Infection

The most important threat to survival of the fully resuscitated patient is infection,

with burn wound sepsis and pneumonia being the leading causes of death.

156 The

local mechanical defenses of the skin and respiratory tract often are damaged in burn

victims, making these common foci for fatal infections. Loss of circulation to the burn

wound margins does not allow proper functioning of cellular and humoral defense

mechanisms, which increases susceptibility to infection. Devitalized tissue and tissue

exudates provide an ideal environment for the proliferation of bacteria. Colonization

of gram-positive bacteria occurs if topical antimicrobial therapy is not initiated

promptly, and gram-negative bacteria may predominate by the fifth day after injury.

156

Systemic antibiotics are of limited benefit in full-thickness burns and are used only to

treat infections documented by wound biopsy, which reveal in excess of 10

5 bacteria

per gram of burn tissue.

157 Topical antimicrobials, local wound care, and strict

infection control practices are the mainstays of controlling burn wound infections.

Devitalized tissue initiates and perpetuates a sepsis-like state in the absence of an

identifiable focus of infection.

156 For this reason, as well as for infection control,

early excision of devitalized tissue and closure of the burn wound by skin grafting or

substitutes have been adopted by many burn centers.

Inhalation Injury

Burn injuries complicated by inhalation injury are associated with greatly increased

mortality rates. Injury to the tracheobronchial mucosa is caused by inhalation of

smoke or flames and may result in bronchospasm, ulceration of the mucous

membranes, damage to cell membranes, edema, and impairment of bacterial ciliary

clearance. Even patients with minor burns can have inhalation injury and require

hospital admission. The early symptoms of pulmonary injury (hoarseness, dyspnea,

tachypnea, and wheezing) may not be evident for 24 to 48 hours, so patients with

suspected inhalation injury (i.e., facial burns or entrapment in a closed space) must

be examined carefully. Singed nasal hair, a soot-coated tongue or oropharynx, and

upper airway edema are indications of inhalation injury. The diagnosis is established

by bronchoscopy, and management may include endotracheal intubation and

mechanical ventilation. Maintenance of the patient’s fluid status is essential.

Corticosteroids do not influence survival rates and should not be routinely

administered to patients with inhalation injury. They can also increase morbidity and

mortality associated with burns and inhalation injury by increasing the risk of

infection.

156

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Clinical Management of Minor Burns

TRIAGE

CASE 42-6

QUESTION 1: S.T., a 17-year-old, nonobese boy, has just burned the calf of his right leg on the muffler of his

motorcycle. Immediately after being burned, S.T. was able to rinse his leg with cool water from a garden hose.

The burn on his leg is about twice the size of the palm of his hand and appears erythematous and weeping. He

sustained no other injury, but now he is in considerable pain. S.T. has no significant medical history. Should S.T.

be referred to a healthcare provider or can he safely self-treat his burn? What patient information is necessary

to consider in making this decision?

Before recommending treatment for a patient with a minor burn, it is important to

accurately assess the patient to determine whether he or she can self-treat safely or

whether referral or hospitalization is necessary. The location and severity of the

burn, the patient’s age and state of health, and the cause of the burn injury all must be

considered.

American Burn Association Treatment Categories

Three treatment categories for burn injuries are recommended by the American Burn

Association: major burn injuries; moderate, uncomplicated burn injuries; and minor

burn injuries.

158

Major burn injuries are second-degree burns with greater than 25% TBSA

involvement in adults (20% in children); all third-degree burns with 10% TBSA

involvement; all burns involving the hands, face, eyes, ears, feet, and perineum

that may result in functional or cosmetic impairment; high-voltage electrical

injury; and burns complicated by inhalation injury, major trauma, or poor-risk

patients (elderly patients and those with debilitating disease).

Moderate, uncomplicated burns are second-degree burns with 15% to 25% TBSA

involvement in adults (10%–20% in children); third-degree burns with 2% to

10% TBSA involvement; and burns not involving risk to areas of specialized

function, such as the eyes, ears, face, hands, feet, or perineum.

Minor burn injuries include second-degree burns with less than 15% TBSA

involvement in adults (10% in children), third-degree burns with less than 2%

TBSA, and burns not involving functional or cosmetic risk to areas of specialized

function.

Patients with minor burn injuries may be treated on an outpatient basis if no other

trauma is present; if circumferential burns of the neck, trunk, arms, or legs are not

present; and if the patient is able to comply with therapy. After initial evaluation by a

healthcare provider, patients may self-treat a second- or third-degree burn only if

less than 1% BSA is involved.

