg) were significantly lower in COPD compared to the controls, control v. COPD, respectively (p<0.05). CONCLUSION: Utilizing PLM, a model that interrogates the vascular responsiveness of locomotor muscles, which are instrumental in activities of daily living, patients with COPD exhibit vascular dysfunction compared to healthy controls. These results suggest that vascular dysfunction in the legs, in combination with the clearly dysfunctional lungs, likely contributes to physical inactivity and an increased risk of CVD in patients with COPD.