Autologous Blood-Derived Products (ABDPs) for the Treatment of Chronic Wounds

Autologous blood-derived therapies have emerged as a unique and promising treatment option for chronic wounds. From whole blood clots to spun-down clot constituents, these therapies are highly versatile and tend to have a lower cost profile, allow for point-of-service preparation, and inherently carry minimal to no risk of rejection or allergic reaction when compared to many alternative cellular and matrix-like products. Subsequently, a diversity of processing systems, devices, and kits have surfaced on the market for preparing autologous blood-derived products (ABDPs) and many have demonstrated preclinical and clinical efficacy in facilitating chronic wound healing. However, not all ABDPs are created equal, and the lack of standardization among product formulations and cell concentrations as well as varying complexities in preparation protocols has led to unreliable substrate viabilities and overall inconsistent conclusions on efficacy. Additionally, external factors, such as the ease of drawing blood, the health of a patient's blood, and the reimbursement landscape have dissuaded some practitioners from incorporating ABDPs into an algorithm of care for recalcitrant wounds. Here, we attempt to categorize ABDPs into "classes" and examine their efficacy, advantages, and limitations when used as both a primary therapy and an adjunct for treating chronic wounds as well as comment on some potential considerations that may help gear future product development and application.

PACE: randomized, controlled, multicentre, multinational, phase III study of PLX-PAD for critical limb ischaemia in patients unsuitable for revascularization: randomized clinical trial

BACKGROUND

Revascularization is the primary treatment modality for chronic limb-threatening ischaemia (CLTI), but is not feasible in all patients. PLX-PAD is an off-the-shelf, placental-derived, mesenchymal stromal cell-like cell therapy. This study aimed to evaluate whether PLX-PAD would increase amputation-free survival in people with CLTI who were not candidates for revascularization.

METHODS

People with CLTI and minor tissue loss (Rutherford 5) who were unsuitable for revascularization were entered into a randomized, parallel-group, placebo-controlled, multinational, blinded, trial, in which PLX-PAD was compared with placebo (2 : 1 randomization), with 30 intramuscular injections (0.5 ml each) into the index leg on days 0 and 60. Planned follow-up was 12-36 months, and included vital status, amputations, lesion size, pain and quality-of-life assessments, haemodynamic parameters, and adverse events.

RESULTS

Of 213 patients enrolled, 143 were randomized to PLX-PAD and 70 to placebo. Demographics and baseline characteristics were balanced. Most patients were Caucasian (96.2%), male (76.1%), and ambulatory (85.9%). Most patients (76.6%) reported at least one adverse event, which were mostly expected events in CLTI, such as skin ulcer or gangrene. The probability of major amputation or death was similar for placebo and PLX-PAD (33 and 28.6% respectively; HR 0.93, 95% c.i. 0.53 to 1.63; P = 0.788). Revascularization and complete wound healing rates were similar in the two groups. A post hoc analysis of a subpopulation of 121 patients with a baseline haemoglobin A1c level below 6.5% showed improved 12-month amputation-free survival (HR 0.46, 0.21 to 0.99; P = 0.048).

CONCLUSION

Although there was no evidence that PLX-PAD reduced amputation-free survival in the entire study population, benefit was observed in patients without diabetes mellitus or whose diabetes was well controlled; this requires confirmation in further studies. Trial registration: NCT03006770 (http://www.clinicaltrials.gov); 2015-005532-18 (EudraCT Clinical Trials register - Search for 2015-005532-18).

Novel Reconstructive Ladder for Reestablishing Functional Skin Graft Coverage in Chronic Lower Extremity Wounds

Background

Chronic lower extremity (LE) wounds frequently require significant interventions to close. The success of any method depends on an adequately prepared wound bed, while factors including wound size, perfusion, contamination, or exposed tissue structures can thwart efforts. We propose a standardized algorithm of care utilizing an acellular dermal matrix, split-thickness skin graft (STSG), and negative pressure wound therapy (NPWT) for the treatment of LE wounds.

Methods

This was a single-center, retrospective cohort study examining patients who underwent LE wound debridement, placement of fetal bovine dermis (FBD), and STSG between 2016 and 2022. The primary outcome was wound closure, while secondary outcomes were wound infection and amputation-free survival.

Results

Twenty patients (mean age 59 years, M:F 12:8)-including 24 LE venous ulcers (29.4%), amputation sites (29.4%), diabetic foot ulcers (25.0%), and atypical wounds (16.7%) with an average area of 39.15 cm2-underwent debridement and FBD placement followed by STSG a median of 61 days thereafter. Of these patients, 83.3% received NPWT after FBD and STSG with 86% closure. There was successful engraftment in 92% of wounds whose FBD placement was within 2 months of STSG. Of wounds that had <50% engraftment, 75% had a STSG placed over 2 months after FBD placement. Of those patients with post-STSG infection, 75% had the graft placed >2 months after FBD placement, one of which required proximal amputation.

Conclusions

By following a treatment plan including debridement with treatment of infection, application of FBD with placement of STSG within 2 months thereafter, and reinforcing NPWT, chronic wounds will have an increased rate of successful reepithelialization. Many cases experienced delays from FBD engraftment until STSG application due to schedule and insurance impediments, which led to less favorable outcomes. Therefore, a protocol that involves scheduling the placement of STSG 4 weeks after successful engraftment of FBD has been adopted.

The Shift to Synthetics: A Review of Novel Synthetic Matrices for Wound Closure

Since the late 1990s, a growing number of "skin substitutes" have become available to practitioners seeking to heal large surface wounds. These extracellular matrices were originally from xenograft sources, and then from very highly engineered living human cellular tissues. More recently, they consist of biosynthetic materials that are combinations of silicone, collagen and chondroitin. The list of xenograft materials as well as minimally manipulated human tissues, such as human skin-, amniotic- and placental-based products, has grown exponentially. Over the last 5 years, truly synthetic materials have become part of the armamentarium available for closing large wounds. The first notable product in this category was made of polyurethane. These purely synthetic products do not have any components made of naturally occurring structures, such as collagen. In this review, we seek to create a rudimentary framework in which to understand these synthetic products and to review the current literature that supports the use of these novel yet intriguing therapies.

Acellular Fish Skin for Tissue Replacement

In modern practice, xenografts play a crucial role in wound management due to their regenerative properties. Of the various xenografts currently available on the market, acellular fish skin (AFS) grafts have emerged as a more effective alternative to existing xenografts and other standard of care (SOC) treatments for wound healing. Since AFS grafts require minimal processing, they maintain their structural integrity and natural properties, including an abundance of Omega-3 fatty acids, which is a distinctive, pro-regenerative feature. AFS grafts are also unique in that they are not derived from mammalian tissue, so there is no risk of viral transmission and no cultural or religious barriers to use. AFS grafts have been shown to be more cost-effective in the treatment of diabetic foot ulcers (DFUs) and result in a higher percentage of healed wounds, fewer amputations, and better patient quality of life. Several studies and case reports have highlighted the versatility of AFS in not only acute and chronic wound healing, but also for burn wound skin regeneration. Additionally, AFS may have promise as an implantable biologic matrix for suture line reinforcement in hernia repairs or breast and dura reconstruction.

