Postprocedural Skin Perfusion Pressure Correlates With Clinical Outcomes 1 Year After Endovascular Therapy for Patients With Critical Limb Ischemia

Oxygen Therapy to Enhance Wound Healing After Revascularization

Oxygen is one of the important factors for wound healing and infection control. The revascularization procedure is amended to correct the tissue hypoxia problem by increasing the blood flow to obtain an adequate amount of oxygen. Hypoxic wounds are still the issue in the cases of unsuccessful or incomplete revascularization. The issue needs to be clarified and confirmed by proper methods for management to achieve wound healing and prevent limb loss. Oxygen therapy may benefit in the case of remaining hypoxia or wound infection in postrevascularization.

Longitudinal changes in skin perfusion pressure after endovascular therapy in patients with chronic limb-threatening ischemia

PURPOSE

The skin perfusion pressure (SPP) increases after endovascular treatment (EVT) for up to 1 month, although changes beyond 1 month remain unreported. This study aimed to investigate the changes in the SPP over time after EVT.

MATERIALS AND METHODS

This was a single-center, prospective, observational study. We included patients with chronic limb-threatening ischemia who underwent EVT between January 2019 and July 2022. We evaluated the SPP after EVT monthly for up to 3 months and compared the changes in the SPP between patients with different comorbidities. Moreover, we investigated the independent predictors of recurrent foot ischemia using a multivariate analysis.

RESULTS

Overall, 87 patients were included in the study. The mean preprocedural dorsal and plantar SPP was 33.9 ± 14.7 and 33.4 ± 13.1 mmHg, respectively. After the procedure, the SPP significantly increased at 1 month but decreased during months 2 and 3 (the dorsal SPP at 1, 2, and 3 months was 59.6 ± 20.3, 48.3 ± 20.9, and 39.7 ± 14.7, respectively, p < 0.01; the plantar SPP at 1, 2, and 3 months was 57.3 ± 18.2, 48.2 ± 15.6, and 40.5 ± 15.3, respectively, p < 0.01). Changes in the SPP did not differ among patients with different comorbidities. The multivariate analysis revealed that severe infrapopliteal calcification was an independent predictor of recurrent foot ischemia (odds ratio, 3.8; 95% confidence interval, 1.1-13.4; p = 0.04).

CONCLUSION

The SPP after EVT significantly increased at 1 month and decreased monthly for up to 3 months. Severe infrapopliteal calcification was the sole predictor of foot ischemia recurrence. Meticulous follow-up after EVT and regular hemodynamic examinations are important.

Quantifying tissue perfusion after peripheral endovascular procedures: Novel tissue perfusion endpoints to improve outcomes

Peripheral artery disease (PAD) is a flow-limiting condition caused by narrowing of the peripheral arteries typically due to atherosclerosis. It affects almost 200 million people globally with patients either being asymptomatic or presenting with claudication or critical or acute limb ischemia. PAD-affected patients display increased mortality rates, rendering their management critical. Endovascular interventions have proven crucial in PAD treatment and decreasing mortality and have significantly increased over the past years. However, for the functional assessment of the outcomes of revascularization procedures for the treatment of PAD, the same tests that have been used over the past decades are still being employed. Those only allow an indirect evaluation, while an objective quantification of limb perfusion is not feasible. Standard intraarterial angiography only demonstrates post-intervention vessel patency, hence is unable to accurately estimate actual limb perfusion and is incapable of quantifying treatment outcome. Therefore, there is a significant necessity for real-time objectively measurable procedural outcomes of limb perfusion that will allow vascular experts to intraoperatively quantify and assess outcomes, thus optimizing treatment, obviating misinterpretation, and providing significantly improved clinical results. The purpose of this review is to familiarize readers with the currently available perfusion-assessment methods and to evaluate possible prospects.

