Utility of skin perfusion pressure values with the Society for Vascular Surgery Wound, Ischemia, and foot Infection classification system

Abstract

ObjectiveThe addition of skin perfusion pressure (SPP) might enhance the predictive value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system. The purpose of the present study was to evaluate the SPP for each WIfI classification stage among patients with foot wounds by cross-referencing the results of prospectively monitored limb outcomes and to derive the SPP criteria that could be combined with other measurements to grade ischemia for the WIfI classification. MethodsFrom July 2015 to June 2017, patients with foot wounds that met the WIfI classification criteria were prospectively enrolled. We assessed the limbs using the WIfI ischemia grade without measuring the transcutaneous oxygen pressure but measured the SPP. After monitoring for 1 year, the predictability of the WIfI stages was analyzed according to whether the limbs had not healed (unchanged or worsened wounds, minor or major amputation, all-cause death) or had healed (improved or healed wounds) by comparing stages 1 and 2 with stages 3 and 4. We also statistically analyzed the SPP values that could be the boundary values between each ischemia grade and reevaluated the predictability of the WIfI stages with the boundary SPP values. ResultsWe enrolled a total of 91 limbs for 76 patients (mean age, 70.5 ± 12.0 years). The mean SPP values stratified by ischemia grade 0 to 3 were 52.1, 41.1, 27.1, and 18.8 mm Hg, respectively (an SPP of <30 mm Hg indicates severe ischemia). After monitoring for 1 year, 19 of 48 limbs in stage 1 and 2 and 35 of 43 in stage 3 and 4 were in the nonhealed group and 29 limbs in stage 1 and 2 and 8 limbs in stage 3 and 4 were in the healed group. The SPP boundary values between each ischemia (I) grade were calculated as 45 mm Hg for I-0/I-1, 35 for I-1/I-2, and 25 for I-2/I-3. When jointly using the boundary SPP values, the ischemia grade changed for 23 limbs, altering the distribution of the WIfI stages and limb outcomes: 11 of 38 limbs in stage 1 and 2 and 43 of 53 in stage 3 and 4 were transferred to the nonhealed group. The sensitivity, efficiency, and negative predictive value of WIfI staging improved when staging with SPP: from 65% to 80%, 70% to 77%, and 60% to 71%, respectively. ConclusionsThe SPP boundary values that could be used with ischemia grade in the WIfI classification were identified as 45, 35, and 25 mm Hg. The addition of SPP could improve the accuracy of the evaluation.