In-Service Exam
Burns - 2003





A 30-year-old man is brought to the emergency department after sustaining second-degree burns of the trunk involving 10% total body surface area (TBSA). The burns are cleansed, and several blisters are debrided. In order to provide antimicrobial activity, which of the following dressings should be applied to the wounds?

(A) Fibronectin-coated skin substitute (Transcyte)
(B) Porous collagen-glycosaminoglycan membrane (Integra)
(C) Silicone membrane-nylon fabric composite (Biobrane)
(D) Silver-coated wound dressing (Acticoat)

The correct response is Option D.

Treatment of partial-thickness burns can be accomplished through cleansing of the burn and application of either an antimicrobial or occlusive dressing. Most patients are treated with silver sulfadiazine (Silvadene); however, if a sulfa allergy is present, bacitracin, polymyxin/bacitracin (Polysporin), or mupirocin (Bactroban) can be used. Acticoat is a dressing material coated with a thin soluble layer of silver ion; it reportedly provides antimicrobial activity for as long as five days. The greatest advantage is a decrease in the number of dressing changes, with a subsequent decrease in pain, as well as decreased cost.

Biobrane and Transcyte are occlusive dressings that can be used for management of clean second-degree burns as long as they are applied within the first 24 hours. These dressings do not provide antimicrobial activity. Biobrane consists of a nylon fabric containing chemically bound collagen that is partially imbedded in a silicone film. As blood and serum clot within the nylon fabric, it adheres to the wound until epithelialization occurs, and then it sloughs. Transcyte consists of cultured human dermal fibroblasts on a semipermeable membrane bonded to nylon mesh. The mesh allows for growth of the dermal tissue, and the membrane forms a synthetic epidermis.

Integra is a bioengineered dermal substitute consisting of a bilayered membrane system. It is used for skin replacement after debridement of deep partial-thickness or full-thickness burns. The dermal replacement layer comes from bovine tendon cartilage, and the epidermal replacement is a synthetic silicone polymer that is removed following degradation of the dermal layer. A thin skin graft is then placed on the "neodermis."

References
1. Kao CC, Garner WL. Acute burns. Plast Reconstr Surg. 2000;105:2482-2491.
2. Yin HQ, Langford R, Burrell RE. Comparative evaluation of antimicrobial activity of Acticoat antimicrobial barrier dressing. J Burn Care Rehab. 1999;20:195-200.

Administration of anti-inflammatory agents to patients who have sustained frostbite is most likely to result in which of the following beneficial effects?

(A) Decreased production of prostaglandin I2
(B) Decreased production of thromboxane B2
(C) Increased production of prostaglandin F2a
(D) Increased production of prostaglandin I2

The correct response is Option B.

Based on theories regarding the pathophysiology of frostbite injury, adverse changes that occur within the microvasculature at the site of injury are thought to be caused by inflammatory mediators. The prostaglandins thromboxane B2 and prostaglandin F2a are thought to induce microvascular thrombosis because they cause platelet aggregation and vasoconstriction. In contrast, the prostaglandins I2 and E2 have antiplatelet activity, resulting in vasodilation. It is thought that the frostbite injury increases production of thromboxane B2 and decreases production of prostaglandin I2, resulting in an imbalance in favor of microvascular thrombosis. Experimental studies have shown increased levels of these mediators within the frostbitten tissue in both experimental animal models and in the blister fluid of frostbite patients. In addition, studies have demonstrated that specific thromboxane inhibitors can increase the survival of threatened tissue.

Because anti-inflammatory agents, such as aspirin and ibuprofen, inhibit cyclooxygenases, administration of these agents will decrease production of thromboxane B2 and prostaglandin F2a and thus block their harmful effects. However, an adverse effect of these agents is their inhibition of prostaglandin I2 and prostaglandin E2 production, which limits their protective effect.

References
1. Heggers JP, McCauley RL, Phillips LG, et al. Cold induced injury: frostbite. In: Herndon DN, ed. Total Burn Care. Philadelphia, Pa: WB Saunders Co; 1996:408-414.
2. Ozyazgan I, Tercan M, Melli M, et al. Eicosanoids and the inflammatory cells in frostbitten tissue: prostacyclin, thromboxane, polymorphonuclear leukocytes, and mast cells. Plast Reconstr Surg. 1998;101:1881-1886.
3. Robson MC, Smith DJ. Cold injuries. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;1:849-866.

