The use of ultrasound therapy in wound healing

Sonocatalytic Optimization of Titanium-Based Therapeutic Nanomedicine

Recent considerable technological advances in ultrasound-based treatment modality provides a magnificent prospect for scientific communities to conquer the related diseases, which is featured with remarkable tissue penetration, non-invasive and non-thermal characteristics. As one of the critical elements that influences treatment outcomes, titanium (Ti)-based sonosensitizers with distinct physicochemical properties and exceptional sonodynamic efficiency have been applied extensively in the field of nanomedical applications. To date, a myriad of methodologies has been designed to manipulate the sonodynamic performance of titanium-involved nanomedicine and further enhance the productivity of reactive oxygen species for disease treatments. In this comprehensive review, the sonocatalytic optimization of diversified Ti-based nanoplatforms, including defect engineering, plasmon resonance modulation, heterojunction, modulating tumor microenvironment, as well as the development of synergistic therapeutic modalities is mainly focused. The state-of-the-art Ti-based nanoplatforms ranging from preparation process to the extensive medical applications are summarized and highlighted, with the goal of elaborating on future research prospects and providing a perspective on the bench-to-beside translation of these sonocatalytic optimization tactics. Furthermore, to spur further technological advancements in nanomedicine, the difficulties currently faced and the direction of sonocatalytic optimization of Ti-based therapeutic nanomedicine are proposed and outlooked.

Interstitial Matrix Prevents Therapeutic Ultrasound From Causing Inertial Cavitation in Tumescent Subcutaneous Tissue

We search for cavitation in tumescent subcutaneous tissue of a live pig under application of pulsed, 1-MHz ultrasound at 8 W cm^-2 spatial peak and pulse-averaged intensity. We find no evidence of broadband acoustic emission indicative of inertial cavitation. These acoustic parameters are representative of those used in external-ultrasound-assisted lipoplasty and in physical therapy and our null result brings into question the role of cavitation in those applications. A comparison of broadband acoustic emission from a suspension of ultrasound contrast agent in bulk water with a suspension injected subcutaneously indicates that the interstitial matrix suppresses cavitation and provides an additional mechanism behind the apparent lack of in-vivo cavitation to supplement the absence of nuclei explanation offered in the literature. We also find a short-lived cavitation signal in normal, non-tumesced tissue that disappears after the first pulse, consistent with cavitation nuclei depletion in vivo.

Therapeutic ultrasound for venous leg ulcers

BACKGROUND

Venous leg ulcers are a type of chronic, recurring, complex wound that is more common in people aged over 65 years. Venous ulcers pose a significant burden to patients and healthcare systems. While compression therapy (such as bandages or stockings) is an effective first-line treatment, ultrasound may have a role to play in healing venous ulcers.

OBJECTIVES

To determine whether venous leg ulcers treated with ultrasound heal more quickly than those not treated with ultrasound.

SEARCH METHODS

We searched the Cochrane Wounds Specialised Register (searched 19 September 2016); the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library 2016, Issue 8); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations, MEDLINE Daily and Epub Ahead of Print) (1946 to 19 September 2016); Ovid Embase (1974 to 19 September 2016); and EBSCO CINAHL Plus (1937 to 19 September 2016). We also searched three clinical trials registries and the references of included studies and relevant systematic reviews. There were no restrictions based on language, date of publication or study setting.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared ultrasound with no ultrasound. Eligible non-ultrasound comparator treatments included usual care, sham ultrasound and alternative leg ulcer treatments.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the search results and selected eligible studies. Details from included studies were summarised using a data extraction sheet, and double-checked. We attempted to contact trial authors for missing data.

