Low-frequency ultrasound (20-40 kHz) as an adjunctive therapy for chronic wound healing: a systematic review of the literature and meta-analysis of eight randomized controlled trials

Static magnetic field enhances the bone remodelling capacity of human demineralized bone matrix in a rat animal model of cranial bone defects

The regeneration of bone defects that exceed 2 cm is a challenge for the human body, necessitating interventional therapies. Demineralized bone matrices (DBM) derived from biological tissues have been employed for bone regeneration and possess notable osteoinductive and osteoconductive characteristics. Nevertheless, their efficiency in regenerating critically sized injuries is limited, and therefore additional signaling cues are required. Thanks to the piezoelectric properties of the bone, external physical stimulation is shown to accelerate tissue healing. We have implanted human DBM in critically sized cranial bone defects in rat animal models and exposed them to an external magnetic field (1 T) to enhance endogenous bone formation. Our in vitro experiments showed the superior cytocompatibility of DBM compared to cell culture plates. Furthermore, alkaline phosphatase activity after 14 days and Alizarin red staining at 28 days demonstrated differentiation of rat bone marrow mesenchymal stem cells into bone lineage on DBM. Computer tomography images together with histological analyses showed that implanting DBM in the injured rats significantly enhanced bone regeneration. Notably, combining DBM transplantation with a 2 h daily exposure to a 1 T magnetic field for 2 weeks (day 7 to 21 post-surgery) significantly improved bone regeneration compared to DBM transplantation alone. This research indicates that utilizing external magnetic stimulation significantly enhances the potential of bone allografts to regenerate critically sized bone defects.

Innervation of an Ultrasound-Mediated PVDF-TrFE Scaffold for Skin-Tissue Engineering

In this work, electrospun polyvinylidene-trifluoroethylene (PVDF-TrFE) was utilized for its biocompatibility, mechanics, and piezoelectric properties to promote Schwann cell (SC) elongation and sensory neuron (SN) extension. PVDF-TrFE electrospun scaffolds were characterized over a variety of electrospinning parameters (1, 2, and 3 h aligned and unaligned electrospun fibers) to determine ideal thickness, porosity, and tensile strength for use as an engineered skin tissue. PVDF-TrFE was electrically activated through mechanical deformation using low-intensity pulsed ultrasound (LIPUS) waves as a non-invasive means to trigger piezoelectric properties of the scaffold and deliver electric potential to cells. Using this therapeutic modality, neurite integration in tissue-engineered skin substitutes (TESSs) was quantified including neurite alignment, elongation, and vertical perforation into PVDF-TrFE scaffolds. Results show LIPUS stimulation promoted cell alignment on aligned scaffolds. Further, stimulation significantly increased SC elongation and SN extension separately and in coculture on aligned scaffolds but significantly decreased elongation and extension on unaligned scaffolds. This was also seen in cell perforation depth analysis into scaffolds which indicated LIPUS enhanced perforation of SCs, SNs, and cocultures on scaffolds. Taken together, this work demonstrates the immense potential for non-invasive electric stimulation of an in vitro tissue-engineered-skin model.

Biodegradable piezoelectric skin-wound scaffold

Electrical stimulation (ES) induces wound healing and skin regeneration. Combining ES with the tissue-engineering approach, which relies on biomaterials to construct a replacement tissue graft, could offer a self-stimulated scaffold to heal skin-wounds without using potentially toxic growth factors and exogenous cells. Unfortunately, current ES technologies are either ineffective (external stimulations) or unsafe (implanted electrical devices using toxic batteries). Hence, we propose a novel wound-healing strategy that integrates ES with tissue engineering techniques by utilizing a biodegradable self-charged piezoelectric PLLA (Poly (l-lactic acid)) nanofiber matrix. This unique, safe, and stable piezoelectric scaffold can be activated by an external ultrasound (US) to produce well-controlled surface-charges with different polarities, thus serving multiple functions to suppress bacterial growth (negative surface charge) and promote skin regeneration (positive surface charge) at the same time. We demonstrate that the scaffold activated by low intensity/low frequency US can facilitate the proliferation of fibroblast/epithelial cells, enhance expression of genes (collagen I, III, and fibronectin) typical for the wound healing process, and suppress the growth of S. aureus and P. aeruginosa bacteria in vitro simultaneously. This approach induces rapid skin regeneration in a critical-sized skin wound mouse model in vivo. The piezoelectric PLLA skin scaffold thus assumes the role of a multi-tasking, biodegradable, battery-free electrical stimulator which is important for skin-wound healing and bacterial infection prevention simultaneuosly.

A Novel Wound Therapy Modality: Autologous Wound Edge Dotted Full-Thickness Skin Grafting Improving Diabetic Foot Ulcer Healing

Aim

To explore the therapeutic efficacy of autologous wound edge-dotted full-thickness skin grafting in improving diabetic foot ulcer healing.

Methods

Sixty-three patients were divided into three groups: conventional wound therapy (CWT) (n = 23), platelet-rich plasma (PRP) (n = 20), and graft (n = 20). All participants were followed up for 12 weeks. The therapeutic efficacy of the three different wound treatment modalities was analyzed.

Results

After follow-up, 37 (58.7%) patients showed complete wound re-epithelialization, of which 10 (43.5%) occurred in the CWT group, 14 (70.0%) in the PRP group, and 13 (65.0%) in the graft group. Multivariate Cox analysis showed that the independent predictive factors for ulcer healing were different treatment modalities (graft: HR = 3.214, 95% CI=1.300-7.945, P < 0.05; platelet-rich plasma: HR = 3.075, 95% CI=1.320-7.161, P < 0.01), ABI (HR = 9.917, 95% CI=2.675-36.760, P < 0.01), and TcPO2 (HR = 1.040; 95% CI=1.005-1.076; P < 0.05). Stratified analysis showed that higher ABI in graft group or PRP group had higher wound healing rate (graft group: HR = 3.748, 95% CI=1.210-11.607, P < 0.05; PRP group: HR = 5.029, 95% CI=1.743-14.509, P < 0.05); higher TcPO2 in the graft group had higher wound healing rate (HR = 15.805, 95% CI=4.414-56.594, P < 0.01). Additionally, the wound healing time (P < 0.0167) and cumulative healing rate (P < 0.05) in both the PRP group and graft group were more advantageous. The graft group promotes wound re-epithelialization earlier and faster than in the CWT group and PRP group (P < 0.05). Meanwhile, the graft group had lower medical costs (P < 0.0167).