Implantable Biologics for Soft Tissue Surgery Reinforcement

Soft tissue reinforcement focuses on medical grafts that are designed to support and regenerate soft tissue under or near suture lines. Soft tissue is defined as areas of similarly specialized cells that function to connect, support, and surround other structures and organs of the body. These tissues include skin, subcutaneous tissue, fascia, ligaments, tendons, fibrous tissues, fat, synovial membranes, and muscle. Most of the implantable devices used for this purpose are made of collagen, the most abundant protein in mammals and a key component of the extracellular matrix of soft tissues that allows for tissue repair. For suture line reinforcement, exogenous collagen from various sources is implanted under or in continuity with the suture line to allow for increased strength and better healing. First introduced in the field of breast reconstruction, this practice is now also used in hernia repair, dural repair, vaginal slings, amputation reinforcement, tendon repair reinforcement, and even dental soft tissue regeneration.

Circulating endothelial precursor cells are associated with a healed diabetic foot ulcer evaluated in a prospective cohort study

The goal of this multicentre study was to evaluate whether circulating endothelial precursor cells and microparticles can predict diabetic foot ulcer healing by the 16th week of care. We enrolled 207 subjects, and 40.0% (28.4, 41.5) healed by the 16th week of care. Using flow cytometry analysis, several circulating endothelial precursor cells measured at the first week of care were associated with healing after adjustment for wound area and wound duration. For example, CD34+ CD45dim , the univariate odds ratio was 1.19 (95% confidence interval: 0.88, 1.61) and after adjustment for wound area and wound duration, the odds ratio was (1.67 (1.16, 2.42) p = 0.006). A prognostic model using CD34+ CD45dim , wound area, and wound duration had an area under the curve of 0.75 (0.67, 0.82) and CD34+ CD45dim per initial wound area, an area under the curve of 0.72 (0.64, 0.79). Microparticles were not associated with a healed wound. Previous studies have indicated that circulating endothelial precursor cells measured at the first office visit are associated with a healed diabetic foot ulcer. In this multicentred prospective study, we confirm this finding, show the importance of adjusting circulating endothelial precursor cells measurements by wound area, and show circulating endothelial precursor cells per wound area is highly predictive of a healed diabetic foot ulcer by 16th week of care.

Blood-Borne Microparticles Are an Inflammatory Stimulus in Type 2 Diabetes Mellitus

The proinflammatory state associated with diabetes mellitus (DM) remains poorly understood. We found patients with DM have 3- to 14-fold elevations of blood-borne microparticles (MPs) that bind phalloidin (Ph; Ph positive [+] MPs), indicating the presence of F-actin on their surface. We hypothesized that F-actin-coated MPs were an unrecognized cause for DM-associated proinflammatory status. Ph+MPs, but not Ph-negative MPs, activate human and murine (Mus musculus) neutrophils through biophysical attributes of F-actin and membrane expression of phosphatidylserine (PS). Neutrophils respond to Ph+MPs via a linked membrane array, including the receptor for advanced glycation end products and CD36, PS-binding membrane receptors. These proteins in conjunction with TLR4 are coupled to NO synthase 1 adaptor protein (NOS1AP). Neutrophil activation occurs because of Ph+MPs causing elevations of NF-κB and Src kinase (SrcK) via a concurrent increased association of NO synthase 2 and SrcK with NOS1AP, resulting in SrcK S-nitrosylation. We conclude that NOS1AP links PS-binding receptors with intracellular regulatory proteins. Ph+MPs are alarmins present in normal human plasma and are increased in those with DM and especially those with DM and a lower-extremity ulcer.

Skin Expansion Technology in Acute Burns and Chronic Wounds

The ability to grow skin has long been a topic of study and therapeutic interest. Currently, the main ways of doing this are 1) by placing tissue-expansion devices in the subcutaneous space and expanding skin over time, which can then be moved to cover contiguous structures, and 2) via processes that require relatively long (30 days) incubation periods to grow the patient's autogenous skin into laminar sheets. Over the past five years, there have been significant developments in the ability to expand skin cells, either at the bedside or in the laboratory, but much more rapidly than with previous methods. We explore and discuss the current skin cell-expansion techniques, focusing on point-of-care therapeutic interventions that can be used in the burn population as well as the chronic wound population, hair follicle stem-cell incubation techniques and studies supporting this therapy, as well as micro bullae grafting, and morcellated skin cell therapy. The current data supporting these therapeutic interventions and their current direction are outlined in detail.

Further evidence that wound size and duration are strong prognostic markers of diabetic foot ulcer healing

Diabetic foot ulcers (DFU) are a critical problem for those with diabetes mellitus. Predicting the healing likelihood of a DFU is important to implementing appropriate care, allocating resources, having access to advanced therapies, having successful clinical trials, calibrating clinical trial results, and providing information to administrative entities on patient and provider outcomes. Prognostic modeling can also be important when attempting to compare results across trials or care centers. In a prospective cohort study, we demonstrate and replicate that simple wound characteristics like wound area and wound duration can be used to predict wound healing by the 16^th week of care. The models were based on previous literature and replicated using a machine learning algorithm. The use of wound duration and wound area in a prognostic model continues to be important when comparing study results, center-based outcomes, as well as designing clinical trials.

Fetal bovine acellular dermal matrix for the closure of diabetic foot ulcers: a prospective randomised controlled trial

AIM

The purpose of this clinical trial was to evaluate the safety and efficacy of a fetal bovine acellular dermal matrix (FBADM) plus standard of care (SOC) for treating hard-to-heal diabetic foot ulcers (DFUs).

METHOD

A prospective, multi-centre, randomised controlled trial was carried out. The study included a 2-week run-in period, a 12-week treatment phase and a 4-week follow-up phase. The primary endpoint was complete wound closure at 12 weeks.

RESULTS

Twenty-one US sites enrolled and randomised 226 patients with hard-to-heal DFUs. The study was terminated early due to the COVID-19 pandemic, which led to a modified intent-to-treat (mITT) population of 207 patients, with 103 in the FBADM group and 104 in the SOC group. Of these participants, 161 completed the study per protocol (mPP population), with 79 receiving FBADM, and 82 without. At the first analysis point, patients treated with FBADM were found to be significantly more likely to achieve complete wound closure compared with SOC alone (mITT: 45.6% versus 27.9% p=0.008; mPP: 59.5% versus 35.6% p=0.002). The difference in outcome yielded an odds ratio of 2.2 (95% confidence interval (CI): 1.2, 3.9; p=0.008). Median time to closure within 12 weeks was 43 days for the FBADM group compared to 57 days for the SOC group (p=0.36). The median number of applications of FBADM to achieve closure was one. Adverse events were similar between groups and no product-related serious adverse events occurred.

CONCLUSIONS

These results indicate that in many cases a single application of FBADM in conjunction with SOC offers a safe, faster and more effective treatment of DFUs than SOC alone.

