filtration rate, and renal blood flow. The renal medulla is the most sensitive to hypoxia with damage to

renal tubular cells. Patients present with oliguria and decreased creatinine clearance. Early renal failure

often results from hypovolemia-induced ischemic injury. However, overresuscitation can also

compromise renal perfusion by causing abdominal compartment syndrome. Late renal failure occurs

after the fifth postburn day and is frequently caused by sepsis or nephrotoxic antibiotics. Continuous

renal replacement therapy and pharmacologic treatments such as dopamine have not definitively been

shown to improve outcomes.

The initial care of acute renal failure patients should focus on reversing underlying causes and

correcting any fluid and electrolyte imbalances. The physician should ensure adequate volume status,

avoid nephrotoxins, and dose medications appropriately.

Metabolic Response and Nutrition

Early nutrition is now the cornerstone of burn care. Tube feeding should begin soon after admission.

Attempts to feed postpyloric should be done, however, gastric feeding is also acceptable. Tube feeds are

often needed even in patients who are able to feed themselves due to the need to enable wound healing

and keep up with the hypermetabolic response to burn injuries. Feedings can be continued during

surgery as long as prone positioning is not planned.

The metabolic rate is significantly greater in burn patients than in other critically ill patients and

leads to accelerated lean body mass wasting. Positive nitrogen balance is key to prevent skeletal muscle

breakdown and highlights the importance of early nutritional support. The general composition of

enteral feeding should include at least 60% calories from carbohydrates not exceeding 1,600 kcal/day,

12% to 15% from lipids and essential fatty acids, and 20% to 25% from protein. Failure to meet large

energy and protein requirements can impair wound healing and alter end-organ function. Even though

adequate nutrition is crucial, overfeeding must be avoided. A randomized, double-blind, prospective

study demonstrated that aggressive high-calorie feeding with enteral and parenteral nutrition was

associated with increased mortality.66 The daily caloric requirements can be calculated using the Curreri

formula: ([25 kcal] [body wt kg]) + ([40] [% TBSA area burn]) 1 to 2 g/kg/day of protein for synthetic

needs of the patient. Burn patients should receive a small proportion of calorie requirements from fat

than other ICU patients. The liver in a burn patient produces less very low density lipoprotein causing

hepatic triglyceride elevation. Increased fat leads to increased complications including fatty liver,

infection, hyperlipidemia, hypoxia, and mortality. Decreased gastrointestinal absorption and increased

urinary losses can also lead to deficiencies in vitamin C, E, zinc, iron and selenium. Burn patients, like a

subset of trauma and gastrointestinal surgery patients have been shown to benefit from glutamine

supplementation.

5 Acute response to thermal injury is biphasic with the hypodynamic shock state at 24 to 72 hours

and hyperdynamic catabolic state beginning on the fifth postburn day. Patients have supraphysiologic

cardiac output, elevated body temperature, supranormal oxygen consumption, supranormal glucose

consumption and altered glucose metabolism, increased CO2 production, and accelerated tissue

catabolism. This response is thought to be caused by excessive release of catabolic hormones including

catecholamines, glucagon, and cortisol. There is a shift from anabolic–catabolic homeostasis to

hypercatabolic state requiring increased substrates for energy. The resting metabolic rate is directly

related to the severity of burn injury and a persistent hypermetabolic state is unsustainable. This

hypermetabolism can be reduced by promptly treating sepsis as well as performing early excision and

grafting of burn wounds. Recent studies have shown efficacy of a nonselective beta-blocker such as

propranolol which inhibits the effect of catecholamines and slows muscle catabolism. Herndon et al67

demonstrated that propranolol in acute burns in the pediatric population improved net muscle synthesis

and increased lean body mass. Additionally, current standard of care includes providing pharmacologic

agents such as oxandrolone (testosterone analog given 0.1 mg/kg q12h). Oxandrolone improves muscle

synthetic activity, increases expression of muscle anabolic genes, and increases net muscle protein

synthesis improving lean body mass composition and has been shown to reduce weight loss, improve

donor site wound healing, and decrease hospital stay. Patients with burn injuries greater than 30%

should receive oxandrolone for 6 months as the hypermetabolic state has been shown to persist

following major burn injury. Despite being well tolerated, patients on oxandrolone should have liver

function tests monitored weekly. Human growth hormone and insulin-like growth factor have also been

investigated but results have been indeterminate.