Conclusion

Autologous wound edge dotted full-thickness skin grafting has a higher cost-performance ratio than traditional diabetic foot ulcer wound care and is worthy of further clinical application.

Biomaterials releasing drug responsively to promote wound healing via regulation of pathological microenvironment

Wound healing is characterized by complex, orchestrated, spatiotemporal dynamic processes. Recent findings demonstrated suitable local microenvironments were necessities for wound healing. Wound microenvironments include various biological, biochemical and physical factors, which are produced and regulated by endogenous biomediators, exogenous drugs, and external environment. Successful drug delivery to wound is complicated, and need to overcome the destroyed blood supply, persistent inflammation and enzymes, spatiotemporal requirements of special supplements, and easy deactivation of drugs. Triggered by various factors from wound microenvironment itself or external elements, stimuli-responsive biomaterials have tremendous advantages of precise drug delivery and release. Here, we discuss recent advances of stimuli-responsive biomaterials to regulate local microenvironments during wound healing, emphasizing on the design and application of different biomaterials which respond to wound biological/biochemical microenvironments (ROS, pH, enzymes, glucose and glutathione), physical microenvironments (mechanical force, temperature, light, ultrasound, magnetic and electric field), and the combination modes. Moreover, several novel promising drug carriers (microbiota, metal-organic frameworks and microneedles) are also discussed.

Debridement of Diabetic Foot Ulcers

Diabetic foot ulcerations have devastating complications, including amputations, poor quality of life, and life-threatening infections. Diabetic wounds can be protracted, take significant time to heal, and can recur after healing. They are costly consuming health care resources. These consequences have serious public health and clinical implications. Debridement is often used as a standard of care. Debridement consists of both nonmechanical (autolytic, enzymatic) and mechanical methods (sharp/surgical, wet to dry debridement, aqueous high-pressure lavage, ultrasound, and biosurgery/maggot debridement therapy). It is used to remove nonviable tissue, to facilitate wound healing, and help prevent these serious outcomes. What are the various forms and rationale behind debridement? This article comprehensively reviews cutting-edge methods and the science behind debridement and diabetic foot ulcers.

The efficacy of low-frequency ultrasound as an added treatment for chronic wounds: A meta-analysis

We performed a meta-analysis to evaluate the effect of low-frequency ultrasound as an added treatment for chronic wounds. A systematic literature search up to May 2022 was performed and 838 subjects with chronic wounds at the baseline of the studies; 412 of them were using the low-frequency ultrasound (225 low-frequency high-intensity contact ultrasound for diabetic foot wound ulcers, and 187 low-frequency low-intensity non-contact ultrasound for a venous leg wound ulcers), and 426 were using standard care (233 sharp debridements for diabetic foot wound ulcers and 193 sham treatments for venous leg wound ulcers). Odds ratio (OR), and mean difference (MD) with 95% confidence intervals (CIs) were calculated to assess the effect of low-frequency ultrasound as an added treatment for chronic wounds using the dichotomous, and contentious methods with a random or fixed-effect model. The low-frequency high-intensity contact ultrasound for diabetic foot wound ulcers had significantly lower non-healed diabetic foot wound ulcers at ≥3 months (OR, 0.37; 95% CI, 0.24-0.56, P < .001), a higher percentage of diabetic foot wound ulcers area reduction (MD, 17.18; 95% CI, 6.62-27.85, P = .002) compared with sharp debridement for diabetic foot wound ulcers. The low-frequency low-intensity non-contact ultrasound for a venous leg wound ulcers had a significantly lower non-healed venous leg wound ulcers at ≥3 months (OR, 0.31; 95% CI, 0.15-0.62, P = .001), and higher percentage venous leg wound ulcers area reduction (MD, 18.96; 95% CI, 2.36-35.57, P = .03) compared with sham treatments for a venous leg wound ulcers. The low-frequency ultrasound as an added treatment for diabetic foot wound ulcers and venous leg wound ulcers had significantly lower non-healed chronic wound ulcers at ≥3 months, a higher percentage of chronic wound ulcers area reduction compared with standard care. The analysis of outcomes should be with caution because of the low sample size of all the 17 studies in the meta-analysis and a low number of studies in certain comparisons.

Quantitative Analysis of Acoustic Pressure for Sonophoresis and Its Effect on Transdermal Penetration

Ultrasound facilitates the penetration of macromolecular compounds through the skin and offers a promising non-invasive technique for transdermal delivery. However, technical difficulties in quantifying ultrasound-related parameters have restricted further analysis of the sonophoresis mechanism. In this study, we devise a bolt-clamped Langevin transducer-based sonophoresis device that enables us to measure with a thin lead zirconate titanate (PZT) sensor. One-dimensional acoustic theory accounting for wave interaction at the skin interface indicates that the acoustic pressure and cavitation onset on the skin during sonophoresis are sensitive to the subcutaneous support, meaning that there is a strong need to perform the pressure measurement in an experimental environment replacing the human body. From a series of the experiments with our new device, the transdermal penetration of polystyrene, silica and gold nanoparticles is found to depend on the size and material of the particles, as well as the hardness of the subcutaneous support material. We speculate from the acoustic pressure measurement that the particles' penetration results from the mechanical action of cavitation.

Debridement of diabetic foot ulcers: public health and clinical implications – a systematic review, meta-analysis, and meta-regression

Background

Diabetic foot ulceration (DFU) has devastating complications and a lifetime occurrence of 15%–34%. Debridement of DFU is regarded as an intervention that accelerates ulcer healing and may reduce complications including amputations, infections, and poor quality of life (QoL), which have serious public health and clinical implications. A systematic review (SR) of SRs and of randomized controlled trials (RCTs) with meta-analyses (MAs) on debridement of DFU that synthesizes all human experimental evidence is warranted.

Objectives

Are debridement methods in DFU beneficial over other forms and standard gauze dressings (control condition) in these outcomes?

Study eligibility criteria

All SRs/MAs/RCTs comparing debridement methods for DFU with alternative methods of debridement and with control.

