Factors Affecting Wound Healing

The physiological changes that occur with ageing place the older patient at higher risk of poor wound healing. Reduced skin elasticity and collagen replacement influence healing. The immune system also declines with age making older patients more susceptible to infection. Older people can also present with other chronic diseases, which affect their circulation and oxygenation to the wound bed.

This leads to an electrolyte imbalance and impaired cellular function. It is a particular problem in patients with burns and fistulae.

Effective hand washing greatly reduces the risk of transferring pathogenic organisms from one patient to another by direct contact or by contamination of inanimate objects that are shared.

Infection has been defined as the deposition and multiplication of organisms in tissue with an associated host reaction. If the host reaction is small or negligible then the organism is described as colonising the wound rather than infecting it. It is important to distinguish between colonisation and infection since colonised wounds will heal without the need for antibiotics (Cutting 1994).

Contamination is the deposition and survival, but not the multiplication, of the organism Ayton 1985).

Wound infection is a problem because, at the most fundamental level, infection stops a wound from healing by:

• Prolonging the inflammatory phase
• Disrupting the normal clotting mechanisms
• Promoting disordered leukocyte function and ultimately preventing the development of new blood vessels and formation of granulation tissue.

Assessment of a wound in order to identify wound infection should not be limited to swabbing the wound for bacteriological analysis.

Infection occurs when virulence factors expressed by one or more micro-organisms in a wound out-compete the person's immune system. Subsequent invasions and spread of microorganisms in good tissue provokes a series of local and systemic responses such as:

i) Surgical (acute wounds)

• local pain / tenderness
• local swelling / oedema
• increased exudate either serous or purulent or haemoserous
• separation of wound edges / wound breakdown
• pyrexia
• delayed healing

ii) Chronic wounds

• delayed healing
• increased fragility or change in appearance of granulation tissue
• unexpected pain / tenderness
• pocketing or bridging of epithelial tissue
• an abnormal smell
• presence of exudate either serous or purulent haemoserous
• local swelling / oedema
• extending margin or erythema
• pyrexia
• wound breakdown

Anti-inflammatory, cytotoxic, immunosuppressive and anticoagulant drugs all reduce healing rates by interrupting cell division or the clotting process.

• Good wound oxygenation is essential for wound healing. Oxygen influences angiogenesis, epithelialisation and resistance to infection
• Discourage smoking

• The need for good personal and oral hygiene should be discussed with the patient.

• Protein is required for all the phases of wound healing, particularly important for collagen synthesis.
• Glucose balance is essential for wound healing.
• Iron, required to transport oxygen.
• Minerals, zinc, copper, are important for enzyme systems and immune systems. Zinc deficiency contributes to disruption in granulation tissue formation.
• Vitamins A, B complex and C, are responsible for supporting epithelialisation and collagen formation. It is also important for the inflammatory phase of wound healing.
• Carbohydrates and fats. These provide the energy required for cell function. When the patient does not have enough, the body breaks down protein to meet the energy needs. Fatty acids and essential for wound healing.
• Refer to Dietician if patient is malnourished

PATIENT EDUCATION - suggest to patient that:

• Food is there to be enjoyed
• Variety in what we eat is healthy
• They should eat the right amount to be a healthy weight. This will vary for age, sex and level of activity.
• They should try not to eat too much fat, sugar or salt.
• The diet should provide plenty of vitamins and minerals
• Keep levels of alcohol within recommended limits.