The 'Stuck' Wound 

Wounds that exhibit impaired healing have failed to progress through the normal stages of healing. These wounds often enter a state of pathologic inflammation due to a postponed, incomplete, or uncoordinated healing; becoming ‘stuck’ in the inflammatory and proliferative stages. The epidermis fails to migrate at the wound margins, which interferes with normal cellular migration over the wound bed. Most chronic wounds are ulcers associated with ischemia, diabetes mellitus, venous stasis disease or pressure. Unsurprisingly, non-healing wounds result in enormous health care expenditures. As mentioned, healing consists of four overlapping, and precisely programmed phases. The events of each phase must happen in a regulated way. Interruptions or prolongation in the process can lead to delayed wound healing or a non-healing wound (14).

 

In chronic wounds there is excess production of matrix molecules due to underlying cellular dysfunction and dysregulation. Fibrinogen and fibrin are also common in chronic wounds and it is thought that they scavenge growth factors and other molecules involved in promoting wound repair. Chronic wound fluid is biochemically different from acute wound fluid; it becomes more viscous, and can block cell proliferation; essential for the wound healing process (14).

 

Factors That Impair Wound Healing

Excess exudate (wound fluid) can cause maceration of healthy skin tissue around the wound and inhibit wound healing. Chronic wound  fluid has relatively higher levels of tissue destructive proteinase enzymes and is therefore more corrosive. The smell and staining caused by exudate can have a negative impact on a patient’s general health and quality of life. Foreign bodies introduced deep into the wound during injury can cause chronic inflammatory responses, delaying healing and sometimes leading to granuloma or abscess formation.

 

Other problems associated with wound healing include the formation of keloid (raised) scars resulting from excess collagen production in the latter part of the wound healing process. Pathogenic bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pyrogenes and some Proteus and Clostridium species can be detrimental to healing. Inadequate control measures to manage infected wounds can lead to cellulitis (cell inflammation) and ultimately bacteraemia and septicaemia; potentially fatal.

 

There are factors that need to be controlled and managed effectively, including preventing infection, optimising exudate control and removing foreign bodies which could lead to complications (8). Poor nutritional status and old age reduce the ability to fight infection. Protein, vitamins (e.g. vitamin C) and mineral deficiencies impair the inflammatory phase and collagen synthesis, leading to prolonged healing. Underlying diseases such as diabetes and anemia delay wound healing because compromised circulation results in the delivery of inadequate nutrients, blood cells and oxygen to the wound. Drugs such as steroids suppress the body’s inflammatory responses and thereby impede the inflammatory stage of wound healing, eventually leading to a compromised immune system. Glucocorticoids for example have been shown to impair wound healing in both rats and humans (8). Multiple factors therefore lead to impaired wound healing.

 

Generally, the factors that influence repair can be categorized into local and systemic. Local factors are those that directly influence the characteristics of the wound itself, while systemic factors are the overall health or disease state of the individual that affect his or her ability to heal. Most of these factors interconnect, and the systemic factors act through the local effects, affecting wound healing (15).

 

Drugs and agents that impair healing include vasoconstrictors, e.g. nicotine, cocaine and adrenaline, which cause tissue hypoxia by adversely affecting the microcirculation. They should be avoided in patients with acute, surgical, or chronic wounds. Little evidence exists to suggest that immunosuppressant’s and antineoplastic drugs (such as azathioprine, ciclosporin, cyclophosphamide and methotrexate) affect wound healing in humans. Patients taking immunosuppressants however, have a slightly increased risk of developing malignant ulcers (16).