Data sources

Cochrane Wounds Group Specialized Register, Cochrane Central Register of Controlled Trials (Cochrane Library), Ovid MEDLINE, PubMed, EMBASE, EBSCO, CINAHL, and Web of Science.

Participants and interventions

Adults with type 1/2 diabetes with DFU and any debridement method compared with alternative debridement methods or control.

Main Outcomes

Amputation rates, wound infections, QoL, proportion of ulcers healed, time to complete healing, ulcer recurrence, and treatment cost.

Study selection and analysis

Data extraction/synthesis by two independent reviewers pooled using a random-effects model with sensitivity analysis.

Results

10 SRs were retrieved and reported qualitatively. Six SRs included MAs. This SR included 30 studies, with 2654 participants, using 19 debridement combinations. The debridement methods were compared with findings pooled into MAs. Meta-regression (MR) did not identify significant predictors/moderators of outcomes.

Limitations

The studies may have been under-powered. The inclusion/exclusion criteria varied and the increased risk of bias contributed to low-quality evidence.

Discussion/Conclusion

Weak evidence exists that debridement methods are superior to other forms of debridement or control in DFU.

Implications

Researchers should follow standardized reporting guidelines (Consolidated Standards of Reporting Trials). Clinicians/investigators could use the findings from this SR/MA/MR in guiding patient-individualized decision making and designing future RCTs.

Ultrasound-Assisted Wound (UAW) Debridement in the Treatment of Diabetic Foot Ulcer: A Systematic Review and Meta-Analysis

A systematic review and meta-analysis were carried out to investigate the effect of ultrasound-assisted wound (UAW) debridement in patients with diabetic foot ulcers (DFUs). All selected studies were evaluated using the Cochrane risk of bias tool to assess the risk of bias for randomized controlled trials. PubMed and Web of Science were searched in October 2021 to find randomized clinical trials (RCT) assessing the effect of UAW debridement on DFUs. RevMan v5.4. was used to analyze the data with the Mantel-Haenszel method for dichotomous outcomes. A total of 8 RCT met our inclusion criteria, with 263 participants. Concerning the healing rate comparing UAW versus the control group, a meta-analysis estimated the pooled OR at 2.22 (95% CI 0.96-5.11, p = 0.06), favoring UAW debridement, with low heterogeneity (x² = 7.47, df = 5, p = 0.19, I² = 33%). Time to healing was similar in both groups: UAW group (14.25 ± 10.10 weeks) versus the control group (13.38 ± 1.99 weeks, p = 0.87). Wound area reduction was greater in the UAW debridement group (74.58% ± 19.21%) than in the control group (56.86% ± 25.09%), although no significant differences were observed between them (p = 0.24). UAW debridement showed higher healing rates, a greater percentage of wound area reduction, and similar healing times when compared with placebo (sham device) and standard of care in patients with DFUs, although no statistically significant differences were observed between groups.

Novel Diagnostic Technologies and Therapeutic Approaches Targeting Chronic Wound Biofilms and Microbiota

Purpose of Review

To provide an up-to-date overview of recent developments in diagnostic methods and therapeutic approaches for chronic wound biofilms and pathogenic microbiota.

Recent Findings

Biofilm infections are one of the major contributors to impaired wound healing in chronic wounds, including diabetic foot ulcers, venous leg ulcers, pressure ulcers, and nonhealing surgical wounds. As an organized microenvironment commonly including multiple microbial species, biofilms develop and persist through methods that allow evasion from host immune response and antimicrobial treatments. Suppression and reduction of biofilm infection have been demonstrated to improve wound healing outcomes. However, chronic wound biofilms are a challenge to treat due to limited methods for accurate, accessible clinical identification and the biofilm's protective properties against therapeutic agents. Here we review recent approaches towards visual markers for less invasive, enhanced biofilm detection in the clinical setting. We outline progress in wound care treatments including investigation of their antibiofilm effects, such as with hydrosurgical and ultrasound debridement, negative pressure wound therapy with instillation, antimicrobial peptides, nanoparticles and nanocarriers, electroceutical dressings, and phage therapy.

Summary

Current evidence for biofilm-targeted treatments has been primarily conducted in preclinical studies, with limited clinical investigation for many therapies. Improved identification, monitoring, and treatment of biofilms require expansion of point-of-care visualization methods and increased evaluation of antibiofilm therapies in robust clinical trials.

Advances in Biological Application of and Research on Low-Frequency Ultrasound

In recent years, the in-depth study of low-frequency sonophoresis (LFS) has greatly elucidated its biological effects in various therapeutic applications, including drug delivery, enhanced healing, thrombolytic technology, anti-inflammatory effects and tumor treatment. Specifically, numerous studies have reported its use in drug delivery and synergistic antitumor activity, indicating a new treatment direction for cancer. However, there are significant gaps in the understanding of LFS in terms of frequency and sound intensity safety; these issues are becoming increasingly important in understanding the biological effects of LFS ultrasound. This article reviews the treatment mechanism and current applications of LFS technology and discusses and summarizes its safety and application prospects.

Ultrasonic-assisted wound debridement: report from a closed panel meeting

Mechanical debridement can be considered as an alternative to surgical debridement if surgery is not available, or is considered impractical or too high risk. One form of selective mechanical debridement is ultrasonic-assisted wound (UAW) debridement. As the published evidence on this is limited, a closed international expert meeting was held to review the existing evidence base on it, present preliminary findings of research currently in progress and discuss individual cases selected from the clinical experts' own practice. The panel also explored the potential barriers to the implementation of UAW debridement and how these might be addressed. It concluded there is sufficient evidence that UAW debridement is an effective method of cleansing and debriding almost all hard-to-heal wounds. Patients who are most likely to benefit from it are not medically stable, on anticoagulants, unable to visit a hospital for wound treatment, and/or have wounds with a poor vascular supply or are close to critical structures. The panel also observed that UAW debridement can be used to prepare the wound for negative pressure wound therapy (NPWT) or as an adjunctive to it. Given the potential to experience pain during the procedure, the panel considered that patients will benefit from topical analgesia. The panel noted that health professionals, patients and visitors must be protected from the aerosolisation associated with UAW, to reduce risk of cross-contamination.

Treatment of prosthetic vascular graft infection in the groin with ultrasound debridement: A case report

Introduction

Prosthetic graft infection (PGI) is associated with low patient survival rates. The effectiveness of ultrasound debridement in chronic wound healing has been previously reported; however, data on the use of ultrasound technology and its effect on the treatment of PGI are still lacking. We report a case in which PGI in the groin was managed by graft removal using ultrasound debridement.

