ACUTE OR INTERMEDIATE PHASE OF BURN CARE
The acute or intermediate phase of burn care follows the emergent/ resuscitative phase and begins 48 to 72 hours after the burn injury. During this phase, attention is directed toward continued assess-ment and maintenance of respiratory and circulatory status, fluid and electrolyte balance, and gastrointestinal function. Infection pre-vention, burn wound care (ie, wound cleaning, topical antibacterial therapy, wound dressing, dressing changes, wound débridement, and wound grafting), pain management, and nutritional support are priorities at this stage and will be discussed in detail.
Airway obstruction caused by upper airway edema can take as long as 48 hours to develop. Changes detected by x-ray and arte-rial blood gases may occur as the effects of resuscitative fluid and the chemical reaction of smoke ingredients with lung tissues be-come apparent. The arterial blood gas values and other parameters determine the need for intubation or mechanical ventilation.
As capillaries regain integrity, at 48 or more postburn hours, fluid moves from the interstitial to the intravascular compartment and diuresis begins (Table 57-4). If cardiac or renal function is inadequate, for instance in the elderly patient or in the patient with preexisting cardiac disease, fluid overload occurs and symp-toms of congestive heart failure may result. Early detection allows for early intervention and carefully calculated fluid intake. Vasoactive medications, diuretics, and fluid restric-tion may be used to support circulatory function and prevent congestive heart failure and pulmonary edema.
Cautious administration of fluids and electrolytes continues during this phase of burn care because of the shifts in fluid from the interstitial to intravascular compartments, losses of fluid from large burn wounds, and the patient’s physiologic responses to the burn injury. Blood components are administered as needed to treat blood loss and anemia.
Fever is common in burn patients after burn shock resolves. A resetting of the core body temperature in severely burned patients results in a body temperature a few degrees higher than normal for several weeks after the burn. Bacteremia and septicemia also cause fever in many patients. Acetaminophen (Tylenol) and hypo-thermia blankets may be required to maintain body temperature in a range of 37.2° to 38.3°C (99° to 101°F) to reduce metabolic stress and tissue oxygen demand.
Central venous, peripheral arterial, or pulmonary artery ther-modilution catheters may be required for monitoring venous and arterial pressures, pulmonary artery pressures, pulmonary capillary wedge pressures, or cardiac output. Generally, however, invasive vascular lines are avoided unless essential because they provide an additional port for infection in an already greatly compromised patient.
Infection progressing to septic shock is the major cause of death in patients who have survived the first few days after a major burn. The immunosuppression that accompanies exten-sive burn injury places the patient at high risk for sepsis. The infection that begins within the burn site may spread to the bloodstream.
Despite aseptic precautions and the use of topical antimicrobial agents, the burn wound is an excellent medium for bacterial growth and proliferation. Bacteria such as Staphylococcus, Proteus, Pseudo-monas, Escherichia coli, and Klebsiella find optimal conditions forgrowth within the burn wound. The burn eschar is a nonviable crust with no blood supply; therefore, neither polymorpho-nuclear leukocytes or antibodies nor systemic antibiotics can reach the area. Phenomenal numbers of bacteria—more than 1 billion per gram of tissue—may appear and subsequently spread to the bloodstream or release their toxins, which reach distant sites. Staph-ylococci and enterococci are the organisms responsible for more than 50% of nosocomial bloodstream infections in patients with burn injuries. Fungi such as Candida albicans also grow easily in burn wounds.
When the burn wound is healing through spontaneous re-epithelialization or is being prepared for skin grafting, it must be protected from sepsis. Burn wound sepsis has these characteristics:
· 105 bacteria per gram of tissue
· Sludging and thrombosis of dermal blood vessels
The primary source of bacterial infection appears to be the patient’s intestinal tract, the source of most microbes. The intestinal mucosa normally serves as a barrier to keep the internal environ-ment free from a variety of pathogens. After a severe burn injury, the intestinal mucosal barrier becomes markedly permeable. Be-cause of this impaired intestinal mucosal barrier, the disturbed microbial flora and endotoxins found in the intestinal lumen pass freely into the systemic circulation, finally causing infection. If the intestinal mucosa receives some type of protection against permeability change, infection could be avoided. Early enteral feeding is one step to help avoid this increased intestinal perme-ability and prevent early endotoxin translocation (Cioffi, 2000; Peng, Yuan & Ziao, 2001).
