Electrotherapy and wound healing - Part 2

Introduction

In the first article in this series, we introduced the idea of using electrotherapy for wound healing. It’s perhaps not the first approach clinicians think of but we feel it is a legitimate approach and worth considering; especially when other approaches are not proving to be effective. In this article we look at what is known and unknown about this approach. We then look at spinal cord injury and treatment of pressure ulcers in this population. We give an example fo using a Hasomed RehaMove unit with Sequence Mode and a RISE unit to support this application.

To Recap

Electrotherapy has a long history of application in medicine - serious and successful but tainted from time to time by quackery. There is quite a lot of research but the topic is complex with many influences. It is possible to find research that suggests electrotherapy can reduce inflection - although we would generally suggest the presence of infection is a contraindication. Certainly the balance of evidence suggests that it can increase perfusion and indeed accelerate wound healing. The devil is in the detail.

Skin Battery

We described in Part 1 how the body features many “bioelectric” processes. Indeed each cell in the body is an electrical unit. A wound to the skin actually disrupts what we referred to as the natural “skin battery”. We know that the human epidermis actually exhibits this “battery-like behaviour”.

The skin battery was first observed in the 1800’s and then Barker et al (1982) were able to measure the voltage more accurately. In physiological solution there are no free electrons to carry current but unbroken skin layers of the epidermis and dermis maintain this skin battery through ionic movement.

Things change when the skin is broken. Broken skin generates a small electric current when wounded. Healing is arrested when the flow of current is disturbed or when the current flow is stopped during pro-longed wound opening. A detailed description of the processes at work can be found in the review article by Thakral et al (2013).

The mechanisms by which healing occurs in response to electrotherapy remain unclear (Hunckler & de Mel, 2017) but it is suspected that it restarts or accelerates wound healing by initiating the natural electrical current that occurs in injured skin.

Effects on Infection

Bacterial load and infection are thought to be important factors in chronic wounds and delayed healing (Edwards and Harding, 2004; Halbert et al, 1992; Madsen et al, 1996).

Bacterial colonisation of  greater than 105 organisms per gram of tissue is associated with infection and delayed wound healing in chronic wounds (Bendy et al, 1964; Robson et al, 1969).

Thakral et al suggest that the bacteriostatic and bactericidal effects of electrotherapy may lower the bioburden in the wound bed, therefore providing one mechanism to facilitate wound closure. There are no clinical studies that report infection or adverse events in the electrical stimulation randomised controlled trials (RCTs) that the authors evaluated.

Effects on Perfusion

In addition to increased skin perfusion, electrical stimulation therapy has been shown to improve venous flow. Thakral et al (2013) reviewed six randomised clinical trials that examined the effects of electrical stimulation on perfusion using a variety of measurement approaches. In addition to increased skin perfusion positive effects on venous flow were noted. Transcutaneous electrical stimulation was evaluated with 24 healthy volunteers and shown to increase the activity of the calf muscle pump.

Effects on wound healing

Thakral et al ( 2013) identified 21 randomised clinical trials that used electrical stimulation to treat wounds such as pressure ulcers, venous stasis ulcers, vascular ulcers and diabetic foot wounds. The authors noted the difficulty posed in drawing conclusions due to the small sample sizes, variation in outcome measures and the type and dose of electrical stimulation used. Some of the studies looked at the percentage change in wound area at 4-6 weeks as a primary outcome rather than the time to complete healing.

So where does that leave us?

We have seen that research has been positive with no real complications across a range of clinical wound healing applications. The approach is relatively safe to use with few contraindications.

Having said this, there is a lack of clarity of the “best” form of electrical stimulation to use or indeed the dose necessary. Further work is certainly necessary. However, faced with a chronic wounds clients sometimes look to try electrotherapy to resolve their problem. What should they do?

Application in spinal cord injury

The following represents something of an application consensus of individuals with experience of both electrotherapy and spinal cord injury.

The success of electrotherapy protocols in wound healing have varied according to diagnosis, depth of the lesion and severity of metabolic compromise, but the results have been rewarding, as well as statistically significant, in the spinal injury patient population.

Successful protocols have included daily stimulation for a total time of two or more hours. Some investigators have employed a very low intensity direct current. Others have used a pulsed current and created some tetanic muscle contraction in the area of the pressure ulcer. Electrodes may be placed adjacent to the wound.

Not all spinal cord injured patients are candidates for electrotherapy to augment their wound healing. Although research suggest that electrotherapy can positively affect infection, caution is necessary in this case where a deep pocket of infection might not be obvious. Tests must be performed first of all to determine if there is a larger area of infection under the skin and if the infection has a pathway to other organs or to a joint. It is important to determine if there is infection of the underlying bone, or osteomyelitis.

Surgical intervention may be necessary to clean the area and to graft muscle and skin to cover the bony prominences [ie a myocutaneous rotational flap graft]. Electrotherapy may be of value prior to such surgery for the purpose of reducing spasticity. If the spasticity can be modulated before surgery, it may not be necessary to cut nerves, or do a neurectomy, to keep the spasticity from interfering with post-operative healing.

After wound closure, the mechanical integrity of the skin will not be the same as the original and it will be essential to continue routine skin checks and to review custom seating devices to maintain relieved pressure over bony areas.