Presentation of case

A 70-year-old man was diagnosed with chronic limb-threatening ischemia and underwent a femoral-femoral bypass with a polytetrafluoroethylene graft. Eight months postoperatively, he developed an infection at the femoral incision site. Graft removal was performed using ultrasound debridement. The estimated blood loss was 10 mL. The wound healed, and the patient has remained in good health for 2 years postoperatively.

Discussion

When the ultrasonic probe is applied to the wound, ultrasonic energy penetrates into the tissue, and a fibrinolytic action removes necrotic or infected tissue without removing healthy tissue, thereby minimizing bleeding. Using this technique, we were able to perform effective debridement at not only the wound but also the anastomosis.

Conclusion

It is our opinion that this technique can be used to achieve adequate debridement with little bleeding during graft removal and may provide a new option for the treatment of PGI.

Ultrasound Devices to Treat Chronic Wounds: The Current Level of Evidence

Chronic wounds cause considerable morbidity and utilize significant health care resources. In addition to addressing wound etiology and treating infection, regular debridement is a key component of wound care with a proven ability to accelerate healing. In this regard, a significant innovation in wound care has been the development of ultrasound debridement technology. The purpose of this review is to evaluate the current evidence behind the technology with an emphasis on noncontact low-frequency (NCLF) ultrasound. A number of studies, especially those evaluating NCLF technology, have demonstrated the potential of ultrasound debridement to effectively remove devitalized tissue, control bioburden, alleviate pain, and expedite healing. However, most of the studies are underpowered, involve heterogeneous ulcer types, and demonstrate significant methodological limitations making comparison between studies difficult; there is a paucity of data on cost-effectiveness. Future clinical trials on ultrasound debridement technology must address the design issues prevalent in current studies, and report on clinically relevant endpoints before adoption into best-practice algorithms can be recommended.

Vibrational stress affects extracellular signal-regulated kinases activation and cytoskeleton structure in human keratinocytes

As the outermost organ, the skin can be damaged following injuries such as wounds and bacterial or viral infections, and such damage should be rapidly restored to defend the body against physical, chemical, and microbial assaults. However, the wound healing process can be delayed or prolonged by health conditions, including diabetes mellitus, venous stasis disease, ischemia, and even stress. In this study, we developed a vibrational cell culture model and investigated the effects of mechanical vibrations on human keratinocytes. The HaCaT cells were exposed to vibrations at a frequency of 45 Hz with accelerations of 0.8g for 2 h per day. The applied mechanical vibration did not affect cell viability or cell proliferation. Cell migratory activity did increase following exposure to vibration, but the change was not statistically significant. The results of immunostaining (F-actin), western blot (ERK1/2), and RT-qPCR (FGF-2, PDGF-B, HB-EGF, TGF-β1, EGFR, and KGFR) analyses demonstrated that the applied vibration resulted in rearrangement of the cytoskeleton, leading to activation of ERK1/2, one of the MAPK signaling pathways, and upregulation of the gene expression levels of HB-EGF and EGFR. The results suggest that mechanical vibration may have wound healing potential and could be used as a mechanical energy-based treatment for enhancing wound healing efficiency.

Ultrasonic debridement management of lower extremity wounds: retrospective analysis of clinical outcomes and cost

Objective:

The aim of this study was to assess wound healing outcomes following direct, low-frequency, high-intensity, ultrasonic debridement as a surgical adjunct for non-healing lower extremity wounds.

Methods:

A retrospective review was conducted for patients undergoing lower extremity wound treatment with direct, low-frequency (22.5 kHz), high-intensity (~60 W/cm2) ultrasonic debridement between January 2010 and January 2016. Clinical outcomes were assessed up to 180-days post-ultrasonic debridement. Descriptive statistics, cost and univariate analysis were performed.

Results:

Overall, 82 wounds in 51 patients were included. Mean age was 57.0 years (range: 32–69), and average body mass index (BMI) was 30.8 kg/m². Patient comorbidities consisted of smoking (47%; n=24), hypertension (75%; n=38), diabetes (45%; n=23), and peripheral vascular disease (51%, n=26). Average wound age at initial presentation was 1013 days (range: 2–5475 days) with an average wound size of 9.0cm x 7.4cm. At 180-days post-debridement, 60% (n=49) of wounds had completely healed. Readmission (47%; n=24) and reoperation (45%; n=23) rates were characterised by the reason for readmission and reoperation respectively. Readmission for wound healing (70%, n=39) was primarily for further debridements (41%; n=16). Wound infection (30%; n=7) was the most common readmission for wound complications (30%; n=17). Reoperations primarily consisted of treatments for further wound healing 96% (n=51). Cost analysis showed a lower total treatment cost for patients with improved healing ($78,698), compared with non-improved wounds ($137,707).

Conclusion:

In a complex, heterogeneous cohort of chronic extremity wounds, the use of direct, low-frequency, high-intensity, ultrasonic debridement is a safe and reliable adjunctive therapy for the management of these wounds.

Development of Low Frequency (20-100 kHz) Clinically Viable Ultrasound Applicator for Chronic Wound Treatment

This paper details the systematic approach used to develop a viable clinical prototype of a therapeutic ultrasound applicator and discusses the rationale and deliberations that led to the design strategy. The applicator was specifically devised to treat chronic wounds and-to the best of the author's knowledge-is the first truly wearable device with a proven record of reducing healing time, directly translating to a reduction of healthcare costs. The prototype operates in the kHz (20-100) range of frequencies and uses noncavitational and nonthermal levels of ultrasound energy. Hence, in the absence of inertial cavitation and temperature elevation, the tissue-ultrasound interaction is considered to be dependent on stable cavitation (if any) and radiation force. The peak acoustic output pressure amplitude is limited to 55 kPa, corresponding to a spatial peak-temporal peak intensity of 100 mW/cm2. This level of intensity is considered to be safe to apply for extended (up to 4 h) periods of time. The patch-like applicator design is suitable to be embedded in wound dressing. With its lightweight (<20 g) and circular (40 mm dia) disk-shape architecture, the applicator is well suited for chronic wound treatment. A small ( n = 8 ) pilot study on the effects of the applicator on diabetic ulcers (DUs) healing time is presented. The average time to wound closure was 4.7 weeks for subjects treated with the active ultrasound applicator, compared to 12 weeks for subjects treated with a sham applicator, suggesting that patients with DUs may benefit from the proposed treatment.

