NONINVASIVE QUANTIFICATION OF MUSCLE OXYGEN IN SUBJECTS WITH AND WITHOUT CLAUDICATION

The disabling pain of intermittent claudication (IC) arises from oxyge n deprivation in the lower limbs during walking. Measurement of the ox ygen deficiency within the limb tissue now appears possible with recen tly expanded understanding of the photon transport through tissue for photons in the visible and near infrared range. Noninvasive measuremen t consists of preferentially measuring photons that have traveled more deeply into limb tissues and that, therefore, may reach locations of ischemic tissue. Oxygen measurements appear to be possible up to a dep th approaching 1.5 cm beneath the surface of the skin. The present stu dy reports on data acquired from the limbs of 11 subjects with IC and 12 subjects without IC. The subjects with IC are patients with clinica l findings of claudication based upon segmental Doppler pressure profi les and subjective reports by the patient of pain during exercise. The subjects without IC are individuals with no prior history of ischemic vascular disease. The results consist of photon reflectance measureme nts at red and infrared wavelengths (approximately 660 nm and 880 nm r espectively) taken before, during, and after exercise. Infrared reflec tance indices are plotted as well as oxygenation indices generated fro m combining red and infrared reflectances. A compilation of exercise d ata shows responses that are generally consistent with the expected ph ysiological responses to mild exercise in subjects with and without IC . We anticipate that the findings of this study may lead to an objecti ve noninvasive testing procedure for measuring the ischemic and exerci se-induced changes in muscle oxygenation in the presence of claudicati on. If the testing of ischemic hypoxia continues to show consistency a nd accuracy in determining the disability of the subjects with IC, fut ure studies can more effectively test modes of conservative management , such as cessation of smoking, alternative exercise regimens, weight loss, and alternative pharmacological agents.