Burns Flashcards

Question

A 25-year-old patient has been in the burn intensive care unit (ICU) intubated and sedated for 2 weeks after an 80% TBSA burn. He suddenly develops hypotension, tachycardia, and melena. What type of surgical problem is this patient most likely to have? ``` A. Curling’s ulcer B. Cushing’s ulcer C. Marjolin’s ulcer D. Dieulafoy’s lesion E. Boerhaave’s syndrome ```

Answer 1

ANSWER: A COMMENTS: Patients who are critically ill are at risk for a number of gastrointestinal emergencies as a result of their index injury. A Curling’s ulcer is upper gastrointestinal bleeding in a burn patient, related to gastritis. Incidence is now decreased to 4% due to improved critical care, chemical ulcer prophylaxis, and early tube feeding. A Cushing’s ulcer is similar, but presents in patients with severe neurologic injury and is likely related to increased intracranial pressure. Management of both types of ulcers is similar, with the patient receiving aggressive resuscitation, correction of coagulopathies, proton pump inhibitor administration, and endoscopic coagulation or clipping of any visible sources of bleeding. Selected arterial embolization can be used as an adjunct. Surgery is a last resort for patients who have persistent bleeding. A Marjolin’s ulcer is the malignant transformation of a chronic wound (burn scars, hidradenitis suppurativa, venous stasis ulcers, fistula tracts, or any other chronic wound) into squamous cell carcinoma. This type of squamous cell carcinoma is very aggressive and will need wide local excision and metastatic workup. A Dieulafoy’s lesion is a vascular malformation of large vessels (1 to 3 mm), in the stomach, usually along the lesser curve submucosa, and can result in massive blood loss. The mucosal defect overlying the vessel is often small, but the vessel itself is usually amenable to endoscopic clipping, which is successful >80% of the time. Boerhaave’s syndrome is an esophageal perforation, usually distal, resulting from esophageal sphincter dysfunction caused by repeated vomiting.

Answer 2

ANSWER: A COMMENTS: The correct burn size estimation is crucial to burn care. The percentage of the TBSA burned guides all aspects including need for transfer, fluid administration, and prognosis. Overestimation can have negative effects, primarily overresuscitation and resultant problems of respiratory failure and compartment syndromes. Underresuscitation is also problematic as patients can progress into shock or renal failure. There are many different methods used to calculate TBSA, but the easiest and the most rapid assessment tool is called the “rule of nines,” which divides the body into the following sections: head and neck, 9%; each upper extrem- ity (front and back), 9%; anterior trunk, 18%; posterior trunk, 18%; anterior lower extremity (each), 9%; posterior lower extremity (each), 9%; and perineum/genitalia, 1%. Only partial-thickness (second degree) or full-thickness (third degree) burns should be included in the TBSA calculation; any areas of superficial, or first- degree, burns are not included. Another pitfall is using the adult “rule of nines” to calculate infant or pediatric TBSA. More detailed tools, such as the Lund-Browder chart, analyze the body surface area more accurately by smaller divisions and are adjusted for age (children have proportionally larger heads and smaller legs). Alter-natively, small or scattered patches of burn can be estimated by using the surface of the patient’s palm to represent 1% TBSA. Providers should also be cautioned that any scoring system is only an initial guideline for starting resuscitation and that fluid administration, hemodynamics, lab values, and urine output should be closely monitored to prevent over- or underresuscitation.