Monoclonal antibodies have been shown to limit the depth of burn injury by inhibiting neutrophil adhesion in which of the following zones?

(A) Zone of adherence
(B) Zone of coagulation
(C) Zone of hyperemia
(D) Zone of stasis

The correct response is Option D.

Patients with burn injuries have destruction of tissue proportionate to the length of time that the tissue has been exposed to the heat source and the temperature at the surface of the skin. There are three zones that can be described to delineate the pathophysiology of burn injury.

The zone of coagulation is that area of the skin that is exposed to the highest temperature, resulting in irreversible, uniform necrosis of cells. This zone involves the burn eschar and extends downward.

The zone of stasis surrounds the zone of coagulation; in this area, the cells sustain less direct injury initially. Instead, progressive injury occurs following the development of ischemia and subsequent impairment of blood flow. This zone is characterized by the formation of microthrombi within platelets, endothelial swelling, neutrophil adherence, deposition of fibrin, and vasoconstriction, leading to eventual cell death. However, because injury in this zone is potentially reversible, there have been numerous experiments involving the zone of stasis in an attempt to limit burn depth. Several experimental animal studies have shown that antibodies directed to receptors on neutrophils can block their adherence to vessel walls, preventing microvascular occlusion and leukocyte-mediated endothelial injury. The total burn surface area is subsequently decreased.

In the zone of hyperemia, there is vasodilation and increased blood flow caused by vasoactive mediators. Cellular injury in this zone is minimal and is completely reversible.

The zone of adherence describes anatomic regions within the body in which skin and subcutaneous tissue are connected to the underlying fascia. It is important for the surgeon to recognize these zones when planning and performing suction lipectomy, as excessive suctioning may result in contour deformities.

References
1. Bucky LP, Vedder NB, Hong HZ. Reduction of burn injury by inhibiting CD18-mediated leukocyte adherence in rabbits. Plast Reconstr Surg. 1994;93:1473-1480.
2. Choi M, Rabb H, Arnaout MA, et al. Preventing the infiltration of leukocytes by monoclonal antibodies blocks the development of progressive ischemia in rat burns. Plast Reconstr Surg. 1995;96:1177-1185.
3. Kao CC, Garner WL. Acute burns. Plast Reconstr Surg. 2000;101:2482-2492.
4. Williams WG, Philips LG. Pathophysiology of the burn wound. In: Herndon DN, ed. Total Burn Care. Philadelphia, Pa: WB Saunders Co: 1996:63-70.

A 40-year-old man sustains deep partial-thickness and full-thickness burns over 45% total body surface area (TBSA). Following fluid resuscitation for 24 hours, his temperature is 38.9%C (102.1%F), pulse rate is 120 bpm, respirations are 24/min, and blood pressure is 105/60 mmHg. Serum leukocyte count is 18,000/mm3 and urine output is 70 mL/hr. Which of the following is the most likely cause of these findings?

(A) Bronchopneumonia
(B) Burn wound sepsis
(C) Inadequate fluid resuscitation
(D) Inadequate pain control
(E) Systemic inflammatory response

The correct response is Option E.

This 40-year-old man with burn injuries has findings consistent with systemic inflammatory response syndrome (SIRS), an inflammatory condition that can be caused by soft-tissue trauma, bacteremia, sepsis, ischemia, or pancreatitis. SIRS typically occurs in patients who have burns of more than 30% total body surface area (TBSA); the cell damage caused by the burn often incites the inflammatory reaction. Hyperactivity of the immune system causes alterations in the metabolic, cardiovascular, gastrointestinal, and coagulation systems. Affected patients have hypermetabolism and exhibit increased cellular, endothelial, and epithelial permeability and microthrombosis.

