Care of Burns. Serious burns require inpatient care, ideally in a verified burn center.

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1 感謝長庚吳吉妮醫師整理製作

2 Care of Burns Serious burns require inpatient care, ideally in a verified burn center. The majority of burns can be successfully managed in the outpatient setting. However, poorly provided outpatient burn care can be frustrating and painful for patients and providers. Styles of outpatient burn care are variable, but proper patient selection and monitored wound healing are essential. Large burns are managed in four general phases: Initial evaluation and resuscitation. Wound excision and biologic closure. Definitive wound closure. Rehabilitation and reconstruction.

3 Etiology and Pathogenesis The vapor and fluid barrier created by the epidermal layer facilitates the maintenance of fluid and electrolyte homeostasis within very narrow limits. The dermis provides strength and flexibility, and the reactive dermal vasculature facilitates control of internal body temperature within very narrow limits. The appendages provide lubrication and prevent desiccation. All of these critical functions are lost when substantial areas of the skin are burned.

4 Local & Systemic Response to Burn Wounds Local response Coagulation of tissue Progressive thrombosis of surrounding vessels in the zone of stasis over the first postinjury hours An ability to truncate this secondary microvascular injury and its associated tissue loss is a major area of ongoing investigation. Systemic response (Larger burns) Release of mediators from the injured tissue Secondary diffuse loss of capillary integrity and accelerated transeschar fluid losses By-products of bacterial overgrowth within the devitalized eschar

5 Infection of Burn Wounds Burn wounds are initially clean but are rapidly colonized by endogenous and exogenous bacteria Proteases result in eschar liquefaction and separation This leaves a bed of granulation tissue or healing burn, depending on the depth of the original injury In patients with large wounds involving >40% TBSA, the infectious challenge generally cannot be localized by the immune system, leading to systemic infection Rare survival

6 Fever The systemic response to injury is characterized clinically by fever, a hyperdynamic circulatory state, increased metabolic rate, and muscle catabolism. It is effected by a complex cascade of mediators, including changes in hypothalamic function resulting in increases in glucagon, cortisol, and catecholamine secretions; deficient gastrointestinal barrier function with translocation of bacteria and their by-products into the systemic circulation; bacterial contamination of the burn wound with systemic release of bacteria and bacterial by-products; and some element of enhanced heat loss via transeschar evaporation. It is likely that this response has significant survival value, but control of some of the adverse aspects of this response, particularly muscle catabolism, is an active area of ongoing investigation.

7 Burn-Specific Survey History Mechanism of injury Closed space exposure and extrication time Delay in seeking attention Fluid and pain medication given during transport Prior illnesses and allergies Prior child protective services involvement Head, Eye, Ear, Nose, Throat (HEENT) Early examination of the globes for corneal burns Clinical assessment for intraocular hypertension if deep facial burns Perioral and intraoral burns and carbonaceous material Progressive hoarseness Consider hot liquid aspiration Continuously assess endotracheal tube security

8 Neck Radiographic evaluation if indicated by injury mechanism Rare need for neck escharotomies Cardiac Cardiac monitoring after significant electrical injury Pulmonary Chest escharotomies indicated if near circumferential torso burn and difficulty with ventilation Inhalation injury associated with airway obstruction and bronchospasm initially Vascular Perfusion of burned extremities should be closely monitored Escharotomy indicated for decreasing perfusion Fasciotomy indicated after electrical or deep thermal injury when flow compromised Compartment pressures can followed in equivocal extremities Worrisome extremities should be decompressed based on serial examination

9 Abdomen NG tubes often indicated especially prior to air transport Inappropriate volume requirement may be a sign of an occult intraabdominal injury Torso escharotomies may be required to facilitate ventilation Ulcer prophylaxis indicated in all with serious burns Consider abdominal compartment syndrome in very large burns or delayed resuscitation Genitourinary Catheterization is appropriate in all who require a fluid resuscitation Ensure that the foreskin is reduced over the bladder catheter Neurologic Level of consciousness often reduced during the hours after injury CT scanning useful to exclude head injury if mechanism appropriate