The Use of Cellular- and/or Tissue-Based Therapy for the Management of Pyoderma Gangrenosum: A Case Series and Review of the Literature

Pyoderma gangrenosum (PG) is an uncommon inflammatory neutrophilic disorder with a spectrum of clinical presentations with variable courses. Most cases are associated with an autoimmune disorder and manifest in middle-aged adults as a painful lesion that progresses to painful necrotizing ulcers of the lower extremity. Owing to its variability, clinical diagnosis remains difficult and many patients are often misdiagnosed, with resulting delay in treatment. While early immunosuppressant therapy is key to preventing progression of PG, surgical treatment has been met with criticism because of the risk of potentiating pathergy, an exaggerated skin reaction due to trauma. This article presents a case series in which 3 patients with PG lesions underwent different treatment methods, including surgical debridement and use of fetal bovine dermis (FBD). The use of FBD in conjunction with medical treatment provided pain relief and wound coverage as well as encouraged growth of granulation tissue and long-term stability. Commercial cellular and tissue-based products used to aid in accelerating PG wound closure are also reviewed.

Cryopreserved Allograft Use in Vascular Surgery

In vascular surgery, bypass procedures are standard treatments for many arterial and venous diseases. The choice of conduit for the bypass operation is fundamental in planning for the appropriate intervention for each individual patient. Although an autogenous conduit is superior, this option is not available in many patients, and prosthetic grafts have been the preferred conduit in a variety of clinical situations. However, since prosthetic graft infections are seen in all realms of vascular surgery, from arteriovenous access to aortic graft infections and lower-extremity bypass infections, cryopreserved arterial and venous allografts, which are relatively resistant to infection, have become the conduit of choice. This discussion will focus on the clinical applications of cryopreserved allografts in vascular surgery, specifically lower-extremity peripheral bypass, aortic disease, and dialysis access.

Cost Effectiveness of Fish Skin Grafts Versus Standard of Care on Wound Healing of Chronic Diabetic Foot Ulcers: A Retrospective Comparative Cohort Study

INTRODUCTION

Health care policy decision makers seek the highest quality products at the lowest cost for their patients. Cost-benefit analysis is a helpful tool and can be used together with other sources of information to ensure the most efficient use of medical resources.

OBJECTIVE

The objective of this retrospective comparative cohort study is to evaluate the cost effectiveness of fish skin therapy compared with standard of care (SOC) on chronic diabetic foot ulcers (DFUs).

METHODS

Retrospective patient data collected in a single wound care setting from 2014 to 2017 were included. In total, 59 DFUs treated with fish skin were used to calculate transition probabilities for a Markov model in which a hypothetical patient cohort treated with fish skin was compared with an identical hypothetical patient cohort treated with SOC. Cost was from the perspective of the payer, and the time horizon was set at 1 year.

RESULTS

The model indicated that fish skin treatment could result in lower costs ($11 210 vs. $15 075 per wound), more wounds healing (83.2% vs. 63.4%), fewer amputations (4.6% vs. 6.9%), and a higher quality of life (0.676 vs. 0.605 quality-adjusted life year [QALY]) than the SOC. A probabilistic sensitivity analysis, based on a Monte Carlo simulation, indicated that the fish skin treatment (on DFUs) would be 93.6% likely to be cost effective for a willingness to pay at $100 000 per QALY and 71.4% likely to be cheaper than SOC.

CONCLUSIONS

Including fish skin grafts in the SOC for DFU treatment has the potential to reduce costs while improving patient outcomes.

A dual compression system: preliminary clinical insights from the US

There is growing evidence on an interconnection between the venous and lymphatic systems in venous leg ulceration, and the possible effects of prolonged oedema and lymphatic impairment in delayed wound healing. Compression therapy is a widely accepted treatment for venous and lymphatic disorders, as it decreases recurrence rates and prolongs the interval between recurrences. Compression bandages improve venous return, increase the volume and rate of venous flow, reduce oedema and stimulate anti-inflammatory processes. The pressure at the interface (IP) of the bandage and the skin is related to the elastic recoil of the product used and its resistance to expansion. The pressure difference between the IP in the supine and standing positions is called the static stiffness index (SSI). Elastic materials provide little resistance to muscle expansion during physical activity, resulting in small pressure differences between resting and activity, with an SSI <10mmHg. Stiff, inelastic materials with a stretch of <100% resist the increase of muscle volume during physical activity, producing higher peak pressures, an SSI of >10mmHg and a greater haemodynamic benefit than elastic systems. UrgoK2 is a novel dual-layer high-compression system consisting of an inelastic (short stretch) and elastic (long stretch) bandage, resulting in sustained tolerable resting pressure and elevated working pressures over extended wear times. It is indicated for the treatment of active venous leg ulcers and the reduction of chronic venous oedema. Each bandage layer has a visual aid to enable application at the correct pressure level. Published European studies have assessed this compression system, exploring its consistency of application, tolerability and efficacy. This article presents the first reports of health professionals' clinical experience of using the compression system in the US, where it has been recently launched. Initial feedback is promising.

One-year safety, healing and amputation rates of Wagner 3-4 diabetic foot ulcers treated with cryopreserved umbilical cord (TTAX01)

An open label, multicenter 16‐week trial of cryopreserved human umbilical cord (TTAX01) was previously undertaken in 32 subjects presenting with a Wagner grade 3 or 4 diabetic foot ulcer, with 16 (50%) of these having confirmed closure following a median of one product application (previous study). All but two subjects (30/32; 94%) consented to participate in this follow‐up study to 1‐year postexposure. No restrictions were placed on treatments for open wounds. At 8‐week intervals, subjects were evaluated for adverse events (AEs) and wound status (open or closed). Average time from initial exposure to end of follow‐up was 378 days (range 343‐433), with 29 of 30 (97%) subjects completing a full year. AEs were all typical for the population under study, and none were attributed to prior exposure to TTAX01. One previously healed wound re‐opened, one previously unconfirmed closed wound remained healed, and nine new wound closures occurred, giving 25 of 29 (86.2%) healed in the ITT population. Three of the new closures followed the use of various tissue‐based products. Three subjects whose wounds were healed required subsequent minor amputations due to osteomyelitis, one of which progressed to a major amputation (1/29; 3.4%). One additional subject underwent two minor amputations prior to healing. Overall, the study found TTAX01 to be safe in long‐term follow‐up and associated with both a low rate of major amputation and a higher than expected rates of healing.

Wound Conforming Matrix Containing Purified Homogenate of Dermal Collagen Promotes Healing of Diabetic Neuropathic Foot Ulcers: Comparative Analysis Versus Standard of Care

Objective: To compare outcomes of diabetic foot ulcers (DFUs) treated with a collagen Wound Conforming Matrix (WCM) or standard of care (SOC).

Approach: WCM, a highly purified homogenate of 2.6% fibrillar bovine dermal collagen that conforms to the wound surface, was evaluated in comparison to daily saline-moistened gauze dressing changes (SOC) as part of a retrospective subset analysis of a randomized controlled trial in DFU. Following a 2-week run-in period during which patients received SOC, patients whose wounds did not reduce in area by >30% during run-in were randomly assigned to receive WCM (one or two applications) or SOC.

Results: Statistically significant acceleration of early healing rates was observed following a single application of WCM with weekly outer dressing changes compared with daily saline-moistened gauze dressing changes (SOC). Over a 4-week period, 50% of patients receiving a single application of WCM achieved ≥75% reduction in wound area compared with 13% for SOC. WCM appeared to be safe and well tolerated, with no adverse events related to treatment and no evidence of an immunologic reaction to bovine collagen.

Innovation: WCM is unique in its intimate contact with the wound bed and its ability to progress a wound toward healing with a single application.