Glucose Control

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Burn injury results in an increase in hepatic gluconeogenesis and impaired insulin-mediated glucose

transport into skeletal and cardiac muscles and adipose tissue. Hypermetabolism seen in burn injury also

leads to hyperglycemia and insulin resistance and thus glucose should be monitored in large burn injury

patients. Currently, data do not support strict glucose control (<110 mg/dL) but moderate blood

glucose control is recommended (<180 mg/dL) and may decrease infectious complications.68

WOUND MANAGEMENT

There are a variety of burn wound dressing materials. Patient factors such as burn wound depth,

condition, location of the burn, and comfort during dressing changes dictate the choice utilized.47

Although the indications for systemic antibiotic therapy have not been clearly defined, use of

antimicrobial dressings is recommended. Silvadene (silver sulfadiazine) is a silver-containing cream that

has broad-spectrum coverage against both gram-negative and positive bacteria. Silvadene is commonly

used on the skin of both partial- and full-thickness burn injuries. Its use is contraindicated in patients

with sulfa allergies and over wounds near the eyes.69 A self-limited leukopenia is commonly seen during

the initial days of Silvadene treatment, but its use can be continued as leukocyte counts recover quickly

without intervention. Sulfamylon (mafenide acetate) is an analogous agent that is used over

cartilaginous areas such as the nose or ear due to increased tissue penetration compared to other

dressing materials. Since topical Sulfamylon cream can be used without secondary dressing, it can be

used for open burn wound therapy and regular examination of the burn wound surface. Both the cream

and a 5% solution of Sulfamylon are equally effective.70 Sulfamylon cream is useful for ear burns when

there is risk of cartilage exposure. Sulfamylon may cause increased pain in the burn wound. In addition

to the cream, Sulfamylon soaks can also be used for burn and postoperative dressings. Patients receiving

large surface area Sulfamylon dressings should be monitored for complications such as hyperchloremic

metabolic acidosis that can occur due to its mechanism of action as a carbonic anhydrase inhibitor.

Silver nitrate can also be used by soaking dressings in a 0.5% to 1.0% concentration solution and

applied 3 to 4 times a day. These dressings offer several advantages over Sulfamylon soaks as they

cover fungus in addition to bacteria and are more cost effective. If not careful, however, silver nitrate

does cause significant staining of anything it contacts. If grafts are placed in an area with surrounding

cellulitis, silver soaks can be used during the first few days when the compressive dressing is still

needed.

Bacitracin and Xeroform are additional examples of antimicrobial-type dressing regimens and can be

used after the first dressing takedown. While both can be used anywhere on the body, bacitracin is

commonly used for facial burns.

For patients who are at lower risk of infection based on the appearance of burn wounds, dressings

may be changed with less frequency to achieve a balance between pain control and the need for wound

coverage. Acticoat is one such option that is mainly used in partial-thickness burn injuries. This dressing

consists of silver-impregnated sheets that have antimicrobial properties and can be changed less

frequently, reducing pain and cost.71 The nanocrystalline particles in Acticoat are able to reduce wound

infection and promote wound healing compared to older silver products, including silver nitrate.72

When using Acticoat, it is important to remember to moisten it with water and not normal saline as

sodium can inactivate the silver. There are other commercial products in addition to Acticoat that utilize

the principle of nanocrystalline dressings. These dressings can be attached with mild adhesive

(Mepilex), wrapped or placed on like a glove (Silveron).

While dressing changes are sometimes used to optimize a wound before and after operative

interventions, dressings also have the potential to completely heal a wound without the need for

surgical intervention depending on the overall appearance of the burn and patient as a whole. Thus, a

proper wound care team must not only include a critical care physician and surgeon, but it must also

include a specialized wound care nurse to appropriately address this central modality of care for any

burn patient.

Donor sites can be the most painful area for the patient and thus consistent donor site care should be

provided. Like other wounds, these wounds heal in a moist environment and though dry Xeroform can

be used, this can be extremely painful for the patient. We prefer a non-adherent dressing like mepilex

that maintains wound moisture in addition to having an antimicrobial silver.

OPERATIVE INTERVENTIONS

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Excision and Grafting

After initial stabilization of the patient, which generally takes 24 to 48 hours, surgical intervention

should occur as soon as possible since there are no benefits to delaying surgery when it is clear that a

burn wound is of sufficient depth that it will not heal on its own.73,74 Early excision of devitalized tissue

appears to reduce the local and system effects of mediators released from burned tissue, thus reducing

the progressive pathophysiologic derangements. Excision also removes dead skin which can serve as a

nidus for wound infection. Tangential excision with a sharp blade on a guarded device removes necrotic

tissue while preserving as much of the underlying viable tissue as possible. For large burn wounds,

debridement should occur within 2 to 4 days of the initial injury. If there are insufficient donor sites to

autograft all of the burn wounds, the debrided wound should be covered temporarily with allograft.75

Alternatively, the burn can be completely excised within the first several days after injury, and a

temporary skin substitute can be used to close the wound remaining after available autologous skin has

been harvested and grafted (Fig. 12-3). Sequential debridement and grafting is the backbone of burn

care in those suffering from large TBSA burns. The use of allograft also allows the surgeon to assess the

depth of the injury and the adequacy of excision. If the homograft has good take, then it is likely an

autograft will also take.

