Ultrasound Assisted Wound Therapy: An Exceptional Adjunct to Wound Bed Preparation

For the readership of this journal, wound bed preparation is certainly not a new concept, although it is one that has gained increasing discussion and understanding over recent years. As the authors of this article began practicing in the same clinic in 2001, the routine of obtaining a clean wound bed by debridement, working toward control of the bioburden with some of the early antimicrobials, and using topical products to balance the moisture environment was in the literature1,2 and also had becoming standard practice. Add to that intervening with advanced and active devices such as collagen, cell therapies, negative pressure wound therapy and growth factors, offering patients the best care the authors believed available at the time. Since then, much has been written, acronyms developed, increased attention and focus on the importance of addressing the wound edge has emerged, and wound bed preparation unquestionably has become a standard of care.3,4 Then in the summer of 2004, the authors were introduced to a technology that has helped professionals to continue to meet that standard: Ultrasound Assisted Wound Therapy (UAW).

The medical use of ultrasound is not a new concept. The use of ultrasound to treat many disorders began to appear in the literature as early as 1949.5 Therapeutic ultrasound delivers energy through mechanical vibrations in the form of sound waves at frequencies above detection by the human ear (>20 kHz). Historically, ultrasound is commonly associated with diagnostic imaging in which high-frequency ultrasound waves with minimal physiological effects are utilized. In addition, high-frequency therapeutic ultrasound (in the 1 to 3 mHz range) has been used in physical therapy, physical medicine, and rehabilitation and sports medicine for many years for treatment of soft tissue injuries and wounds.6 In recent years, low-frequency ultrasound has been employed to impact tissues in the wound bed.
Low-frequency ultrasound provides two largely non-thermal effects, which are cavitation and acoustic streaming.7 The cavitation phenomenon may be described as the creation of miniscule gas bubbles in tissue fluid and the expansion and contraction in size of these bubbles in tandem with the variation in the ultrasound field pressure levels. At certain amplitudes of the sound waves, the bubbles implode; this implosion results in the formation of tiny shock waves. Because necrotic tissue has less tensile strength than viable tissue, these locally generated shock waves in turn liquefy the necrotic tissue, other wound debris, and associated biofilm, while not injuring viable tissue. The acoustic streaming initiates a unidirectional movement in fluid in an ultrasound field. This activity stimulates cell activity and enhances clinical outcomes.8,9

Ultrasound Assisted Wound Therapy has been utilized as a wound debridement and cleansing technique for years in the United Kingdom, Russia, and Germany. This technique of wound debridement has many advantages; the results can be as immediate as sharp or surgical debridement, generally requires only topical anesthesia, is selective for nonviable or necrotic tissue but can also be effectively used for excisional debridement. UAW is bactericidal10 at the surface and also penetrates into surrounding tissues, and can be performed in a variety of settings by trained personnel.
There are three devices which utilize thermal, contact ultrasound energy (see Ultrasound Sidebar), The SonicOne™, (Misonix, Inc., Farmingdale, NY) The Sonoca® 180, (Söring, Inc., North Richland Hills, Tex) and the latest in this line of devices, The Qoustic Wound Therapy System™ (Arobella Medical, LLC, Minnetonka, Minn). From a clinical standpoint, the authors’ clinic had the somewhat unique opportunity to have experience with all three of them. They all carry their own unique
differences, but the end result is ultimately the same: a clean wound with a visible difference. This therapy has been part of the clinic’s operations for 4 years, and it would now be very
difficult to practice without it.

Indications for the use of UAW include but are not limited to11
l Locally infected wounds.
l Wounds with impaired circulation.
l Wounds with the need for debridement, irrigation, and topical treatment.
l Pressure ulcers, diabetic foot ulcers, lower extremity diabetic ulcers, venous ulcers.

Contraindications
l Untreated advancing cellulitis with signs of systemic response.
l Wounds with metal components such as joint replacements, plates and screws, or implanted electronic devices within the treatment field.

l Uncontrolled pain.
In summary, as with any therapy or device, there are pros and cons. When thinking about UAW Therapy, the authors see it as pro. ‘oh well’, and a con.

On the ‘con’ list, there is only really one, and that is the price. These are costly devices, and unfortunately, don’t have additional reimbursement that ‘pays’ for them directly, above and beyond normal clinic charges. But as credit card commercials have helped us to understand, some things are simply priceless. Many hospital-based clinics are likely approaching the time when requests for budget and capital expenses for next year are being submitted, so this should be on your wish list.
On the ‘oh well’ list, there are a few things that clinicians just have to get used to and better at.

Time
It is a bit longer procedure, and often may follow instrument debridement that can de-bulk the necrotic tissue. The time for set-up, the procedure, cleaning, and preparing for the sterilizing of the instruments can add about an hour to the total time of the visit. It gets easier and faster with a bit of practice and coordination within the clinic.

Fluids
Because of the flow of fluid through the handset of the two of the devices, there is definitely aerosolization and overflow of the fluid, which simply requires preparation with absorptive padding and full PPE (gown, face shield or mask and goggles). The newer system, the Qoustic by Arobella, there is less fluid flow and a reduction in aerosolization, but PPE is still probably a good idea. Newer, more absorbent pads available such as the Ultrasorbs® Pad (Medline, Inc., Mundelein, Ill) make handling the fluid flow almost a non-issue.
On the pro list, one can only summarize. The benefits are better understood through use.

Wound Bed
A remarkable difference in the appearance of the wound. UAW Therapy provides excellent preparation for healing, but also preparation for advanced products such as skin equivalents, matrix products and growth factors. The obvious visible reduction in surface debris, coupled with the understanding of how the energy is effects the tissue generates a confidence in the effects that the therapy can provide.

Patient Tolerance
There is overall a dramatic difference in the patient’s report of pain with UAW Therapy then sharp instrument debridement. This also gets better with practice and use; keeping the probe moving, the level of intensity used, flow of fluids, etc. Topical anesthetics are all that are required.
Portability
The units are on rolling stands, so can be taken from the outpatient center to the inpatient setting easily.

Multispecialty Use
The therapy can be provided by physicians, nurses, and therapists alike. Nurse and therapist use will be dictated by their practice act, job description and competencies on file at their place of practice.
While seemingly a high expenditure with no direct reimbursement, there is unquestionably a high return on investment in terms of adjunctive care for chronic wounds. The proof is in the use—try one at a wound center near you. n

Dr. Walter Conlan is the Medical Director for Wound Healing at Osceola Regional Medical Center in Kissimmee, Fla and Seminole Wound Healing in Longwood, Fla.

Dot Weir is the Wound Care Director for Osceola Regional Medical Center in Kissimmee.