Infection impedes burn wound healing by promoting excessive inflammation and damaging tissue. A major secondary source of pathogenic microbes is the environment. Infection control is a major role of the burn team in providing appropriate burn wound care. Cap, gown, mask, and gloves are worn while caring for the patient with open burn wounds. Clean technique is used when caring directly for burn wounds.
Tissue specimens are obtained for culture regularly to moni-tor colonization of the wound by microbial organisms. These may be swab, surface, or tissue biopsy cultures. Swab or surface cultures are noninvasive, simple, and painless. However, data ob-tained from such cultures apply only to the area sampled; there-fore, invasive wound biopsy cultures may be required. Antibiotics are seldom prescribed prophylactically because of the risk of pro-moting resistant strains of bacteria. Systemic antibiotics are ad-ministered when there is documentation of burn wound sepsis or other positive cultures such as urine, sputum, or blood. Sensitivity of the organisms to the prescribed antibiotics should be deter-mined before administration. Several parenteral antimicrobial agents may be given together to treat the infection. Careful at-tention is paid to antibiotic use in the burn unit because inap-propriate use of antibiotics significantly affects the microbial flora present in the unit.
Various measures are used to clean the burn wound. Hydro-therapy in the form of shower carts, individual showers, and bedbaths can be used to clean the wounds. Total immersion hydro-therapy is performed in some settings. Because of the high risk of infection and sepsis, the use of plastic liners and thorough de-contamination of hydrotherapy equipment and wound care areas are necessary to prevent cross-contamination. Tap water alone can be used for burn wound cleansing. The temperature of the water is maintained at 37.8°C (100°F), and the temperature of the room should be maintained between 26.6° and 29.4°C (80° to 85°F). Hydrotherapy, in whatever form, should be limited to a 20- to 30-minute period to prevent chilling of the patient and additional metabolic stress.
During the bath, the patient is encouraged to be as active as possible. Hydrotherapy provides an excellent opportunity for ex-ercising the extremities and cleaning the entire body. When the patient is removed from the tub after the bath, any residue ad-hering to the body is washed away with a clear water spray or shower. Unburned areas, including the hair, must be washed reg-ularly as well. At the time of wound cleaning, all skin is inspected for any hints of redness, breakdown, or local infection. Hair in and around the burn area, except the eyebrows, should be clipped short. Intact blisters may be left, but the fluid should be aspirated with a needle and syringe and discarded.
Conscientious management of the burn wound is essential. When nonviable loose skin is removed, aseptic conditions must be established. Wound cleaning is usually performed at least daily in wound areas that are not undergoing surgical intervention. When the eschar begins to separate from the viable tissue beneath (approximately 1.5 to 2 weeks after the burn), more frequent cleaning and débridement may be in order.
After the burn wounds are cleaned, they are gently patted with towels and the prescribed method of wound care is performed. Physician preferences, the availability of skilled nursing staff, and resources in terms of number of personnel, supplies, and time must be considered in choosing the best method for a given pa-tient. Whatever the method, the goal is to protect the wound from overwhelming proliferation of pathogenic organisms and invasion of deeper tissues until either spontaneous healing or skin grafting can be achieved.
Patient comfort and ability to participate in the prescribed treatment are also important considerations. Wound care proce-dures, particularly tub baths, are metabolically stressful. There-fore, the patient is assessed for signs of chilling, fatigue, changesin hemodynamic status, and pain unrelieved by analgesic med-ications or relaxation techniques.
There is general agreement that some form of antimicrobial ther-apy applied to the burn wound is the best method of local care in extensive burn injury. Topical antibacterial therapy does not ster-ilize the burn wound; it simply reduces the number of bacteria so that the overall microbial population can be controlled by the body’s host defense mechanisms. Topical therapy promotes con-version of the open, dirty wound to a closed, clean one.
