34
Burns
Jeffrey Hammond
Objectives
1. To describe the assessment of the burn wound, including total body surface area and depth, and to explain how this assessment relates to the early management of a major burn.
2. To discuss fluid resuscitation, including choice of fluid and rate of administration.
3. To discuss the recognition and management of inhalation injury.
4. To describe the options for wound coverage.
5. To discuss the role of rehabilitation therapists in the patient’s recovery.
Case
A 65-year-old man sustained a burn injury in a housefire. He was semi- conscious when pulled from the house by firefighters. He has blister- ing burns to the face, to half of both the chest and back, and to both upper extremities, including the hands. The wounds to the arms cover at least 75% of the circumference of the arms. The firefighters removed his smoldering clothing and wrapped him in clean sheets. They placed a peripheral intravenous line in the antecubital fossa through the burn wound and started supplemental oxygen via a face mask. The patient now is responding to questions, is groaning in pain, is hoarse, and is appearing somewhat anxious. He is coughing carbonaceous sputum, but he denies shortness of breath. He has a history of “high sugar” con- trolled by weight loss and diet. He is a social drinker and has a 40 pack per year smoking history, but he stopped 10 years ago. His last set of vital signs, performed 10 minutes prior to emergency department arrival, revealed a systolic blood pressure of 110, a heart rate of 105, and a respiratory rate of 26.
621
Introduction
Thermal injuries entail destruction of the skin envelope as a result of the transfer of energy in the form of heat, cold, chemicals, radia- tion, or electricity. Burn injury represents a formidable public health problem. Each year in the United States, 300,000 people are burned seriously enough to warrant medical care. Of these, approxi- mately 6000 will die. One third of these deaths are in children less than 15 years of age. For each death, three serious disabilities result, and each burn victim carries significant physical and psychological scars.
Treatment of the injuries requires knowledge not only of the man- agement of the local burn wound, but also of fluid resuscitation and hemodynamic, fluid, and electrolyte management, of rational use of antibiotics and infection control, of nutritional support, of pain man- agement, of physical medicine and rehabilitation, and of psychoso- cial intervention.Regionalization of burn care into burn centers has led to improved results. However, all surgeons and emergency medi- cine specialists may be challenged with the initial care and resuscita- tion of burn patients and, occasionally, with long-term care of smaller or more moderate injuries. Discussion in this chapter is limited to the more common heat-related thermal injury. See Algorithm 34.1 for an initial approach to burn care.
Assess and secure airway Determine risk of inhalation injury Complete ATLS primary survey
Determine depth and extent of burn injury Map and document Lund-Browder chart
Establish IV access and start crystalloid fluid resuscitation Establish flowsheet to document response to Parkland formula
Cover wounds after preliminary debridement
Initiate transfer to burn or trauma center as indicated
Adjunct treatments: NG tube, Foley catheter, pain medication, tetanus prophylaxis
Algorithm 34.1. Algorithm of an initial approach to burn care. ATLS, Advanced Trauma Life Support; NG, nasogastric.
First Principles
The initial response and approach to the burn patient set the stage for further care and outcome. First, remember that the burn victim is a trauma victim.One must consider the possibility of associated injuries and not focus solely on the external manifestation of the burn. The ABC of trauma care (airway, breathing, and circulation), as outlined in the Advanced Trauma Life Support (ATLS) course, should be fol- lowed, beginning with when the patient is first seen.Burn injuries do not bleed in the acute phase, and therefore evidence of blood indicates an associated injury.
The integrity of the airway must be ensured. The burn patient rapidly can become edematous, even at areas distant to the burn wound. Upper airway edema may or may not be associated with an inhalation injury. Obvious perioral or intraoral burns, stridor, hoarse- ness, or use of accessory muscles of respiration are good indicators to protect the airway with endotracheal intubation. Because of the increased mortality associated with emergency tracheostomy in the burn patient, it is important to err on the side of safety. This is true especially for patients requiring interfacility transport. An endotracheal tube always can be removed later. Once an adequate airway has been assured and the primary trauma survey has been completed, the burn wound must be assessed.In the case presented above, the patient, who was burned in an enclosed space, has facial burns and hoarseness sug- gestive of early onset of upper airway edema.