Answer 3

ANSWER: D COMMENTS: The Parkland formula (4 mL of lactated Ringer’s solution × TBSA × weight in kg) is most commonly used to estimate the fluid resuscitation requirements for the first 24 h after a burn injury. This formula calls for 4 mL/kg per %TBSA burn to be given over a 24-h period. Half of the volume should be given over the first 8 h after injury and the remainder over the following 16 h. A common error is not taking into account fluid already administered prior to arrival, which can lead to overestimation of the amount of fluid needed. Another error is calculating the start time of fluid administration from presentation to the hospital, instead of the time of injury. For this patient, the initial calculation is 4 mL × 100 kg × 70 TBSA = 28,000 mL of lactated Ringer’s solution to be given in the first 24 h after injury. Half (14,000 mL) should be given over the first 8 h, taking into account the 5000 mL administered prior to arrival for a remaining balance of 9000 mL to be given in the remaining 4 h (9000 mL/8 h = 2250 mL/h). The remainder should be given over the following 16 h (14,000 mL/16 h = 875 mL/h). Pediatric patients will need the normal weight- based rate of maintenance fluids with glucose due to their low glycogen stores and inability to concentrate urine. It is important to remember that any formula used to guide resuscitation is only the best estimate of the patient’s needs. Many factors, including the patient’s cardiovascular status, concomitant injuries from trauma, medical comorbidities, and age can all affect the response to volume administration. The patient’s response to resuscitation should be monitored and IV fluids adjusted to the patient’s urine output. The most useful marker of resuscitation is adequate hourly urine output, defined as 30 to 50 mL/h in adult patients and 1 mL/ kg/h in children in the absence of myoglobinuria. Crystalloid boluses should be avoided unless required because of hypotensive episodes (mean arterial pressure persistently less than 60 mmHg) or to resuscitate blood loss from other traumatic injuries. Intravenous fluids are rapidly extravasated as a result of the capillary leakage that occurs in the first 48 h. Decreased urine output for 1 to 2 h would require increasing the hourly fluid rate. Adequate or excessive urine output may prompt the reduction of fluid administration rates. It is important to decrease fluid administration if not required because the morbidity (abdominal and extremity compartment syndromes, pulmonary edema) from massive volumes of resuscitation fluid is not insignificant.

Answer 4

ANSWER: B COMMENTS: Inhalation injury occurs in up to a third of major burns and significantly increases mortality in patients when com- bined with cutaneous burns. Conceptually, inhalation injury can be divided into three types, all of which can coexist within any given patient: CO poisoning (and other toxic inhalation), upper airway thermal injury, and lower airway injury. Upper airway burns occur as a result of a thermal injury, as well as the toxic substances in smoke. The capacity for the oropharynx to absorb heat generally prevents the thermal injury from extending lower into the airway. Oropharyngeal thermal injury can be diagnosed by direct laryngoscopy and, if significant, is an indication for prophylactic endotracheal intubation to control the airway before life-threatening airway edema develops, particularly after large-volume resuscitation ensues. Endotracheal tubes may be difficult to secure if the patient has facial burns. They may be tied with cotton tape wrapped around the face. Airway edema occurs a maximum of 12 to 24 h after injury, and if airway protection is required, the patient may remain intubated for 72 h. Short courses of steroids may be considered in patients without significant burns, but they are contraindicated in those with large burns because of infectious and wound complications. Extubation may be performed when the patient has met weaning parameters and edema has subsided. Lower airway inhalation injury results from exposure of the respiratory epithelium to toxic irritants in smoke or steam. Chest x-ray findings on admission are typically normal because infiltrates and lung injury tend to develop in delayed fashion over the days following injury. Damage to the airway leads to inflammation, sloughing of mucosa, and impaired ciliary function, which results in edema, hemorrhage, bronchoconstriction, and bronchial obstruction. Pulmonary edema, ARDS, and pneumonia may complicate inhalation injury, with pneumonia occurring in up to 50% of patients. Lower airway inhalation injury is diagnosed most commonly by fiberoptic bronchoscopy, although nuclear medicine ventilation–perfusion scanning has been used. Treatment is primarily supportive and consists of aggressive pulmonary toilet, supplemental oxygen, and endotracheal intubation if required for either airway protection or oxygenation. Bronchoscopy may be used as an adjunct for pulmonary toilet if airway plugging leads to lobar collapse, but it is not always required for management. Aerosolized heparin is administered by some centers to aid mobilization of fibrin-rich casts, which contribute to airway obstruction. Laboratory and clinical research is ongoing for therapies dealing with smoke inhalation injury. Patients with severe inhalation injury may be extremely difficult to ventilate, and ventilatory strategies vary among burn centers. Low–tidal volume ventilation, high-frequency oscillatory ventilation, and even extracorporeal membrane oxygenation (ECMO) have been used by burn units.

