Burn injuries are among the leading causes of accidental death. Every year, an estimated 500,000 people in the US suffer burn injuries requiring medical attention, and up to 40,000 require hospitalization.[1] Hospital stays may be lengthy and may involve multiple surgical procedures.

Burns can result from thermal, chemical, and electrical injuries. Each type is treated differently, as described below.

Serious burns are complex injuries affecting skin, muscles, tendons, bones, nerves, and blood vessels. Skin damage impairs the body’s normal fluid and electrolyte balance, thermal regulation, and ability to fight infection. Long-term effects include diminished muscle and joint function and impaired manual dexterity. Involvement of the respiratory system can lead to airway obstruction and respiratory failure and arrest. Burns can also cause permanent disfigurement with concomitant sexual and psychological concerns regarding intimacy and self-esteem.

Risk Factors

The following factors are associated with increased risk of burns:

Use of wood stoves.

Exposed heating sources or electrical cords.

Unsafe storage of flammable or caustic materials.

Careless smoking. Cigarettes are the leading cause of house fires.

Water heaters set above 120°F.

Microwave-heated foods and containers.

Age. Children under 4, especially those who are poorly supervised, are at particular risk. Adults over age 60 are at higher risk of hospitalization due to burns.[2]

Gender. Globally there is variation in gender differences and rates of burn injury. In the US, however, no gender differences were found.

Substandard or older housing.

Substance abuse. Use of alcohol and illegal drugs increases risk.

Absent or nonfunctioning smoke detectors. The presence of a functioning detector decreases risk of death by fire.

Diagnosis

A detailed history will assess the mechanism, duration, and timing of the burn. Physical examination will ascertain burn location and severity and check for dehydration, disfigurement, and infection. Tissue culture is rarely needed to verify infection. Even minor burns can exacerbate diabetes, hypertension, and cardiac disease. Patients with these conditions who sustain significant burns, largely determined by percent of affected body surface area, should usually be referred to a burn center. Fires in enclosed spaces should raise the suspicion for smoke-inhalation injury. Clinicians should also be attentive to injuries that suggest physical abuse.

The traditional classification of burns as first, second, third, or fourth degree has been largely replaced by a system reflecting the requirement of surgical intervention. Burns are now classified based on the mechanism and depth. The depth is classified as superficial or epidermal, superficial partial-thickness, deep partial-thickness, or full thickness. Severe, deep-tissue extension burns are those that penetrate the subcutaneous layer and fascia and may involve muscle or bone.[3]

Superficial Burns

Burns that affect only the epidermis are superficial and are characterized by erythema or discoloration, mild swelling, and pain. Sun overexposure is a common cause. These burns do not cause blisters, and injuries heal in 3-6 days.

Partial-Thickness Burns

Superficial partial-thickness burns affect the epidermis and superficial layers of the dermis, causing a red color and blistering. Fluid is lost through damaged skin, and the burns are painful and tender since nerve endings are still intact. These burns will blanch with pressure, and injuries heal in 1-3 weeks. Scarring is uncommon, but skin color changes can persist for several months after the burn is healed.

Deep partial-thickness burns affect the deep layers of dermis, damaging glandular tissue and follicles. Blisters are present, but the skin usually has a mottled appearance. Healing takes > 3 weeks, and scarring is common.

Full-Thickness Burns

Burns that penetrate all layers of the dermis and sometimes extend into the subcutaneous tissue are classified as full-thickness burns. Injuries may have a charred appearance and/or contain white or gray patches. Healing occurs only at the wound edges, and by secondary intention. Scarring is significant, unless skin grafting is performed.

Severe, Deep-Tissue Extension Burns

Fat, muscle, tendon, and bone may be affected.

Treatment

Burn patients require specialized care and support. The American Burn Association (ABA) estimates the level of care required for burns according to the location, depth, and percentage of total body surface area (TBSA) affected. The Lund-Browder chart is the most precise tool for estimating TBSA and should always be used for burns in children, because it takes into account the changes in body proportions at different ages. The Rule of Nines is a faster method for estimating TBSA in adults. It assigns percentages of the skin surface in multiples of nine (e.g., a leg is assumed to be 9% of the skin surface, as is the abdomen, and both arms together).

