❖ Wound-healing process
A dynamic process that restores anatomic and functional integrity, wound healing works on a con- tinuum from injury to healing
◆In healing by primary intention, the wound is surgically closed (such as with sutures, staples, glue, or Steri-Strips), and healing occurs by fi brous adhesion; granulation tissue isn’t apparent, and there’s little or no scar tissue; examples include surgical wounds and superfi cial traumatic wounds
◆In healing by secondary intention, the wound’s edges are too far apart to be surgically closed, and there’s marked tissue loss; the wound is instead closed naturally by the formation and adhesion of granulation tissue and epithelialization; examples include pressure ulcers, dehisced surgical wounds, and traumatic injuries
◆In healing by tertiary intention, also known as delayed primary closure, there’s a delay in wound closure, resulting in granulation of the wound edges; later surgical closure results in more scar formation; these wounds are sometimes left open for several days to allow edema or infection to resolve or exudate to drain
Wound healing consists of several phases
◆The injury is a break in the skin’s integrity
◆Hemostasis is a brief period of vasoconstriction at the site of injury as the body attempts to prevent excessive bleeding
◆The infl ammatory phase starts right after the injury and lasts from 2 to 6 days; this defensive reaction to tissue injury involves increased blood fl ow and capillary permeability and aids in phagocytosis or auto- lytic debridement; it’s marked by increased heat, redness, swelling, and pain in the affected area
◆During the proliferative phase, granulation tissue forms and epithelialization begins
◗ Granulation tissue is a pink-to-red, moist tissue that contains new blood vessels, collagen, fi bro- blasts, and infl ammatory cells; the tissue fi lls the open deep wound and acts as a kind of scaffolding for the eventual migration of epithelial cells
◗ During epithelialization, epithelial cells migrate across the wound’s surface, forming a layer of new tissue; these cells look silvery and form a perimeter around the granulation tissue
◆As epithelial closure occurs, the wound contracts and begins to close
◆During the fi nal maturation phase, collagen reorganizes and strengthens, a process that continues for months and sometimes years; chronic wounds may regain 50% of their original tensile strength after 2 to 3 weeks, but they’ll ultimately regain only 70% to 75% of their original strength
The following chart summarizes the type and cause, location, related signs and symptoms, and appearance of acute and chronic wounds. Specifi c nursing measures vary with the type of wound.
Type and cause Location Related signs
and symptoms
Appearance Surgical wound
● Sterile incision, which is then closed with glue, staples, sutures, or Steri-Strips
● Heals by fi rst intention
● Anywhere on body
● Usually follows
integumentary cleavage line, which enhances healing
● Vary with type of surgery
● Even, sharp wound margins
● Clean, with no drainage or scab formation
Wound-healing process ❍ 53
Type and cause Location Related signs and symptoms
Appearance Arterial ulcer (ischemic ulcer)
● Insuffi cient arterial perfusion to an extremity
● Risk increases with history of peripheral vascular disease, diabetes mellitus, or advanced age
● Between toes (web space) or on tips of toes
● Over phalangeal heads
● Around lateral malleolus
● On areas subjected to trauma or rubbing from shoes
● Thin, shiny, dry skin
● Thickened nails
● Pallor in affected limb on elevation and dependent rubor
● Cyanosis
● Decreased temperature in affected limb
● Absent or diminished pulses in affected limb
● Severe pain
● Punched-out appearance of wound edges
● Gangrene or necrosis
● Deep, pale wound bed
● Blanched, purpuric
● Signs of cellulitis
● Minimal exudate
Diabetic ulcer
● Peripheral neuropathy
● Risk increases with history of diabetes mellitus or arterial insuffi ciency
● On plantar aspect of foot
● Over metatarsal heads
● Under heels
● Diminished or absent sensation in foot
● Foot deformities
● Increased temperature in foot without sweating
● Atrophy of subcutaneous fat
● Altered gait
● Signs of peripheral vascular disease
● Even, well-defi ned wound margins
● Depth of wound bed variable, possibly with undermining
● Signs of cellulitis or underlying osteomyelitis
● Variable amounts of exudate
● Possible necrosis
● Possible granulation tissue
Venous ulcer
● Disturbance in return blood fl ow from legs
● Risk increases with history of valve incompetence, perforating veins, deep vein thrombophlebitis or thrombosis, previous ulcers, obesity, or advanced age
● On medial lower leg and ankle
● Above medial malleolus
● Edema
● Possible dilated superfi cial veins
● Dry, thin skin
● Evidence of previously healed ulcer
● Lack of pain sensation at wound site
● Possible dermatitis
● Irregular wound margins
● Superfi cial wound bed
● Ruddy, granular tissue
● Moderate to heavy exudate
Pressure ulcer
● Excessive pressure (either high pressure over a short time or low pressure over a longer time) that causes localized tissue damage
● On bony prominences, especially sacrum and heels
● Possible local pain ● Suspected deep tissue injury: purple or maroon localized area of discolored intact skin or blood-fi lled blister resulting from damage of underlying soft tissue from pressure, shear, or both; may be preceded by tissue that’s painful, fi rm, mushy, boggy, and warmer or cooler than adjacent tissue