The Efficacy of the Transdermal Isosorbide Dinitrate Patch in Patients With Chronic Limb-Threatening Ischemia

Recently, the number of patients with peripheral artery disease (PAD), including those with chronic limb-threatening ischemia (CLTI), has increased because of the increasing number of diabetic or dialysis patients worldwide. Revascularization is an important therapy for patients with CLTI. However, we sometimes experience refractory cases with insufficient peripheral circulation or microcirculation after revascularization. In this situation, additional therapy can be administered, such as low-density lipoprotein apheresis, high-pressure oxygen therapy, and spinal cord stimulation. However, they are not effective in some cases. Some reports have also indicated that transdermal isosorbide dinitrate patch (ISDN-P) is a useful therapy for PAD. As the efficacy of ISDN-P for patients with CLTI is not well-known, we examined it in this study. We assessed the skin perfusion pressure (SPP) after affixing an ISDN-P on the foot, because SPP measurement has proved useful in the assessment of PAD and is a good indicator of wound healing potential. The SPP (dorsal and plantar aspects) after ISDN-P application on the foot of healthy volunteers increased (n = 8; mean ± SD, 12.6 ± 7.9 [P = .12], and 21.2 ± 7.7 mm Hg [P < .05], respectively), as did SPP of patients with CLTI (n = 10; mean ± SD, 19.8 ± 2.5 [P < .01], and 14.1 ± 5.9 mm Hg [P < .05], respectively). All the patients who received an ISDN-P on the foot had no major complication, and no significant change in blood pressure. In conclusion, the ISDN-P is one of the effective and safe therapies for patients with CLTI.

Below-the-Ankle Arrival Time as a Novel Limb Tissue Perfusion Index: Two-dimensional Perfusion Angiography Evaluation

Purpose: To identify lower limb 2-dimensional (2D) perfusion angiographic parameters that are related to skin perfusion pressure (SPP), a predictor of wound healing in patients with chronic limb-threatening ischemia (CLTI) undergoing below-the-knee (BTK) endovascular treatment (EVT). Materials and Methods: Thirty-three consecutive patients (mean age 74.5 years; 18 men) with 47 isolated BTK lesions in 33 limbs (Rutherford category 3–5) underwent EVT. Dorsal and plantar SPPs were measured before EVT and the day after. The indexed blood flow below the ankle was measured using 2D perfusion angiography before and after EVT to determine changes in perfusion parameters [arrival time (AT), time to peak, wash-in rate, mean transit time, and width and area under the time-density curve] at rest vs during hyperemia induced with a 20-mg intra-arterial papaverine infusion. Correlations between the 2D perfusion parameters and SPPs were assessed using the Pearson coefficient. The cutoff points to predict mean SPPs >40 mm Hg were analyzed using a receiver operating characteristic curve; outcomes are reported as the area under the curve (AUC) with 95% confidence interval (CI). Results: After EVT at rest and during hyperemia, only AT was significantly changed, although hyperemia produced significant changes in all the pre-/post-EVT 2D perfusion parameters except the wash-in rate. Dorsal and plantar SPPs after EVT were significantly increased and correlated with hyperemic AT and the AT ratio (hyperemia/at rest values) below the ankle. Hyperemic ATs <6.3 seconds and AT ratios <0.78 were predictive factors for a mean SPP >40 mm Hg, with AUCs of 0.83 (95% CI 0.67 to 0.99) and 0.78 (95% CI 0.61 to 0.95), respectively. Conclusion: Hyperemic ATs <6.3 seconds or AT ratios <0.78 below the ankle may be essential to obtain sufficient SPPs for limb salvage in BTK lesions. Thus, the use of 2D perfusion angiography enabled the monitoring of lower limb tissue perfusion throughout EVT and may thereby optimize treatment of CLTI.

Peripheral artery disease: the new frontiers of imaging techniques to evaluate the evolution of regenerative medicine

Introduction: Stem cells (ESC, iPSC, MSC) are known to have intrinsic regenerative properties. In the last decades numerous findings have favored the development of innovative therapeutic protocols based on the use of stem cells (Regenerative Medicine/Cell Therapy) for the treatment of numerous diseases including PAD, with promising results in preclinical studies. So far, several clinical studies have shown a general improvement of the patient's clinical outcome, however they possess many critical issues caused by the non-randomized design of the limited number of patients examined, the type cells to be used, their dosage, the short duration of treatment and also their delivery strategy. Areas covered: In this context, the use of the most advanced molecular imaging techniques will allow the visualization of very important physio-pathological processes otherwise invisible with conventional techniques, such as angiogenesis, also providing important structural and functional data. Expert opinion: The new frontier of cell therapy applied to PAD, potentially able to stop or even the process that causes the disease, with particular emphasis on the clinical aspects that different types of cells involve and on the use of more innovative molecular imaging techniques now available.

