The significance of regional hemoglobin oxygen saturation values and limb-to-arm ratios of near-infrared spectroscopy to detect critical limb ischemia.

This study examines the application of near-infrared spectroscopy to noninvasively detect critical limb ischemia using regional hemoglobin oxygen saturation in percentage values and regional hemoglobin oxygen saturation limb-to-arm ratios. The regional hemoglobin oxygen saturation values and regional hemoglobin oxygen saturation limb-to-arm ratios were calculated in 61 patients with critical limb ischemia (group A). Measurements were performed in rest at four fixed spots at the most affected lower limb and at a reference spot at both upper arms. Similar measurements were performed in the left lower limb of 30 age-matched control patients without peripheral arterial disease (group B). The regional hemoglobin oxygen saturation values and regional hemoglobin oxygen saturation limb-to-arm ratios were significantly different at all measured spots between the groups (all p < 0.001), except for the regional hemoglobin oxygen saturation limb-to-arm ratios of the distal vastus lateralis (p = 0.056). However, a broad overlap of individual regional hemoglobin oxygen saturation values and regional hemoglobin oxygen saturation limb-to-arm ratios was found in both groups, which resulted in poor discriminative predictive value of single measurements. Single measurements of regional hemoglobin oxygen saturation values and regional hemoglobin oxygen saturation limb-to-arm ratios at all measured spots have poor discriminative predictive value in detection of critical limb ischemia. Measurement of regional hemoglobin oxygen saturation values and regional hemoglobin oxygen saturation limb-to-arm ratios at any of the measurement spots has no added value in detecting lower limb ischemia in individuals compared with current diagnostic modalities.