Bioelectrical Stimulation: An Introduction To The Future of Wound Care
Bioelectrical Stimulation: An Introduction To The Future of Wound Care
Co-authored by Professor Ardeshir Bayat BSc (Hons) MB BS PhD & Chloe Stockwell Clark BSC (Hons), Biology, Cell
Wound management remains a contentious challenge in the clinical sector, impacting top tier medical systems and significantly increasing the overall cost of medical care. The sector has cost the UK NHS an estimated £8.3 billion per year, of which £2.7 billion and £5.6 billion were associated with managing healed and unhealed wounds, respectively. Reports show 81% of the total annual NHS cost was incurred within the community setting. This equates to 3.8 million patients annually presenting with some form of wound(1). Despite recent advances in the wound care sector, there is still an unmet need for a treatment modality capable of improving both the rate and quality of wound healing. The integration of such wound care technology would significantly benefit the wider health economy, patient recovery and overall quality of care.
Phases and treatment modalities for wound healing
After tissue damage, wound healing follows a series of physiological events. The phases of wound healing include; hemostasis, inflammation, proliferation, and remodeling. Patients’ healing response time may vary due to local and systemic factors such as the ones listed below:
The wound care needs of patients can be complex and requires a coordinated, multidisciplinary, team-based approach which uses different scientific and technological modalities.
Clinical pathways of wound management may involve; metabolic control, debridements, wound care products, antibiotics, reconstructive and/or vascular intervention, hyperbaric oxygen treatments and electrical stimulation. Involvement of the patient in the treatment with the help of new therapeutic approaches is an important part of the wound management process.
The Role of Electrical Stimulation
Electrical stimulation (ES) treatment modality is gaining interest and popularity amongst health professionals due to its convenient, non-invasive and drug-free nature. As a result, ES is becoming more established within different healthcare settings including; primary care, secondary/clinical care and home care environments. It is a highly accessible technology in terms of cost and practical application, whilst being indicated for wounds of various aetiologies.
The key areas of wound care where ES could have the largest impact are:
- Chronic Wound Healing - Facilitated healing for chronic wounds including diabetic foot ulcers, vascular ulcers, burns, pressure wounds etc.
- Acute Wound Healing - Accelerated healing for post-operative surgical sites, soft tissue injuries and common wounds.
- Prevention -It is predicted that ES improves the causes and consequences of chronic wound formation on the skin. It is used for diabetic neuropathy with or without impaired circulation, vascular diseases (venous or arterial), and immobility patients who are at risk of decubitus ulcers.
How are Electrical Stimulation Formulations Developed?
The complex series of wound healing processes and cascades on both cellular and systemic levels have been well established. More recently, it has become evident that when ES is applied similarly to naturally occurring bioelectrical activity of tissues and cells, it can be beneficial to the biomolecular mechanisms needed to support and facilitate the underlying healing processes. In response, advanced ES can be formulated and optimised specifically for the purpose of facilitating wound healing.
Research and published literature on the application of ES for wound healing have uncovered a range of parameters that elicit particular physiological responses that are advantageous and supportive of the different stages of healing. Therefore, it is essential that ES used for wound healing has been formulated using parameters known to be specifically beneficial for wound healing, over other basic or generic waveforms. In order to incorporate all waveform parameters and optimise ES application, it is best practice for the treatments to be formulated and preprogrammed into software that delivers the optimised treatments of ES without the need for manual adjustment or manipulation of the current being applied. As a result, high efficacy, user friendly and relatively low-cost ES wound care technology can be harnessed and readily available for clinician and patient use.
It is essential that ES used for wound healing has been formulated using parameters known to be specifically beneficial for wound healing, over other basic or generic waveforms
Microcurrent Stimulation (MCS):
For the application of ES for wound healing, Microcurrent Stimulation (MCS) is used to provide electrical current that is most similar to endogenous bioelectrical activity of cells and tissues, and has been shown to facilitate the biomolecular processes involved in wound healing and tissue repair.
When developing and formulating effective microcurrent waveforms, some of the key parameters include;
- Waveform Shape e.g. square, rectangular, sinusoidal.
- Current Type e.g. direct, pulsed or alternating current.
- Polarity e.g. biphasic or monophasic. The polarity of the electrical current is a significant factor in healing, with negative and positive polarities being beneficial at different stages of the healing process(2).
- Amplitude e.g. Wound healing amplitudes range between 0-500 microamps (µA).
- Frequency Ranges used are often between 0.5 - 500 Hertz (Hz).
- Pulse e.g. Duration/width, spacing and burst patterns.
Physiological Responses to ES/MCS Stimulation
There are a number of mechanisms of action and physiological responses reported in scientific literature in response to ES/MCS for wound healing. These include;
1. ‘Current of Injury’
Wounds that result from trauma or surgery are associated with changes in bioelectric potentials, termed ‘current of injury’(3). This has been observed at the wound site, and plays a key role in the repair process (4). These fields measure an estimated 140 mV/mm and play important roles in controlling several aspects of the cell biology of wound healing(3).
In essence, damaged tissues generate the current of injury, which appear to drive elements of the healing response (5-9). Alterations in normal endogenous bioelectricity, due to pathology or trauma, can impact the natural repair process and impair wound healing. There is evidence to suggest that the application of exogenous current across the wound site, facilitates and restores the natural repair process through various mechanisms. This includes; acting as a guidance cue and promoting wound healing (10-11).
Evidence suggests that the application of exogenous current across the wound site, facilitates and restores the natural repair process.
2. Down-regulation of Inflammation
Regardless of whether the wound is from surgery or trauma, managing inflammation is critical. In some cases, wounds do not progress to the normal healing stage with formation of a final mature scar, but instead remain in the inflammatory process, which can progress to chronic wounds(12). Research has revealed:
The third physiological response, angiogenesis, is a physiological process that involves the growth of renewed blood vessel formation from the existing vasculature. Cells of metabolically active tissues are a few hundred micrometers away from a blood capillary. Adequate perfusion is essential, and blood vessel capillaries are necessary for ensuring adequate diffusion exchange of nutrients and metabolites in various tissues of the body(17).
Angiogenesis is a vital component of the processes involved in wound healing(18-19). There is evidence to suggest that inadequate angiogenesis can be conducive to wound healing impairment and chronic wound formation(20-24).
Bai and colleagues (2005) reported that a direct current electrical signal may act as a directional cue and play a role in the spatial organisation of vascular structure(25). Also, it has been observed that electrotherapy can mediate angiogenesis(26-27), which is facilitated by increased expression of vascular endothelial growth factor (VEGF). Moreover, experimental gene and protein investigations are in accordance with these findings by showing up-regulation of angiogenesis and down-regulation of inflammation in electrotherapy treated wounds (28), and also promoting wound healing(29-33).
It is most likely that a combination of different biomolecular responses elicited by ES has enabled enhanced healing in respect to both the rate of healing and quality of the reformed tissue structure.
Summarising Wound Care and Electrical Stimulation
To conclude, scientific literature and a growing body of evidence suggests that bioelectricity plays a key role in the repair process of injured tissue, and provides a robust rationale for the application of exogenous current to promote wound healing(10-11). In response, ES demonstrates a promising and novel therapy application for use in combination with gold standard wound care. Conveniently, ES can be readily applied to different types of wounds, especially where the natural repair mechanism is impaired due to underlying pathology. However, such promising wound care technology is entirely dependent on the application of evidence-based formulations of ES/MCS in order to yield positive and optimized outcomes.
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