Diagnostic and Therapeutic Ultrasound on Venous and Arterial Ulcers: A Focused Review

GENERAL PURPOSE

To provide information about the use of ultrasound for diagnostic and therapeutic treatment of venous and arterial ulcers.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After completing this continuing education activity, you should be able to: ABSTRACT: To review the diagnostic and therapeutic use of ultrasound on venous and arterial ulcers.

METHODS

PubMed was searched for peer-reviewed articles using the search terms "ultrasound for venous ulcers" and "ultrasound for arterial ulcers." The search yielded 282 articles on ultrasound for venous ulcers and 455 articles for ultrasound on arterial ulcers. Data from 36 articles were selected and included after abstract review.

RESULTS

Ultrasound is an established diagnostic modality for venous and arterial disease and is indicated for wound debridement. Recent evidence continues to support its superiority over standard of care in healing venous ulcers, but findings conflict in terms of the effectiveness of low-frequency ultrasound over high-frequency ultrasound. There are currently no standardized treatment protocols for ultrasound.

CONCLUSIONS

Diagnostic ultrasound is used to assess venous and arterial disease and guide appropriate treatment for ulcers. Therapeutic low-frequency ultrasound is used to debride the wound bed, as an adjunctive topical wound treatment with standard of care, and to guide the application of other advanced therapies to chronic wounds. Better trial designs and consistent data are needed to support the effectiveness of ultrasound therapy on venous and arterial ulcers.

[Research progress of chronic wound debridement]

Objective

To review the research progress of chronic wound debridement.

Methods

The recent related literature concerning the mechanisms, advantages, limitations, and indications of the technologies of chronic wound debridement was extensively consulted, reviewed, and summarized.

Results

Debridement is essential for chronic wound healing, which includes autolytic debridement, enzymatic debridement, biodebridement, mechanical debridement, sharp/surgical debridement, ultrasound debridement, hydrosurgery debridement, and coblation debridement. Each technique has its own advantages and disadvantages.

Conclusion

There are many types of technologies of chronic wound debridement, which can be chosen according to clinical conditions. It is showed there are more significant advantages associated with the technique of coblation debridement relatively, which also has greater potential. Further study is needed to improve its efficacy.

What Is the Role of Diagnostic and Therapeutic Sonication in Periprosthetic Joint Infections?

BACKGROUND

Periprosthetic joint infection (PJI) is one of the most dreaded complications in joint replacement surgery. Diagnosis and treatment can be difficult and biofilms are of major concern due to their low susceptibility toward antibiotics.

METHODS

This review focuses on the use of sonication as an evolving diagnostic and adjunct treatment modality in the context of PJI. Therapeutic application of sonication is discussed separately for its (i) direct action on bacteria, (ii) synergistic effects with antibiotics, and (iii) effects on release of antibiotics from bone cement.

RESULTS

Used as a diagnostic tool, sonication shows promising results with respect to sensitivity and specificity when compared to conventional methods, notably after previous administration of antibiotics. As an adjunct treatment modality, the chemical, physical, and mechanical effects of sonication are primarily driven by cavitation and recognized as the main cause for bactericidal effects but the exact underlying mechanisms have not been identified yet. Sonication alone does not have the ability to completely eradicate biofilms but synergistic effects when used in conjunction with antibiotics have been reported. There is also evidence for enhanced antibiotic release from bone cement.

CONCLUSION

Sonication is as an evolving modality in the context of PJIs. As a diagnostic tool, it has not been introduced in routine clinical practice and sonication as a treatment modality in PJIs is still in an experimental stage. Factors such as frequency, pressure, chemical activity, intensity, and exposure time need to be evaluated for optimal application of sonication and may also improve study comparison.

The effect of 22.5 kHz low-frequency contact ultrasound debridement (LFCUD) on lower extremity wound healing for a vascular surgery population: A randomised controlled trial

The aim of this study was to compare changes in wound size and appearance and health complication rates in patients with vasculopathy and lower-extremity wounds treated with or without low-frequency contact ultrasound debridement (LFCUD) This study was a randomised controlled trial. The study was conducted in a vascular surgery service, including outpatient wound clinic and inpatient ward, in a tertiary care academic centre. In total, 70 patients with vasculopathy and lower-extremity wounds of mixed aetiology were enrolled in the trial; 68 completed the study. Patients were randomised to receive LFCUD plus usual care (n = 33) or usual care (n = 37) at 4 weekly visits, and were followed thereafter for up to 12 wk. The main outcome measures included closed wounds, change in wound surface area (WSA), and wound appearance by the revised Photographic Wound Assessment Tool (revPWAT). After 4 weekly LFCUD treatments, patients in the LFCUD group had significantly better wound appearance (total revPWAT score) compared with the control group treated only with usual care (P = <0.05). LFCUD-treated wounds also had a significant reduction in WSA over 4 wk that was not found in the UC group. LFCUD treatment was also associated with a greater number of healed wounds, odds ratio 5.00 (95% CI 1.24-20.25), and fewer instances of wound deterioration. Weekly LFCUD applications to patients with significant vasculopathy resulted in superior healing outcomes when compared with current usual wound care practice.

The Effect of Ultrasound-Assisted Debridement Combined with Vacuum Pump Therapy in Deep Sternal Wound Infections

Purpose: To assess whether a combined treatment of low-frequency (25 kHz) ultrasonic-debridement systems followed by vacuum-assisted wound closure (VAC) produces a better outcome in deep sternal wound infections (SWIs) compared to that of VAC alone.

Methods: We evaluated 45 consecutive patients (25 males) between January 2013 and December 2016, in whom deep SWI was treated with a combination of low-frequency ultrasonic debridement system followed by vacuum-assisted closure (group A, n = 23) or with only vacuum-assisted closure therapy (group B, n = 22). Our final step in both groups was a secondary wound closure with a musculocutaneous flap.