Answer 5

ANSWER: D COMMENTS: Intentional burns comprise assault burns and self- inflicted burns. It is important for the provider to be cognizant of the risk factors for intentional burns and to identify injury patterns characteristic of this type of injury. Vulnerable populations for intentional burns vary secondarily to geographic and cultural forces. In the United States, vulnerable populations include those with mental illness or history of drug abuse, victims of domestic violence, the elderly, and most often, children. Maguire et al. published a systematic review of 26 studies to identify the injury patterns of intentional burns in children that were most suspicious for intentional motives. They found 15 unique characteristics of intentional burns grouped into mechanism (immersion), agent (hot tap water), pattern (clear upper margins, symmetrical scalding), distribution (isolated scald on the lower extremities, buttock, or perineum), and additional clinical features (history discordant with physical examination, associated injuries including fractures, introverted child on physical examination, and previous episodes of abuse). With any of these characteristics, the provider should rule out intentional injury. Additional potential abuse-related burn patterns include skin fold sparing, stocking and glove distribution, and uniform scald depth. Characteristics not representative of intentional burns include spill/flowing water injury, scald from hot beverage, and irregular margin and depth. However, it is important for the provider to take the entire history and physical examination into account as low-risk characteristics do not entirely rule out intentional injury. No study has demonstrated large TBSA, child age, or gender as risk factors.

Answer 6

ANSWER: E COMMENTS: The simultaneous trauma and burn patient poses additional diagnostic and management challenges to the health care provider. Roughly 5%–7% of burn admissions will have additional traumatic injuries. In a large, 10-year retrospective study from Los Angeles County Burn Center, mortality for concomitant burn and trauma patients was 13% versus 6% of burns without additional trauma. Patients with inhalation injury were the highest-risk subgroup with a mortality of 41%. The origin of injury is most commonly from motor vehicle crashes, followed by falls from height in house fires. The management of the combined burn and trauma patient begins similar to that of the monotrauma patient with assessment of the patient’s airway, breathing, and circulation. In combined burn and trauma patients, each of the three components of the primary survey has nuanced features that focus on the diagnosis of burn-specific injuries, or those anatomic structures at increased risk of injury from burns and traumatic injury. For example, in the evaluation of the airway, the provider must assess for inhalation injury and progressive upper airway edema with careful attention to the cervical spine prior to manipulation of the neck during intubation or bronchoscopy. During the assessment of the patient’s ability to breathe, victims of automobile or structural fires are at risk for CO or cyanide poisoning, both of which can cause hypoxia and further exacerbate an existing traumatic brain injury. Treatment is 100% oxygen. Poor respiratory function may be secondary to a number of causes including inhalation injury, thoracic trauma, or ARDS. Judicious fluid administration, not deliberate underresuscitation, is indicated. A special subgroup of patients may require tube thoracostomy with overlying thoracic burns. These should be placed through healthy skin, if available, or otherwise through burn eschar. Hypotension in the traumatically burned victim must be first ruled out as secondary to hemorrhage. Resuscitation begins with 2 L of crystalloid and assessment of the patient’s hemodynamic response, followed by adequate resuscitation by calculation of the patient’s 24-h volume requirements. For those who require laparotomy with abdominal burns, a paramedian incision has been associated with higher rates of dehiscence. Furthermore, special attention should be paid to the mode of abdominal wall closure in a burn patient who requires large-volume crystalloid resuscitation to prevent abdominal compartment syndrome.

