A complete understanding of the anatomy and physiology of the skin, the phases of the healing process, the types of wounds, and the options for wound repair is essential for recognizing factors that may complicate or delay wound healing. Each consideration plays a key role in assessing and managing wounds of all types. In this column, we examine the various factors that may delay or impede healing-local and systemic.
Wound healing can be delayed by factors local to the wound itself, including desiccation, infection or abnormal bacterial presence, maceration, necrosis, pressure, trauma, and edema.
* Desiccation. A moist environment allows wounds to heal faster and less painfully than a dry environment, in which cells typically dehydrate and die. This causes a scab or crust to form over the wound site, which impedes healing. If the wound is kept hydrated with a moisture-retentive dressing, epidermal cell migration is enhanced, encouraging epithelialization.
* Infection or abnormal bacterial presence. If an infection is present, as evidenced by purulent drainage or exudate, induration, erythema, or fever, a wound culture should be obtained to identify the offending bacteria and guide antibiotic therapy.When a pressure ulcer or full-thickness wound extending to the bone fails to heal, the patient should be assessed for signs of osteomyelitis. Any abnormal culture or other test results should be reported to the physician so that appropriate antibiotics are prescribed to treat the infection.
* Maceration. Urinary and fecal incontinence can alter the skin's integrity. Educating caregivers about proper skin care is essential for successful skin and wound management.
* Necrosis. Dead, devitalized (necrotic) tissue can delay healing. Slough and eschar are the 2 types of necrotic tissue that may appear in a wound. Slough is moist, loose, stringy necrotic tissue that is typically yellow. Eschar, which appears as dry, thick, leathery tissue, may be black. In most cases, necrotic tissue must be removed before repair and healing can occur.
* Pressure. When pressure at the wound site is excessive or sustained, the blood supply to the capillary network may be disrupted. This impedes blood flow to the surrounding tissue and delays healing.
* Trauma and edema. Wounds heal slowly-and may not heal at all-in an environment in which they are repeatedly traumatized or deprived of local blood supply by edema.
Wound healing can be delayed by systemic factors that bear little or no direct relation to the location of the wound itself. These include age, body type, chronic disease, immunosuppression, nutritional status, radiation therapy, and vascular insufficiencies.
* Age. Wounds in older patients may heal more slowly than those in younger patients, mainly because of comorbidities that occur as a person ages. Older patients may have inadequate nutritional intake, altered hormonal responses, poor hydration, and compromised immune, circulatory, and respiratory systems, any of which can increase the risk of skin breakdown and delay wound healing.
* Body type. Body type may also affect wound healing. An obese patient, for example, may experience a compromise in wound healing due to poor blood supply to adipose tissue. In addition, some obese patients have protein malnutrition, which further impedes the healing. Conversely, when a patient is emaciated, the lack of oxygen and nutritional stores may interfere with wound healing.
* Chronic diseases. Coronary artery disease, peripheral vascular disease, cancer, and diabetes mellitus are a few of the chronic diseases that can compromise wound healing. Patients with chronic diseases should be followed closely through their course of care to provide the best plan.
* Immunosuppression and radiation therapy. Suppression of the immune system by disease, medication, or age can delay wound healing. Radiation therapy can cause ulceration or change in the skin, either immediately after a treatment or after all treatment has ended.
* Laboratory values. Nutritional markers are not the only laboratory values that must be considered when evaluating healing. Measuring the hemoglobin level helps assess the oxygen-carrying capacity of the blood; however, it may also be necessary to assess hepatic, renal, and thyroid functions to determine the patient's healing capacity.
* Nutritional status. Ongoing nutritional assessment is necessary because the visual appearance of the patient or the wound is not a reliable indicator of whether the patient is receiving the proper amount of nutrients. Albumin and prealbumin levels, total lymphocyte count, and transferrin levels are markers for malnutrition and must be assessed and monitored regularly, as protein is needed for cell growth.
* Vascular insufficiency. Various wounds or ulcers-such as arterial, diabetic, pressure, and venous ulcers-can affect the lower extremities. Decreased blood supply is a common cause of these ulcers. The clinician must identify the type of ulcer to ensure appropriate topical and supportive therapies.
Source: Hess CT. Clinical Guide to Skin and Wound Care. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008.