An objective assessment of intermittent claudication by near-infrared spectroscopy

Changes in tissue oxygenation in the calf muscle were measured by near-infrared spectroscopy (NIRS) in 62 patients who complained of intermittent claudication in the calf during a treadmill test. Three distinctive patterns of oxygenated and deoxygenated haemoglobin were observed. None of the type 0 cases were severe (i.e., unable to walk for more than 5 minutes), while 37 and 82% of the type 1 and type 2 cases were severe, respectively. The mean maximum walking distance of type 1 was significantly longer than that of type 2 (179 +/- 70 m and 109 +/- 46 m, respectively; p < 0.005), while the mean ankle-brachial pressure index at rest of type 1 was not significantly different from that of type 2 (0.68 +/- 0.19 and 0.61 +/- 0.23, respectively). Our results indicate that NIRS can be used to accurately assess the severity of intermittent claudication.