Impact of photobiomodulation therapy on chronic wound healing

As a complex and highly regulated process occurring in overlapping phases, wound healing is key to retaining physiological function of the skin. Characterised by an excessive and unrelenting inflammatory phase, persistent infection, and diminished cellular response to environmental stimuli, chronic wounds significantly pose a burden to patients and service providers, including the entire healthcare system. Chronic wounds include venous, ischemic and diabetic foot ulcers, and purulent wounds, such as surgical site infections. Most distressing, the response of chronic wounds to exorbitantly expensive conventional therapeutic methods is often diminished, and once healed these wounds are frequently considered “high risk for recurrence”, particularly in the case of diabetic foot ulcers. With the projected epidemic of diabetes mellitus and an aging population in developing countries, it is important to substantiate cheaper and safer therapeutic techniques for the management of chronic wounds to allow health care providers access to treatment alternatives for their patients. For this reason, the development of innovative non-invasive therapeutic modalities is crucial. For some time now, photobiomodulation therapy (PBMT), formally referred to as low-level light/laser therapy (LLLT), has been used to induce physiological changes and therapeutic benefits. Despite the overwhelming evidence regarding its therapeutic capability, PBMT is not universally accepted as the induced effects at a tissue, cellular and molecular level are not completely understood, and mistrust or cynicism towards alternative and unconventional medicine. PBMT involves the use of low-powered (usually less than 1 W/cm²) light emitting diodes (LEDs), lasers or broadband light, mostly in the visible red and near infrared (NIR) light spectrum (600 – 1,100 nm). It is used in a wide variety of applications, and is typically used to alleviate pain, reduce inflammation and oedema, and speed up healing or induce healing in non-responsive chronic wounds of a wide range of aetiologies. Further evidence of the efficiency of existing and future wound therapies is necessitated for their acceptance and appropriate use. This chapter explores the impact of PBMT on wound healing and the basic biochemical reactions involved.