Quantitative near-infrared spectroscopy on patients with peripheral vascular disease

We have used near-infrared spectroscopy to measure the hemoglobin saturation at rest and during exercise on patients affected by peripheral vascular disease (PVD). The instrument used in our study is a frequency-domain tissue oximeter which employs intensity modulated (110 MHz) laser diodes. We examined 9 subjects, 3 of which were controls and 6 were patients affected by stage II PVD. The optical probe was located on the calf muscle of the subjects. The measurement protocol consisted of: (1) baseline (similar to 5 min); (2) stationary bicycle exercise (similar to 5 min); (3) recovery (similar to 15 min). The change in hemoglobin saturation during exercise (Delta Y) and the recovery time after exercise (t(rcc)) were significantly greater in the PVD patients (Delta Y = -21+/-3%, t(rcc) = 5.9+/-3.8 min) than in the control subjects (Delta Y = 2+/-3%, t(rcc) = 0.6+/-0.1 min).