Conclusion: WCM is a treatment modality to accelerate DFU healing rates, with the potential to reduce the likelihood of infection and other complications, and cost of care.

Fish skin grafts compared to human amnion/chorion membrane allografts: A double-blind, prospective, randomized clinical trial of acute wound healing

Chronic, nonhealing wounds consume a great deal of healthcare resources and are a major public health problem, associated with high morbidity and significant economic costs. Skin grafts are commonly used to facilitate wound closure. The grafts can come from the patient's own skin (autograft), a human donor (allograft), or from a different species (xenograft). A fish skin xenograft from cold-water fish (Atlantic cod, Gadus morhua) is a relatively recent option that shows promising preclinical and clinical results in wound healing. Chronic wounds vary greatly in etiology and nature, requiring large cohorts for effective comparison between therapeutic alternatives. In this study, we attempted to imitate the status of a freshly debrided chronic wound by creating acute full-thickness wounds, 4 mm in diameter, on healthy volunteers to compare two materials frequently used to treat chronic wounds: fish skin and dHACM. The purpose is to give an indication of the efficacy of the two therapeutic alternatives in the treatment of chronic wounds in a simple, standardized, randomized, controlled, double-blind study. All volunteers were given two identical punch biopsy wounds, one of which was treated with a fish skin graft and the other with dehydrated human amnion/chorion membrane allograft (dHACM). In the study, 170 wounds were treated (85 wounds per group). The primary endpoint was defined as time to heal (full epithelialization) by blinded assessment at days 14, 18, 21, 25, and 28. The superiority hypothesis was that the fish skin grafts would heal the wounds faster than the dHACM. To evaluate the superiority hypothesis, a mixed Cox proportional hazard model was used. Wounds treated with fish skin healed significantly faster (hazard ratio 2.37; 95% confidence interval: (1.75-3.22; p = 0.0014) compared with wounds treated with dHACM. The results show that acute biopsy wounds treated with fish skin grafts heal faster than wounds treated with dHACM.

An open-label trial of cryopreserved human umbilical cord in the treatment of complex diabetic foot ulcers complicated by osteomyelitis

Clinical trials of potential new therapies for diabetic foot ulcers rarely enroll patients whose wounds extend to muscle, fascia, or bone with clinical and radiographic evidence of underlying osteomyelitis. An open‐label, multicenter trial of cryopreserved human umbilical cord (TTAX01) was undertaken in 32 subjects presenting with such complex wounds with a mean duration of 6.1 ± 9.0 (range: 0.2–47.1) months and wound area at screening of 3.8 ± 2.9 (range: 1.0–9.6) cm². Aggressive surgical debridement at baseline resulted in 17 minor amputations and an increase in mean wound area to 7.4 ± 5.8 (range: 1.1–28.6) cm². All subjects were placed on systemic antibiotics for at least 6 weeks in conjunction with baseline application of TTAX01. Repeat applications were made at no less than 4‐week intervals over the 16‐week trial. Initial closure occurred in 18 of 32 (56%) wounds, with 16 (50%) of these having confirmed closure in 16 weeks with a median of one‐product application. Cases with biopsy confirmed osteomyelitis (n = 20) showed initial closure in 12 (60%) wounds and confirmed closure in 10 (50%) wounds. Four of the five ulcers presenting as recurrences experienced confirmed closure. Mean overall time to healing was 12.8 ± 4.3 weeks. Mean wound area reduction from baseline was 91% for all wounds. Of the 16 wounds without confirmed closure during the 16‐week treatment period, five (31.3%) achieved 99–100% wound area reduction by their final visit. The product was well tolerated. Two minor amputations occurred during the study period due to recurrent or persistent osteomyelitis; however, there were no major amputations.

Management of Non-Reconstructable Critical Limb Ischemia

At least 15% of patients with critical limb ischemia are not candidates for standard revascularization. In this day and age, with new techniques-including retrograde access to the foot-and numerous angioplasty and atherectomy techniques available, the critical limb ischemia patient can still be faced without options. Distal bypass surgery may still remain the gold standard, and likely permits the patient to have the best options for healing, but carries significant comorbidities after undergoing the procedure. There are patients who do not have targets of interest in their foot for arterial revascularization and there are patients who have very poor conduit or are very poor candidates due to their medical comorbidities. Guidelines as to who should and should not undergo surgery-or even percutaneous revascularization-are starting to become more widely accepted. We are starting to see the tide change and there is interest in this cohort of patients. There are patients with no distal target that may benefit from an arteriovenous bypass, which is regaining popularity and can be done completely endovascularly. The patient that may be a very poor candidate for intervention may benefit from arterial counterpulsation therapy and/or topical oxygen therapy (which are commercially available). They may also benefit from placental stem cell injection, which is undergoing Phase II trial assessment. We will review the current literature as it surrounds these potential therapeutic interventions for patients with significant lower extremity ischemia who do not have standard revascularization options.

PLX-PAD Cell Treatment of Critical Limb Ischaemia: Rationale and Design of the PACE Trial

BACKGROUND

Critical limb ischaemia (CLI) is a life threatening condition with a considerable risk of major amputation and death. Besides revascularisation, no treatment has been proven to reduce the risks. Therapeutic angiogenesis by gene or cell therapy has not demonstrated definitive evidence in randomised controlled trials. PLX-PAD is an "off the shelf" allogeneic placental derived, mesenchymal like cell therapy, which, in preclinical studies, has shown pro-angiogenic, anti-inflammatory, and regenerative properties. Favourable one year amputation free survival (AFS), and trends in reduction of pain scores and increase of tissue perfusion have been shown in two small, open label, phase I trials.

METHODS

The PACE study is a phase III randomised, double blind, multicentre, multinational placebo controlled, parallel group study to evaluate the efficacy, tolerability, and safety of intramuscular injections of PLX-PAD cells to treat patients with atherosclerotic CLI with minor tissue loss (Rutherford Category 5) up to the ankle level, who are unsuitable for revascularisation or carry an unfavourable risk benefit for that treatment. The study will enroll 246 patients, who after screening are randomised in a ratio of 2:1 to treatment with intramuscular injections of PLX-PAD 300 × 10⁶ cells or placebo on two occasions, eight weeks apart. The primary efficacy endpoint is time to major amputation or death (amputation free survival), which will be assessed in follow up of at least 12 months and up to 36 months.

CONCLUSIONS

Based on favourable pre-clinical and initial clinical study results, the PACE phase III randomised controlled trial will evaluate placenta derived PLX-PAD cell treatment in patients with critical limb ischaemia, with an unfavourable risk benefit for revascularisation. Clinicaltrials.gov: NCT03006770.

Managing the Diabetic Foot Ulcer: How Best Practices Fit the Real 2018 United States

Diabetes Mellitus is a serious systemic illness that has an epidemic-like increasing prevalence in the United States, as well as the rest of the world. With the increasing number of people with diabetes comes the higher incidence of diabetes-related complications. One of these known complications, diabetic foot ulcers (DFU), has an estimated lifetime incidence of 15% in diabetics. Having a DFU increases the risk of infection, amputation, and even death, which is why prompt treatment and surveillance of such ulcers is imperative. Multiple organizations and journals have recently published best practices to heal and close DFU. Despite these guidelines, it is estimated that only 50% of all diabetic foot ulcers close within one year in the United States. To further confuse this picture, many trials include postoperative wounds that behave in a very different way than chronic wounds. The management of diabetic ulcers requires an understanding of not only the pathophysiology along with a multi-modal approach involving local wound care, pressure prevention, infection control, and, in some, revascularization, but also how care is delivered in the United States presently. In this review, we hope to elucidate the current knowledge and modalities used in ulcer management and to focus on key areas and best practices to inform the clinician, both in what they should do and what they can do.

