Near-Infrared Spectroscopy with Treadmill Exercise to Assess Lower Limb Ischemia in Patients with Atherosclerotic Occlusive Disease

Abstract

We used near-infrared spectroscopy (NIRS) to measure exercise-induced ischemia in patients with intermittent claudication, and compared these results with those obtained by ankle-brachial pressure index (ABPI) analysis. Sixty-two patients with intermittent claudication caused by atherosclerotic occlusive disease exercised on a treadmill until reaching the maximal tolerated walking distance. We measured the ABPI at rest and after exercise until it returned to the baseline value. A NIRS probe was positioned on the patient's calf, which allowed the continuous monitoring of oxygen saturation (StO2), oxygenated hemoglobin (Oxy Hb), and deoxygenated hemoglobin (Deoxy Hb) in the calf muscles before, during, and after exercise. During exercise, the StO2 and Oxy Hb decreased, and the Deoxy Hb increased. The time taken for each measurement to return to the baseline value was defined as the recovery time. The recovery times obtained by NIRS and ABPI were compared. The recovery time for ABPI correlated well with that for StO(2 (rhos = 0.73), Oxy Hb (rhos = 0.63), and Deoxy Hb (rhos = 0.65); however, the recovery times measured by NIRS were shorter than the recovery time for the ABPI. Near-infrared spectroscopy is a reliable method for monitoring peripheral circulation during and after exercise, although the data generated provided slightly different information than the results obtained by ABPI.