The Language of Burn Care
What sets burns apart from other forms of trauma is the damage to and loss of the protective shell that keeps the outside out. Skin is more than a passive envelope, however; it is a dynamic organ that has active biologic and immunologic functions. The response to injury and resul- tant treatment decisions depend in great measure on the size—
expressed as the percent of the total body surface area (TBSA)—and depth of the burn.These are the key components of the language of burn care. An accurate assessment of burn size is critical to the selec- tion of an appropriate fluid resuscitation regimen, nutritional support calculations, decisions on transfer to tertiary facilities, and prognosis for survival.
Dermatopathologists divide the skin into more than a dozen layers, but, for practical purposes, skin is composed of three zones: epidermis, superficial dermis, and deep dermis. These are of importance in burn care since the depth of burn determines the potential for primary skin regeneration versus scarification (the need for surgical coverage by skin grafting or flap rotation).
First-degree burns involve the epidermis only.These injuries pre- sent as painful, reddened wounds similar to a severe sunburn. While painful and requiring analgesia, they have no physiologic significance and should not be counted in the TBSA calculation.
Second-degree burns involve the superficial dermisand produce a painful and moist or blistered wound. These wounds generally close, that is, reepithelialize, in 7 to 10 days. Note that a closed wound is not the same as a healed burn wound, since a burn wound may require 3 to 18 months to mature.
Third-degree burns involve the deep dermal layer and may pene- trate into the subcutaneous fat.These wounds have the appearance of parchment or tanned hide. Coagulated vessels may be seen through the burn wound, called an eschar. These wounds usually are painless, because of the destruction of dermal pain corpuscles, but sensation to touch may be preserved. Because the skin appendages, such as hair follicles and sweat glands from which skin regeneration occurs, are destroyed, these wounds close only with scar tissue produced by epithe- lial migration from wound edges. For the best cosmetic and functional results, third-degree burns require skin grafting or flap closure.
So-called fourth-degree burns, involving bone or periosteum, are the result of charring or high-voltage electrical injury.
Assessment of burn depth is a clinical decision.A burn wound is not homogeneous. Factors that are significant predictors of depth include location of the burn, patient age, preexisiting medical condi- tions, and etiology of the burn injury. Hot water scalds usually are second-degree wounds, while immersion burns, due to the longer contact time, are third degree. Flame burns generally are third degree, and grease or tar burns can be deceptively deep. The burn is a dynamic rather than a static wound, and serial inspection over several days may reveal that the burn wound has “progressed” in depth as marginally viable skin tissues in the zone of injury die.
The “rule of nines” often is taught as a rapid evaluation of burn size. This method divides the body into multiples of 9% TBSA. The head, for example, is 9%, while both the anterior and posterior torso are 18% each. The problem with this methodology is that it is highly inaccurate and frequently leads to overestimation of burn size by factors of 100%. This especially is true in children, for whom the head has a larger percentage of TBSA and the limbs a smaller percentage. It is best used as a “quick and dirty” field assessment.
A more formal and accurate method of burn size calculation is to use standard body nomograms, such as the Lund-Browder chart. This nomogram is accurate for 95% of the population. Using such a chart (Fig. 34.1) facilitates documentation. Since adult proportions are reached at about age 12, separate nomograms exist for adults and chil- dren. For burns that are highly irregular in shape, such as tar injuries or grease splatters, a “hand count” method may be helpful. Each indi- vidual’s hand is approximately 1.25% of his/her TBSA.
Inhalation Injury
The presence or absence of inhalation injury is a major determinant of survival in burns. Inhalation injury is associated with mortality rates of as high as 78%. True respiratory burns of the lower pulmonary
Figure 34.1. Example of emergency department “burn sheet.”
tract are rare, generally occurring only with the inhalation of super- heated steam. What commonly is thought of as a respiratory “burn” is a response to inhalation of the products of combustion, or carbon monoxide toxicity. Incomplete products of combustion, such as alde- hydes, nitrogen dioxide, and hydrochloric acid, can cause direct parenchymal lung damage. Carbon monoxide, with an affinity for oxygen more than 200 times that of hemoglobin, seriously can impair oxygen delivery to tissues.