10 Extremities Wound Monitor perfusion if there are near circumferential burns or electrical injury Limbs at risk should be dressed so they can be easily reexamined Evaluate wounds for size, depth, and circumferential components Wounds often underestimated in depth and overestimated in size initially Laboratory and Radiography Blood gas when inhalation injury present Normal carboxyhemoglobin does not eliminate significant exposure Baseline hemoglobin and electrolytes can be helpful later Urinalysis for occult blood useful in those with deep thermal or electrical injuries Radiographic evaluation as indicated by mechanism of injury

11 Essentials of Burn Management Burn size, extent, depth, and circumferential components influence decisions regarding outpatient care, hospitalization or transfer. Burn extent is best estimated using the Lund Browder diagram that compensates for the changes in body proportions with age. An alternative is a rule-ofnines for adults and children. For scattered or irregular burns, the entire palmar surface of the patient s hand represents approximately 1% TBSA over all ages.

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14 Classification of Burn Wounds Burns are classified by depth: A. 1st degree: Red, dry, and painful and are often deeper than they appear, sloughing the next day B. 2nd degree: Red, wet, and very painful with enormous variability in their depth, ability to heal, and propensity to hypertrophic scar formation C. 3rd degree: Leathery, dry, insensate, and waxy D. 4th degree: Involve underlying subcutaneous tissue, tendon, or bone

15 Circumferential Burns Circumferential burns require special monitoring and possible surgical decompression. If across the torso, they will interfere with ventilation. If they involve an extremity, limb-threatening ischemia may occur during resuscitation.

16 Burn complications Outpatient Wound sepsis, usually streptococcal cellulitis These patients often need admission for antibiotics, observation, and sometimes surgery Excessive pain and anxiety Especially around dressing changes Medication and carefully monitored membrane dressings Some patients will require admission Underestimation of burn depth These patients may require admission for surgery

17 The most common burn wound infection is streptococcal cellulitis, which presents initially with surrounding erythema that progresses to lymphangitis and systemic toxicity.

18 Inpatient Wound sepsis, often invasive Septic shock and organ failures Inadequately controlled pain and anxiety Compartment syndromes Ocular exposure Respiratory failure Gut failure Pancreatitis Cholecystitis Urosepsis Donor site infection Soft-tissue contractures

19 Systemic Derangement of Large Burns Two phases: Ebb phase of reduced perfusion and metabolic rate, which lasts hours Flow phase of protein catabolism and a hyperdynamic circulation, lasting until well after wound closure Management of this physiology is an essential part of inpatient burn care. Careful monitoring and early intervention are essential to successful outcomes.

20 Issues to Consider When Making a Decision for Outpatient Burn Care No airway compromise or need for airway monitoring Wound size <10% TBSA (fluid resuscitation not needed) Able to take in adequate fluid by mouth Adult able to perform wound cleansing, inspection, and dressing changes No clearly full-thickness burn areas that will require surgery No significant burns of the face, ears, hands, genitals, or feet

21 American Burn Association Burn Center Transfer Criteria 2 nd -and 3 rd -degree burns >10% TBSA in patients <10 or >50 y/o 2 nd -and 3 rd -degree burns >20% TBSA in other age groups Burn injury in patients with preexisting medical disorders that could complicate management, prolong recovery, or affect mortality 2 nd -and 3 rd -degree burns involve the face, hands, feet, genitalia, perineum, and major joints 3 rd -degree burns >5% TBSA in any age group Electrical burns including lightning injury Chemical burns Inhalation injury Hospitals without qualified personnel or equipment for the care of children should transfer children with burns to a burn center with these capabilities. Burn injury in patients who will require special social/emotional and/or long-term rehabilitative support, including cases involving suspected child abuse, substance abuse.

22 Inpatient Care of Larger Burns Has 1. Initial Evaluation and Resuscitation (0 72 Hours) Clearly identify all injuries Perform an accurate individualized fluid resuscitation Ensure effective decompression of extremities and torso Distinct Phases 3. Definitive Wound Closure (Week 1 Week 6) Replace temporary wound membranes with permanent coverage Close physiologically small, but functionally critical areas (e.g., hands and face) Separate patient from ICU 2. Initial Excision and Biologic Closure (Day 1 Day 7) Accurately identify all wounds requiring surgery Excise the bulk of all fullthickness wounds Effect definitive or temporary biologic closure of wounds created by excision 4. Rehabilitation and Reconstruction (Day 1 through 2 Years) Initiate early ranging, splinting, and antideformity positioning Progress to active strength and endurance training Initiate scar management program Foster reintegration with family and community

23 Treatments of Burn Wounds The ultimate goal of burn-wound management is closure and healing of the wound. Early surgical excision of burned tissue, with extensive debridement of necrotic tissue and grafting of skin or skin substitutes, greatly decreases mortality rates associated with severe burns.