The types of burn cases that should be referred to a burn unit include:[4]

• Partial-thickness burns covering more than 10% TBSA.
• Burns involving the face, hands, feet, genitalia, perineum, or major joints.
• Deep partial thickness and fourth-degree burns.
• Electrical burns.
• Chemical burns.
• Inhalation injuries.
• Patients with preexisting medical disorders that could complicate management or recovery.
• Patients with concomitant trauma (such as fractures) in which the burn injury poses the greatest risk of morbidity or mortality.
• Burns in children.
• Patients who will require special social, emotional, or long-term rehabilitative intervention.

Burn injuries are dynamic in nature, and even minor-appearing injuries can worsen with time (burn wound conversion) and need to be reassessed in 24 to 72 hours.[5],[6] Immediate care can be lifesaving. Before burns are treated, the burning agent must be prevented from inflicting further damage. Materials such as melted synthetic shirts, hot tar, or chemicals should be immediately removed, or in special cases (e.g., hydrofluoric acid), chemically inactivated.

Burns should be thoroughly cleaned under local or general anesthesia. Sterile dressings may be applied, although minor burns may need only topical treatment (see below). Tetanus vaccination and analgesics may be administered as needed. Burns that do not heal as predicted or that match the ABA referral criteria above require a specialist consultation or referral.

Superficial Burns

Superficial burns should be cooled in cool or room-temperature water if possible, or a cool moist cloth can be applied until pain subsides. Very cold water and ice should not be used, as these may damage skin. Mild soap and water can then be used to clean the wound. Burst blisters or sloughed skin should be debrided prior to dressing application; however, most superficial burns do not require a dressing.

Partial Thickness

Partial-thickness burns should be treated with a combination of a topical antimicrobial agent (e.g., chlorhexidine, silver sulfadiazine, or combination antibiotics) and a gauze dressing, such as fine mesh gauze, bismuth-impregnated petroleum-based gauze (Xeroform), biosynthetic gauze, silicon-coated gauze, hydrogel, or silver treated gauze.[7] Regular close follow-up is imperative for optimal dressing changes, to appropriately manage pain, to monitor for signs of infection or hypertrophic scar development, and to assess for other complications that require specialty assessment or intervention.

As stated above, all other burn injuries should be assessed and treated by a specialized team at a recognized burn center.

Nutritional Considerations

Nutritional support is a key component of burn care. Elevations in metabolic rate far above that predicted by the Harris-Benedict equation occur in adults with a burn covering 25% of TBSA, a hypermetabolic state that exceeds the metabolic increases found in any other disease state.[8] Resting metabolic rate (RMR) is approximately 180% of basal rate during acute admission in these patients, and their calorie needs may exceed 5,000 kcal/day.[9] Patients with a surface burn of 40% can lose 25% of preadmission weight in three weeks without nutrition support; losses exceeding 10% are associated with significantly poorer outcome, including impaired immunity and delayed healing.[9],[10]

Energy and Macronutrient Support

Significant weight loss is preventable with nutritional support. Recommended daily energy intake is as follows: for adults, 25 kcal/kg plus 40 kcal per each percent of burn area; for children, 1,800 kcal plus 2,200 calories per m² of burn area.[8] Individualized nutrition assessment is recommended for patients with burns on > 20% of TBSA.[11]

Enteral nutrition support with a high-protein, high-carbohydrate diet is recommended, and timing may be critical. Feedings started within ~ 4-36 hours following injury appear to have advantages over delayed (> 48 hours) feedings. If patients are hemodynamically stable (a prerequisite for prevention of bowel ischemia), these benefits include reductions in sepsis associated with gut permeability and clinical infection, as well as significantly shortened hospital stays.[12] Enteral support can reduce the burn-related increase in secretion of catabolic hormones and help maintain gut mucosal integrity. The duodenal route is better tolerated than gastric feeding, due to an 18% failure rate in the latter from regurgitation.[10] Total parenteral nutrition (TPN) is typically not recommended because of its ineffectiveness in preventing the catabolic response to burns.[10] TPN, sometimes in combination with enteral nutrition, can lead to overfeeding, impaired immunity, liver failure, and increased mortality, when compared with enteral nutrition.[8]

