Oxygen uptake kinetics during exercise are slowed in patients with peripheral arterial disease.

Abstract

Patients with peripheral arterial disease (PAD) have arterial occlusions that limit peripheral blood flow. This study evaluated the dynamic response in O₂ consumption (V˙o ₂) at the onset of constant-load exercise (V˙o ₂kinetics) in patients with PAD. Eight patients with bilateral PAD, seven patients with unilateral PAD, nine age-matched nonsmoking controls, and seven smoking controls performed graded treadmill exercise to assess peak V˙o ₂. Subjects also performed constant-load exercise tests at 2.0 miles/h at 0 and 4% grade to determineV˙o ₂ kinetics. PeakV˙o ₂ was reduced 50% in patients with PAD compared with both control groups ( P < 0.05). At 4% grade, phase 2V˙o ₂ kinetics were significantly slowed for the PAD groups compared with controls (60.1 ± 15.7 and 58.7 ± 8.3 s, unilateral and bilateral PAD groups, respectively; compared with 28.4 ± 19.3 and 27.9 ± 8.1 s, nonsmoking and smoking controls, respectively; P < 0.05). No relationship was found between V˙o ₂ kinetics and disease severity. These data demonstrate thatV˙o ₂ kinetics are markedly slowed in patients with PAD. The impairment inV˙o ₂ kinetics is not related to smoking status or arterial disease severity and therefore may reflect altered control of skeletal muscle metabolism.