MAIN RESULTS

Eleven trials are included in this update; 10 of these we judged to be at an unclear or high risk of bias. The trials were clinically heterogeneous with differences in duration of follow-up, and ultrasound regimens. Nine trials evaluated high frequency ultrasound; seven studies provided data for ulcers healed and two provided data on change in ulcer size only. Two trials evaluated low frequency ultrasound and both reported ulcers healed data.It is uncertain whether high frequency ultrasound affects the proportion of ulcers healed compared with no ultrasound at any of the time points evaluated: at seven to eight weeks (RR 1.21, 95% CI 0.86 to 1.71; 6 trials, 678 participants; low quality evidence - downgraded once for risk of bias and once for imprecision); at 12 weeks (RR 1.26, 95% CI 0.92 to 1.73; 3 trials, 489 participants; moderate quality evidence - downgraded once for imprecision); and at 12 months (RR 0.93, 95% CI 0.73 to 1.18; 1 trial, 337 participants; low quality evidence - downgraded once for unclear risk of bias and once for imprecision).One trial (92 participants) reported that a greater percentage reduction in ulcer area was achieved at four weeks with high-frequency ultrasound, while another (73 participants) reported no clear difference in change in ulcer size at seven weeks. We downgraded the level of this evidence to very low, mainly for risk of bias (typically lack of blinded outcome assessment and attrition) and imprecision.Data from one trial (337 participants) suggest that high frequency ultrasound may increase the risk of non-serious adverse events (RR 1.29, 95% CI 1.02 to 1.64; moderate quality evidence - downgraded once for imprecision) and serious adverse events (RR 1.21, 95% CI 0.78 to 1.89; moderate quality evidence downgraded once for imprecision).It is uncertain whether low frequency ultrasound affects venous ulcer healing at eight and 12 weeks (RR 3.91, 95% CI 0.47 to 32.85; 2 trials, 61 participants; very low quality evidence (downgraded for risk of bias and imprecision)).High-frequency ultrasound probably makes little or no difference to quality of life (moderate quality evidence, downgraded for imprecision). The outcomes of adverse effects, quality of life and cost were not reported for low-frequency ultrasound treatment.

AUTHORS' CONCLUSIONS

It is uncertain whether therapeutic ultrasound (either high or low frequency) improves the healing of venous leg ulcers. We rated most of the evidence as low or very low quality due to risk of bias and imprecision.

Therapeutic Ultrasound in Lower Extremity Wound Management

In medical practice, ultrasound (US) is used for diagnosis and therapy. High-frequency (1-4 MHz) and low-frequency (20-120 KHz) therapeutic US are relevant to wound healing. The heating effects of high-frequency US are important, whereas the mechanical effects of low-frequency US must be considered. The physiological effects of low-frequency US include metabolic enhancement, perfusion, wound cleansing, and the acceleration of wound granulation. The therapeutic efficacy of US depends on dose (W/cm2 time)and dosage (frequency of application, series). At adequate doses, high-frequency and low-frequency therapeutic US induce in vitro cell proliferation; protein synthesis; and the production of cytokines by fibroblasts, osteoblasts, and monocytes. The mechanical effects of low-frequency US cause transient cavitation in wound surfaces for soft and smooth wound cleaning, ulcer debridement, and the stimulation of granulation. These effects can be determined in clinical studies, though the quality of the studies done so far and of the evidence of the usefulness of US is poor. Nevertheless, high-frequency and low-frequency US may be reasonable options in the management of chronic wounds.

Low intensity ultrasound perturbs cytoskeleton dynamics

Therapeutic ultrasound is widely employed in clinical applications but its mechanism of action remains unclear. Here we report prompt fluidization of a cell and dramatic acceleration of its remodeling dynamics when exposed to low intensity ultrasound. These physical changes are caused by very small strains (10^-5) at ultrasonic frequencies (10⁶ Hz), but are closely analogous to those caused by relatively large strains (10^-1) at physiological frequencies (10⁰ Hz). Moreover, these changes are reminiscent of rejuvenation and aging phenomena that are well-established in certain soft inert materials. As such, we suggest cytoskeletal fluidization together with resulting acceleration of cytoskeletal remodeling events as a mechanism contributing to the salutary effects of low intensity therapeutic ultrasound.

