Near infrared spectroscopy for noninvasive assessment of claudication.

The purpose of this study was to explore the application of near-infrared spectroscopy (NIRS) to the assessment of peripheral arterial occlusive disease (PAOD). Muscle blood flow, oxygen consumption, arterial inflow capacity, O2 resaturation, and recovery times were determined at rest, under ischemic and hyperemic conditions, and continuously during and after walking exercise in 11 claudicants and 15 nonclaudicants. Blood flow and oxygen consumption (VO2) at rest and blood flow following walking exercise did not differ significantly between claudicants and nonclaudicants. In contrast, VO2 after walking exercise was increased by a factor 4.1 in claudicants compared to a factor of 1.7 in nonclaudicants. The oxygen resaturation rate after arterial occlusion and the oxygen resaturation rate after walking exercise were significantly lower in claudicants. Claudicants showed a higher degree of hemoglobin deoxygenation during walking exercise than nonclaudicants. A high postexercise VO2 is correlated with a low ankle-branchial index (ABI). The resaturation rates and recovery times following walking exercise and arterial occlusion correlated significantly with ABI parameters. A significant negative correlation was found between hemoglobin deoxygenation during exercise and the ABI parameters. A high correlation was observed between the oxygenated hemoglobin (O2Hb) recovery time and the ABI recovery time after walking exercise. NIRS appears to be an effective noninvasive method for assessing the imbalance between oxygen demand and oxygen delivery in the leg muscles of PAOD patients at rest and during exercise.