Early diagnosis of inhalation injury can be difficult, and it usually is a clinical diagnosis supported by an index of suspicion. Classic signs such as singed nasal hairs and carbonaceous sputum are unreliable.
The history of being burned in an enclosed space is a crucial element to elicit. The strongest correlation for a pulmonary injury is a history of being burned in an enclosed space coupled with the presence of facial burns or the history of patient incapacitation from drugs or alcohol.
The initial chest x-ray (CXR) or arterial blood gas (ABG) often are normal after inhalation injury. They should be viewed as screening tests and indicators of underlying pathology. The serum carbon monoxide level may be used to tailor therapy, but it may be unreliable if supplemental oxygen already has been administered. The concen- tration of carboxyhemoglobin is reduced by 50% for each 40-minute period of treatment with high-flow oxygen. Hyperbaric oxygen treat- ment is not routinely necessary and should be reserved for patients with CO levels greater than 40% or for those with neurologic symp- toms. Bronchoscopy has been advocated as a diagnostic tool, but it adds little to the accuracy of the history and the physical examination.
Direct laryngoscopy allows direct investigation for upper airway edema. Regardless of the CXR or ABG, the patient in the case presented very likely has an inhalation component based on the history of a burn in an enclosed space and the signs of facial burns, hoarseness, and car- bonaceous sputum.
Since signs and symptoms of inhalation injury may appear over an 18- to 36-hour period, patients at risk or patients suspected of being at risk should be admitted for a 24-hour period of observation.
Steroid therapy is not beneficial and carries a risk of superimposed infection; bronchodilator therapy and aggressive chest physiotherapy are advantageous. Prophylactic antibiotics are not recommended due to the risk of selection pressure for the emergence of resistant organ- isms. Ventilatory support may be necessary in severe cases. The pre- ferred route is via endotracheal or nasotracheal intubation. The airway should be secured before edema necessitates a surgical airway;
tracheostomy or cricothyroidotomy carries a higher morbidity and mortality rate.
Treatment: The First 24 Hours
The purpose of fluid resuscitation in the early postburn period is reex- pansion of plasma volume within the extracellular space. Delivery of sodium ion into the extracellular space results in reestablishment of
cellular membrane potentials and restores microvascular integrity.
Controversy over the type and regimen of fluid resuscitation remains.
All agree, however, that restoration of plasma volume is essential in preventing renal failure and shock.
The standard approach is to use the Parkland formula to establish daily needs(4 mL ¥ weight in kg ¥ % TBSA burned). The formula for estimating insensible water loss, expressed in milliliters per hour, is (25 + % TBSA burned) BSA. Access is via large-bore peripheral intravenous lines. As in the case presented at the beginning of the chapter, these lines may be placed through the burn wound if access sites are limited.
Lactated Ringer’s solution is the preferred crystalloid. Dextrose should not be used initially due to the risk of osmotic diuresis. This formula is a rough guide, however, and one fifth of patients need more and one fifth need less. The patient’s response, as judged by urine output, guides therapy. For this reason, diuretics are to be avoided. Central venous or pulmonary artery pressures usually are unreliable. The patient is the formula.
Colloidgenerally is avoided in the first 24 hours. In some formulas, colloids in the form of albumin or fresh frozen plasma are added in the second 24 hours or when the capillary leak has stopped. A diuretic phase begins on the third to fifth postburn day with mobilization of the resuscitation fluid. During this phase, there is a risk of hypokalemia.
Emergency care of burns, either major or minor, requires adequate tetanus prophylaxis. The burn wound is anaerobic, and cases of clini- cal tetanus have been described even from superficial second-degree injuries. A booster of tetanus toxoid is recommended for patients already immunized. For those never immunized, both passive and active immunization using tetanus immune human globulin (Hyper- Tet) is suggested.
Efforts are directed at maintaining body temperature and prevent- ing hypothermia. Iced saline is not used for initial debridement or wound coverage in the emergency department for that reason.