Results: In both groups, a similar variety of bacteria were isolated. The time between eradication and secondary wound closure was significantly shorter in group A (7.3 ± 4.8 vs. 19.9 ± 17.2 days, p = 0.001). After a third debridement session, 95.7% of microbiological cultures were negative in group A versus 54.5% in B ( p = 0.001). Duration of antibiotic treatment (p = 0.003) and hospitalization time ( p = 0.0001) were significantly shorter in group A.

Conclusion: The use of low-frequency ultrasonic debridement system is an effective, less invasive technique to combat wound infection. In combination with vacuum-assisted closure therapy, we documented good mid-term results in our patients.

Use of Noncontact Low-Frequency Ultrasound in Deep Tissue Pressure Injury: A Retrospective Analysis

PURPOSE

The purpose of this study was to examine the effect of noncontact low-frequency ultrasound (NLFU) on deep tissue pressure injury (DTPI), both hospital-acquired and those present on admission (POA).

DESIGN

Retrospective, descriptive study.

SAMPLE AND SETTING

Medical records from 44 adult patients with a DTPI treated with NLFU were reviewed; 22 had a hospital-acquired DTPI (HADTPI) and 22 had DTPI POA. Their mean age was 71.3 ± 16.3 years (mean ± SD); 52% were male. The study setting was a 318-bed community hospital in the Mid-Atlantic region of the United States.

METHODS

Data were collected from the medical records including demographic and relevant clinical characteristics, DTPI measurements, and DTPI evolution/resolution. Data were summarized and examined using descriptive statistics (eg, frequencies and percentages and means and standard deviations). Differences between groups were examined using paired t tests or the Mann-Whitney U test and the chi-square test as appropriate. In addition, the heel DTPI subgroup (N = 8) was examined separately due to the small sample size.

RESULTS

All patients with HADTPI and DTPI POA treated with NLFU exhibited a statistically significant decrease in injury size from initiation to discontinuation of NLFU therapy (24.6 cm vs 14.4 cm, P = .02). No statistically significant difference in wound resolution was found between HADTPI versus DTPI POA (27% vs 18%, P = .47). Mean size of both HADTPI and DTPI POA decreased significantly from 15.9 to 13.4 cm (P = .045) by NLFU therapy. Wounds were classified as resolved at completion of treatment in 23% (10 out of 44) of all treated patients. Of all patients with the potential to be resolved (not discharged early or expired) 63% (10 out of 16) had wounds classified as resolved.

CONCLUSION

Study findings suggest that NLFU is a viable and promising treatment option for both HADTPI and DTPI POA. Future studies are needed to confirm these results and to examine efficacy and feasibility of DTPI across care settings.

Low-Frequency Ultrasound Debridement in Chronic Wound Healing: A Systematic Review of Current Evidence

Chronic wounds are painful and debilitating to patients, pose a clinical challenge to physicians, and impose financial burden on the health-care system. New treatment options are therefore highly sought after. Ultrasound debridement is a promising technology that functions to disperse bacterial biofilms and stimulate wound healing. In this review, we focus on low-frequency ultrasound (20-60 kHz) and summarize the findings of 25 recent studies examining ultrasound efficacy. Ultrasound debridement appears to be most effective when used 3 times a week and has the potential to decrease exudate and slough, decrease patient pain, disperse biofilms, and increase healing in wounds of various etiology. Although current studies are generally of smaller size, the results are promising and we recommend the testing of low-frequency ultrasound therapy in clinical practice on a larger scale.

Overcoming T. gondii infection and intracellular protein nanocapsules as biomaterials for ultrasonically controlled drug release

One of the pivotal matters of concern in intracellular drug delivery is the preparation of biomaterials containing drugs that are compatible with the host target.

Does the new low-frequency ultrasonic debridement technology pose an infection control risk for clinicians, patients, and the clinic environment?

BACKGROUND

Low-frequency ultrasonic debridement (LFUD) is a technology that uses sound waves conducted through saline mist to debride wound tissue. Whilst this technology purportedly reduces wound-healing times, the airborne mist generated is potentially problematic. Theoretically, the saline mist could carry an increased number of microbes into the surrounding environment, posing an infection control risk to the patient, clinician, and clinical environment. This research aimed to establish the degree and extent to which there is microbial spread during the use of, and following the use of, LFUD. The total number of colony forming units was identified for use of LFUD without the suction attachment (control) and with the suction attachment (intervention).

METHODS

This was a prospective, observational study with repeated measures across each treatment (before, during, and after). Quota sampling in a 2 × 2 × 2 factorial design was undertaken so that half of the 24 treatments were conducted at each health service (Monash Health vs Peninsula Health), in different treatment environments (inpatient vs outpatient), and half were conducted with and without suction. The use of suction was not randomized but was determined at the treating clinician's discretion. Patients treated in the inpatient environment lay on their beds, whereas patients in the outpatient environment sat in a treatment chair.

RESULTS

There was higher microbial count during treatment (P < .001) with a higher microbial count associated with lower ultrasound amplitude (P = .028), lower saline flow rate (P = .010), no suction attachment (P = > .001), and a larger wound area (P = .002). All were independently associated with greater microorganism aerosolization. There was no correlation between the type of handpiece selected, the presence of wound infection, and the treatment time or treatment environment.

CONCLUSIONS

This research has assisted in developing guidelines for cleaning of equipment and environments following treatment, as well as around the use of personal protective equipment required to protect the staff member and the patient during the use of LFUD. Additionally, recommendations have been made regarding the specific LFUD settings to reduce the risk of cross-infection to the clinic environment. These include selecting a higher ultrasound amplitude and saline flow rate as well as the use of suction where clinically possible.

Slough and biofilm: removal of barriers to wound healing by desloughing

The presence of non-viable tissue in a chronic wound presents a barrier against effective wound healing, hence removal facilitates healing and reduces areas where microorganisms can attach and form biofilms, effectively reducing the risk of infection. Wound debridement is a necessary process in those wounds that have evidence of cellular debris and non-viable tissue. As slough is a form of non-viable tissue we hypothesise that it will support the attachment and development of biofilms. Biofilms are entities that have serious implications in raising the risk of infection and delaying wound healing. In those wounds that contain only slough, high-risk debridement methods are not considered necessary for its removal. The use of mechanical techniques for removing the slough is regarded as posing a much lower risk to the patient and the wound bed. The process of removing slough from a wound is referred to as 'desloughing'. We propose that mechanical desloughing is a low-risk method of debridement to aid the specific removal of slough. Slough in a wound is a recurrent issue for a large majority of patients. Consequently, desloughing should not be deemed a one-off process but an on-going procedure referred to as 'maintenance desloughing'. Maintenance desloughing will help to achieve and maintain a healthy wound bed and aid the removal of wound biofilms, facilitating wound healing.

