Evaluation of peripheral arterial occlusive disease and postsurgical viability using reflectance spectroscopy of skin

Abstract

Hypothesis: Stress-induced changes in skin microcirculation allow staging of peripheral arterial vascular pathology using diffuse reflectance spectroscopy (DRS) of the skin. Design and Methods: The changes in relative concentration of oxyhemoglobin and deoxyhemoglobin in the cutaneous microvasculature were assessed at rest, during limb elevation, dependency, and cuff-mediated reactive hyperemia for the forearm of 25 normal subjects and 105 feet of patients with peripheral arterial occlusive disease (PAOD) (normal = 28, claudication = 34, limb threatening ischemia = 44). Thirty-four patients who had revascularization procedures were again evaluated within the first week postoperatively. Results: Two measurements correlated with clinical staging: (1) the relative absorbance of oxyhemoglobin after 225 s of limb dependency and (2) the time to reach 50% of peak reactive hyperemia response (Spearman's rank: r s = 0.625, P < 0.001). Using these criteria alone, ischemic limbs were identified to a sensitivity of 69% and specificity of 95%. Significant post-revascularization improvement was identified in 14 of 34 patients' legs which had previously been classified as limb-threatening ischemia ( n = 14, W = 105, P < 0.001). Conclusions: These simple bedside evaluations of the superficial skin microvasculature allow staging of large vessel vascular insufficiency and may suggest and differentiate focal areas of tissue at risk for ulceration or necrosis.