24 Skin Grafts Skin grafts are transplanted skin from a donor to recipient site with the goal of closing a surgical defect or wound. Grafts are completely detached from the donor site and receive all nutrients from the wound bed of the recipient site. The three basic types of skin grafts: FTSGs (full-thickness skin grafts) consist of epidermis with fullthickness dermis STSGs (split-thickness skin grafts) consist of epidermis with partialthickness dermis Composite grafts are full-thickness skin grafts with cartilage attached to the graft Skin grafts are also categorized by their donor origin. Autografts (donor = recipient) Allografts (human to human) Xenografts (animal to human)

25 FTSGs When possible, FTSGs are chosen over STSGs because of their similarity in thickness and texture to surrounding skin and their relative lack of significant wound contraction. Since STSGs generally result in a depressed, hypopigmented, scar without normal epidermal texture, they are reserved for larger wounds that cannot be covered with FTSGs. FTSGs have essential nutrient requirements and, therefore, should not be placed at a site where the vascular supply is poor. FTSGs will not survive if transplanted directly over bone, cartilage, or tendon.

26 STSGs Because these grafts are much thinner than FTSGs, they have a less rigorous demand for vascular support and have an increased survivability profile. STSGs appear more like scar tissue than skin; they are depressed, hypopigmented and have a shiny texture. They are used to cover large defects unable to be closed by other methods, to allow better wound bed surveillance, to line tubed pedicle flaps, or to resurface mucosa. Meshing is beneficial since it expands the donor tissue, allows wound exudate to drain preventing seroma and hematoma formation, and has been found to increase graft survival. Increased wound contraction and decreased cosmesis, however, are associated with meshing.

27 Wound Healing of Skin Grafts The healing of a skin graft is quite different from that with acute injury One distinguishing feature of a skin graft is the complete dependence of the graft on the recipient wound bed for revascularization On the basis of histological studies, graft healing has classically been divided into three identifiable phases: (1) Imbibition The net diffusion of plasma from the recipient site into the overlying skin graft (2) Inosculation The anastomoses of graft blood vessels with the recipientderived vessels (3) Neovascularization The ingrowth of new blood vessels from the recipient wound bed into the graft

28 Treatment: Outpatient Small and superficial burns with a corresponding low risk of infection, so clean rather than sterile technique is reasonable The wound should be kept generally clean and regularly inspected for infection. Desiccated exudates and topical medications should be periodically cleansed. Most small burns are adequately managed with a daily cleansing and dressing change. If topical agents are used, wounds may be cleansed with lukewarm tap water and a bland soap. Soaking adherent dressings prior to removal will decrease the pain associated with daily wound care. The wound is gently cleansed with a gauze or clean washcloth, inspected for any sign of infection, patted dry with a clean towel and redressed. It is important to instruct each patient to return promptly if they notice erythema, swelling, increased tenderness, lymphangitis, odor, or drainage so that infectious complications can be addressed early. A membrane dressing is applied once it is clear that early surgery is not needed, early infection is unlikely, and wounds are superficial.

29 Pain and anxiety can be an issue for many. Some will benefit from an oral narcotic given minutes prior to a planned dressing change. If dressings are occlusive, pain between dressing changes tends to be modest. Increasing pain and anxiety associated with dressing changes; inability to keep scheduled follow-up appointments; delayed healing; signs of infection or a wound, which appears deeper than appreciated at the time of the initial examination, should prompt early return and specialty evaluation. Wounds selected for outpatient management are usually fairly superficial and heal within 2 weeks, but patients with mid and deep dermal injuries may have a deeper component with resulting scarring that may benefit from specialty evaluation. Finally, wounds of the face, ears, hands, genitals, and feet have functional and cosmetic importance out of proportion to their wound size. In some cases, early specialty evaluation may be prudent, as initial care can have an impact on long-term outcome.