Criteria for choosing a topical agent include the following:
· It is effective against gram-negative organisms, Pseudomonasaeruginosa, Staphylococcus aureus, and even fungi.
· It is clinically effective.
· It penetrates the eschar but is not systemically toxic.
· It does not lose its effectiveness, allowing another infection to develop.
· It is cost-effective, available, and acceptable to the patient.
· It is easy to apply, minimizing nursing care time.
The three most commonly used topical agents are silver sulfadi-azine (Silvadene), silver nitrate, and mafenide acetate (Sulfamylon). These agents are described in Table 57-5. Many other topical agents are available, including povidone–iodine ointment 10% (Betadine), gentamicin sulfate, nitrofurazone (Furacin), Dakin’s solution, acetic acid, miconazole, and chlortrimazole. Bacitracin may be used for facial burns or on skin grafts initially.
A newer product used in burn wound care is Acticoat Anti-microbial Barrier dressing. Acticoat is a silver-coated dressing approved for treatment of burn wounds and donor sites. This dressing is kept moist with water for a controlled, sustained re-lease of silver over the wound to provide an antimicrobial barrier. Acticoat has been shown to have a better antimicrobial perfor-mance than the traditional silver-based products commonly used in burn wound treatment. Acticoat is also cost-effective. The dressing can be left in place for up to 5 days, decreasing patient discomfort, the cost of dressing supplies, and nursing time for dressing changes. The dressing has been shown clinically to be very effective for prevention of burn wound infection (Yin, Langford & Burrell, 1999).
No single topical medication is universally effective. Using dif-ferent agents at different times in the postburn period may be necessary. Bacteriologic cultures are required to monitor the effect of topical medications. Prudent use and alternation of anti-microbial agents result in less resistant strains of bacteria, greater effectiveness of the agents, and a decreased risk of sepsis.
Before a topical agent is reapplied, the previously applied top-ical agent must be thoroughly removed. The number of times the dressings are changed and soaked is planned to promote optimal therapeutic use of the topical agent.
When the wound is clean, the burned areas are patted dry and the prescribed topical agent is applied; the wound is then covered with several layers of dressings. A light dressing is used over joint areas to allow for motion (unless the particular area has a graft and motion is contraindicated). A light dressing is also applied over areas for which a splint has been designed to conform to the body contour for proper positioning. Circumferential dressings should be applied distally to proximally. If the hand or foot is burned, the fingers and toes should be wrapped individually to promote adequate healing.
Burns to the face may be left open to air once they have been cleaned and the topical agent has been applied. Careful attention must be given to burns left exposed to ensure that they do not dry out and convert to a deeper burn.
Close communication and cooperation among the patient, surgeon, nurse, and other health care team members are essential for optimal burn wound care. Different wound areas on a given patient may require a variety of wound care techniques. Diagrams posted at the bedside are useful to inform staff of the current pre-scription for wound care, splints to be applied over dressings, and the exercise regimen to be followed before dressings are reapplied.
There is a role for occlusive dressings in treating specific wounds. An occlusive dressing is a thin gauze that is impregnated with a topical antimicrobial agent or that is applied after topical anti-microbial application. Occlusive dressings are most often used over areas with new skin grafts. Their purpose is to protect the graft, promoting an optimal condition for its adherence to the recipient site. Ideally, these dressings remain in place for 3 to 5 days, at which time they are removed for examination of the graft.
When these dressings are applied, precautions are taken to prevent two body surfaces from touching, such as fingers or toes, ear and scalp, the areas under the breasts, any point of flexion, or between the genital folds. Functional body alignment positions are maintained by using splints or by careful positioning of the patient.
Dressings are changed in the patient’s unit, hydrotherapy room, or treatment area approximately 20 minutes after an analgesic agent is administered. They may also be changed in the operat-ing room after the patient is anesthetized. A mask, goggles, hair cover, disposable plastic apron or cover gown, and gloves are worn by health care personnel when removing the dressings. The outer dressings are slit with blunt scissors, and the soiled dress-ings are removed and disposed of in accordance with established procedures for contaminated materials.