Does physical therapy and rehabilitation improve outcomes for diabetic foot ulcers?

One of the most common and serious complications of diabetes mellitus is ulceration of the foot. Among persons with diabetes, 12%-25% will present to a healthcare institution for a foot disorder during their lifespan. Despite currently available medical and surgical treatments, these are still the most common diabetes-related cause of hospitalization and of lower extremity amputations. Thus, many adjunctive and complementary treatments have been developed in an attempt to improve outcomes. We herein review the available literature on the effectiveness of several treatments, including superficial and deep heaters, electro-therapy procedures, prophylactic methods, exercise and shoe modifications, on diabetic foot wounds. Overall, although physical therapy modalities seem to be useful in the treatment of diabetic foot wounds, further randomized clinical studies are required.

Seeking effective interventions to treat complex wounds: an overview of systematic reviews

BACKGROUND

Numerous, often multi-faceted regimens are available for treating complex wounds, yet the evidence of these interventions is recondite across the literature. We aimed to identify effective interventions to treat complex wounds through an overview of systematic reviews.

METHODS

MEDLINE (OVID interface, 1946 until October 26, 2012), EMBASE (OVID interface, 1947 until October 26, 2012), and the Cochrane Database of Systematic Reviews (Issue 10 of 12, 2012) were searched on October 26, 2012. Systematic reviews that examined adults receiving care for their complex wounds were included. Two reviewers independently screened the literature, abstracted data, and assessed study quality using the Assessment of Multiple Systematic Reviews (AMSTAR) tool.

RESULTS

Overall, 99 systematic reviews were included after screening 6,200 titles and abstracts and 422 full-texts; 54 were systematic reviews with a meta-analysis (including data on over 54,000 patients) and 45 were systematic reviews without a meta-analysis. Overall, 44% of included reviews were rated as being of high quality (AMSTAR score ≥ 8). Based on data from systematic reviews including a meta-analysis with an AMSTAR score ≥ 8, promising interventions for complex wounds were identified. These included bandages or stockings (multi-layer, high compression) and wound cleansing for venous leg ulcers; four-layer bandages for mixed arterial/venous leg ulcers; biologics, ultrasound, and hydrogel dressings for diabetic leg/foot ulcers; hydrocolloid dressings, electrotherapy, air-fluidized beds, and alternate foam mattresses for pressure ulcers; and silver dressings and ultrasound for unspecified mixed complex wounds. For surgical wound infections, topical negative pressure and vacuum-assisted closure were promising interventions, but this was based on evidence from moderate to low quality systematic reviews.

CONCLUSIONS

Numerous interventions can be utilized for patients with varying types of complex wounds, yet few treatments were consistently effective across all outcomes throughout the literature. Clinicians and patients can use our results to tailor effective treatment according to type of complex wound. Network meta-analysis will be of benefit to decision-makers, as it will permit multiple treatment comparisons and ranking of the effectiveness of all interventions. Please see related article: http://dx.doi.org/10.1186/s12916-015-0326-3.

Osteomyelitis of the foot and ankle: diagnosis, epidemiology, and treatment

Osteomyelitis of the foot and ankle is a common, potentially devastating condition with diagnostic and treatment challenges. Understanding the epidemiology and pathogenesis of osteomyelitis can raise clinical suspicion and guide testing and treatments. History and physical examination, laboratory studies, vascular studies, histologic and microbiologic analyses, and various imaging modalities contribute to diagnosis and treatment. Treatment including empiric broad-spectrum antibiotics and surgery should take a multidisciplinary approach to optimize patient factors, ensure eradication of the infection, and restore function. Optimization of vascular status, soft tissues, limb biomechanics, and physiologic state of the patient must be considered to accelerate and ensure healing.

Ultrasound mediated transdermal drug delivery

Transdermal drug delivery offers an attractive alternative to the conventional drug delivery methods of oral administration and injections. However, the stratum corneum serves as a barrier that limits the penetration of substances to the skin. Application of ultrasound (US) irradiation to the skin increases its permeability (sonophoresis) and enables the delivery of various substances into and through the skin. This review presents the main findings in the field of sonophoresis in transdermal drug delivery as well as transdermal monitoring and the mathematical models associated with this field. Particular attention is paid to the proposed enhancement mechanisms and future trends in the fields of cutaneous vaccination and gene therapy.

Low-intensity vibration improves angiogenesis and wound healing in diabetic mice

Chronic wounds represent a significant health problem, especially in diabetic patients. In the current study, we investigated a novel therapeutic approach to wound healing – whole body low-intensity vibration (LIV). LIV is anabolic for bone, by stimulating the release of growth factors, and modulating stem cell proliferation and differentiation. We hypothesized that LIV improves the delayed wound healing in diabetic mice by promoting a pro-healing wound environment. Diabetic db/db mice received excisional cutaneous wounds and were subjected to LIV (0.4 g at 45 Hz) for 30 min/d or a non-vibrated sham treatment (controls). Wound tissue was collected at 7 and 15 d post-wounding and wound healing, angiogenesis, growth factor levels and wound cell phenotypes were assessed. LIV increased angiogenesis and granulation tissue formation at day 7, and accelerated wound closure and re-epithelialization over days 7 and 15. LIV also reduced neutrophil accumulation and increased macrophage accumulation. In addition, LIV increased expression of pro-healing growth factors and chemokines (insulin-like growth factor-1, vascular endothelial growth factor and monocyte chemotactic protein-1) in wounds. Despite no evidence of a change in the phenotype of CD11b+ macrophages in wounds, LIV resulted in trends towards a less inflammatory phenotype in the CD11b− cells. Our findings indicate that LIV may exert beneficial effects on wound healing by enhancing angiogenesis and granulation tissue formation, and these changes are associated with increases in pro-angiogenic growth factors.