Example Applications with Equipment

We have used the Edition 5, RISE and RehaMove units in wound healing when approved medically for specific clients.

Here is the process we have used with the Hasomed RehaMove stimulator with a client

A client writes - Mr BK T6/7 ASIA A

It would seem there is not enough gluteus maximus to protect my Ischium on one cheek. I am booked into **** for X-rays & seating diagnostics once fit to travel. At the moment hopefully its been caught in time before anything too serious happens as only red marks on the skin under the Ischium, but the reality for me for the next few weeks is to keep off my butt. I can work from home but still a real bummer – literally.

Here is the approach we took illustrated as a flow chart

For this application we used Sequence Mode software with the Hasomed RehaMove unit. The stimulation parameter ranges are as follows:-

RehaMove FES unit

The Hasomed RehaMove unit can be used in wound healing with an appropriate selection of current, frequency and pulsewidth. The unit has 8 channels and uses bipolar rectangular pulses with adhesive electrodes. Although it is most often seen as part of our FES Cycling system when using the included Sequence Mode software it becomes a very powerful tool for many applications including wound healing.

• Pulse width range 20 - 500 micro seconds

• Current range 5 - 130 mA


• Frequency 5 - 50 Hz

For this application, Sequence Mode was being used just on one channel. When using the system, Sequence Mode continues to cycle using the channel on and off times that are set by the user. The user can vary the pulse width, current and the overall cycle time during operation. The pulses used were rectangular form, biploar pulses with no DC component.

Note the strategy with dealing with the red marks was to increase perfusion in the area until these were resolved and then the user would switch to the process of increasing muscle mass.

To treat the red marks stimulation parameters were set to produce a barely perceptible muscle contraction which was then held for 3 seconds. The process commenced with 15 minutes per day of stimulation and gradually increasing to 1 hour per day.

To build muscle mass we used a slightly higher frequency to produce a smooth contraction. On and off in a ratio of 3 to 2.

Red marks were resolved at 4 weeks.

We have also used the RISE and Edition 5 units to accelerate would healing.

Electrode placement using the RISE stimulator

Blue elastic wraps were used to secure wet sponge/carbon rubber electrodes above and below the wound sites. The sponges have pockets to contain the electrodes and must be secured firmly to the tissue. The sponges should be wet throughout the process.

The frequency used was 40Hz with bipolar rectangular pulses of 250 microseconds duration. Current levels were set to produce a slight tetanic contraction held on for 4 seconds and then off for 4 seconds. This protocol to be used for 1 hour per day and for 6 to 7 days per week until healing occurs.

In the case of denervation much longer pulse widths are necessary but the process is largely the same.

General Contraindications

Although electrotherapy when applied correctly is a safe process there are always some relative and absolute contrindications. The recommendations will vary with the specific equipment and manufacturers guidance. Typical contraindications relate to use over metal implants, pacemakers and other implants in the area as well as situations of acute inflamation, inflection or tumours. Some types of wound dressings contain metal ions and traces of these should be removed before applying stimulation.

Conclusion

There are many opportunities to improve clinical outcomes with electrotherapy. In many ways, electrical stimulation appears to be a perfect adjunctive therapy. First, no device-related complications or adverse effects have been reported in the existing literature. The approach is safe and easy to use.

As it decreases bacterial infection, increases local perfusion, and accelerates wound healing, it addresses the three pivotal factors in surgical wound complications. Electrical stimulation offers a unique treatment option to heal complicated and recalcitrant wounds, improve flap, replantation and graft survival, and even improve surgery results. This is an approach that can even be applied throughout the recovery process. Electrical stimulation is a simple, inexpensive intervention to improve surgical wound healing. Rigorous clinical trials are needed though to help understand the dosing, timing, and type of electrical stimulation to be used. It is not easy to provide general application guidelines that are fully evidence based. As always, application whould be carried out with clearance from a physician.

References

Barker AT, Jaffe LF, Vanable JW Jr. The glabrous epidermis of cavies contains a powerful battery. Am J Physiol 1982; 242: R35866.

Bendy RH Jr, Nuccio PA, Wolfe E, Collins B, Tamburro C, Glass W, et al. Relationship of quantitative wound bacterial counts to healing of decubiti: effect of topical gentamicin. Antimicrob Agents Chemother (Bethesda) 1964; 10: 14755.

Edwards R, Harding KG. Bacteria and wound healing. Curr Opin Infect Dis 2004; 17: 916.


Foulds IS, Barker AT. Human skin battery potentials and their possible role in wound healing. Br J Dermatol 1983; 109: 51522.

Halbert AR, Stacey MC, Rohr JB, Jopp-McKay A. The effect of bacterial colonization on venous ulcer healing. Aust J Dermatol 1992; 33: 7580.

Hunckler J and de Mel A. A current affair: electrotherapy in wound healing. Journal of Multidisciplinary Healthcare 2017:10 179–194

Madsen SM, Westh H, Danielsen L, Rosdahl VT. Bacterial colonization and healing of venous leg ulcers. APMIS 1996; 104: 8959.


Robson MC, Heggers JP. Bacterial quantification of open wounds. Mil Med 1969; 134: 1924.

Thakral, G et al. Electrical stimulation to accelerate wound healing. Diabetic Foot & Ankle 2013, 4: 22081 - http://dx.doi.org/10.3402/dfa.v4i0.22081