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

Abstract

Objective: The 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.Methods: From 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.Results: We enrolled a total of 91 limbs for 76 patients (mean age, 70.5 6 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. Conclusions:The 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.

Injury Precipitating Tissue Loss and Time to Referral to a Vascular Center in Patients with Chronic Limb-Threatening Ischemia

“…The lack of a clear initial injury leading to tissue loss was not significantly associated with WIfI severity (all P＞0.05). Similar findings were observed when WIfI ischemia classification was based on other SPP cutoff points 20) (Supplemental Table 1). Supplemental Tables 2 to 5 show the sensitivity analysis in which missing data were not imputed and handled by listwise deletion.…”

“…The cumulative link model with a logit link function was adopted to examine whether the lack of a clear initial injury leading to tissue loss and time to referral would be associated with the severity of tissue loss. Although our SPP-based WIfI ischemia grading (＜30 mmHg as I-3 and 30-39 mmHg as I-2) was in line with the latest domestic clinical guideline 17) , we additionally performed the analysis where the WIfI ischemia grade was based on another classification (an SPP of ＜25, 25-34, 35-44, and ≥ 45 mmHg as I-3, -2, -1, and -0, respectively) 20) . All analyses were conducted per patient; for patients with bilateral CLTI, the limb presenting with the more severe tissue loss was treated as the representative one.…”

Arterial spectral waveform analysis in the prediction of diabetic foot ulcer healing

“…A previous study showed that integrating skin perfusion pressure assessment into the WIfI classification system resulted in more accurate staging. 6 Although the presence of PAD is a major determinant of ulcer healing, other factors must also be considered when determining the chance of ulcer healing. The National Diabetic Foot Care Audit analysed data on over 27,000 ulcers and identified 15 important variables including the presence of PAD, size and number of ulcers, gender, inactive charcot, duration of diabetes, acute comorbidities and time to first expert assessment.…”

Consensus on the application of negative pressure wound therapy of diabetic foot wounds

“…In clinical practice, a small amount of necrotic tissue may remain within the wound and, even after several rounds of debridement, it is unlikely that hidden foci of infection would have been removed. Therefore, there is a risk that infection may spread after NPWT [ 66 ]. In addition, even after revascularization of the ischemic wound, there is a short-term risk of reclosure of blood vessels and wound ischemia.…”