Wound healing is a continuous process which begins at the time of injury.

The process of normal healing can be divided into three phases: inflammation, repair, and maturation.

a. Inflammation. The process of inflammation begins within minutes following a laceration. An increased blood supply with edema and engorgement of surrounding vessels accounts for the inflammatory appearance.

b. Repair. A healthy patient with optimal wound care can expect a semblance of order in the wound to appear on the third day. The cellular and chemical activity during this phase results in “granulation tissue.” Although signs of inflammation subside successively during this phase, the wound remains red, raised, and often itchy.

c. Maturation. During this phase of wound healing, there is a progressive decrease in the vascularity of the scar and an increase in the strength of the scar. Maturation of a scar can occur up to two years after the injury took place. Ideal scarring occurs in three stages.

(1) Stage I–0 to 4 weeks; the scar is soft, fine, and weak.

(2) Stage II–4 to 12 weeks; the scar is red, hard, thick, and strong.

(3) Stage III–12 to 40 weeks; the scar is soft, supple, white, and loose.

d. Complications. Wound complication refers to anything abnormal in the healing process. The term also refers to the loss of function of a body organ, the function loss caused by the initial wound. Infection is the single most common wound complication. Other complications of wound healing include bleeding, dying tissue, and improper healing.

(1) Continued bleeding. Bleeding must be stopped to allow the healing process to proceed.

(2) Dying tissue. Tissues at the site of severe injuries may have been severely damaged by being deprived of their blood supply with its oxygen and nutrients. These tissues will die and must be removed or carried away in the capillaries for healing to take place properly.

(3) Results of improper healing. Here are a number of possible results of wounds that have not healed properly.

(a) Keloid. A keloid is excessive scar tissue growth. Keloids occur primarily in dark-skinned people. Given the proper conditions, anyone can develop a keloid, however. It can be removed surgically for cosmetic reasons. A keloid is the result of improper wound healing.

(b) Abscess. An abscess is a localized infection in which there is an accumulation of pus. Pus is a liquid accumulation of phagocytes (also called leukocytes). An infecting microorganism causes the abscess. The particular microorganism involved determines whether the pus is white, yellow, pink, or green.

(c) Cellulitis. Cellulitis is an inflammation of the deep, subcutaneous tissues and sometimes muscles, usually caused by infection of a wound or burn. Cellulitis sometimes occurs when an abscess is forming. This condition is serious because the infection can spread rapidly and extensively in the tissue spaces.

(d) Empyema. Empyema is the collection of pus in an already existing cavity, such as in the gallbladder or the lung.

(e) Fistula. A fistula is an abnormal passage between two internal organs. A wound that heals improperly could cause such a passage.

(4) Blood supply. Since blood supplies the products used in healing, any factor that restricts blood circulation to a wound area interferes with healing. Dead or edematous tissue, restrictive bandages, and damaged arteries can all slow the healing process.

e. Physiological Responses to Wounds. Once the skin and tissue have been injured, the process of healing begins. Many factors influence the body’s ability to grow new tissue.

(1) Age. Very young and very old people heal more slowly than those in other age groups. People in these age groups have less ability to fight infection, and fighting infection is a major part of the healing process.

(2) Malnutrition. Malnourishment and obesity are both forms of malnutrition that affect wound healing.

(a) A person who is undernourished has less fat and carbohydrate reserve; therefore, body protein (necessary for wound healing) must be used to provide energy needed for basic metabolic functions. This results in an imbalance of nitrogen which in turn depresses fibroblastic synthesis of collagen, the connective tissue for scar formation. A person suffering from Vitamin C deficiency may not be able to produce fibroblast, causing a delay in wound healing.

(b) In obese individuals, fatty tissue may keep foreign matter from being seen. Fatty tissue has relatively few blood vessels, causing such tissue to separate easily. Tissue that separates easily heals slowly.

(3) Abnormalities in endocrine function. Healing is slow if there are such abnormalities. In a person suffering from chronic vascular changes, the injured tissues of the wound may not get enough blood to heal at a normal rate. Persons having corticosteroid therapy will find that wounds heal more slowly.

(4) Hormone production and carbohydrate metabolism. The combined effect of the increased hormone production is to increase the metabolism of carbohydrates. The metabolism of carbohydrates is important in the body’s response to trauma. If the body’s store of carbohydrates is depleted (severe crush injuries, starvation), the body will begin to use fats and proteins in place of carbohydrates. Eventually, there will not be enough carbohydrates to aid in the healing process.