High-carbohydrate, low-fat diets for burn patients result in less proteolysis and more improvement in lean body mass and may reduce infectious morbidity and shorten hospitalization time when compared with a high-fat regimen.[9],[11] However, the benefit of a high-carbohydrate formula must be balanced against the risk for hyperglycemia, which can negatively influence the outcome of critically ill patients.[10] Nearly all burn patients experience insulin resistance as part of their hypermetabolic response and will need to be placed on an insulin drip to maintain tight control of blood glucose. Fat sources containing omega-3 fatty acids may help reduce the risk of hyperglycemia while also improving the inflammatory response.[11] Some data suggest that an approximately 1:1 ratio of omega-6 fatty acids to omega-3 fatty acids is optimal for immune enhancement; however, this remains a matter of controversy.[13]

Protein and fluid needs must also be considered carefully. Protein oxidation rates are 50% higher in burn patients, and protein needs are ~ 1.5-2.0 g/kg.8 Children need 2.5-4.0 g/kg/day.[13]

Glutamine, an amino acid formed in the skeletal muscle, is depleted following a burn injury. Glutamine supplementation at 25 g/kg/day has shown to reduce incidence of infections, hospital stays, and mortality.[8]

Water loss can be as much as 4 L/m2/day and a range of 30-50 mL/hour is given depending on the size of the burn, degree of hypernatremia, and urine output.[9],[14]

Micronutrient Support

Additional vitamin-mineral supplements may be indicated. Levels of the fat-soluble vitamins A and E and carotenoids fall below normal in burn injury patients.[15] Vitamin D synthesis is impaired in the skin of burn patients, both acutely and long-term. Blood levels appear to continue to fall, are below the normal range several years after recovery, and may negatively affect lumbar spine bone mineral density. Consequently, supplementation with the recommended dietary allowance of 400 IU of vitamin D per day has been suggested for patients with significant burns.[16],[17] However, the best dosage of vitamin D for children is unclear.[13]

Patients with major burns also suffer acute trace-element deficiencies, at least partly because of large exudative losses through the burned areas.[18] A lack of certain trace elements (e.g., selenium and zinc) can exacerbate poor immunity, and burns are the second-leading cause of immunodeficiency (after HIV infection).[9] Although a role for free radicals and lipid peroxides in burn trauma has been established, little research has been done on the effects of antioxidant supplements in human burn injury.[19] However, the addition of selenium, zinc, and copper to a standard trace-element formula and enteral nutrition was associated with a significant decrease in the number of bronchopneumonia infections and with a shorter hospital stay.[18]

Evaluating Nutritional Response to Feeding

The response of burn patients to their nutritional intake should be evaluated weekly or biweekly, based on the patient’s overall clinical status. Nitrogen balance studies are not as useful, as a large amount of protein is extruded from the wound beds daily. In addition, standard measures of nutritional repletion, such as visceral proteins (e.g., albumin and ferritin), are influenced not only by nutritional status, but also by inflammatory processes. When low concentrations are observed, the simultaneous concentrations of acute phase reactants, such as C-reactive protein, must be compared with their own reference standard to separate nutritional effects from inflammatory effects. Nevertheless, weekly or biweekly pre-albumin levels can guide nutritional status.[20]

Orders

Low-fat, high-protein, high-carbohydrate enteral tube feedings with appropriate caloric content. Weekly or biweekly assessments of nutritional status.

Nutrition consultation.

Physical therapy, occupational therapy, and mental health consultations, as appropriate.

What to Tell the Family

Burn injuries can be very traumatic. Burn patients may be hospitalized for prolonged periods and may require multiple surgeries. In severe burns, the patient will be physically incapacitated and emotionally traumatized. It is important for the family to know that the patient may need a great deal of support. This is especially true for deep partial thickness and full thickness burns. The family will play an essential role in supporting the patient.

References