Answer 7

ANSWER: E COMMENTS: Systemic antibiotics are not indicated for prophylaxis. Topical antimicrobial agents delay colonization and infection of wounds but have not changed mortality as much as early excision and grafting have. Silver sulfadiazine is the most commonly used agent for burns in the United States. Advantages include a broad spectrum of activity, soothing effect in most patients, and no significant metabolic activity. Silver sulfadiazine does not penetrate eschar, so it does not treat established wound infections. Many providers have implicated it as a cause of early postburn neutropenia, but this neutropenia is typically self-limited, and more current information suggests that it is more likely the result of margination of neutrophils rather than depletion by the topical agent. One other caution is the use of silver sulfadiazine in a sulfa-allergic patient. Mafenide acetate penetrates eschar and is therefore useful for the treatment of burn wound infections; it has a broad spectrum of activity against gram-negative organisms. It may be applied as a cream or a solution and is often used after grafting. Mafenide acetate is a carbonic anhydrase inhibitor that may cause metabolic acidosis when used on large areas. It is also painful on application, particularly to partial-thickness burns. Silver nitrate has a broad spectrum of activity and may be used for burn wound dressings. Dressings need to be repeatedly impregnated with an aqueous solution to prevent precipitation onto the wound. Concentrated silver nitrate may cause chemical burns and hyponatremia, along with the rare case of methemoglobinemia. Wounds, normal skin, linens, and the patient environment will be stained black by silver nitrate. Ointments of bacitracin, neomycin, and polymyxin B are commonly used for facial burns. Mupirocin has been used against methicillin- resistant Staphylococcus aureus (MRSA). Acticoat (Smith & Nephew, London, England) is a dressing impregnated with elemental silver that may be applied to burn wounds or grafts. Sheets of Acticoat are usually moistened in sterile water before application because sodium chloride will cause precipitation and inactivation of the silver ions. Silver disrupts bacterial cellular respiration, and silver dressings may be left in place for up to 7 days if necessary.

Answer 8

ANSWER: D COMMENTS: Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are systemic disease processes that cause varying degrees of epidermal sloughing, with mortality ranging from 5% to 30%. Commonly associated with drug ingestion with an immunologic basis, it is important for the provider to quickly identify and stop any potential culprit drug, as a delay in the cessation of drug administration decreases survival. Furthermore, early transfer of patients to a burn unit is the standard of care in initial management after the diagnosis of SJS/TEN is made. The SCORTEN illness severity score was created and validated in the year 2000 as a predictor of mortality in patients with SJS/TEN. On multivariate analysis of 165 patients with SJS/ TEN, prognostic risk factors, vitals, and laboratory values (corresponding odds ratios for mortality) are as follows: age > 40 years (2.7), associated malignancy (4.4), heart rate > 120 beats per min (2.7), serum BUN > 28 mg/dL (2.5), TBSA > 30% (3.3), serum bicarbonate < 20 mmol/L (4.3), and serum glucose > 252 mmol/L (5.3). Each independent predictor is attributed one point. Mortality ranges from 3.2% with one risk factor to over 90% with five or more risk factors. Treatment for SJS/TEN is supportive, with wound care and monitoring in the burn ICU to prevent additional superinfection.

Answer 9

ANSWER: A COMMENTS: Early excision and grafting of deep burns has been one of the great advances in burn surgery. Although universally accepted now, early excision of a large burn during the initial-stage burn shock was initially considered to be prohibitively dangerous. In 1960, a paper concluded that early excision and grafting should only be used “in experienced hands, [sic] in so far as the risks require further investigation.” However, over the years research has clearly demonstrated the advantages of early excision of both small- and large-TBSA full-thickness burns. In 1982, researchers at the University of Washington demonstrated decreased rates of burn wound sepsis and hospitalization in patients treated by early excision (excision prior to 14 days) and grafting versus waiting for autoexcision of the eschar in TBSA burns of 20%–40%. This study was later corroborated by a 1989 prospective study by Herndon et al., which randomized patients with TBSA burns (>30%) into early excision or topical antibiotic treatment until autoexcision. Mortality in the early-excision group was 9% versus 45% in the delayed-excision cohort. Additional studies have shown decreases in mortality, intensive care stays, and hospital expenditure. Theories on the survival advantage of the early removal of full-thickness burns include removal of a hyperinflammatory focus and prevention of secondary wound infection.

