What Is Defined as a Chronic Wound?
A chronic wound is any wound that fails to progress through the normal stages of healing and remains open beyond the expected period, typically for more than four weeks despite appropriate care.
Chronic wounds represent a major challenge in clinical practice because they arise from a wide range of causes and affect diverse patient groups, including people with diabetes, older adults, patients with circulatory insufficiency, individuals who are bedridden and develop pressure ulcers, and patients who have undergone radiotherapy.
Despite the variety of underlying causes, the pathophysiology of chronic wounds converges on a common feature: the tissue surrounding the wound enters a state of biological inactivity.
The cells responsible for driving the healing process, including fibroblasts, keratinocytes and macrophages, either fail to migrate to the wound or are unable to perform their functions because of inadequate oxygenation, persistent inflammatory activity or depleted regenerative capacity.
As a result, the patient becomes trapped in a cycle in which the wound does not close, infection persists and pain becomes chronic.
Characteristics of Chronic Wounds
Chronic wounds share several common characteristics, regardless of their underlying cause. At tissue level, bacterial colonization may interfere with healing, while persistent inflammation keeps the wound in an “open” state. Cell apoptosis may occur within the healing zone, and the tissue may show a reduced response to growth factors.
Local hypoxia is almost always present and represents the common factor linking these pathological processes.
In clinical practice, chronic wounds require careful assessment of the underlying cause before any treatment decision is made. Effective healing can begin only when the root of the problem has been addressed, whether this is vascular disease, diabetes, radiation-induced tissue injury or sustained pressure.
Scientific Evidence
There is extensive scientific evidence supporting the use of hyperbaric oxygen therapy in chronic wounds of various aetiologies. Studies have shown that restoring adequate local tissue oxygenation is a key factor in reactivating the healing process in biologically inactive tissues. The activation of fibroblasts, the induction of vascular endothelial growth factor (VEGF) to stimulate neovascularisation and the bactericidal action against anaerobic pathogens are among its well-documented mechanisms of action.
The Undersea and Hyperbaric Medical Society (UHMS) and the European Committee for Hyperbaric Medicine (ECHM) recognize hyperbaric oxygen therapy as an indicated approach for chronic wounds of specific aetiologies, while emphasizing that it should be used as an adjunct to standard treatment rather than as a stand-alone intervention.
The Role of Hyperbaric Oxygen Therapy
In chronic wounds, hyperbaric oxygen therapy aims to reverse the biological inactivity of the affected tissue.
It does not replace systematic wound care, infection control or treatment of the underlying cause. Instead, it is used alongside these measures, providing the tissue with the biological conditions required for the healing process to begin.
The increased availability of oxygen dissolved in the plasma enables fibroblasts to resume collagen synthesis, helps macrophages clear necrotic tissue more effectively and allows keratinocytes to migrate across the wound surface and promote epithelialisation.
The stimulation of neovascularisation is perhaps its most important long-term contribution. The formation of new capillaries produces a lasting improvement in local tissue oxygenation, creating more favorable conditions for sustained wound healing.
The number of sessions depends on the type and chronicity of the wound and typically ranges from 20 to 40.