Dressings that adhere to the wound can be removed more comfortably if they are moistened with tap water or if the patient is allowed to soak for a few moments in the tub. The remaining dressings are carefully and gently removed. The patient may partic-ipate in removing the dressings, providing some degree of control over this painful procedure. The wounds are then cleaned and débrided to remove debris, any remaining topical agent, exudate, and dead skin. Sterile scissors and forceps may be used to trim loose eschar and encourage separation of devitalized skin. During this procedure, the wound and surrounding skin are carefully inspected. The color, odor, size, exudate, signs of re-epithelialization, andother characteristics of the wound and the eschar and any changes from the previous dressing change are noted.
As debris accumulates on the wound surface, it can retard ker-atinocyte migration, thus delaying the epithelialization process. Débridement, another facet of burn wound care, has two goals:
· To remove tissue contaminated by bacteria and foreign bodies, thereby protecting the patient from invasion of bacteria
· To remove devitalized tissue or burn eschar in preparation for grafting and wound healing
There are three types of débridement—natural, mechanical, and surgical.
With natural débridement, the dead tissue separates from the un-derlying viable tissue spontaneously. After partial- and full-thickness burns, bacteria that are present at the interface of the burned tis-sue and the viable tissue underneath gradually liquefy the fibrils of collagen that hold the eschar in place for the first or second postburn week. Proteolytic and other natural enzymes cause this phenomenon. Using antibacterial topical agents, however, tends to slow this natural process of eschar separation. It is advanta-geous to the patient to speed this process through other means, such as mechanical or surgical débridement, thereby reducing the time during which bacterial invasion and other iatrogenic prob-lems may arise.
Mechanical débridement involves using surgical scissors and for-ceps to separate and remove the eschar. This technique can be performed by skilled physicians, nurses, or physical therapists and is usually done with daily dressing changes and wound cleaning procedures. Débridement by these means is carried out to the point of pain and bleeding. Hemostatic agents or pressure can be used to stop bleeding from small vessels.
Dressings are also useful débriding agents. Coarse-mesh dress-ings applied dry or wet-to-dry (applied wet and allowed to dry) will slowly débride the wound of exudate and eschar when they are removed. Topical enzymatic débridement agents are available to promote débridement of the burn wounds. Because such agents do not have antimicrobial properties, they should be used with topical antibacterial therapy to protect the patient from bac-terial invasion.
Early surgical excision to remove devitalized tissue along with early burn wound closure is now being recognized as one of the most important factors contributing to survival in a patient with a major burn injury. Aggressive surgical wound closure has re-duced the incidence of burn wound sepsis, thus improving sur-vival rates (Gibran & Heimbach, 2000). Early excision is carried out before the natural separation of eschar is allowed to occur.
Surgical débridement is an operative procedure involving either primary excision (surgical removal of tissue) of the full thick-ness of the skin down to the fascia (tangential excision) or shaving the burned skin layers gradually down to freely bleeding, viable tis-sue. Surgical excision is initiated early in burn wound manage-ment. This may be performed a few days after the burn or as soon as the patient is hemodynamically stable and edema has decreased.
Ideally, the wound is then covered immediately with a skin graft, if needed, and an occlusive dressing. If the wound bed is not ready for a skin graft at the time of excision, a temporary biologic dress-ing may be used until a skin graft can be applied during subse-quent surgery.
The use of surgical excision carries with it risks and compli-cations, especially with large burns. The procedure creates a high risk of extensive blood loss (as much as 100 to 125 mL of blood per percent body surface excised) and lengthy operating and anesthesia time. However, when conducted in a timely and effi-cient manner, surgical excision results in shorter hospital stays and possibly a decreased risk of complications from invasive burn wound sepsis.
Eschar separation in full-thickness burns is typically delayed in elderly patients, and older patients are frequently poor risks for surgical excision. Therefore, prolonged hospitalization, immobi-lization, and associated problems may be common. If the elderly patient can tolerate surgery, early excision with skin grafting is the treatment of choice because it decreases the mortality rate in this population. Prevention of complications of prolonged hos-pitalization, immobility, and surgery is essential in the care of the elderly burn patient.