Effects of low-frequency ultrasound on microcirculation in venous leg ulcers

Background:

Therapeutic low-frequency ultrasound (US) has been used for many years to improve wound healing in chronic wounds like venous leg ulcers. No human data are available for the possible effects of single US applications on microcirculation and their frequency-dependency.

Aims:

To investigated the role of therapeutic low-frequency US on microcirculation of venous leg ulcers in vivo.

Patients and Methods:

This is a pilot study on an inpatient basis. We use a newly developed low-frequency continuous-wave US-equipment composed of a US transducer based on piezo-fiber composites that allow the change of frequency. In this study, we apply US of 34 kHz, 53.5 kHz, and 75 kHz respectively. Twelve patients with chronic venous leg ulcers are analyzed. As an adjunct to good ulcer care, therapeutic US is applied, non-contacting, once a day, in a subaqual position for 10 minutes. Microcirculation is assessed in the ulcers adjacent to skin before US-therapy, immediately after the treatment and 30 minutes later. We use a micro-light guide spectrophotometer (O2C, LEA Medizintechnik GmbH, Gieίen, Germany) for calculation of blood flow velocity, hemoglobin oxygen saturation (SCO₂) and relative hemoglobin concentration (rHb) in 2 and 8 mm depth. Contact-free remission spectroscopy (SkinREM3, Color Control Chemnitz GmbH, Chemnitz, Germany) allows contact free measurements in the VIS-NIR range of the spectrum (400 ± 1600 nm).

Results:

It is seen that therapeutic US is well tolerated. One patient dropped out from a treatment series since he developed erysipelas responding to standard antibiotic. Effects were seen at 34 kHz only. The SO₂ values increased after single US application. The values for rHb were higher in the superficial layer of the wound bed (depth 2 mm) compared to deeper parts (8 mm depth). US treatment did not result in significant changes of rHb and blood cell velocity. The data obtained by remission spectroscopy disclose an increase of oxygenized hemoglobin.

Conclusions:

The major findings are that continuous-wave low-frequency US of 34 kHz, but not, 53.5 kHz or 75 kHz, has a temporary stimulatory effect on microcirculation mainly due to an improved oxygenation. Further studies with treatment series are necessary.

Therapeutic ultrasound for venous leg ulcers

BACKGROUND

Venous leg ulcers pose a significant burden for patients and healthcare systems. Ultrasound (US) may be a useful treatment for these ulcers.

OBJECTIVES

To determine whether US increases the healing of venous leg ulcers.

SEARCH STRATEGY

We searched the Cochrane Wounds Group Specialised Register (searched 24 February 2010); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2010); Ovid MEDLINE (1950 to February Week 2 2010); In-Process & Other Non-Indexed Citations (searched 24 February 2010); Ovid EMBASE 1980 to 2010 Week 07; EBSCO CINAHL 1982 to 24 February 2010.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing US with no US.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the search results and selected eligible studies. Details from included studies were summarised using a data extraction sheet, and double-checked. We tried to contact trial authors for missing data.

MAIN RESULTS

Eight trials were included; all had unclear, or high, risks of bias, with differences in duration of follow-up, and US regimens. Six trials evaluated high frequency US and five of these reported healing at 7 - 8 weeks. Significantly more patients healed with US than without it at 7 - 8 weeks (pooled RR 1.4, 95% CI 1.0 to 1.96), but later assessments at 12 weeks showed the increased risk of healing with US was no longer statistically significant (pooled RR 1.47, 95% CI 0.99 to 2.20). One poor-quality study of high-frequency US found no evidence of an effect on healing after three weeks' treatment.Two trials evaluated low frequency US and reported healing at different time points. Both trials reported no evidence of a difference in the proportion of ulcers healed with US compared with no US: both were significantly underpowered.

