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This issue of the journal highlights important clinical and research issues relating to the increased utilization of physical modalities in wound care. "Physical modalities" is an umbrella term that encompasses a variety of treatment options practitioners may use to manage wounds. These modalities are based on physical energy, which is nothing new in medicine: The use of physical energy to treat maladies in both body and mind can be traced to antiquity. In the past, physical energy has been used for diagnostic purposes, such as x-ray and magnetic resonance imaging. In the conceptual framework for applying external physical energy to the human body, energy is harnessed and delivered by a focused, safe method to evoke a response in the target tissues. The applied energy may be diagnostic (eg, ultrasound), constructive (eg, healing), or destructive, depending on the intent and the targeted body structure. For example, therapeutic radiation used in a patient with cancer may harm the patient's skin while it destroys a tumor and possibly saves the patient's life.

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Current physical modalities deliver focused energy to the skin and the subjacent tissues. These modalities include


* electrical stimulation-delivers direct or alternating electric current to the wound, using microstimulators packaged in various configurations and various delivery microelectrodes (surface or implantable)


* electrical stimulation-used to enhance bone formation and connective tissue regeneration, chronic wound tissue regeneration, and nerve tissue regeneration, all reportedly without adverse effects


* systemic hyperbaric oxygen (HO)-oxygen applied at pressure greater than 1 atm (1 atm is ambient pressure at sea level [760 mm Hg or 14.7 psi]); administered in a full-body chamber with the patient breathing 100% oxygen intermittently as the pressure of the treatment chamber is increased to 2 to 3 atm (equivalent to 1500-2500 mm Hg or 30-45 psi).


* topical HO-oxygen applied directly to the base of an open wound at a pressure slightly above atmospheric, for example, 1.03 atm (22 mm Hg or 0.4 psi)


* negative-pressure wound therapy-designed to enhance tissue migration and wound closure through the use of subatmospheric (negative) pressure


* light-emitting diodes-use near-infrared light to provide energy in the form of red light


* diathermy-uses high-frequency current to generate heat in body tissues and facilitate repair


* iontophoresis-based on the electrical principle that like charges repel and unlike charges attract; used to drive electrically charged medications into subjacent tissue


* phonophoresis-uses sound waves to move the therapeutic agent into the skin.



The presumption is that most of these modalities assist wound healing by enhancing the local wound environment. For example, they do so by increasing


* oxygenation,


* blood flow,


* chemotaxis of white blood cells,


* activity of the fibroblasts,


* wound contraction,


* epidermal migration,


* tensile strength,


* edema reduction,


* nitric oxide production, and


* mechanical pressure, which enhances wound closure.



Ultrasound is not new and can be traced to Lazzaro Spallanzani. In 1790, he experimented with bats and found that they maneuvered through the air using their hearing rather than sight. After the sinking of the Titanic in 1912, Paul Langevin invented the hydrophone to detect icebergs. This was the first transducer, a device that was able to send and then receive low-frequency sound waves. The hydrophone was later used to detect submarines in World War I. This was a major step in the history of ultrasound. Subsequently, the use of ultrasound has been advancing for both imaging and therapeutic applications. Some of the potential benefits to ultrasound as a physical modality are catalogued in the article found on page 316 in this issue, "In Vitro Activity of the Qoustic Wound Therapy System against Planktonic and Biofilm Bacteria."


Vibration as a modality has been used in the US Space program as a countermeasure to the lack of dynamic and static loading of the muscles and bones during prolonged weightlessness. The unintended consequences of space flight on the human body are muscle atrophy and loss of bone density. During normal gravity-related walking, the muscles and bones are stimulated by natural human intrinsic microelectric currents that travel in the central and peripheral nervous system as a result of normal human locomotion. In addition, muscle vibrations have an anabolic effect on the tissues by creating bone density; it is possible to extrapolate a potential effect on the tissues by enhancing blood flow as proposed in this issue on page 321, "Vibration Therapy Accelerates Healing of Stage I Pressure Ulcers in Older Adult Patients." To apply the therapeutic mechanisms of vibration or wounds takes some imagination and requires hypothesis-driven research and clinical evidence. I do have some concerns about using grade pressure ulcers as a model for wound healing, given the controversies about grade 1 pressure ulcers and their precision: Is a grade 1 pressure ulcer the tip of the iceberg (a grade 4 waiting to declare itself)? Could vibration be considered a type of massage, and is massage contraindicated in pressure ulcers? (Clinical anecdote passed uncritically by generations of clinicians.)


Certainly, we have more questions than answers. Not all of these physical modalities have strength-of-evidence ratings to support their generalized use in wound care-yet. Scientific data from randomized, prospective clinical trials are beginning to emerge and to be accepted by both practitioners and payers.


Because we live in a technology-driven world, more applications are sure to be implemented now and in the future. I think that we should methodically define the clinical problem and design technology applications to the clinical problem, not the other way around. In my view, these physical modalities are best used in combination with standard wound care, such as debridement, off-loading, and appropriate moist wound dressings as indicated for the patient's wound. As wound care practitioners, we should be prepared to embrace the latest technology that brings physical modalities to the bedside and uphold established principles of wound care.


Richard "Sal" Salcido, MD

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Selected References


National Aeronautics and Space Administration. Good vibrations. Last accessed May 28, 2010.


Salcido RS. Physical modalities and wound care. Adv Skin Wound Care 2004;17:100.