Increase in skin perfusion pressure predicts amputation-free survival after lower extremity bypass surgery for critical limb ischemia

The objective of this study was to determine how postoperative skin perfusion pressure (SPP) as a measure of blood flow after revascularization affects limb prognosis in patients with critical limb ischemia (CLI). We retrospectively reviewed 223 consecutive bypass surgery cases performed in 192 patients with CLI during a 10-year period. SPP was measured 1–2 weeks before and after the procedure. An SPP of 40 mmHg was set as the cut-off value for revascularization. Patients were grouped according to their postoperative SPPs, and amputation-free survival (AFS) was analyzed. An SPP of ≥ 40 mmHg was recovered in 75% of the patients, but no significant difference was found between this group and the group that did not reach 40 mmHg. On the other hand, the values increased by ≥ 20 mmHg from the preoperative values in 70% of the patients. This group had a significantly better AFS than the group that did not increase by 20 mmHg. Logistic regression analysis revealed that (1) a preoperative SPP of < 20 mmHg and (2) a high serum albumin level (> 3.0 g/dL) were significant factors in increasing SPP by 20 mmHg. These results showed that an increase in SPP of ≥ 20 mmHg after bypass surgery was associated with better limb prognosis.

Skin perfusion pressure for the prediction of wound healing in critical limb ischemia: a meta-analysis

INTRODUCTION

The purpose of this meta-analysis was to determine the value and efficacy of skin perfusion pressure (SPP) for the prediction of wound healing in patients with critical limb ischemia.

MATERIAL AND METHODS

Medline, Cochrane, EMBASE, and Google Scholar databases were searched from inception until December 31, 2014 using combinations of the following keywords: skin perfusion pressure, limb ischemia, wound healing, prediction. Randomized controlled trials, 2-arm prospective studies, and retrospective studies that measured SPP in patients with limb ischemia were included. The outcome was the sensitivity and specificity of SPP for the prediction of wound healing.

RESULTS

Five studies were included in the meta-analysis. The mean patient age ranged from 62.2 to 71.5 years, and the majority were male. The pooled sensitivity of SPP for the prediction of wound healing was 79.9% using 30 mm Hg as the cut-off, 67.1% using 40 mm Hg, and 76.1% for all included studies (95% CI: 73.9-84.9%, 55.8-76.8%, and 70.7-80.8%, respectively). The pooled specificity was 78.2% using 30 mm Hg, 84.2% using 40 mm Hg, and 82.1% for all included studies (95% CI: 61.5-89.0%, 74.0-90.9%, 73.7-88.3%, respectively).

CONCLUSIONS

Skin perfusion pressure can accurately predict wound healing in patients with critical limb ischemia.

Pathophysiological Significance of Velocity-Based Microvascular Resistance at Maximal Hyperemia in Peripheral Artery Disease

AIM

Maximal hyperemic response, leading to examination of microvascular resistance in lower-limb lesions is not well understood. This study aimed to investigate the infrainguinal arterial physiological response through a hyperemic condition and the pathophysiological significance of microvascular resistance in peripheral artery disease.

METHODS

Sixteen limbs with focal stenosis of the superficial femoral artery (SFA) and 16 control limbs were analyzed. We assessed the fractional flow reserve (FFR), vascular flow reserve (VFR), and hyperemic microvascular resistance (h-MR) of the SFA with a pressure/Doppler flow sensor-tipped combination guidewire before and after endovascular therapy (EVT). Skin perfusion pressure (SPP) on both the dorsal and the plantar sides of the foot was measured at baseline before and after the endovascular procedures.

RESULTS

FFR (p＜0.05) and VFR (p＜0.05), but not h-MR, improved after EVT. There was no association between h-MR and FFR or VFR before EVT. h-MR was negatively correlated with the dorsal SPP before EVT (r=－0.589, p＜0.05). h-MR in patients with high h-MR before EVT significantly decreased after EVT (p＜0.05). Patients with high, but not those with low, h-MR before EVT exhibited a significant increase in dorsal and plantar SPP after EVT (p＜0.05, each).

CONCLUSION

EVT for SFA stenosis improved FFR and VFR comprehensively, with no apparent change in h-MR. However, high h-MR before EVT may play a predictive role for limb perfusion improvement associated with h-MR reduction after EVT.