The diagnosis of SIRS can be made in any patient with burn injury who meets at least two of the following criteria, occurring as a sudden alteration above baseline levels in the absence of any other condition:

1. Body temperature lower than 36%C (96.8%F) or higher than 38.5%C (101.5%F)
2. Heart rate greater than 90 bpm
3. Respirations greater than 20/min, or carbon dioxide partial pressure (pCO2) less than 32 mmHg
4. Serum leukocyte count less than 4000/_L, greater than 12,000/_L, or containing more than 10% band forms

Although the precise mechanism that causes SIRS is unknown, the humoral or cellular immune system activates the onset of symptoms. Because the complement system is typically activated in burn patients, this may interact with the coagulation, fibrinolysis, and kallikrein-kinin systems to trigger the onset of the syndrome. Other critical mediators include heat shock proteins, tumor necrosis factor-alpha, the interleukins IL-1, IL-6, and IL-8, and endotoxin.

Bronchopneumonia would be unlikely in a patient who sustained burn injuries only 24 hours ago and more often occurs in the second week following injury. Burn wound sepsis occurs when proliferating microorganisms exceed 105 per gram of tissue and can be characterized by fever, tachycardia, and leukocytosis, but again this would not appear within the first 24 hours after injury. Inadequate fluid resuscitation is unlikely in a patient with adequate urinary output. Inadequate pain control would cause tachypnea and tachycardia, but not fever or leukocytosis.

References
1. Hinder F, Traber DL. Pathophysiology of the systemic inflammatory response syndrome. In: Herndon DN, ed. Total Burn Care. Philadelphia, Pa: WB Saunders Co; 1996:207-216.
2. Kao CC, Garner WL. Acute burns. Plast Reconstr Surg. 2000;101:2482-2492.
3. Mannick JA, Rodrick ML, Lederer JA. The immunologic response to injury. J Am Coll Surg. 2001;193:237-244.

To minimize the risk for hypertrophic scar formation and subsequent skin contractures in a patient who has sustained partial-thickness burns of the neck, attempts at healing by second intention should be limited to a maximum of how many weeks?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 6

The correct response is Option C.

To minimize the risk for development of hypertrophic scars and subsequent skin contractures in a patient who has sustained partial-thickness burns of the neck, the wound should not remain open for more than three weeks. According to the results of one study, hypertrophic scars formed in 33% of patients whose wounds healed within three weeks, compared with 78% of patients whose wounds were left open for more than 21 days.

Burn scar contractures of the neck can be released using Z-plasty, local flaps, or thick split-thickness or full-thickness grafts. The surgeon may need to release the platysma with the scar in order to restore full extension. Long-term postoperative splinting and compression are essential for graft take. Tissue expansion of unburned adjacent skin is another alternative for resurfacing the burned area.

References
1. Cole JK, Engrav LH, Heimbach DM, et al. Early excision and grafting of face and neck burns in patients over 20 years. Plast Reconstr Surg. 2002;109:1266.
2. Deitch EA, Wheelahan TM, Rise MP, et al. Hypertrophic burn scars: analysis of variables. J Trauma. 1983;23:895.
3. Jonsson CE, Dalsgaard CJ. Early excision and skin grafting of selected burns of the face and neck. Plast Reconstr Surg. 1991;88:83.
4. Robson MC, Barnett RA, Leitch IO, et al. Prevention and treatment of post burn scars and contracture. World J Surg. 1992;16:87.

A 25-year-old laborer sustains a burn of the dorsal aspect of the dominant right hand in a fire. Physical examination shows a deep partial-thickness burn that involves the entire dorsal aspect of the hand. Which of the following is the most appropriate management?

(A) Early excision of the burn wound and split-thickness skin grafting
(B) Coverage of the burn wound with a silicone membrane-nylon fabric composite (Biobrane)
(C) Aggressive topical wound care and occupational therapy
(D) Excision of the burn wound and coverage with a groin flap
(E) Excision of the burn wound and delayed split-thickness skin grafting

The correct response is Option A.

In this patient who has sustained a deep partial-thickness burn of the hand, the most appropriate management is early excision of the burn eschar followed by split-thickness skin grafting over the excised portions. An early return to full hand function is especially crucial in this patient, a laborer who has sustained a burn to his dominant right hand. Occupational therapy can be initiated immediately after excision and skin grafting to maximize hand function, allowing him to return to work as soon as possible.

Synthetic dressings should not be used to cover deep partial-thickness burns. Conservative therapy will only delay the appropriate treatment and make hand therapy more difficult. Coverage with a groin flap is an excessive, unnecessary procedure in this patient. Skin grafting should be delayed only if the depth and extent of the patient's burn injuries are unknown. In these situations, a waiting period of seven days may be beneficial.

