The Perfusion Index May be an Accurate Tool for Predicting the Progression of Ischemia in Patients with Peripheral Arterial Disease

To test the reliability of the perfusion index (PI), a new index of blood flow in the lower extremities, we studied 246 patients (368 legs) with ischemic foot symptoms between January 2020 and November 2024. The average PI (PIave) was measured with a saturation monitor probe applied to all toes. The PIave value was obtained within 5 minutes for each foot and decreased as the ischemia severity increased. Skin perfusion pressure was significantly positively correlated with PIave ( r = .215; P < .001). Of the 201 limbs of conservatively treated patients, 12 of 74 limbs with a PIave < .27 progressed to chronic limb-threatening ischemia (CLTI), while only 2 of 127 limbs with a PIave ≥ .27 progressed (χ 2 test; P < .001; negative predictive value: 98%). Logistic regression analysis revealed that PIave < .27 was significantly associated with disease progression. In conclusion, the PI is a simple and useful marker for accurately indicating the degree of ischemia in the toes. The PI can predict that a patient will not progress to CLTI in the next 3 months with conservative treatment and may contribute to safe follow-up.