Risk Factors Wound Healing and Wound Complications

Introduction

Acute wounds in normal, healthy individuals heal through an orderly sequence of physiologic events. Some individuals have one or more factors that contribute to impaired wound healing, which can lead to chronic nonhealing wounds and ulcers or can complicate the surgical course.

General Principles

Impaired wound healing —A wound is a disruption of the normal structure and function of the skin and underlying soft tissue. Impaired wound healing often occurs in the setting of multiple, smaller contributing issues to stall the healing process; however, infection or ischemia alone can impair wound healing. When the healing process is stalled, a chronic wound may develop, and this is more likely to occur in patients with underlying medical disorders. The most common nonhealing wounds affecting the lower extremities are associated with chronic venous insufficiency, peripheral artery disease, and diabetes mellitus.

Risk factors — Risk factors associated with impaired wound healing leading to wound healing complications or chronic nonhealing wounds are listed.

  • Infection
  • Smoking
  • Aging
  • Malnutrition
  • Immobilization
  • Diabetes
  • Vascular disease
  • Immunosuppressive therapy
  • Others

Infection

The presence of infection impairs several steps of the wound healing process Infection also results in cellular death, which will increase the local inflammatory environment. New tissue growth also cannot occur in the presence of necrotic tissue.

Smoking and Nicotine Replacement Therapy

Smoking is associated with adverse outcomes following surgery, including surgical site infection and pulmonary complications. The detrimental effect of smoking on wound healing is multifactorial, with mechanisms that include vasoconstriction causing a relative ischemia of operated tissues, a reduced inflammatory response, impaired bacteriocidal mechanisms, and alterations of collagen metabolism.

Aging

Skin is not excluded from the complex processes of aging. The supply of cutaneous nerves and blood vessels decreases with age, in addition to a general thinning of tissue, including dermis and basement membrane.

Malnutrition

Adequate nutrition is imperative for the prevention of infection, which has deleterious effects on wound healing.

Immobilization

Patients undergoing periods of prolonged immobilization. These are typically pressure wounds, occurring in areas of bony prominence such as the sacrum, knees, ankle malleoli, and heels.

Immunosuppressive Therapy

  • Chemotherapy
  • Glucocorticoids (Steroids)
  • Radiation

Diabetes

Diabetes is a particularly important risk factor for the development of chronic wounds from neuropathy and vasculopathy, which increase the risk of infection and delay healing. Diabetes is frequently associated with peripheral artery disease (PAD) with atherosclerosis developing at a younger age and affecting more distal arteries below the knee (eg, popliteal, tibial arteries). PAD in combination with diabetic neuropathy contributes to higher rates of nonhealing wounds and limb loss in diabetic patients compared with those without diabetes. Up to one-third of people with diabetes in the United States will develop a foot ulcer. Peripheral artery obstruction is present in approximately 20 percent of these patients and diabetic neuropathy in up to 50 percent of these patients.

Vascular Disease

Peripheral artery disease — Peripheral artery disease (PAD) with multilevel arterial obstruction decreases arterial blood flow, diminishes the delivery of oxygen and nutrients to the tissues, and impairs removal of metabolic waste products.

Chronic Venous insufficiency — A venous wound, also known as a venous ulcer or stasis ulcer, is a type of chronic wound that results from venous insufficiency or dysfunction in the veins of the lower extremities. Venous Insufficiency occur when the valves in the leg veins do not work properly, leading to poor blood circulation and an accumulation of blood and fluid in the lower legs. Over time this
condition can result in venous wounds. Venous leg ulcers account for approximately 40 percent of wounds of the lower extremities.

Edema

Peripheral edema can be caused by a variety of conditions, but regardless of the etiology, the accumulation of interstitial fluid reduces the integrity of the skin and subcutaneous tissue, making it prone to injury.

Obesity

Obese individuals have a higher incidence of wound complications, including seroma, hematoma, wound infection, and wound dehiscence, as well as a higher incidence of pressure ulcers and venous ulcers.