Answer 10

ANSWER: D COMMENTS: Excision of deep partial- and full-thickness burn wounds should be done after resuscitation is complete and the patient is normothermic and hemodynamically stable. Although the advantages of early excision and grafting are well described, watchful waiting is appropriate to observe for healing in burns of indeterminate depth to avoid unnecessary grafting to those portions that will heal. Wounds expected to heal within 3 weeks are best treated with antimicrobial dressings, whereas full-thickness burns, as well as deep partial-thickness wounds with delayed healing, require grafting. Fascial excision refers to the removal of burned skin and subcutaneous tissue down to the level of the fascia, frequently with electrocautery. This approach provides a bed that readily takes graft and is usually easy to define. However, such deep debridement often results in fragile, esthetically displeasing grafts. Tangential excision involves sequentially cutting away eschar with a handheld knife with a depth guard until viable dermis or subcutaneous tissue is present as noted by diffuse punctate bleeding. Experience is important in judging the depth of excision required to support a graft. Hemostasis may be achieved with a combination of electrocautery, suture ligature, thrombin spray, direct pressure, and dilute epinephrine solution in gauze pads. Skin grafts may be full thickness for smaller grafts or split thickness for larger ones, depending on the amount of dermis present when harvested. Harvesting is most commonly done with a dermatome. Thinner grafts will heal with greater contraction, but thicker grafts come at the cost of loss of dermis at the donor site, which leads to prolonged times until healing and increased donor site scarring. Meshing of grafts (ranging from 1:1 to 4:1) may be used to allow egress of fluid from the wound bed through the graft and to increase the area covered when donor sites are limited. Widely meshed grafts are associated with prolonged healing, increased scarring, and more contraction than are less meshed or sheet grafts. A variety of dressings may be placed over grafted areas, the goal of which is to maintain contact of the graft with the wound bed to allow graft survival, prevent shearing, and facilitate subsequent vascular ingrowth into the graft.

Answer 11

ANSWER: B COMMENTS: After debridement and excision of burn eschar, closure of the wound with immediate autografting, when possible is preferred. Full-thickness skin grafts are the best possible cutaneous replacement, but they are not feasible for burns of significant size because the full-thickness donor site must be closed primarily. Meshed split-thickness grafts may be used to cover areas larger than the donor site harvested, but for large burns and patients with limited donor sites, even meshed autografts will not be able to cover all open wounds. Wounds not able to be autografted immediately may be covered with biologic dressings while awaiting donor site healing before reharvesting. Human allograft has been widely used as a temporary biologic dressing. It is usually meshed to allow drainage of fluid and applied in a similar fashion to other skin grafts. Allograft will vascularize and engraft, provide wound closure for 2 to 4 weeks, and subsequently be rejected and need to be replaced with new allograft or autograft if available. Sheets of allograft may be placed over widely meshed autograft at the time of surgery to protect grafts as the interstices epithelialize. Porcine xenograft is cheaper and more easily stored before use, but it does not vascularize and engraft. It may be used similar to allograft for temporary biologic coverage of burn wounds, as well as for exfoliative diseases of the skin (e.g., TEN). Cultured epidermal autografts grown from patient keratinocytes are promising as a skin substitute but are not yet in widespread availability and are associated with high cost and complexity. Dermal substitutes such as the Integra Dermal Regeneration Template (Integra Lifesciences, Plainsboro, NJ) have seen more clinical use. The Integra dermal template is a bilaminate composed of an outer silicone film that provides barrier function and an inner layer of type 1 collagen and chondroitin sulfate. This inner layer serves as a template for the ingrowth of autologous fibroblasts, endothelial cells, and other mesenchymal cells. After vascularization of the Integra, the silicone film is removed, and very thin autografts may be applied to the neodermis. Reported advantages include neodermis architecture similar to that of uninjured dermis, which results in improved cosmetic and functional results, as well as rapid healing of thin autograft donor sites. Disadvantages include wound infection and increased length of time and immobilization before final autograft closure.