A Novel Topical Wound Therapy Delivery System

INTRODUCTION

Wound care dressings have evolved over time, from bandaging to the development of occlusive dressings to negative pressure wound therapy. A novel therapeutic delivery system dressing has been cleared by the United States Food and Drug Administration. This semi occlusive wound dressing has been developed to provide local, continuous delivery of aqueous topical agents, such as therapeutics (anesthetics, antiseptics, antibiotics, steroids, topical beta-blockers, immune modulatory agents, growth factors, and fibrinolytic agents, among others), at a rate of about ¾ mL per day, thus maintaining a hydrated environment and providing topical treatment. This type of system may be beneficial in situations where systemic therapies cannot be used, wounds are small and few, wounds may need frequent application of medication or moisture, or low and steady delivery of medications is needed.

OBJECTIVE

The authors assessed a delivery system dressing with different types of liquid medications for the management of hard-to-heal, chronic lower extremity wounds.

MATERIALS AND METHODS

Patients aged ≥ 18 and ≤ 90 years with stalled chronic wounds > 30 days' duration were selected for the use of a topical delivery system, which consists of a semi occlusive wound dressing and fluid delivery unit that can provide local application of small therapeutic quantities of medication directly to the wound.

RESULTS

Several successful cases with the use of this device are presented in which pain relief, enhancement of epithelial migration, inflammation reduction, bacterial control, and wound size reduction were achieved.

CONCLUSIONS

This delivery system dressing is an effective and safe treatment option for wounds. Advantages include reduced potential of systemic side effects, flexibility in what can be delivered, constant rate of medication delivery, and convenience.

Abstract 509: Screening for Carotid Occlusive Disease in Patients With Mild Peripheral Vascular Disease

Objectives: Peripheral vascular disease (PVD) is a systemic disorder, which can affect all territories of arteries. In order to maximize screening survey yield: we aimed to describe the association between positive lower extremity (LE) non-invasive flow studies in symptomatic patients and occult carotid occlusive disease (COD).

Methods: A retrospective chart review was performed on 420 patients who underwent carotid duplex ultrasound and non-invasive flow studies (NIFS; aka Pulse volume recordings) for evaluation of COD and LE PVD respectively. Additional clinical variables collected included age, gender, and indication for NIFS and indication for carotid duplex. The respective studies were performed within a year of each other. Statistical analysis was performed using SPSSv20 software and SAS statistical software. Univariate analysis was performed using Mann-Whitney, student t-test and receiver operating curve (ROC).

Results: 66% (266/420) of the patients were male and 43% (181/420) of patients had documented history of bruit. Patients with mild PVD (ABI between 0.81 and 1) were more likely to have clinically significant COD than patients with moderate to severe PVD (ABI < 0.8) (25% vs 16.19%, P=0.03). Therefore, severity of peripheral vascular disease did not correlate with likelihood of clinically significant COD (p>0.05). ROC analysis was performed (AUC=0.602, p=0.05). Low ABI 0.50 was found to be 92% sensitive (Se) but only 14% specific (Sp). The optimal ABI cutoff point for predicting COD was 0.95 (Se=40%,Sp 60%, Youden’s index 0.194)

Conclusion: Therefore, routine screening for COD in patients with lower extremity peripheral vascular disease is unlikely to uncover clinically significant carotid stenosis. These findings do not indicate a population of patients for which a combined prospective screening is warranted.

Extracellular Matrices (ECM) for Tissue Repair

Persistence of skin wounds due to underlying disease, bacterial contamination, and/or repeated trauma, causes a chronic condition where a functional extracellular matrix (ECM) cannot be established and the normal wound-healing cascade is unable to progress. These open chronic wounds leave the body susceptible to infection and present a major healthcare problem. To this end, a broad range of biologic ECM scaffolds have been developed that can provide other therapeutic options aside from traditional wound care approaches. These tissue engineered ECM scaffolds aim to facilitate the restoration of functional skin-like tissue by altering the chronic wound environment and facilitating cellular attachment, proliferation, and differentiation. This discussion will center on reviewing current ECM scaffolds and highlighting their properties and mechanism of action with respect to the clinical application in chronic, non-healing wounds.

A Prospective, Postmarket, Compassionate Clinical Evaluation of a Novel Acellular Fish-skin Graft Which Contains Omega-3 Fatty Acids for the Closure of Hard-to-heal Lower Extremity Chronic Ulcers

INTRODUCTION

A novel piscine acellular fish-skin graft product has 510k clearance on the US market. This product (Omega3, Kerecis, Isafjordur, Iceland) is to be used similarly to extracellular matrices (ECMs) on the market (eg, bovine and porcine) except that it contains fats, including omega-3 polyunsaturated fatty acids that have been associated with anti-inflammatory properties in many studies. While many current ECMs are effective on open wounds, studies have largely excluded application to hard-to-heal ulcers. To test this product in a real-world environment, the authors chose to look specifically at hard-to-heal ulcers based on previously defined wound and patient factors.

METHODS

The primary objective was to assess the percentage of wound closure area from baseline after 5 weekly fish-skin graft applications in 18 patients with at least 1 "hard-to-heal" criteria. Patients underwent application of the fish skin for 5 sequential weeks, followed by 3 weeks of standard of care. Wound area, skin assessments, and pain were assessed weekly.

RESULTS

A 40% decrease in wound surface area (P < 0.05) and a 48% decrease in wound depth was seen with 5 weekly applications of the fish-skin graft and secondary dressing (P < 0.05). Complete closure was seen in 3 of 18 patients by the end of the study phase.

CONCLUSION

This fish-skin product appears to provide promise as an effective wound closing adjunctive ECM. This is true when used in this compassionate setting, where many other products fail. This study lacks a control arm and an aggressive application schedule, but the investigators believe it represents real-world practice.

Use of NPWT with and without Soft Port technology in infected foot wounds undergoing partial diabetic foot amputation

OBJECTIVE

Negative pressure wound therapy (NPWT) has previously been shown to be effective in closing diabetic foot wounds that have undergone amputation over a 16-week period. For patients with plantar foot wounds, NPWT is a key therapy. An alternative NPWT with and without a novel soft, flexible port system needs to be evaluated for its comparable efficacy. Our objective was to show the non-inferiority of an alternative negative pressure system, and in a small subset, a novel foam dressing system.

METHOD

We performed a single centre prospective study of patients with diabetes undergoing open bone resection in the foot for acutely infected wounds. Wounds were treated with NPWT/soft port technology (SPT), for 112 days or until primary closure or the wound was deemed ready for delayed primary closure. Rate of closure and quality of life were analysed. A previously published cohort was used as a control.