Major or moderate, uncomplicated burns necessitate hospital admission, and

surgical referral is recommended for patients of all ages who have deep second- or

third-degree burns covering 3% of the TBSA.

Both the American Burn Association and the American College of Surgeons

recommend transfer to a burn center for all acutely burned patients who meet any of

the following criteria

159

:

Partial-thickness burns of at least 20% TBSA in patients aged 10 to 50 years

Partial-thickness burns of at least 10% TBSA in children younger than 10 or adults

older than 50 years

Full-thickness burns of at least 5% TBSA in patients of any age

Patients with partial- or full-thickness burns of the hands, feet, face, eyes, ears,

perineum, or major joints

Patients with high-voltage electrical injuries, including lightning injuries

Patients with significant burns from caustic chemicals

Patients with burns complicated by multiple trauma in which the burn injury poses

the greatest risk of morbidity or mortality (in such cases, if the trauma poses the

greater immediate risk, the patient may be treated initially in a trauma center until

stable before being transferred to a burn center)

Patients with burns who suffer an inhalation injury

Patients with significant ongoing medical disorders that could complicate

management, prolong recovery, or affect mortality

Patients who were taken to hospitals without qualified personnel or equipment for

the care of children

Burn injury in patients who will require special social, emotional, or long-term

rehabilitative support, including cases involving suspected child abuse or

substance abuse

Age- and Disease-Related Recommendations

Children younger than 2 years of age and elderly patients with a burn injury should be

referred for evaluation because these patients may not tolerate any trauma associated

with the burn. In addition to medical issues, children with burns that result from

suspected child abuse should be hospitalized for legal, psychosocial, and protective

reasons. Burn patients with any other medical condition, such as diabetes mellitus,

cardiovascular disease, immunodeficiency disorders (e.g., human immunodeficiency

virus [HIV]-associated disease, patients receiving cancer chemotherapy), renal

disease, obesity, or alcoholism, may be more susceptible to complications from the

burn and may have compromised wound healing.

ETIOLOGY

The etiology of a burn should always be considered because this may provide some

insight into the burn presentation and its management. Electrical burns can appear to

be superficial because external injury may occur at only the entrance and exit sites of

the current. These burns, however, can cause extensive damage to underlying nerve

and muscle tissue that is not initially evident. Except for very minor electrical burns,

these patients should be referred for further evaluation. S.T. has sustained a

superficial second-degree burn over about 2% of his TBSA. Even though the burn

wound on his leg was caused by thermal injury and is relatively minor, S.T. should

be referred for further evaluation and treatment.

TREATMENT

CASE 42-6, QUESTION 2: How should S.T.’s burn be treated? What treatment alternatives may be used

for S.T.? What immunization should S.T. be questioned about?

Goals of Treatment and Immediate Care

Treatment goals for first- and second-degree burns are to relieve the pain associated

with the burn; to prevent desiccation and deepening of the wound and infection; and

to provide a protective environment for healing. Immediate care of the wound should

be application of cold, wet compresses or immersion in cool water.

S.T. may have prevented extension of the burn to deeper layers of tissue and

alleviated some of his pain from the burn by immediately irrigating the wound with

cool water. Next, the area should be cleansed with a mild hypoallergenic soap (e.g.,

Basis, Purpose) and water. The sterile, nonadherent, fine-mesh gauze dressing

impregnated with hydrophilic petrolatum (e.g., Xeroflo, Kendall; 3% bismuth

tribromophenate) should be placed over the

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wound. This type of dressing offers bacteriostatic activity and prevents the gauze

from adhering to the wound and allows the burn exudate to flow freely through the

dressing, thus preventing maceration.

A second layer of absorbent gauze should be placed over the petrolatum gauze,

and a supportive layer of rolled gauze can be used to keep the dressing in place. The

outer layer must not be too constricting, and the dressing should be replaced every 48

hours after recleaning the area and inspecting for signs of infection. If S.T.’s wound

continues to weep, it may be beneficial to soak his wound or apply a towel saturated

with water, normal saline, or Burow solution (diluted 1:20 or 1:40) for 15 to 30

minutes at least 4 times daily (see Chapter 39, Dermatotherapy and Drug-Induced

Skin Disorders). The use of butter, grease, or similar home remedies should be

avoided in the treatment of burns because these measures tend to retain the thermal

energy sustained in the burn and may increase the area of thermal injury. Because

burn patients are susceptible to secondary tetanus infections, S.T. should receive a

tetanus toxoid booster if he has not been immunized within the previous 10 years.

