Interruption of tissue integrity, either intentional or unintentional, requires understanding of the mechanism and factors that cause wounding and influence wound healing.³^,⁷^,⁸ When tissue is cut, the body’s inherent defense mechanisms respond immediately to begin repair. Three mechanisms of wound healing are recognized: first intention/primary union, second intention, and third intention/delayed primary closure (Fig. 29-1).³ Each mechanism has practical applications in the making and closing of incisions or traumatic wounds. The degree of contamination and the amount of viable tissues are factors in the determination of which method of healing is used.

FIG. 29-1 Mechanisms of wound healing. *(From Trott AT:* Wounds and lacerations: Emergency care and closure, *ed 3, St. Louis, 2005, Mosby.)*

Other types of intentional wounds

Occlusion banding.

Hemorrhoid ligation results in ischemia and degeneration of a hemorrhoid. A Silastic band is placed around the hemorrhoid using a special spring-loaded applicator. Other types of occlusion banding are performed on fallopian tubes with ligatures, Silastic bands, or plastic clips through a laparoscope. Portions of tissue distal to the occlusion point separate from perfused tissues, interrupting the continuity of the lumen of the part in the banding process.

Chemical wounds.

Chemicals can intentionally be applied to skin or other tissue surfaces to denude or coagulate the area. These chemicals cause inflammation and reepithelialization of the surface. This procedure is common in facial peels used in plastic and dermatologic surgery.

Traumatic wounds

After traumatic injury, preservation of life is the first critical concern. The patient’s general condition is of prime consideration, and the plan of care is individualized to meet the patient’s needs. Injuries are evaluated, and those that pose the greatest hazards to life or to return to normal function are cared for first.

The primary objective after life support is wound closure with minimal deformity and functional loss. Minor injuries are cared for in the emergency department. Patients with major injuries undergo treatment in the emergency department before going to the OR as quickly as the condition warrants it. Traumatic wounds can be considered closed or open, simple or complicated, clean or contaminated. Wound closure is predicated on the type, location, severity, and extent of injury.

Continuity of skin is interrupted in simple wounds but without loss or destruction of tissue and without implantation of a foreign body. These lacerations are usually caused by a sharp-edged object cutting or penetrating at a low velocity. These wounds can be closed by first intention unless underlying structures or organs have been injured.

Complicated wounds

In complicated wounds, tissue is lost or destroyed by crush or burn or a foreign body is implanted by high-velocity penetration. If a penetrating wound was made by an object, such as a knife or bullet, this object is not removed until the surgeon explores the wound in the OR. The device should be stabilized to prevent additional injury. Movement of a foreign object may cause further trauma. The depth of a penetrating wound is irrigated and may be excised.

The complicated wound may be closed by second or third intention. Skin grafting may be necessary if the dermis has been destroyed. Any object removed from the patient’s wound may be forensic evidence. The hospital’s policy and procedure manual should be consulted for guidance on handling potential police evidence.

Clean wounds

Clean wounds heal by first intention after closure of all tissue layers and wound edges. The cosmetic care of lacerated areas is important, as is treatment to provide normal function and satisfactory appearance of a part.

Contaminated wounds

When dirty objects penetrate skin, microorganisms multiply rapidly. Within 6 hours, contamination can become infection. Debridement is performed to remove devitalized tissue, and the wound is irrigated. Devitalized tissue is removed because it acts as a culture medium. The wound may be left open to heal by second or third intention. Closure may be delayed for several days.

The patient’s history should be assessed for tetanus bacillus immunization. Tetanus is most likely to occur in deep wounds contaminated by soil or animal feces. Adsorbed tetanus toxoid (0.5 mL) may be given as an initial immunizing dose or as a booster if the patient has been immunized within the previous 5 years. Tetanus immune globulin (human, 250 to 500 units) also should be given to any patient who has a severe wound or who has had the wound for more than 24 hours and has not been immunized within the previous 10 years.

Delayed full-thickness injury

Industrial accidents commonly include crush injury or deep injection of substances, such as paint or printer’s ink, beyond the level of the dermis. The full extent of the tissue damage may not be apparent for several days after the event because the effects of the injury cause increasing tissue loss. The patient may have occlusive dressings or casting for the initial apparent injuries but should be continually assessed for signs of increasing tissue necrosis or full-thickness tissue loss. Electrocution or lightning strikes act similarly by causing deep tissue necrosis several days after the initial wounding.