RESULTS

Of the 30 patients initially recruited, 29 met eligibility requirements and had NPWT applied a median of 2 days postoperatively. There were seven patients (24%) who had delayed primary closure (mean=58 days) and 52% had sufficient progress to change in treatment (15/29; mean=62 days). Only one patient reached the 112-day mark without sufficient progress to be closed. The primary method of delayed primary closure was split-thickness skin graft. There was a reduction in wound area 56.3% (initial mean area=17.4cm(2) to final mean area=7.6 cm(2); p=0.001) at the end of treatment (mean=58.7 days) reduced to 4.3cm(2) a 67.2% reduction (p=0.004) at the end of study (112 days).

CONCLUSION

The alternative NPWT and the soft port technology was well tolerated and effective in the population in aggregate. There was no inferiority between the two technologies. The aggregate closure or progression to be ready for closure rate of 75% at 69 days compares very favourably with previously published data for NPWT in this population of 56% at 56 days (range: 26-92 days). Both cohorts did significantly better than previously published standard of care closure rates of 39% at 77 days.

DECLARATION OF INTEREST

J.C. Lantis is a paid consultant for Smith & Nephew, Acelity, Macrocure and Manukamed. This trial as supported by an institutional grant to St Luke's and Roosevelt Hospital sponsored by Smith & Nephew. The outcome of the trial had no bearing on the condition of the grant. No investigator holds an equity position in Smith & Nephew. C. Gendics is a paid consultant of Acelity.

Non-Operative Management of Paget-Schroetter Syndrome: A Single-Center Experience

OBJECTIVE

The preponderance of existing literature for the treatment of Paget-Schroetter syndrome (PSS) advocates clot lysis followed by thoracic outlet decompression (TOD). We postulate that long-term anticoagulation has equal outcomes to more invasive and costly surgical intervention, and review our experience with non-operative management of PSS.

METHODS

A retrospective review was conducted, examining patients between 1994-2014. Forty patients were identified with PSS, and 27 of these patients had sufficient follow-up for this analysis. Charts were reviewed for details of clinical presentation, disease course, interventions, duration of oral anticoagulation, ultrasound reports, and symptoms at long-term follow-up.

RESULTS

With a mean follow-up of 54.3 months, 23/27 patients (85%) were asymptomatic after non-operative therapy. In this cohort, 16/27 patients (59%) underwent catheter-directed thrombolysis. Average treatment course with oral anticoagulation was 8.6 months. Four patients (15%) remained symptomatic at follow-up. Two patients (7%) underwent thoracic outlet decompression at another institution, with good results. At least partial recanalization of vessels was documented in 25/27 patients (93%), although recanalization did not correlate with symptoms at long-term follow-up.

CONCLUSIONS

Based upon equivalent functional results, non-operative management appears to offer similar outcomes for some patients with PSS. We propose a patient-tailored approach to the treatment of PSS, in which patients presenting acutely undergo catheter-directed thrombolysis, followed by a 6-12 month course of oral anticoagulation. Persistent symptoms, recurrent disease, lengthy duration of symptoms prior to diagnosis, and identifiable structural abnormalities may be factors predictive of poor outcomes after non-operative intervention.

Recent Advancements in Infrapopliteal Revascularization

Infrapopliteal arterial disease is a challenging problem to treat. A shift toward an endovascular treatment approach over surgical bypass has occurred over recent years. Although current standard percutaneous transluminal balloon and bare metal stents are employed, their durability and outcomes are questionable. A number of endovascular advancements in the treatment of infrapopliteal (IP) arterial disease have recently been made. We review the recent literature for new atherectomy, stent, and balloon technologies.

Single-use negative pressure wound therapy for the treatment of chronic lower leg wounds

OBJECTIVE

Lower extremity ulcers are caused by multiple disease processes and contribute to a high level of patient morbidity and health-care spending in the US. Negative pressure wound therapy (NPWT) has been used extensively for wound bed preparation. Our aim is to assess the efficacy of an affordable, low-profile single-use NPWT (single-use NPWT) on chronic lower extremity wounds that would usually be deemed too small or superficial for traditional NPWT.

METHOD

A prospective pilot study was undertaken in which chronic lower extremity wounds were treated with single-use NPWT. Study visits were biweekly for primary contact dressing change, with the negative pressure unit being changed weekly. Biweekly assessments were made of wound appearance, surface area, depth, exudate amount, peri-wound skin integrity, and signs of clinical infection. Digital photography was performed at each visit. Patients with venous leg ulcers (VLUs) were treated with a 3-layer wrap. Diabetic foot ulcers (DFUs) were treated with off-loading shoes.

RESULTS

The study recruited 12 patients. There were 13 wounds in total; two DFUs, two traumatic/postoperative/pressure ulcers, and nine VLUs. DFUs decreased in size on average 62%, VLUs by 32%, and traumatic/postoperative/pressure wounds by 74%. The wound appearance became more favourable and the wound depth decreased with the use of single-use NPWT.

CONCLUSION

Single-use NPWT is a suitable therapy for chronic lower extremity wounds. Single-use NPWT led to a decrease in wound size and depth, an increased amount of granulation tissue, and a high level of patient satisfaction, with a low complication rate.

DECLARATION OF INTEREST

This study was funded by Smith & Nephew, Hull, UK. JC Lantis is a paid consultant for KCI, Smith & Nephew, Healthpoint and Macrocure. C Gendics is a paid consultant for Macrocure and ManukaMed.

Optimizing Wound Bed Preparation With Collagenase Enzymatic Debridement

Difficult-to-heal and chronic wounds affect tens of millions of people worldwide. In the U.S. alone, the direct cost for their treatment exceeds $25 billion. Yet despite advances in wound research and treatment that have markedly improved patient care, wound healing is often delayed for weeks or months. For venous and diabetic ulcers, complete wound closure is achieved in as few as 25%-50% of chronic or hard-to-heal wounds. Wound bed preparation and the consistent application of appropriate and effective debridement techniques are recommended for the optimized treatment of chronic wounds. The TIME paradigm (Tissue, Inflammation/infection, Moisture balance and Edge of wound) provides a model to remove barriers to healing and optimize the healing process. While we often think of debridement as an episodic event that occurs in specific care giver/patient interface. There is the possibility of a maintenance debridement in which the chronic application of a medication can assist in both the macroscopic and microscopic debridement of a wound. We review the various debridement therapies available to clinicians in the United States, and explore the characteristics and capabilities of clostridial collagenase ointment (CCO), a type of enzymatic debridement, that potentially allows for epithelialization while debriding. It appears that in the case of CCO it may exert this influences by removal of the necrotic plug while promoting granulation and sustaining epithelialization. It is also easily combined with other methods of debridement, is selective to necrotic tissue, and has been safely used in various populations. We review the body of evidence has indicated that this concept of maintenance debridement, especially when combined episodic debridement may add a cost an efficacious, safe and cost-effective choice for debridement of cutaneous ulcers and burn wounds and it will likely play an expanding role in all phases of wound bed preparation.

Negative Pressure Wound Therapy With Instillation (NPWTi) Better Reduces Post-debridement Bioburden in Chronically Infected Lower Extremity Wounds Than NPWT Alone

OBJECTIVE

An overabundance of bacteria in the chronic wound plays a significant role in the decreased ability for primary closure. One means of decreasing the bioburden in a wound is to operatively debride the wound for wound bed optimization prior to application of other therapy, such as Negative Pressure Wound Therapy (NPWT). We undertook a prospective pilot study to assess the efficacy of wound bed preparation for a standard algorithm (sharp surgical debridement followed by NPWT) versus one employing sharp surgical debridement followed by Negative Pressure Wound Therapy with Instillation (NPWTi).