Figure 12-3. Full-thickness friction burn staged with integra to allow for full declaration of the wound prior to grafting. Top row

shows initial injury. Middle row shows integra placement and bottom row shows after final debridement and graft.

During tangential excision, tissue is debrided until healthy, bleeding tissue is reached. Hemodynamic

stability and correction of hematologic and metabolic derangements are helpful for such operative cases

given the large amount of blood that may be lost during debridement. A discussion in the preoperative

time out should take place between the surgeon and anesthetist about the amount of blood loss

expected, the blood products available, and the transfusion triggers for the case. Arterial lines as well as

large bore IVs and often a central line should be in place prior to beginning the operation. In general,

hemoglobin fluids are not an accurate during acute blood loss anemia caused by intraoperative bleeding

after a large debridement. In any burn over 20%, a preoperative blood type and crossmatch should be

performed and packed red blood cells should be placed in the operating room to avoid intraoperative

acute blood loss anemia. Several measures can be used to decrease intraoperative blood loss, but the

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need to debride to bleeding tissue makes bloodless surgery impossible. Techniques to decrease blood

loss include the use of tourniquets on the extremities as well as the use of topical spray thrombin and

epinephrine-soaked Telfa pads placed immediately after excision followed by wrapping this area with

epinephrine-soaked Kerlix gauze. We use 1:1,000,000 epinephrine in a saline solution as a hemostatic

dressing after excision. In regions where circumferential wrapping cannot be performed, epinephrine

solution can be used as an injectable solution to perform dermatoclysis. An 18G spinal needle on the end

of a 60-cc syringe or tumescent device can be used to deliver this solution under the skin in areas of

bleeding. Similarly, we use epinephrine injection solution as a preharvest tumescent solution for donor

sites. This helps create a flat surface on which to run the dermatome and decreases postharvest blood

loss. If working on an extremity, a good strategy is to start proximally and perform the excision

followed by inflation of the tourniquet. Subsequently, the distal excision can be performed under

tourniquet control.

In addition to achieving a healthy and well-vascularized wound bed after debridement, it is also

essential to classify and examine the wounds further during this process. At this time, the distinction

between superficial and deep partial-thickness burns must be made. While superficial partial-thickness

injuries can heal on their own with dressing changes and without grafting, deeper burns must be treated

with skin grafting. Given the association between early debridement and grafting with improved

functional- and scar-related outcomes, the earlier this distinction is made the faster a treatment plan can

be formulated.

Figure 12-4. Grafting back of donor site with 4:1 split-thickness skin graft. (Top) Intraop placement of graft back. (Bottom) 4

weeks postop from graft back.

Grafting exists in many forms and decisions on coverage material and thickness of graft must be made

in a strategic fashion to optimize functional and aesthetic outcomes. The gold standard is to use the

patient’s own tissue or autograft for reconstruction. These grafts can be excised in thicknesses ranging

from 0.008 to 0.018 in, with 0.012 in as a standard. Thinner grafts are helpful if the surgeon is planning

to reharvest donor sites or if the patient has thin skin due to increased age or chronic

immunosuppression, as thin grafts lead to faster donor site healing. Thinner grafts increase the

likelihood of skin graft take and decrease the risk of superficial epidermolysis of the graft, however,

thin grafts also lead to greater secondary contracture. In patients where delayed donor site wound

healing is expected such as elderly patients and patients on chronic immunosuppressives, grafting back

the donor site with 4:1 meshed grafts can accelerate healing (Fig. 12-4).

After a decision regarding the use of allograft versus autograft has been made, attention is turned to

the size and thickness of the skin graft. Commonly, split-thickness skin grafts (STFG) composed of the

epidermis and a thin layer of dermis are utilized to minimize donor site morbidity and optimize graft

take. Thin grafts are more likely to succeed than thick grafts as it is easier to adhere and for

neovascularization to occur. There are certain areas, however, where split-thickness grafts should not be

used since they cause greater secondary contracture and less color match over time as compared to fullthickness grafts. Areas of function, such as the hands and feet, lose a remarkable amount of utility if

afflicted by scar contracture and may benefit from full-thickness grafts.76 If split-thickness skin is used

on the feet and hands, the grafts should be harvested on the thick side and meshing should be avoided if

possible (Fig. 12-5). Similarly, aesthetically important areas, such as the face, are also more amenable

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