Skin Substitutes and Synthetic Dressings

Advances in the development of skin substitutes are being used to achieve the elusive

goal of finding a skin replacement to mimic completely the interaction and functions

of dermis and epidermis. Although this goal has yet to be achieved, a growing

number of synthetic and biologic products are available that can serve important

roles in caring for burn patients.

159 Examples of some of the current modalities are as

follows:

Human Cadaver Skin

Fresh human cadaver skin (allograft) is considered the sine qua non for temporary

closure of burn wounds. It adheres well to a healthy wound bed, resulting in reduced

contamination and reduced protein, heat, and water loss. With improved stabilization

techniques, rejection and disease transmission (e.g., hepatitis) can be delayed for 3 to

5 weeks, and the risk of infection transmission (e.g., hepatitis) is minimized.

Epidermal Substitute: Cultured Epithelial Allografts

Deep injuries (i.e., third-degree or deep dermal burns) lead to dermal damage that

impairs the ability of the skin to heal and regenerate on its own. Skin autografting

after burn excision is considered the current gold standard of care, but lack of

patient’s own donor skin or unsuitability of the wound for autografting may require

the temporary use of dressings or skin substitutes to promote wound healing, reduce

pain, and prevent infection and abnormal scarring. These alternatives include

deceased donor skin allograft, xenograft, cultured epithelial cells, and biosynthetic

skin substitutes.

Allotransplantation is the transplantation of cells, tissues, or organs, sourced from

a genetically nonidentical member of the same species as the recipient. Human

deceased donor skin allografts represent a suitable and much used temporizing option

for skin cover after burn injury. The main advantages for their use include

dermoprotection and promotion of re-epithelialization of the wound and their ability

to act as a skin cover until autografting is possible or reharvesting of donor sites

becomes available. Disadvantages of its use include the limited abundance and

availability of donors, possible transmission of disease, the eventual rejection by the

host, and its handling, storing, transporting, and associated costs of provision. The

technique of culturing autologous human epidermal cells grown from a single fullthickness skin biopsy into confluent keratinizing sheets suitable for grafting has been

available for more than two decades and is especially useful for patients with large

wounds.

160 A lack of mechanical stability of cultured epithelium, causing an

imperfect cover, remains a major concern; therefore, the development of a dermal

substitute (or a vascularized remnant of allogeneic dermis), in combination with

cultured epithelial allografts to increase mechanical stability and decrease wound

contracture, or a laboratory-derived autologous composite continues to receive

scientific investigation.

161

Animal Substitute: Porcine Skin

Xenografts derived from porcine skin has gained acceptance as a temporary dressing

alternative to allograft because of its lower cost and greater availability.

161 At 0°C,

frozen porcine skin has a storage life of 6 to 18 months from the date of manufacture.

As with an allograft, it has the desirable properties of being able to adhere initially

to a clean wound; to cover nerve endings to decrease pain; to function as an autograft

test graft; and to diminish heat, protein, and electrolyte loss. Use of porcine

xenografts is a cost-effective alternative to allografts in the treatment of burn wounds,

especially for partial-thickness skin losses, temporary coverage prior to autograft

and to protect meshed autografts. Although porcine skin shares many physical

properties with human skin, it is susceptible to hyperacute rejection due to preformed

antibodies. A porcine-derived xenograft in a premeshed, de-epithelialized, collagen

matrix that can be stored at room temperature (EZ Derm, Mölnlycke Health Care) is

thought to be more resistant to bacterial degradation.

Dermal Analogs: Allodermal Grafts

Unlike the epidermis, the dermis can be rendered acellular and still perform its basic

protective and supportive functions. With removal of the dermal cells, the antigenic

elements are also eliminated; therefore, alloplastic transplantation can occur without

rejection. The principle of allodermal grafting is that an ultrathin (0.01 cm) meshed

autograft laid on top of the allodermis provides skin quality that is comparable to that

obtained from thick partial-thickness skin grafts.