Although application of cold decreases pain and edema, it may injure marginally viable cells and can induce hypothermia and increase meta- bolic demands if applied to greater than 10% TBSA.
Early in the management scheme, practitioners must determine if the patient requires hospital admission and whether resources for good burn care exist in their institution. Guidelines for admission have been developed by the American College of Surgeons and the American Burn Association (Table 34.1). Transfer to a specialized burn center is warranted if all components of the burn team are not available at the receiving institution.
Treatment: After the Emergency Department
The mainstay of burn treatment is good wound care, with attention to principles of infection control coupled with early wound closure and adequate nutritional support.
All blisters should be debrided except for those on the palms and soles if they are intact.In those areas, the skin is relatively thick, and
preservation of bullae reduces pain and speeds reepithelialization.
Mechanical debridement is necessary; merely submerging the burn patient in a whirlpool is not sufficient.
Once the wound has been debrided, topical drug therapy controls bacterial colonization until spontaneous eschar separation and reepi- thelialization occur or until sharp debridement followed by surgical closure with skin grafts or flaps is completed. The advent of effective topical therapy significantly has reduced mortality from burn wound sepsis. The two major types of topical drug therapy currently in use are silver sulfadiazine (Silvadene, Flamazine) and mafenide acetate (Sulfamylon). Silver sulfadiazine is an all-purpose agent. It should be applied at least twice daily, removing old cream and cellular debris before each new application. If left for long periods, it may cake and produce a neo-eschar. It has only fair to poor eschar penetration, and it may not be effective in deeply burned or avascular areas. This prop- erty makes it more effective for prophylaxis rather than for therapy of burn wound infection. There are no significant metabolic side effects, but an infrequent hypersensitivity-type reaction may result in a tran- sient leukopenia. Silver sulfadiazine should be discontinued if the white blood cell count falls below 2000. It generally is painless on appli- cation. Mafenide acetate is an alternative topical agent with excellent penetration into eschar. Its penetration properties make it a good choice for infected burns and burns in avascular areas, such as the ear. It has broad-spectrum antibacterial properties, but it predisposes to candidal overgrowth. Other disadvantages include pain on application and car- bonic anhydrase inhibition. In large burns, systemic absorption may
Table 34.1. Admission criteria.
Injury size: Adult > 20% TBSA Child> 15% TBSA Third degree > 2% TBSA Inhalation injury
High-voltage electrical injury Chemical burns
Burns in the elderly Circumferential limb injury Suspicion of child abuse Infected burns
Burns in special locations Face, neck, eyes, ears Hands, feet
Flexor creases, joints Perineum, genitalia Significant medical history
Cardiac, renal, hepatic disease Hypertension
Diabetes, sickle cell Unable to care for self TBSA, total body surface area.
Source: Adapted from American College of Surgeons Com- mittee on Trauma. Advanced Trauma Life Support. Chicago:
American College of Surgeons, 1997, with permission.
result in metabolic acidosis, with a compensatory hyperventilation.
Pain on application can be lessened by making the thick cream into a slurry using saline, thus reducing the pH.
Early excisionof the burn wound, popularized in the 1970s, has led to a decrease in complications and a decrease in patient length of stay.
Early excision is defined as within the first 7 days postburn. Tangen- tial excision is the sequential sharp removal of necrotic tissue until viable tissue is identified by the presence of punctate bleeding. This yields a better cosmetic and functional result than full excision, which is the removal of all tissue down to the underlying fascia. Tangential excision is associated with significant blood loss, and it is best per- formed with a planned, team approach. Excisions should be limited in time and should be TBSA debrided; several operative sessions may be required. Circumferential injuries may create a vascular emergency.
The burn need not be totally circumferential or even full thickness. The inelastic burn wound (eschar) acts as a tourniquet; edema from the burn trauma and subsequent fluid resuscitation lead to increased compartment pressure. The classic signs of pain, paresthesia, and pallormay be difficult to assess. Loss of pulses or Doppler signals are seen late, and irreparable neurovascular damage already may have occurred. Direct measurement of compartment pressure is the best way to determine the need for escharotomy.This can be done with a 21-gauge needle connected to a transducer and pressure monitor by high pressure tubing. Pressures greater than 30 mm Hg are sufficient to occlude venous outflow. Individual compartments in the hand or leg can be measured selectively. Escharotomy involves incising the eschar down to underlying subcutaneous tissue. It is a bedside procedure, not to be confused with a fasciotomy. Escharotomy may need to be per- formed on both medial and lateral surfaces. Occasionally, eschar on the torso can create a restrictive respiratory insufficiency that can be relieved by chest escharotomy.