Incidental and chronic wounds

Pressure sores and decubitus ulcers may result from compromised circulation over bony prominences or other pressure points for extended periods. Positioning and padding considerations in the plan of care can help prevent incidental pressure-related injuries in the perioperative environment.

Ulcers

Venous stasis or arterial insufficiency in the legs may cause chronic skin ulcers. Tissue necrosis may occur after radiation therapy. These chronic wounds have tissue loss and usually have heavy bacterial contamination. Topical application of fibronectin (a platelet-derived wound-healing formula) or some other preparation of growth factors from the patient’s own blood may help control infection and promote healing. Growth factors stimulate the growth of tissue, capillaries, and skin. If a wound fails to heal by second intention with formation of granulation tissue, debridement and skin grafting may be necessary.

Iatrogenic wounds

Iatrogenic wounds can happen as the result of therapy or treatment such as radiation burns. Accidental injuries such as trocar wounds on unintended organs caused during a surgical procedure can be classified as iatrogenic. The treatment and healing vary according to the mechanism of injury.

Factors influencing wound healing

Each patient has internal and external forces that influence healing. Most wounds progress to healing unless the closure is poor, an infection ensues, or the tissue is devitalized by other forces. Hemostatic and inflammatory responses must be intact for healing to take place.

The degree of wound contamination is evaluated, and the potential risk for postoperative wound infection is considered. At the conclusion of the surgical procedure, the wound is assigned a classification.

Surgical wound classification

The surgical site may be clean or contaminated when the surgeon makes the initial incision. A clean site may become contaminated depending on the type of wound, the pathologic findings or circumstances that create the need for the surgical procedure, the anatomic location, and the techniques of the OR team. After completion of wound closure, the circulating nurse should verify the wound classification with the surgeon.

The wound class should not be assigned until the dressing is applied. This is documented in the patient’s intraoperative records. Surgical sites are classified by the degree of microbial contamination or exposure that may predispose a patient to a postoperative wound infection.

According to the Centers for Disease Control and Prevention (CDC), risk of infection increases in proportion to contamination of the incision and surrounding tissues exposed during the course of the surgical procedure. The true extent of risk cannot be evaluated until the procedure is completed. The wound is classified at the end of the surgical procedure as one of four types (Box 29-1):

BOX 29-1 Classification of Surgical Wounds from the CDC

Clean wound (expected infection rate: 1% to 5%)

• Elective procedure with wound made in ideal operating room conditions

• Primary closure; wound not drained

• No break in sterile technique during surgical procedure

• No inflammation present

• Alimentary, respiratory, and genitourinary tracts or oropharyngeal cavity not entered

Clean-contaminated wound (infection rate: 8% to 11%)

• Primary closure; wound drained

• Minor break in technique occurred

• No inflammation or infection present

• Alimentary, respiratory, and genitourinary tracts or oropharyngeal cavity entered in controlled conditions without significant spillage or unusual contamination

Contaminated wound (infection rate: 15% to 20%)

• Open fresh traumatic wound of less than 4 hours’ duration

• Major break in technique occurred

• Acute nonpurulent inflammation present

• Gross spillage/contamination from gastrointestinal tract

• Entrance into genitourinary or biliary tracts with infected urine or bile present

Dirty and infected wound (infection rate: 27% to 40%)

• Old traumatic wound of more than 4 hours’ duration from dirty source or with retained necrotic tissue, foreign body, or fecal contamination

• Organisms present in surgical field before procedure

• Existing clinical infection: acute bacterial inflammation encountered, with or without purulence; incision to drain abscess

• Perforated viscus

1. Clean

2. Clean-contaminated

3. Contaminated

4. Dirty and infected

Vasoconstriction caused by smoking decreases blood supply and oxygenation to the wound.¹¹ Carbon monoxide in smoke binds with hemoglobin (forming carboxyhemoglobin) and further diminishes oxygenation. Smoking contributes to respiratory complications. This can cause forceful coughing that can raise intraabdominal pressure and create increased strain on an abdominal wound and impair healing.