Answer 12

ANSWER: D COMMENTS: Three common operations performed by burn surgeons are escharotomies, burn excision, and skin grafting. Escharotomies are performed for full-thickness burns causing life-threatening complications secondary to restricted peripheral blood flow or pulmonary compliance. Surgeons must be aware of the appropriate anatomy to perform a fully effective procedure. For burns of the chest wall, escharotomy incisions are made on bilateral posterior axillary lines with superior borders of clavicles to inferior borders of sub- costal margins. For the hand, a hand escharotomy is performed on the dorsal side of the hand between the metacarpals. Excision of full-thickness burns can be performed by fascial or tangential means by a variety of surgical instruments. A tangential excision will have greater blood loss than a fascial excision, which can be controlled using dressings diluted with epinephrine or fibrinogen and thrombin spray. Skin grafting is performed in a split-thickness or full-thickness manner and must be performed appropriately for a successful graft take. Common donor sites include the thighs or back. After application of mineral oil, a dermatome is used to harvest a split-thickness skin graft.

Answer 13

ANSWER: D COMMENTS: Electrical injuries are classified in the medical literature into low-voltage, high-voltage (>1000 V), and lightning injuries (also termed ultra-high voltage). Patients injured by electricity may, in fact, have injuries by any of the three mechanisms: flash burns from the very high temperatures generated when high- voltage current arcs through the air, flame burns because of ignition of clothing, and true electrical injury as a result of conduction of electrical current through the patient’s body. Low-voltage injuries may cause local tissue injury but rarely lead to systemic injury. High-voltage injuries may cause unpredictable patterns of local injury, including deep tissue destruction belied by the small size of the skin wounds, full-thickness cutaneous wounds at entry/exit sites and areas where arcing occurs across joints or flexor surfaces, and musculoskeletal injuries from severe tetanic contractions of the paravertebral and other muscle groups. Patients with an electrical injury are at particularly high risk for associated traumatic injuries because electrical exposures frequently occur in occupational settings and may involve falls from a height. In fact, the tetanic muscle contractions caused by alternating current tend to cause “hanging up” by workers who grasp an electrical source and pull themselves in; patients who hang up and survive may do so because they subsequently fall and break contact with the current, and can suffer other injuries as a result. Evaluation of patients suffering from a high-voltage electrical injury includes a full examination of the traumatic injury, radiographic studies, electrocardiogram, and bladder catheterization. Patients with no loss of consciousness at the scene, no history of arrhythmias during transport, and a normal admission electrocardiogram do not require cardiac monitoring unless the severity of the injury would otherwise require it. Deep tissue damage secondary to high-voltage current may result in unseen muscle swelling and necrosis. Neurovascular examination should document the extent of disability present at admission, and progressive deterioration in extremity function should prompt consideration of compartment release by fasciotomy. Compartment pressures may be measured if the patient is not likely to need compartment release, but fasciotomy should be prompted by clinical grounds if significant concern exists. Escharotomy refers to the division of band-like circumferential full-thickness burn eschars through to subcutaneous fat only. Fixed deficits or mummified extremities may not benefit from compartment release. Pigmented urine suggestive of myoglobinuria should be treated by fluid resuscitation sufficient to produce a urine output of 100 mL/h. Fasciotomies or even early debridement or amputation of necrotic muscle can be performed to avoid renal failure. Urine myoglobin assays are often not immediately available, but urine that is heme positive by dipstick with no red blood cells on microscopic examination may be presumed to be myoglobinuria resulting from rhabdomyolysis; hematuria found on urinalysis should additionally prompt reconsideration of occult genitourinary trauma. Toddlers may suffer electrical burns to the mouth from chewing on appliance cords. Full-thickness oral burns are typically treated conservatively with attention to preserving mouth opening, and families should be counseled about the possibility of delayed facial artery bleeding after the eschar softens and falls off. High-voltage injuries may result in progressive demyelinating injury and lead to sensory or motor loss weeks or months after the injury. Early cataract formation has been associated with high-voltage electrical exposure.