As one example, AlloDerm (LifeCell) is a shelf-stored, freeze-dried, acellular

human cadaveric dermal matrix. Integra (Integra LifeSciences) is a porous matrix of

cross-linked bovine tendon collagen and glycosaminoglycan and a semi-permeable

polysiloxane (silicone) layer. The inner layer of this material is a 2-mm-thick

combination of collagen fibers isolated from bovine tissue and the

glycosaminoglycan chondroitin-6-sulfate that has a 70- to 200-μm pore size to

facilitate host fibrovascular ingrowth. The outer layer is a 0.009-inch polysiloxane

polymer with vapor transmission characteristics that simulate normal epithelium.

This meshed bilayer allows drainage of wound exudate and provides a flexible

adherent covering for the wound surface. The collagen-glycosaminoglycan

biodegradable matrix provides a scaffold for cellular invasion and capillary

growth.

161

Semisynthetic or Biosynthetic Dressings

Biobrane (Smith & Nephew), a nylon–collagen mesh, is used commonly for partial-

thickness burns.

162,163

It is a bilaminar, semisynthetic, temporary skin substitute made

of a silicone film that is bonded to nylon mesh. Once applied to the burn site, blood

or sera clot in the nylon matrix to adhere the mesh to the wound until epithelialization

occurs. Its adherence is facilitated by collagen peptides bonded to the nylon

underlayer. This substitute has been shown to be as effective as frozen human

allograft for the temporary coverage of freshly excised full-thickness burn wounds

before autografting.

163 Other available biosynthetic dressings are AWBAT (Aubrey)

and AWBAT Plus (Aubrey), which contain a silicone–nylon–collagen membrane.

Silon TSR (BioMed Sciences) is a synthetic copolymer that serves as a temporary

skin replacement, with elasticity, permeability to water vapor and impermeability to

bacteria. These agents peel off within approximately 2 weeks as re-epithelialization

of the wound bed progresses.

162

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For superficial- to partial-thickness burns, numerous agents are available overthe-counter. Duoderm (ConvaTec) is a hydrocolloid dressing, whereas OpSite

(Smith & Nephew) and Tegaderm (3M) are elastomeric polyurethane films. Comfeel

(Coloplast) is a semipermeable polyurethane film coated with a flexible, crosslinked adhesive mass containing sodium carboxy-methylcellulose (NaCMC) as the

principal absorbent and gel-forming agent. This product is permeable to water vapor,

but impermeable to exudates and microorganisms. In the presence of an exudate,

NaCMC absorbs fluids and swells to form a cohesive gel that does not disintegrate

or leave residues in the wound bed.

Hyaluronic Acid

Produced by fibroblasts, this group of dermal matrices has a demonstrated positive

impact on scar-free fetal wound healing and is also used commercially as a dermal

filler. It can be obtained from Streptococcus fermentation or extracted from rooster

combs. It is available as a scaffold for keratinocytes (Laserskin), an acellular dermal

matrix (Hyalomatrix), and as a cellular dermal matrix (Hyalograft-3D).

164

Alternatives in treating S.T.’s second-degree burn include the use of synthetic

dressings and topical antimicrobial agents. Synthetic dressings serve as skin

substitutes that are applied to fresh, clean, and moist burns. They are trimmed to

about the size of the burn and left in place until the burn is healed or the dressing

separates from the wound spontaneously. Indicated for superficial second-degree

burns, biosynthetic dressings keep the wound warm and moist, allowing for a faster

rate of healing. These dressings offer a significantly lower rate of infection, less

frequent dressing changes, with less pain and electrolyte and albumin loss.

Tissue-Engineered Biologic Dressings

Tissue-engineered biologic dressings (examples: Dermagraft, Organogenesis; OASIS

Wound Matrix, Smith & Nephew) have been used in the treatment of burns, chronic

ulcers, surgical wounds, and other desquamating dermatologic conditions.

165,166 Using

an appropriate biologically active matrix to accelerate wound healing and achieving

skin reconstruction is well established. Cellular components migrate to the wound

from preexisting cell populations in adjacent tissue. Both circulating marrow-derived

stem cells and preexisting organ-specific stem cells can contribute to tissue

regeneration.