References
1. Press B. Thermal, electrical, and chemical injuries. In: Aston SJ, Beasley RW, Thorne CH, eds. Grabb & Smith's Plastic Surgery. 5th ed. Philadelphia, Pa: Lippincott-Raven; 1997:161-189.
2. Smith MA, Munster AM, Spence RJ. Burns of the hand and upper limb Ð a review. Burns. 1998;24:493.

PHOTO

A 47-year-old man sustains a high-voltage electrical burn injury to the left upper extremity; a photograph is shown above. Physical examination shows swelling and tenseness of the forearm; there is no circumferential eschar. An exit wound is noted on the left foot. Adequate fluid resuscitation has been performed, and the patient is stable.

Which of the following is the most appropriate immediate management of the right forearm and hand?

(A) Observation
(B) Splinting
(C) Escharotomy
(D) Fasciotomy
(E) Amputation
The correct response is Option D.

Electrical injuries involving a charge of greater than 1000 volts are often misleading because the mildness of the superficial wounds frequently masks the serious underlying problems. Bone and muscle have greater resistance and thus generate significant heat, and the necrotic processes of these tissues are often hidden under viable skin. Serial excision of tissue is required to address this complication. Affected patients also have marked edema and rapidly increasing compartment pressures, which inhibit vascular inflow and can further worsen tissue necrosis. Muscle necrosis may lead to myoglobinuria, which if left untreated can result in myoglobin-induced renal failure. To prevent this life-threatening complication, the urine must be alkalized with administration of sodium bicarbonate, and urinary output must remain at a constantly high rate. Fasciotomies of the hand and forearm should be performed immediately for tissue salvage; the surgeon should continue to assess the viability of the tissue in the hand and forearm following fasciotomy.

Observation is obviously inadequate and even dangerous in a burn patient with compartment syndrome. Similarly, splinting alone will not prevent further injury to the extremity. Although escharotomy does not relieve compartment syndrome, it is a recommended first step in patients who have burn injuries with constricting eschar. Amputation prior to complete demarcation may be required in patients with infected or completely necrotic tissue.

Reference
1. Achauer BM, Applebaum R, Vandercam VM. Electrical burn injury of the upper extremity. Br J Plast Surg. 1994;47:331-340.

PHOTO

A 2-year-old child has the findings shown in the photograph above six days after sustaining a full-thickness burn injury to the left hand when the hand was immersed in boiling water. Silver sulfadiazine dressings have been applied since the time of injury. Which of the following is the most appropriate next step in management?

(A) Continued use of silver sulfadiazine dressings for three weeks
(B) Tangential excision and coverage with split-thickness skin grafts
(C) Tangential excision and coverage with full-thickness skin grafts
(D) Fascial excision and coverage with full-thickness skin grafts
(E) Coverage with cryopreserved acellular dermal homograft and epidermal grafts

The correct response is Option B.

In this 2-year-old child who has a full-thickness burn, the most appropriate management is tangential excision to a level at which punctate bleeding occurs, followed by split-thickness skin grafting. The depth of the burn can be determined by serial examination; in this case, after six days, the wound is not vascularized and has not become epithelized. Because burns that have not healed 21 days after initial injury are associated with a significant risk for hypertrophic scarring and contracture, this child's burn should be excised tangentially to the level of punctate bleeding. In addition, early skin grafting decreases the risk for scarring and permanent stiffness in patients with burns of the hand and increases the rehabilitation potential.

As implied above, continued application of silver sulfadiazine dressings is not appropriate in this patient. Any available full-thickness skin for grafting would most likely not be sufficient for coverage of this full-thickness burn involving most of the hand and forearm; a full-thickness graft is recommended instead for smaller areas that will contract only minimally. Although acellular dermal homograft has been shown to be beneficial in larger burns, its effects are limited in patients with burns limited to the hand who have other donor sites available.

References
1. Brcic A. Primary tangential excision for hand burns. Hand Clin. 1990;6:211-219.
2. Sheridan RL, Hurley J, Smith MA, et al. The acute burned hand: management and outcome based on 10-year experience with 1047 acute hand burns. J Trauma. 1995;38:406-411.