A number of methods of wound closure after debridement or exci- sion are available. There is no substitute for the patient’s own skin.
Most burn wounds can be managed with split-thickness skin grafts 0.010 to 0.012 inch thick. Local or free flaps are the exception rather than the rule. Thicker skin grafts may provide better cosmetic and func- tional results, but they delay donor-site healing, which may be a factor in larger burns in which donor sites need to be reharvested. Except for the face or other critical cosmetic areas, most skin grafts are meshed.
This allows for expansion and larger surface area coverage, and it permits fluid drainage, preventing subgraft seroma or hematoma col- lection. Skin meshing at a 1.5 : 1 ratio generally provide a good cosmetic result; if donor sites are sparse, meshing ratios of 3 : 1 and 6 : 1 can be employed. The most common cause of graft failure is poor adherence from movement. Closely conforming dressings and immobilizing splints maximize graft take. In the absence of donor autograft, cadaver allograft, synthetic materials, or culture-derived skin have been used as substitutes. Wound closure also significantly decreases the dramatic metabolic demands imposed by a large burn.Burns greater than 20% TBSA are associated with a hypercatabolic state characterized
by increased oxygen consumption, increased nitrogen excretion, and loss of lean body mass. Metabolic rate, as calculated by the Harris- Benedict equation, may exceed baseline levels by 2 to 21/2times. This hypermetabolism is both externally driven (evaporative losses) and internally driven (sympathetic discharge).
Another response to a burn injury greater than 20% TBSA is ileus, usually lasting 2 to 3 days. Once this has resolved, enteral support can begin. Establishing the minimum daily caloric needs has been contro- versial. The most commonly used estimate is the Curreri formula:
(25 ¥ kg) + (45 ¥ % TBSA burn). This estimate, however, may predict maximal caloric needs best, and strict adherence to the formula can result in overfeeding. A more realistic approach is to aim for levels approximately 60% to 70% of the Curreri formula and to monitor nutritional outcomes by indirect calorimetry or urine nitrogen levels.
Nitrogen requirements can be estimated at ratio of 1 g nitrogen to 150 calories.
How are Children Different from Adults?
Children are not merely “little adults.” The care of the pediatric burn patient is significantly different in fundamental ways from the care of the adult burn patient. Estimation of burn size in the child requires a different nomogram, since the head comprises a greater surface area and the limbs comprise a lesser surface area in relation to the torso than in adults. Weight to surface area ratios are different as well, and this affects fluid requirements. A 7-kg child has one-tenth the weight of a 70-kg adult but one-fourth the surface area. Resuscitation formulas also must account for a higher ratio of total body water to body weight.
Thus, in small children, the Parkland formula may not deliver enough fluid, and thus it should be supplemented by the daily maintenance dose. Unlike adults, children have limited glycogen stores, and thus, resuscitation fluid should contain glucose. The urine should be moni- tored for glycosuria in order to prevent osmotic diuresis.
Children have a higher rate of heat exchange than adults and poor heat conservation, making them susceptible to hypothermia. Limited renal and respiratory functions in the very young complicate elec- trolyte and nutrition management. Transient systolic hypertension has been described in up to one quarter of pediatric burn patients. Related to plasma renin, this phenomenon resolves with wound closure. Indi- cations for treatment include hypertension persisting for greater than 24 hours, diastolic hypertension, or symptomatic hypertension.
As many as one third of burns in children are suspicious for child abuse, and 2% to 6% of pediatric burns requiring admission to the hospital can be proven to be nonaccidental. A suspicion of inten- tional burning warrants a social service investigation. Both historical and physical findings may alert the physician, nurse, or therapist to the possibility of child abuse (Table 34.2). Suspicion of a nonacciden- tal burn warrants admission to the hospital and a social service inves- tigation, even if the burn itself could be managed on an outpatient basis.