165

Topical Antimicrobial Agents

Silver Sulfadiazine

Silver sulfadiazine 1% cream (Silvadene, generic; Aquacel Ag [hydrofiber dressing

with silver]; ConvaTec) is the usual agent of choice because it has broad-spectrum

gram-positive and gram-negative antibacterial activity, provides reasonable eschar

penetration, and is easy and painless to apply and wash off. The cream is a 1%

suspension of silver sulfadiazine in a water-miscible base. As a consequence of poor

water solubility, the active agent shows only limited diffusion into the eschar. Silver

sulfadiazine cream is most effective when applied to burn wounds immediately after

thermal injury to prevent bacterial colonization of the burn wound surface as a

prelude to intraeschar proliferation. This agent has the advantages of being painless

when applied to the wound and being free from acid–base and electrolyte

disturbances. The limitations of silver sulfadiazine cream include the potential for

allergic reactions owing to its sulfadiazine moiety, silver staining of the treated burn

wound, hyperosmolality, methemoglobinemia, and hemolysis as a result of a

congenital lack of glucose-6-phospate dehydrogenase.

167 Leukopenia, previously

considered to be an adverse drug event associated with use of silver sulfadiazine,

occurs when using other topical agents during burn care.

167 An evidence-based

review of use of silver sulfadiazine in burns suggested that whereas there is evidence

of antibacterial activity, no direct evidence is seen of improved healing or reduced

infection compared with normal dressings.

168

In partial-thickness burns, use of

Aquacel Ag offers less treatment to re-epithelialize burns 100% with less pain, as

compared with silver sulfadiazine.

169 This agent should not be applied around the

eyes or mouth in patients with hypersensitivity to sulfonamides or in pregnant or

breast-feeding women.

Mafenide Acetate

Mafenide acetate (Sulfamylon) is an 11.1% cream formulation of mafenide acetate in

a water-dispersible base, or a 5% powder for topical solution. A recent investigation

in a pediatric burn population demonstrated the effectiveness of a 2.5% solution,

without a change in the incidence of bacteremia or wound infection, and without

experiencing adverse drug events.

170 As a water-soluble agent, mafenide diffuses

freely to establish an effective antibacterial concentration throughout the eschar and

at the interface of viable–nonviable tissue, where bacteria characteristically

proliferate before invasion. Because of this characteristic, mafenide is the best agent

for use if the patient to be treated has heavily contaminated burn wounds, if treatment

is delayed for several days after the burn occurred, or if a dense bacterial population

already exists on and within the eschar. Adverse effects include hypersensitivity

reactions in 7% of patients (usually responsive to antihistamines), pain or discomfort

for 20 to 30 minutes when applied to partial-thickness burns (seldom a cause for

discontinuation), and inhibition of carbonic anhydrase. The inhibition of carbonic

anhydrase can produce both an early bicarbonate diuresis and an accentuation of

postburn hyperventilation. The resulting overall reduction of serum bicarbonate

levels renders such patients liable to a rapid shift from an alkalotic to an acidotic

state. If acidosis should develop during use of mafenide, the frequency of application

should be reduced to once daily, or it should be omitted for 24 to 48 hours, with

buffering used as necessary and with efforts made to improve pulmonary function.

Either topical silver sulfadiazine or mafenide should be applied in a one-eighthinch-thick layer to the entire burn wound with a sterile gloved hand immediately after

initial debridement and wound care. Twelve hours later, to ensure continuous topical

treatment, a one-eighth-inch coat of cream should be reapplied to those areas of the

burn wound from which it has been abraded by clothing. The topical cream should be

cleansed gently once each day from all of the burn wound, and the wound should be

inspected. Daily debridement should be carried out to a point of bleeding or pain

without the use of general anesthesia. After debridement, the wound should be

covered again by the topical cream.

In S.T.’s case, silver sulfadiazine cream could be chosen to treat his burn on an

outpatient basis if an assessment determines that he is at particular risk for infection.

The cream would be applied in a thin layer over the wound and covered with

absorbent gauze and wrapped with rolled gauze. The dressing must be changed twice

daily to maintain an application of cream that is biologically active. Topical

bacitracin and the combination of polymyxin B and bacitracin are transparent

formulations that also can be used, but, because of limited efficacy, may be desirable

for use only on small, second-degree burns on the face.

Oral Analgesics and Topical Protectants

S.T.’s burn pain can be treated with oral OTC analgesics, aspirin, acetaminophen, or

ibuprofen. If these analgesics do not provide adequate relief, oxycodone or

acetaminophen (or equivalent) may be of additional benefit.

171 Topical protectants,

such as allantoin, calamine, white petrolatum, or zinc oxide, are safe and effective in

treating first-degree and minor second-degree burns. These agents protect the burn

from mechanical irritation caused by friction and rubbing and prevent drying of the

stratum corneum.

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