Comparison of healing rate in diabetes-related foot ulcers with low frequency ultrasonic debridement versus non-surgical sharps debridement: a randomised trial protocol

Background

Foot ulceration has been reported as the leading cause of hospital admission and amputation in individuals with diabetes. Diabetes-related foot ulcers require multidisciplinary management and best practice care, including debridement, offloading, dressings, management of infection, modified footwear and management of extrinsic factors.

Ulcer debridement is a commonly applied management approach involving removal of non-viable tissue from the ulcer bed. Different methods of debridement have been reported in the literature including autolytic debridement via moist wound healing, mechanical debridement utilising wet to dry dressings, theatre based sharps debridement, biological debridement, non-surgical sharps debridement and newer technology such as low frequency ultrasonic debridement.

Methods

People with diabetes and a foot ulcer, referred to and treated by the Podiatry Department at Monash Health and who meet the inclusion criteria will be invited to participate in this randomised controlled trial. Participants will be randomly and equally allocated to either the non-surgical sharps debridement (control) or low frequency ultrasonic debridement (intervention) group (n = 322 ulcers/n = 108 participants).

Where participants have more than one ulcer, only the participant will be randomised, not the ulcer. An investigator not involved in participant recruitment or assessment will be responsible for preparing the random allocation sequence and envelopes.

Each participant will receive weekly treatment for six months including best practice podiatric management. Each ulcer will be measured on a weekly basis by calculating total area in centimetres squared. Measurement will be undertaken by a trained research assistant to ensure outcomes are blinded from the treating podiatrist. Another member of the research team will assess the final primary outcome.

Discussion

The primary aim of this study is to compare healing rates for diabetes-related foot ulcers using non-surgical sharps debridement versus low frequency ultrasonic debridement over a six month period. The primary outcome measure for this study is the proportion of ulcers healed by the six month follow-up period.

Secondary outcomes will include a quality of life measure, assessment of pain and health care resource use between the two treatment modalities.

Trial registration

Australian New Zealand Clinical Trial Registry: ACTRN12612000490875.

Updating on understanding and managing chronic wound

The art of healing wounds is quite complex. It requires the patient's local condition in conjunction with their systemic condition to provide the most ideal wound environment. As wound care is expanding with advances in technology, we are facing a variety of different wound care products based on an assortment of bioengineered skin substances, growth factors, oxygen therapies, low frequency ultrasound and even low energy light. While these emerging evidence-based treatments prove to be promising in improving clinical outcomes and quality of life, it challenges providers to provide cost-effective treatment plans. The goal of this paper is to introduce a discussion regarding practical clinical application of various forms of advanced wound technologies in order to optimize the art of wound healing.

The ABC's of wound care

Non-healing wounds represent a challenging problem for physicians and patients alike. Although treatment strategies are aimed at specific causes, there are basic management principles that apply to all wounds. The purpose of this article is to review these core management principles as they apply to lower extremity wounds. Key points include a multidisciplinary approach and individualized plans of care as per specific patient needs. A comprehensive treatment plan will lead to faster healing and improved outcomes.

Characterization of the ultrasound beam produced by the MIST therapy, wound healing system

The MIST Therapy wound healing device (Celleration, Eden Prairie, MN, USA), which uses low-frequency ultrasound to deliver an atomized saline spray to acute wounds, was evaluated in a laboratory environment. The output of the MIST device was characterized by its frequency, transmission in the presence and absence of the saline spray and intensity. When measured up to 500 mm away from the transducer tip, the transmission of 39.5 kHz ultrasound was not significantly attenuated by the saline itself. In the absence of the saline spray, the acoustic intensity range of the MIST device was calculated to be 429-188 mW cm(-2) across the manufacturer-specified treatment range (12.5-20 mm). Because of the acoustic impedance mismatch between air and soft tissue, the MIST Therapy device would deliver only 0.1% of this incident intensity into the wound site.

Sonothrombolysis in ischemic stroke

OPINION STATEMENT

Acute ischemic stroke remains one of the most devastating diseases when it comes to morbidity and mortality, not to mention the personal and economic burden that occurs in long-term. Intravenous thrombolysis with tissue plasminogen activator (tPA) is the only effective acute stroke therapy that improves outcome if given up to 4.5 hours from symptom onset. However, recanalization rates are meager and the majority of treated patients still have residual disability after stroke, emphasizing the need for further treatment options that may facilitate or even rival the only approved therapy. Sonothrombolysis, the adjuvant continuous ultrasound sonication of an intra-arterial occlusive thrombus during thrombolysis, enhances the clot-dissolving capabilities of intravenous tPA presumably by delivering acoustic pressure to the target brain vessel. Higher recanalization rates produce a trend towards better functional outcomes that could be safely achieved with the combination of high-frequency ultrasound and intravenous tPA. However, data on ultrasound targeting of intracranial proximal occlusive lesions other than those in the middle cerebral arteries are sparse. Moreover, recent sonothrombolysis trials were exclusively conducted with operator-dependent hand-held technology hindering its further testing in clinical sonothrombolysis trials. An operator-independent 2-MHz transcranial Doppler device has been developed allowing health care professionals not formally trained in ultrasound apparatus to provide therapeutic ultrasound as needed. Currently, this operator-independent device covering 12 proximal intracranial segments that most commonly contain thrombo-embolic occlusions enters testing in a pivotal multicenter sonothrombolysis efficacy trial. If this trial demonstrates safety and efficacy, adjuvants, such as gaseous microbubbles that further potentiate the thrombolytic effect of intravenous tPA, could be tested along with this device.

New techniques for wound debridement

Debridement is a crucial component of wound management. Traditionally, several types of wound debridement techniques have been used in clinical practice such as autolytic, enzymatic, biodebridement, mechanical, conservative sharp and surgical. Various factors determine the method of choice for debridement for a particular wound such as suitability to the patient, the type of wound, its anatomical location and the extent of debridement required. Recently developed products are beginning to challenge traditional techniques that are currently used in wound bed preparation. The purpose of this review was to critically evaluate the current evidence behind the use of these newer techniques in clinical practice. There is some evidence to suggest that low frequency ultrasound therapy may improve healing rates in patients with venous ulcers and diabetic foot ulcers. Hydrosurgery debridement is quick and precise, but the current evidence is limited and further studies are underway. Debridement using a monofilament polyester fibre pad and plasma-mediated bipolar radiofrequency ablation are both very new techniques. The initial evidence is limited, and further studies are warranted to confirm their role in management of chronic wounds.