Although ultraviolet A (UVA) and ultraviolet B (UVB) have been used in health care for some time to treat dermatological conditions such as psoriasis and also have evidence to support the use of ultraviolet radiation to promote wound healing, ultraviolet C is the type of ultraviolet light that is most commonly utilized today in the treatment of chronic wounds.^1,2 Specifically, ultraviolet C (UVC) is beneficial for the treatment of chronic wounds due to its bactericidal effects.³ As the number of drug-resistant organisms continues to increase, wound clinicians must consider treatment options that not only effectively destroy bacteria without damaging fibroblasts and other cells necessary for wound healing, but also avoid the development of resistance.⁴ UVC accomplishes both of these treatment goals and is a cost-effective, portable, and safe non-carcinogenic treatment modality.^5,6

Understanding the types of ultraviolet light is important in order to choose a wavelength that will deliver the desired outcome (TABLE 19-1, FIGURE 19-1). This chapter focuses on UVC, which has the FDA approval for use on open wounds due to its bactericidal effects.⁷ TABLE 19-2 provides terminology and definitions utilized in the discussion of ultraviolet light. Handheld UVC devices consist of lamps that deliver ultraviolet light at a specific wavelength (254 nm), which falls within the optimal wavelength range for bacterial reduction.^8,9 These devices contain filters specific to UVC that reduce the risk of skin cancer and skin burns often associated with UVA and UVB.¹⁰ Although studies have shown an increase in risk of skin cancer associated with the use of ultraviolet B, there has been no link reported between skin cancer and UVC.^10,11

When delivered at therapeutic levels, UVC can be used as an adjunct to antibiotic therapies and topical antimicrobial dressings in order to decrease the wound bioburden, especially in wounds with inadequate vascular supply which reduces the ability of systemic antibiotics to reach the infected tissues. When the UVC device is held 1 inch from the wound bed, the short-wave UVC is delivered at a precise nanometer (254 nm), resulting in a photochemical effect that leads to bacterial cell death.^3,6

When UVC is delivered at 254 nm, a photochemical effect occurs in one of the four proteins that make up the double-helix structure of cell DNA in bacteria. Where two thymine proteins are located next to each other on the double helix, the photochemical effect generated by the application of UVC causes the thymine proteins to fuse, thereby altering the DNA in the nucleus of the bacteria and rendering the cell useless. The bacteria cell is unable to metabolize or divide and eventually dies (FIGURE 19-2).⁴ The inhibiting function of UVC radiation gives this technology the unique ability to kill bacteria without promoting resistance, unlike systemic and topical antibiotics.¹² UVC delivered at 254 nm is strongly absorbed by organic molecules, such as the DNA of a bacteria cell, as described above. This same level of UVC light is much too low to have the same negative impact on mammalian keratinocytes and other healthy cells needed for wound healing.⁵ The ability of UVC to selectively destroy bacteria cells without causing harm to healthy tissue enables the intervention to eradicate bacteria without negatively impacting wound healing.

Ultraviolet C may be indicated in acute or chronic wounds where the presence of bacteria in the wound bed impedes wound healing. Wounds of many different etiologies may benefit from UVC in the presence of bacteria; however, the clinician must carefully consider the various contraindications and precautions to treatment. See TABLE 19-3 for a list of contraindications, precautions, and possible adverse reactions. If a patient experiences an adverse reaction as a result of UVC treatment, the treatment is discontinued immediately.