30 Topical Medications and Membranes Wound medications and membranes provide three benefits: (1) pain control (2) prevention of wound desiccation (3) reduction of wound colonization Because burns produce a fertile ground for lifethreatening secondary infection, prophylactic topical therapy is often used.

31 Topical Medications Topical wound medications range from aqueous solutions through antibioticcontaining ointments and debriding enzymes. Most topical agents in outpatient use have a viscous carrier that prevents wound desiccation and a more or less broad antibacterial spectrum that reduces wound colonization. Silver sulfadiazine is in common use because it is painless on application and has a broad spectrum of antibacterial activity. Superficial burns are commonly treated with a clear, viscous antibacterial ointment containing low concentrations of various antibiotics. Wounds around the eyes can be treated with topical ophthalmic antibiotic ointments. Significant ear burns should be treated with mafenide acetate, as it is the only agent that will penetrate the relatively avascular cartilage. Nystatin may be mixed with silver sulfadiazine or mafenide acetate as topical therapy for superficial fungal infection

32 Choices of Topical Medications Mupirocin Bacitracin Polymyxin B Topical Aminoglycosides (Neomycin and Gentamicin) Sulfonamides (Silver Sulfadiazine and Mafenide Acetate) Both agents are broad-spectrum antibacterials useful in the treatment of burns. Candida superinfection may be a problem with mafenide cream. Nitrofurazone (Furacin)

33 Wound membranes Wound membranes provide transient physiologic wound closure while the underlying wound heals. Physiologic closure implies a degree of protection from mechanical trauma, vapor transmission characteristics similar to skin, and a physical barrier to bacteria. The major benefit of wound membranes is that, when successful, they minimize wound manipulations. These membranes help create a moist wound environment with a low bacterial density and are generally intended for use on selected clean superficial wounds and donor sites. Occlusive synthetic membranes must be used with caution if wounds are not clearly clean and superficial, as submembrane infection can occur, deepening underlying wounds and causing systemic infection and toxicity.

34 Patient Outcome Hypertrophic scarring Gradual increase in vascularity and collagen deposition Contracture formation, with important functional and esthetic consequences Pruritus and temporary neuropathic pain if burns are deep A long-term follow-up plan, consisting of scar management strategies, rehabilitation, reconstructive surgery, and emotional support will facilitate optimal outcomes. Multidisciplinary burn clinic, ideally part of a comprehensive burn program

35 Hypertrophic scarring and contracture formation can become difficult problems after serious burns (A), but are often amenable to surgical improvement (B).

36 Infection of Burn Wounds Burn wounds are initially clean but are rapidly colonized by endogenous and exogenous bacteria Proteases result in eschar liquefaction and separation This leaves a bed of granulation tissue or healing burn, depending on the depth of the original injury In patients with large wounds involving >40% TBSA, the infectious challenge generally cannot be localized by the immune system, leading to systemic infection Rare survival

37 Infectious Complications of Burns The skin is an essential component of the nonspecific immune system, protecting the host from potential pathogens in the environment. Burns predispose to infection by damaging the protective barrier function of the skin, thus facilitating the entry of pathogenic microorganisms, and by inducing systemic immunosuppression. The frequency of infection parallels the extent and severity of the burn injury. Severe burn injuries cause a state of immunosuppression that affects innate and adaptive immune responses.

38 Epidemiology Multiorgan failure and infectious complications are the major causes of morbidity and death in serious burn injuries. As many as 10,000 patients in the US die of burnrelated infections each year, and 6 of the top 10 complications are infectious. These 10 most common complications are pneumonia (4.6%), septicemia (2.7%), cellulitis/traumatic injury (2.6%), respiratory failure (2.5%), wound infection (2.2%), other infection (2.0%), renal failure (1.5%), line infection (1.4%), acute respiratory distress syndrome (1.2%), and arrhythmia (1.0%)

39 Pathophysiology Loss of the cutaneous barrier Initially, the wound is colonized with G(+) bacteria from the surrounding tissue The avascularity of the eschar, along with the impairment of local immune responses bacterial colonization and proliferation By day 7, the wound is colonized with other microbes, including G (+) bacteria, G(+) bacteria, and yeasts derived from the GI and upper respiratory flora Invasive infection Biofilms