AUTHORS' CONCLUSIONS

The trials evaluating US for venous leg ulcers are small, poor-quality and heterogeneous. There is no reliable evidence that US hastens healing of venous ulcers. There is a small amount of weak evidence of increased healing with US, but this requires confirmation in larger, high-quality RCTs. There is no evidence of a benefit associated with low frequency US.

Therapeutic ultrasound for venous leg ulcers

BACKGROUND

Venous leg ulceration is a common problem, representing a significant burden on the patient and the healthcare system. They are caused by venous insufficiency and tend to be chronic and recurring. Management usually includes use of wound dressings plus compression stockings or bandages. It has been suggested that therapeutic ultrasound may have an adjuvant effect and promote healing however its effects are unclear.

OBJECTIVES

To determine whether therapeutic ultrasound increases the healing of venous leg ulcers.

SEARCH STRATEGY

We searched the Cochrane Wounds Group Specialised Register (August 2007), The Cochrane Central Register of Controlled Trials (CENTRAL) - The Cochrane Library Issue 3, 2007, Ovid MEDLINE - 1950 to July Week 4 2007, Ovid EMBASE - 1980 to 2007 Week 31, Ovid CINAHL - 1982 to August Week 1 2007.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing therapeutic ultrasound with placebo (sham) ultrasound, or other (standard) treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the results of the searches for eligible RCTs and obtained full reports. A third author assessed the results of the update searches for eligible RCTs. Details from the eligible studies were extracted and summarised by a review author using a data extraction sheet. Attempts were made to contact trial authors to obtain missing data or for clarification.

MAIN RESULTS

A total of eight eligible trials were identified and were all of either medium or high risk of bias. Five trials compared ultrasound therapy with placebo (sham) ultrasound, three trials compared ultrasound therapy with standard treatment. Trials varied in terms of ulcer size, regimen and duration of follow up. No trials individually found a statistically significant difference in the number of ulcers healed between any of the therapies, however on pooling trials (different durations of follow up) for the outcome of risk healing, significantly more ulcers were completely healed with ultrasound (RR 1.49, 95% CI 1.07 to 2.09). Some trials also found that ultrasound increases the rate of change of wound size and/or reduces the size of existing ulcers, whilst other trials did not find this effect to be significant. When all trials reporting percentage ulcer area remaining were pooled there was a significant benefit associated with ultrasound (WMD -5.34%, 95% CI -8.38 to -2.30).

AUTHORS' CONCLUSIONS

The available evidence suggests that ultrasound may increase healing of venous leg ulcers. These conclusions are based on the results of only eight small studies of generally poor quality and therefore should be interpreted with caution.

Healing sound: the use of ultrasound in drug delivery and other therapeutic applications

Ultrasound, which is routinely used for diagnostic imaging applications, is now being adopted in various drug delivery and other therapeutic applications. Ultrasound has been shown to facilitate the delivery of drugs across the skin, promote gene therapy to targeted tissues, deliver chemotherapeutic drugs into tumours and deliver thrombolytic drugs into blood clots. In addition, ultrasound has also been shown to facilitate the healing of wounds and bone fractures. This article reviews the principles and current status of ultrasound-based treatments.

[Wound bed preparation of chronic wounds with ultrasound]

The use of different low dose ultrasound systems is an innovative and effective alternative strategy of treatment in wound bed preparation of different chronic wounds. The handling of the ultrasonic systems is easy to learn, their use is safe and little additional equipment is required. Induction of the so called cavitation phenomenon seems to be a major effect which permits selective debridement and reduction of microorganism colonisation. While the suggestion is that granulation tissue is promoted and wound healing accelerated, there are few well documented evidence-based data. Additional randomized controlled trials are needed before the therapeutic efficacy of ultrasound in this clinical setting can be evaluated.

Wound debridement, Part 1: Non-sharp techniques

The first article of a two-part update on wound debridement.