METHODS

Thirteen patients, corresponding to 16 chronic lower leg and foot wounds were taken to the operating room for debridement. The patients were sequentially enrolled in 2 treatment groups: the first receiving treatment with operative debridement followed by 1 week of NPWT with the instillation of quarter strength bleach solution; the other receiving a standard algorithm consisting of operative debridement and 1 week of NPWT. Quantitative cultures were taken pre-operatively after sterile preparation and draping of the wound site (POD # 0, pre-op), post-operatively once debridement was completed (POD # 0, post-op), and on post-operative day 7 after operative debridement (POD # 7, post-op).

RESULTS

After operative debridement (post-operative day 0) there was a mean of 3 (±1) types of bacteria per wound. The mean CFU/gram tissue culture was statistically greater - 3.7 × 10(6) (±4 × 10(6)) in the NPWTi group, while in the standard group (NPWT) the mean was 1.8 × 10(6) (±2.36 × 10(6)) CFU/gram tissue culture (p = 0.016); at the end of therapy there was no statistical difference between the two groups (p = 0.44). Wounds treated with NPWTi had a mean of 2.6 × 10(5) (±3 × 10(5)) CFU/gram of tissue culture while wounds treated with NPWT had a mean of 2.79 × 10(6) (±3.18 × 10(6)) CFU/gram of tissue culture (p = 0.43). The mean absolute reduction in bacteria for the NPWTi group was 10.6 × 10(6) bacteria per gram of tissue while there was a mean absolute increase in bacteria for the NPWT group of 28.7 × 10(6) bacteria per gram of tissue, therefore there was a statistically significant reduction in the absolute bioburden in those wounds treated with NPWTi (p = 0.016).

CONCLUSION

It has long been realized that NPWT does not make its greatest impact by bioburden reduction. Other work has demonstrated that debridement alone does not reduce wound bioburden by more than 1 Log. Wounds treated with NPWTi (in this case with quarter strength bleach instillation solution) had a statistically significant reduction in bioburden, while wounds treated with NPWT had an increase in bioburden over the 7 days.

A prospective, non comparative, multicenter study to investigate the effect of cadexomer iodine on bioburden load and other wound characteristics in diabetic foot ulcers

Few studies regarding wound treatment with topical antimicrobials evaluate change in the bacterial bioburden of the wound with treatment. This study sought out to determine the in vivo effect of cadexomer iodine antibacterial dressing on diabetic foot ulcers (DFUs) that were infected or achieved a critical level of colonisation, looking specifically at wound progression in relation to bioburden. Fifteen patients corresponding to 16 total DFUs met criteria of displaying clinical signs of infection or critical colonisation and were suitable for a topical antibacterial dressing. They underwent weekly treatment for 6 weeks. Cultures were taken at week 0, 3 and 6 as appropriate. At week 6 median log10 bacterial count reduction of 1.0 was observed from baseline (p = 0·025). At week 3- a median log10 bacterial count reduction of 0.3 was observed from baseline (p = 0·049). Over the study period there was a 53.6% median reduction of the wound surface area. There were no patients that completely healed their ulcer over the 6 week study period. There was a statistically significant median reduction in the bacterial load over the 6 week period (p = 0·025) as well as 3 weeks (p = 0·049). This was accompanied by a median reduction of 53.6% in ulcer surface area and 50% in ulcer depth from baseline to final.

In-vivo Pulse Wave Imaging for arterial stiffness measurement under normal and pathological conditions

Numerous studies have identified arterial stiffening as a strong indicator of cardiovascular pathologies such as hypertension and abdominal aortic aneurysm (AAA). Pulse Wave Imaging (PWI) is a novel, noninvasive ultrasound-based method to quantify regional arterial stiffness by measuring the velocity of the pulse wave that propagates along arterial walls after each left ventricular contraction. The PWI method employs 1D cross-correlation speckle tracking to compute axial incremental displacements, then tracks the position of the displacement wave in the anterior wall of the vessel to estimate pulse wave velocity (PWV). PWI has been validated on straight tube aortic phantoms and aortas of healthy humans as well as normal and AAA murine models. This paper presents and compares preliminary PWI results from normal, hypertensive, and AAA human subjects. PWV was computed in select cases from each subject category. The measured PWV values in hypertensive (N = 5) and AAA (N = 2) subjects were found to be significantly higher than in normal subjects (N = 8). In all subjects, the spatio-temporal profile and waveform morphologies of the pulse wave were generated from the displacement data for visualization and qualitative evaluation of the pulse wave propagation. While the waveforms were found to maintain roughly the same shape in normal subjects, those in the AAA and most hypertensive cases changed drastically along the imaged aortic segment, suggesting non-uniform wall mechanical properties.

Multimodal therapy as an algorithm to limb salvage in diabetic patients with large heel ulcers

In many series of diabetic foot ulcer care, heel ulcers greater than 4 cm across have been identified as an independent predictor of limb loss. Therefore, we set out to pursue the most aggressive limb salvage algorithm in patients with heel ulcers greater than 4 cm in diameter. Over 5 years, we identified 21 patients, 39-84 years of age, all with diabetes mellitus, with heel ulcers greater than 4 cm in diameter and had magnetic resonance imaging or bone scan evidence of osteomyelitis. Seven of the 21 patients had end-stage renal disease defined as being haemodialysis dependent. All patients had ankle brachial indices <0·4 or monophasic pulse volume recordings. All patients underwent distal bypass surgery with vein. After adequate perfusion was obtained, all patients underwent partial calcanectomy and intra-operative negative pressure wound therapy (NPWT) placement. This was followed by treatment with recombinant platelet-derived growth factor (PDGF). One patient underwent amputation during the healing process secondary to ongoing sepsis. Twenty of 21 patients healed acutely (within 6 months). Three of 20 patients went on to subsequent below knee amputation within 12 months of healing primarily. At 2 years, 12 of 21 (57%) were ambulating independently, 1 of 21 was dead, 4 of 21 had undergone amputation, 4 (19%) had limbs that were intact but were not ambulating. A total limb salvage rate of 76% at 2 years mirrored the secondary patency rates, with 100% follow up. Heel ulcers require multimodality therapy if they are going to have any chance to heal. We believe the algorithm presented allows for the required revascularisation and a modulation of the heel ulcer microenvironment by augmenting the microcirculation through NPWT, and improving the proliferative capacity with PDGF.

The effect of percutaneous intervention on wound healing in patients with mixed arterial venous disease

BACKGROUND

Open venous ulcers in patients with combined arterial and venous insufficiency are notoriously hard to treat. Patients with an ankle-brachial index (ABI) of 0.5-0.8 have been shown to heal poorly. Because adequate compression therapy is contraindicated in patients with an ABI of <0.7, we decided to undertake an aggressive approach of percutaneous revascularization for these patients.

METHODS

A total of 27 patients with clinical and duplex scan evidence of chronic venous insufficiency, active leg ulcers, and impaired arterial perfusion (ABI: <0.7) were treated using a protocol that required performing percutaneous revascularization before ambulatory compression therapy. The patients were followed at 2-week intervals (average) before and after revascularization. Wound measurements and time to complete closure were also recorded.