40 Streptococci and staphylococci were the predominant causes of burn-wound infection With the advent of antimicrobial agents, Pseudomonas aeruginosa became a major problem in burn-wound management Less common anaerobic bacteria The emergence of fungi (Candida albicans, Aspergillus species, and the agents of mucormycosis) as increasingly important pathogens in burn-wound patients

41 Herpes simplex virus (HSV) has been found in burn wounds, especially those on the neck and face and those associated with inhalation injury. Autopsy reports on patients with severe thermal burns over the last decade have identified an association of P. aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus with death; this association is independent of the percentage of the TBSA covered by burns, the percentage of burns that are full-thickness (as opposed to partial-thickness), inhalation injury, and day of death after a burn. In addition, members of the Acinetobacter calcoaceticusbaumannii complex are among the most common pathogens at some burn centers

42 Clinical Manifestation Wounds must be monitored carefully for changes that may reflect infection. A margin of erythema frequently surrounds the sites of burns and by itself is not usually indicative of infection. Signs of infection Conversion of a partial-thickness to a full-thickness burn Color changes New appearance of erythema or violaceous edema in normal tissue at the wound margins Sudden separation of the eschar from subcutaneous tissues Degeneration of the wound with the appearance of a new eschar

43 Early surgical excision of devitalized tissue is now widely performed, and burn-wound infections can be classified in relation to the excision site as (1) Burn-wound impetigo (2) Burn-related surgical wound infection (3) Burn-wound cellulitis (4) Invasive infection in unexcised burn wounds (separation of the eschar or by violaceous, dark brown, or black discoloration of the eschar) The appearance of a green discoloration of the wound or subcutaneous fat or the development of ecthyma gangrenosum at a remote site points to a diagnosis of invasive P. aeruginosa infection.

44 Wound Biopsies Wound biopsies are necessary for definitive diagnosis of infection The timing of these biopsies can be guided by clinical changes, but in some centers burn wounds are biopsied routinely at regular intervals. The biopsy specimen is examined for histologic evidence of bacterial invasion, and quantitative microbiologic cultures are performed. The presence of >10 5 viable bacteria per gram of tissue is highly suggestive of invasive infection and of a dramatically increased risk of sepsis. Histopathologic evidence of invasion of viable tissue and the presence of microorganisms in unburned blood vessels and lymphatics are more definitive indicators of infection. A blood culture positive for the same organism seen in large quantities in biopsied tissue is a reliable indicator of burn sepsis.

45 Wound Surface Cultures Surface cultures may provide some indication of the microorganisms present in the hospital environment but are not indicative of the etiology of infection. This noninvasive technique might be of use in determining the flora present in excised burn areas or in areas where the skin is too thin for biopsy (e.g., over the ears, eyes, or digits).

46 Infections Other than Wound Infection In addition to infection of the burn wound itself, a number of other infections due to the immunosuppression caused by extensive burns and the manipulations necessary for clinical care put burn patients at risk. Pneumonia, now the most common infectious complication among hospitalized burn patients, is most often nosocomially acquired via the respiratory route; among the risk factors associated with secondary pneumonia are inhalation injury, intubation, fullthickness chest wall burns, immobility, and uncontrolled wound sepsis with hematogenous spread. Septic pulmonary emboli Suppurative thrombophlebitis may complicate the vascular catheterization Endocarditis, urinary tract infection, bacterial chondritis (particularly in patients with burned ears), and intraabdominal infection

47 Systemic Antibiotics Treatment Systemic treatment with antibiotics active against the pathogens present in the wound should be instituted. In the absence of culture data, treatment should be broad in spectrum An antibiotic active against G(+) pathogens (e.g., vancomycin, 1 g IV every 12 h) and with a drug active against P. aeruginosa and other G(-) rods (e.g., ceftazidime, 2 g IV every 8 h) In penicillin-allergic patients, ciprofloxacin (400 mg IV every 12 h) may be substituted for ceftazidime In settings where MRSA is not prevalent, oxacillin (2 g IV every 4 h) may be substituted for vancomycin

48 Tetanus Vaccination All burn-injury patients should undergo tetanus booster immunization if they have completed primary immunization but have not received a booster dose in the last 5 years. Patients without prior immunization should receive tetanus immune globulin and undergo primary immunization

49 Reference Fitzpatrick Dermatology in General Medicine, 8 th edition Harrison s Principles of Internal Medicine, 19 th edition