Skin perfusion pressure as a predictor of ischemic wound healing potential

Skin perfusion pressure (SPP) is the blood pressure that is the requisite for the restoration of microcirculatory or capillary flow following controlled occlusion and subsequent flow return. The purpose of the current review was to evaluate the value of SPP for the prediction of wound healing in patients with limb ischemia. Articles published up to January 31, 2017 were searched in the PubMed database and Chinese database CNKI, using the keywords of 'skin perfusion pressure', 'limb ischemia' and 'wound healing'. Articles were obtained and reviewed to analyze the predictive value of SPP with regard to the healing potential of ischemia wounds on limbs. Three different types of techniques are currently used for the measurement of SPP, namely radioisotope clearance, photoplethysmography and laser Doppler, with laser Doppler as the most widely applied technique, due to its noninvasiveness and ease of operability. SPP may effectively assess wound healing potential in ischemic limbs with high sensitivity and specificity; however, its optimum cut-off point remains uncertain. Compared with other noninvasive microcirculatory assessment tools including ankle-brachial index, toe blood pressure and transcutaneous oxygen pressure, SPP has its advantages including that it is not affected by vascular calcification, anatomical structure or patient condition. In conclusion, SPP may be used as an index to accurately predict wound healing in patients with limb ischemia. However, it is difficult to determine the optimum cut-off of SPP due to the limitations of current data. Further study is necessary to confirm the optimum cut-off value of SPP in predicting wound healing potential.

Predictive Parameters for Clinical Outcome in Patients with Critical Limb Ischemia Who Underwent Percutaneous Transluminal Angioplasty (PTA): A Systematic Review

Purpose

To identify possible risk factors in predicting clinical outcome in critical limb ischemia (CLI) patients undergoing percutaneous transluminal angioplasty (PTA).

Materials and Methods

PubMed and EMBASE were searched for studies analyzing CLI and clinical outcome after PTA from January 2006 to April 2017. Outcome measures were ulcer healing, amputation free survival (AFS)/limb salvage and overall survival. Data on predictive factors for ulcer healing, AFS/limb salvage and survival were extracted.

Results

Ten articles with a total of 2448 patients were included, all cohorts and based on prospective-designed databases. For ulcers, it seems that complete healing can be achieved in most of the patients within 1 year. No significant predictive factors were found. AFS/limb salvage: AFS rates for 1, 2 and 3 years ranged from 49.5 to 75.2%, 37 to 58% and 22 to 59%, respectively. Limb salvage rates for 1, 2 and 3 years ranged from 71 to 95%, 54 to 93.3% and 32 to 92.7%, respectively. All studies had different univariate and multivariate outcomes for predictive factors; however, age and diabetes were significant predictors in at least three studies. Survival: Survival rates for 1, 2 and 3 years ranged from 65.4 to 91.5%, 45.7 to 76% and 37.3 to 83.1%, respectively. Different predictive factors were found; however, age was found in 2 out of 5 studies reporting on predictive factors.

Conclusions

In several studies two factors, age and diabetes, were found as predictive factors for AFS/limb salvage and survival in patients with CLI undergoing PTA. Therefore, we believe that these factors should be taken into account in future research.

Level of Evidence

Level 2a.

Determining End Points for Critical Limb Ischemia Interventions

Critical limb ischemia is a condition that has increased in prevalence and carries a high degree of morbidity. Although endovascular therapy for treatment of patients with critical limb ischemia has undergone significant advances with improved outcomes over the past decade, these patients often have multilevel disease, and it may take weeks or months for ulceration healing. For this reason, the acceptable therapeutic end points during and immediately following revascularization remain somewhat obscure. There are multiple tools available to guide the treating vascular specialist in this regard. Establishment of in-line flow to the foot and the angiosome containing the ulceration, appearance of a "wound blush," restoration of pulses, and bleeding at the ulcer site are basic tenets intraprocedurally. Postprocedural noninvasive testing including the ankle-brachial and toe-brachial indices, segmental pressure measurements, pulse volume recordings, transcutaneous oxygen tension, skin perfusion pressures (SPPs), and toe pressures all play a role in determining the likelihood of clinical improvement. Newer technologies such as two-dimensional (2D) perfusion angiography, fluorescence angiography, and tissue oxygen saturation mapping may allow better real-time assessment of flow restoration. In combination with close clinical follow-up and wound care, these tools provide treating physicians with a better grasp of the necessary end points to optimize patients for clinical improvement.