RESULTS

The results of the patients were compared with their own previous wound healing trajectories. Additionally, their healing rate was compared with previously published rates of impaired arterial perfusion venous wound closure; 25% closure at 10 weeks, 50% at 19 weeks. At enrollment, the average ABI and wound sizes were 0.56 and 12 cm(2), respectively. On average, the wounds had remained open for 17 weeks. After the intervention, the average ABI was 0.97, average time taken to complete closure was 10 weeks, closure rate at 10 weeks was 75%, and absolute closure rate was 100%.

CONCLUSION

Although previous studies have shown that closure of mixed arterial venous ulcers occur without arterial intervention, attaining a near normal ABI allows for timelier wound closure. Therefore, we advocate an aggressive approach of percutaneous revascularization in this population.

Vacuum-assisted closure instill as a method of sterilizing massive venous stasis wounds prior to split thickness skin graft placement

Patients with massive venous stasis ulcers that have very high bacterial burdens represent some of the most difficult wounds to manage. The vacuum-assisted closure (VAC) device is known to optimise wound bed preparation; however, these patients have too high a bacterial burden for simple VAC application to facilitate this function. We present the application of the VAC with instillation of dilute Dakins solution as a way of bacterial eradication in these patients. Five patients with venous stasis ulcers greater than 200 cm(2) that were colonised with greater than 10(5) bacteria were treated with the VAC instill for 10 days with 12.5% Dakins solution, instilled for 10 minutes every hour. Two patients had multi-drug-resistant pseudomonas, three with MRSA. All the five had negative quantitative cultures, prior to split thickness skin graft with 100% take and complete healing at 1 year. Adequate delivery of bactericidal agents to the infected tissue can be very difficult, especially while promoting tissue growth. By providing a single delivery system for a bactericidal agent for a short period of time followed by a growth stimulating therapy, the VAC instill provides a unique combination that appears to maximise wound bed preparation.

Tibial Angioplasty as an Alternative Strategy in Patients with Limb-Threatening Ischemia

The purpose of this study was to assess the technical feasibility and early outcome of tibial angioplasty for a subset of patients with limb-threatening ischemia who were not candidates for bypass grafting. A retrospective analysis was conducted of 19 patients (7 male, 12 female) who underwent crural angioplasty for limb-threatening ischemia using 0.018- or 0.014 inch-based systems. Contraindications to bypass were insufficient conduit in 7 patients and severe comorbid illness in 12. Concurrent treatment of inflow lesions was performed in 12 of 20 limbs via either angioplasty alone (5) or combined with stenting (12). Outcome measures were ankle-brachial indices (ABI), relief of rest pain, and healing or healed wounds. Twenty-three vessels were treated, including 14 tibial occlusions and 9 stenoses. The average length of diseased segment was 11 cm (range, 3-25 cm). Thirteen of 14 occlusions were treated with subintimal recanalization, the remainder with laser recanalization. Technical success was achieved in 22 of 23 treated vessels. Mean preoperative ABI was 0.53 and mean postoperative ABI was 0.85. Palpable pulses were present in 11 of 20 limbs (55%). There was one perioperative mortality (5.2%). Mean follow-up was 3 months. Three failures occurred requiring amputation (15.8%). The remaining 16 patients were improved with healing (8) or healed (4) wounds and relief of rest pain (4). These results indicate that technical success may be achieved with outflow lesion angioplasty in the majority of patients encountered. The durability of this method of therapy is unknown, and our length of follow-up is not sufficient to answer this question. However, an attempt at angioplasty appears justified before primary amputation and before surgical bypass in those patients at high risk for intervention.

Infrainguinal bypass grafting in patients with end-stage renal disease: improving outcomes?

OBJECTIVE

This study was undertaken to examine recent trends in the outcomes of patients with end-stage renal disease (ESRD) undergoing infrainguinal bypass grafting (IBG) with autogenous vein.

METHODS

A retrospective analysis of all IBGs performed on patients with ESRD at a single tertiary care institution during the interval 1993 to 1999 was undertaken. The comparison groups consisted of concurrent series of patients with elevated creatinine (creatinine level > 1.2 mg/dL) and patients with normal renal function undergoing IBG. Procedural variables, angiographic runoff scores, and extent of tissue necrosis at presentation were correlated with outcome. Categoric parameters were compared with chi(2) analysis; rates were computed with life-table analysis.

RESULTS

Of an overall cohort of 622 IBGs performed during this interval, 78 IBGs (12.5%) were performed on 60 patients with ESRD, with a perioperative mortality rate of 1.3% that was comparable to controls. All reconstructions in the ESRD cohort were for limb salvage indications. Four-year survival, primary, assisted primary, and secondary patency rates for the ESRD group were 51% +/- 9%, 60% +/- 11%, 86% +/- 5%, and 86% +/- 5%, respectively; these were not statistically different from the control groups. Limb salvage in the ESRD group was 77% +/- 6% at 4 years and was significantly less then either the elevated creatinine (92% +/- 4%; P <.02) or the normal renal function group (90% +/- 2%: P <.02). Of 16 amputations in the ESRD group, nine were performed in limbs with patent grafts. The only absolute predictor of limb loss despite a patent graft was the presence of a heel ulcer more than 4 cm in diameter. Age, runoff score of the International Society for Cardiovascular Surgery/Society for Vascular Surgery, isolated tibial bypass graft, and location of distal anastomosis were not predictive of hemodynamic failure.

CONCLUSIONS

Patients with ESRD constitute an increasing proportion of patients undergoing IBG in a tertiary care setting. Four-year survival, perioperative mortality, and graft patency rates are similar to patients with normal renal function and support an aggressive approach to this population. Major limb amputation despite a patent graft remains a problem of unique frequency in patients with ESRD. Adequate predictors of hemodynamic failure of IBG in this group do not exist, although a heel ulcer more than 4 cm may indicate an unsalvageable foot.

A comparison of collagen and PTFE patch repair in a rabbit model of congenital diaphragmatic hernia

The use of prosthetic material in severe cases of congenital diaphragmatic hernia is complicated by infection, bowel adhesion, and patch dehiscence. We hypothesized that a bioprosthetic collagen patch would reduce these complications and be remodeled into autogenous tissue over a short period of time. Thirty-two New Zealand White rabbits had two 2 x 2-cm left diaphragmatic defects created. One of these defects was repaired with a collagen bioprosthetic patch (n = 20) and the other with a polytetrafluoroethylene (PTFE) patch (n = 20). Members of a control group (n = 12) had their defects closed primarily. The animals were then placed in either a 6- or 12-week survival cohort. At necrosectomy the repairs were assessed histologically, graded for adhesion formation, and tensiometrically tested. The PTFE patch was noted to have a significantly higher average adhesion grade than the collagen patch. The tensile strength of the two repair methods was statistically equivalent at both time intervals. On histologic examination the collagen patches were surrounded by an increased number of macrophages and fibroblasts. The PTFE patch exhibited no neovascularization or fibroblast deposition at the periphery, but had a much greater surrounding inflammatory response. Thus, there was evidence of early remodeling of the collagen with no increase in the amount of adhesions or loss of strength when compared to the PTFE, while the PTFE patches exhibited a more severe grade of adhesions.