● Stage I: intact skin with localized nonblanchable redness, usually over a bony prominence; possibly no visible blanching on darkly pigmented skin, although color may differ from surrounding area
(continued)
Characteristics of acute and chronic wounds (continued)
Type and cause Location Related signs and symptoms
Appearance Pressure ulcer
● Risk increases with history of advanced age, inadequate tissue perfusion, incontinence, or prolonged
immobility
● On areas where friction and shear can damage tissue
● Foul-smelling odor ● Stage II: partial-thickness tissue loss presenting as a shallow, open ulcer with a red-pink wound bed without slough;
may also present as an intact or open and ruptured serum-fi lled blister
● Stage III: full-thickness tissue loss, possibly with visible subcutaneous fat but with no exposed bone, tendon, or muscle; slough may be present but doesn’t obscure depth of tissue loss; may include undermining and tunneling
● Stage IV: full-thickness tissue loss with exposed bone, tendon, or muscle;
slough or eschar may be present on some parts of wound bed; often includes undermining and tunneling
● Unstageable: full-thickness tissue loss in which the base of the ulcer is covered by slough (yellow, tan, gray, green, or brown) or eschar (tan, brown, or black) or both in the wound bed
Characteristics of acute and chronic wounds(continued)
❖ Factors that affect wound healing
Local factors◆Moisture—for instance, from incontinence—leads to skin maceration and edema, making the epidermis more susceptible to abrasion; the chemicals and bacteria in urine and stool also cause tissue breakdown
◆Necrotic debris and other foreign material in a wound interfere with optimal healing and must be removed; by increasing the bacterial count, dead tissue increases the risk of infection
◆Infection at a level of more than 1 million organisms per gram of tissue inhibits granulation and epithelialization
Systemic factors
◆Aging has a profound impact on all body systems; it affects wound healing by decreasing the infl am- matory response, delaying angiogenesis, decreasing collagen synthesis and degradation, slowing epi- thelialization (resulting in a thinner epidermal layer), decreasing cohesion between the epidermal and dermal layers, decreasing the function of sebaceous glands (resulting in dryness), and altering the func- tion of melanocytes (resulting in skin discoloration)
◆Malnutrition delays or prevents healing by depriving the body of the nutrients it needs to combat the physiologic stress of infection and to meet the increased metabolic demands of tissue repair; patients with chronic or diffi cult-to-heal wounds have special dietary needs (see The role of nutrition in wound healing)
◆Dehydration can hasten debilitation and death; a patient with a large wound can lose far more than 1 L of water per day, the water loss of a healthy adult
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Factors that affect wound healing ❍ 55
◆Vascular insuffi ciency can lead to poor healing and the development of leg ulcers
◗ Arterial insuffi ciency results in an inadequate blood supply, which can lead to tissue hypoxia, infection, and death
◗ Cardiovascular insuffi ciency leads to systemic hypoxemia, which impedes wound healing
◗ Venous insuffi ciency—impaired fl ow toward the heart and elevated pressure in the venous system—leads to the leakage of fi brinogen around capillaries into the dermis; this results in forma- tion of a fi brin layer that blocks tissue oxygenation, nutrient exchange, and waste removal
Metabolic factors
◆A patient with diabetes mellitus requires strict maintenance of normal blood glucose levels for proper wound healing, particularly for the acute phase of tissue repair, during periods of stress, after surgery, and for combating sepsis; poorly controlled diabetes results in notoriously slow and compli- cated wound healing for several reasons
◗ Impaired circulation caused by thickening of the capillary basement membrane results in reduced local blood fl ow
◗ Reduced sensation from diabetic neuropathy signifi cantly reduces sensation in the lower extremi- ties, making patients less aware of injuries and serious infections
The following chart outlines the role protein, calories, vitamins, and minerals play in wound healing.
Nutrient RDA/Healthy adults Effects of defi ciency Effects on healing Protein 0.8/kg Impairs all aspects of
healing and host defenses
Improves tissue integrity; increase to 1.5 to 2 g/kg needed for healing
Calories ● Resting: 1,500
● Sedentary: 2,000
● Very active: 3,500
Muscle wasting May need to increase fi vefold for positive nitrogen balance to promote healing
Vitamin C 60 mg Collagen instability;
decreased tensile strength
Necessary for collagen synthesis; not stored in body so defi ciency occurs quickly
Vitamin A 1,000 mcg Decreased epithelialization, collagen synthesis, resistance to infection by way of decreased macrophage production
Supplementation reverses effects of glucocorticoids
Vitamin B6 2 mcg Decreased protein synthesis
Needed for protein metabolism
Vitamin B12 2 mcg Decreased protein synthesis
Needed for cell proliferation and tissue synthesis
Folate 200 mcg Decreased protein
synthesis
Enables transport of oxygen; decreased absorption in elderly patients so supplementation may be necessary
Zinc 15 mg Decreased immunity,
collagen synthesis
Enables protein synthesis and tissue repair;
healing improves after supplementation in true defi ciency