In-Service Exam
Burns - 2002





Inadequate fluid resuscitation in a burn patient is most likely to result in which of the following conversion mechanisms?

(A) Zone of coagulation to zone of hyperemia
(B) Zone of coagulation to zone of stasis
(C) Zone of stasis to zone of coagulation
(D) Zone of stasis to zone of hyperemia
The correct response is Option C.

There are three zones of injury in burn patients. The zone of coagulation lies in the center of the wound and is characterized by irreversible tissue destruction. It is immediately surrounded by the zone of stasis, an area of decreased perfusion with demonstrated damage to the microvasculature. The surrounding zone of hyperemia sustains the least amount of damage.

During the first 48 hours following burn injury, patients who are not properly resuscitated are at increased risk for conversion of the zone of stasis to a zone of coagulation. In contrast, if appropriate resuscitation is begun immediately, the zone of stasis can be reversed, potentially preventing the development of necrosis.

References
1. Arturson MG. The pathophysiology of severe thermal injury. J Burn Care Rehabil. 1985;6:129-146.
2. Jackson DM. The diagnosis of the depth of burning. Br J Surg. 1953;40:588.
3. Zawacki BE. The natural history of reversible burn injury. Surg Gynecol Obstet. 1974;139:867.

A 33-year-old man who weighs 80 kg is brought to the emergency department eight hours after sustaining deep partial-thickness burns involving 25% total body surface area (TBSA) and full-thickness burns involving 15% TBSA. According to the Parkland formula, how many milliliters (mL) of crystalloid should be administered for initial fluid resuscitation over the next eight hours?

(A) 3200
(B) 6400
(C) 9600
(D) 12,800
(E) 16,000

The correct response is Option C.

In a patient who has a burn injury that covers more than 20% of the total body surface area (TBSA), acute fluid resuscitation should be performed with administration of crystalloid during the initial 24 hours after injury. The Parkland formula is used to estimate the amount of fluid required. According to this formula, lactated Ringer's solution 4 mL/kg/% TBSA burned should be administered during the first 24 hours. A total of 50% of the solution should be administered during the first eight-hour period and the remaining 50% over the next 16 hours.

An 80-kg patient who has burns involving 40% TBSA will require 12,800 mL of fluid during the first 24 hours: 6400 mL during the first eight hours and the remaining 3200 mL in both the second and third eight-hour periods. Because he received no fluid during the first eight hours immediately following injury, 9600 mL of crystalloid should be administered over the next eight hours in order to adequately resuscitate the patient.

References
1. Demling RH. Burns: fluid and electrolyte management. Crit Care Clin. 1985;1:27-45.
2. 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; 1997:168.
3. Salisbury RE. Thermal burns. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;4:3101-3123.

In a patient who sustained third-degree burns one hour ago, which of the following mechanisms associated with the initial inflammatory response is most likely to result in progressive tissue destruction?

(A) Downregulation of integrins
(B) Increased chemotaxis
(C) Inhibition of neutrophil degranulation
(D) Inhibition of tumor necrosis factor-alpha and interleukins 1 and 8
(E) Replacement of neutrophils with macrophages

The correct response is Option B.

During the first few hours after burn injury, multiple cytokines act to mediate a massive inflammatory response. Tumor necrosis factor-alpha (TNF-_) and interleukins 1 and 8 are released, resulting in increased chemotaxis of neutrophils into the wound. Upregulation of integrins also occurs following the release of TNF-_ and interleukins, and cell surface adherence receptors appear on neutrophils and endothelial cells. During this phase, neutrophils migrating into the wound adhere to the capillary endothelium and degranulate, resulting in the release of proteases and toxic oxygen-free radicals, leading to further tissue destruction. Macrophages gradually replace neutrophils over the first few days following injury and produce cytokines, which are critical for wound healing.

References
1. Dziewulski P. Burn wound healing. Burns. 1992;18:466-478.
2. Kao CC, Garner WL. Acute burns. Plast Reconstr Surg. 2000;105:2482-2492.

A 32-year-old man has severe pain and swelling of both hands after being exposed to hydrofluoric acid while working with a rust remover. On examination, there is significant edema, mottling, and exquisite tenderness of the index, long, and ring fingers of both hands. Digital pulses are present on Doppler ultrasonography.

Following copious irrigation of the hands with water, which of the following is the most appropriate next step in management?

(A) Irrigation with 1% copper sulfate
(B) Topical application of phenol
(C) Application of a calcium sulfate splint
(D) Local injection of 10% calcium gluconate
(E) Debridement of the wounds and coverage with split-thickness skin grafts

The correct response is Option D.

This patient has sustained chemical burns to both hands after coming in contact with hydrofluoric acid, a corrosive material derived from elemental fluoride and used in rust removal and plastic and pottery manufacturing. Hydrofluoric acid burns can result in necrosis of soft tissues and decalcification of bone; affected patients can have pain that persists for days. The mechanism of action of this type of burn is due to the high concentration of hydrogen ions within the tissues, as well as liquefaction necrosis caused by the soluble free fluoride ion. Following copious irrigation of the burn site with water to remove as much of the hydrogen ion as possible, 10% calcium gluconate should be injected locally in multiple small doses to prevent vascular compromise. The calcium will bind to the fluoride ion, resulting in immediate relief of pain. A topical calcium gluconate paste can be applied in patients who have less severe burns, and intra-arterial injection is advocated for patients with more severe burns.

Copper sulfate is used for irrigation in patients with phosphorus burns to identify buried particles of phosphorus. Phenol should not be applied because it can be absorbed through intact skin and further worsen injury. In patients who have sustained phenol burn injuries, topical application of polyethylene glycol or vegetable oil is recommended. Similarly, calcium sulfate (eg, plaster of Paris) can result in exothermic burns when used in a splint or cast. Debridement with split-thickness skin grafting should be considered only after the extent of demarcation of the injury is fully known; it may be necessary in patients who have persistent liquefaction necrosis, which manifests as unrelenting pain, even after treatment with calcium gluconate.

Reference
1. Murray J. Cold, chemical and irradiation injuries. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;7:5431-5440.