Rehabilitation Issues
The importance of aggressive, early, and coordinated rehabilitation therapyto the ultimate outcome of the burn patient cannot be overem- phasized. Passive range of motion and splinting begin immediately.
The burn wound will shorten by contraction, resulting in a contrac- ture across flexor creases unless it is opposed.The position of comfort is the position of contracture. All joints should be positioned or splinted in an antideformity position.Efforts to reduce edema facili- tates range of motion. While survival is the primary goal, physical and occupational therapy objectives always are kept in mind. Since the goal is independent function, activities of daily living are stressed.
The risk of hypertrophic scar formation is reduced with early skin coverage. Burn scar in general and hypertrophic scar in particular are more tender and pruritic than superficial injuries or grafted areas. Patients often complain more about itching and heat intolerance than pain. Little can be done other than supportive care with skin moisturizers and analgesics or antihistamines. Long-term treatment of hypertrophic scar involves pressure garments, steroid injection, and scar revision.
In the absence of functional disability, scar revision usually is delayed until the scar matures, a process that can take from 6 to 18 months.
Mental rehabilitationis as important as physical rehabilitation. The patient’s cooperation and the cooperation of the family are essential to a successful outcome. Patient education should begin as early as pos- sible. Depression, grief, and anger are common stages of the rehabili- tation process. Social workers or other counselors are an integral part of the burn team.
Summary
Burn injury results in both physical and psychological trauma. Perhaps among all the trauma care disciplines, effective burn management demands an extended and interdisciplinary team. Optimal outcomes Table 34.2. Historical and physical findings of child abuse by burning.
Historical clues
Burn attributed to sibling
Child brought to emergency room by nonrelated adult Inappropriate parental affect
Treatment delay
Differing historical accounts History of earlier accidents
Inappropriate affect of the child or abnormal response to pain Physical examination clues
Injury inconsistent with history
Injury inconsistent with child’s developmental or chronologic age
“Mirror image” injuries
Burns localized to perineum, genitalia, or buttocks Injury appears older than stated age
Unrelated injuries, old or new
can be obtained only by a comprehensive and systematic approach.
Attention to detail in burn assessment and early resuscitation set the stage. An accurate as possible assessment of burn size and depth is nec- essary for a rational resuscitation plan. It also facilitates decisions relat- ing to possible transfer to a tertiary center and estimation of prognosis.
Planning for early wound closure, adequate nutritional support to counter hypermetabolism, and coordinated rehabilitation and pain management efforts yield the best results.
Selected Readings
American Burn Association. Inhalation injury: diagnosis. JACS 2003;196:308–
312.
American College of Surgeons Committee on Trauma. Advanced Trauma Life Support. Chicago: American College of Surgeons, 1997.
Hammond J, Perez-Stable A, Ward CG. Predictive value of historical and phys- ical characteristics for the diagnosis of child abuse. South Med J 1991;84:166.
Hammond J, Ward CG. Transfers from emergency room to burn center: errors in burn size estimate. J Trauma 1997;27:1161.
Martin RR, Becker W, Cioffi WG, Pruitt BA Jr. Thermal injuries. In: Wilson R, Walt A, eds. Management of Trauma: Pitfalls and Practice, 2nd ed. Baltimore:
Williams & Wilkins 1996.
Saffle J, Zeliff G, Warden GD. Intramuscular pressure in the burned arm: mea- surement and response to escharotomy. Am J Surg 1980;140:825.
Saffle JR. What’s new in general surgery: burns and metabolism. JACS 2003;
196:267–289.
Sheridan RL. Burns. Crit Care Med 2002;30(11 suppl):S500–514.
Sheridan RL. Burn care: results of technical and organizational progress. JAMA 2003;290:719–722.
Ward CG, Hammond J. Burns. In: Kreis DJ Jr, Gomez GA, eds. Trauma Management. Boston: Little, Brown, 1989.
Yurt RW. Burns. In Norton J, Bollinger R, Chang A, et al, eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001.
