Treatment of deep burns

INTRODUCTION — A burn converts normal intact skin into an open wound. The primary goal of burn wound care is wound closure. While cleansing, debridement, and local wound care may be sufficient for healing superficial burns (epidermal [superficial], superficial partial thickness), deep burns (deep partial thickness, full thickness, or deeper) require surgical excision and skin grafting. The earlier this can be accomplished, the more expedited the recovery.

The assessment, initial treatment, and excision and closure of deep burn wounds is reviewed here. The treatment of superficial burns is reviewed separately. (See "Treatment of minor thermal burns" and "Sunburn" and "Treatment of superficial burns requiring hospital admission".)

INITIAL CARE — Burns are considered traumatic injuries, and initial trauma assessment is similar, with evaluation of airway, breathing, and circulation. While some small total body surface area (TBSA) deep burn injuries can be managed in the outpatient setting at the discretion of the burn surgeon, most deep burn injuries will require admission to a burn intensive care unit. Larger TBSA burns (>20 percent) are associated with calculated large fluid resuscitation expectations, with predictable tissue edema affecting not only cutaneous structures but the airway as well. It is prudent to consider elective intubation in patients with >30 percent TBSA deep burn before airway compromise occurs; however, in patients at the extremes of age or with comorbid conditions, a decision to electively intubate should be considered with burns <30 percent TBSA. (See "Overview of the management of the severely burned patient", section on 'Emergency burn care'.)

Burn wound characterization — Decisions for fluid resuscitation and surgical decision making depend on acute characterization of the burn wounds.

●Burn depth – The depth of tissue injury is clinically based on the classification system for cutaneous burn wounds given in the table (table 1 and figure 1). (See 'Accuracy of bedside assessment' below and "Assessment and classification of burn injury", section on 'Classification by depth'.)

●TBSA – Initial estimation of the burn size as a percentage of the TBSA is crucial for triage, initial assessments and treatments, and anticipated long-term management, and is also used in referral criteria. Traditional methods of estimation are based on clinical assessments, but future methods may include specific imaging technology that uses drawings or photographs for calculations [1]. The most widely used tools are the Wallace Rule of Nines [2], the Rule of Palm [3], and use of a Lund and Browder Chart (table 2 and figure 2) [4]. These are reviewed in more detail separately. (See "Assessment and classification of burn injury", section on 'Extent of burn injury'.)

Clinically, the time to healing and development of scarring are also used to characterize burns; the longer the time to heal, the more likely the burn wound will be associated with scarring. Deep burn injuries invariably cause moderate-to-severe scarring. (See "Hypertrophic scarring and keloids following burn injuries", section on 'Incidence and risk factors'.)

Accuracy of bedside assessment — Bedside clinical assessment is the most widely used and cost-effective method to characterize burn depth. This subjective assessment is based upon characteristics that are easily observed (figure 1) without the need for any advanced instrumentation and is most reliable for very shallow burns or very deep burns but can be inaccurate in up to one-third of diagnoses of burns of intermediate depth (ie, superficial versus deep partial-thickness burns) [5,6].

There is considerable variation between different clinicians, which reduces reliability of clinical burn depth characterization [7-9]. The most common inaccuracies are from overestimation of the burn depth [10]. Newer developments in burn depth assessment focus on measurements of tissue perfusion and may help expedite earlier recognition of deeper burns to facilitate expeditious excision [11].

Burns awaiting demarcation — Certain clinical features that distinguish between partial-thickness and full-thickness burns may not be obvious acutely, necessitating serial evaluations and time. As an example, a full-thickness burns may appear pale or patchy initially, rather than white or gray. Any burn that appears to be either deep partial thickness or full thickness is considered full thickness until more accurate differentiation is possible.

Conversion to deeper burn injury — Optimizing burn wound care can be challenging in the face of burn wound conversion, which is a progression of a superficial partial-thickness burn to a deep partial-thickness or full-thickness burn. The pathophysiology of burn wound conversion is multifactorial and varies between patients [12]. One early pathogenesis described conversion through three concentric zones of burn injury: an irrevocably damaged area of coagulation, a threatened but still viable zone of stasis, and an edematous zone of hyperemia. Burn wound conversion is thought to occur as tissue in the zone of stasis denatures, increasing burn depth [13].

Escharotomy — Escharotomies are often indicated for deep partial- and full-thickness burns, mostly when associated with >20 percent TBSA burn. Escharotomies may be performed at the time of initial burn presentation, particularly among those with circumferential burns; however, escharotomy may be needed at a later time as tissue edema increases with fluid resuscitation. Severe tissue edema may compromise vascular flow, potentially leading to compartment syndromes related to the external compression. (See "Abdominal compartment syndrome in adults" and "Acute compartment syndrome of the extremities".)

Vigilant monitoring of distal pulses or Doppler signals, bladder pressure, and peak airway pressures is mandatory when assessing the need for escharotomy of the extremities, abdomen, or chest, respectively. The procedure decompresses the subcutaneous tissue to prevent secondary ischemia. Escharotomy can be performed expeditiously at the bedside either in the emergency department or in the intensive care unit, rarely requiring travel to the operating room. Escharotomy can be performed using a scalpel, but electrocautery decreases blood loss. Longitudinal incisions are made along the entire length of the full-thickness eschar, which increases the compliance of the cutaneous tissue [14]. The open escharotomy wound is dressed with saline-moistened gauze as described below. (See 'Initial wound care and dressings' below.)

While rapid, safe, and effective, escharotomy is not without risk, and complications are more likely when it is performed by inexperienced physicians. Complications include hemorrhage, increased fluid loss, subcutaneous infection, and neuromuscular injury [15,16]. Failure to perform an adequate escharotomy can lead to irreversible tissue ischemia.

Ongoing fluid therapy — Formal fluid resuscitation is typically limited to patients with >20 percent TBSA burn, but special considerations are made in patients at the extremes of age who may otherwise benefit. Oral hydration is usually sufficient in patients with <20 percent TBSA [17], with the addition of a maintenance intravenous fluid rate, if needed. The authors' preferred approach in severely burned patients is to use the Parkland formula to calculate initial fluid resuscitation needs (ie, crystalloid volume). Colloid, specifically albumin, is administered as a rescue method for nonresponders (ie, patients with increasing crystalloid requirements without the expected clinical improvement or without adequate urine output) and plasma for correction of coagulopathy.

Several formulas (eg, Parkland, modified Brooke, Rule of Tens) exist whereby the volume of fluid resuscitation is a function of the total body surface area burned and the weight of the patient. Regardless of the formula used to calculate fluid resuscitation parameters, all are considered a starting point [18]. (See "Emergency care of moderate and severe thermal burns in adults", section on 'Estimating initial fluid requirements'.)

Real-time data and parameters are used to guide ongoing resuscitation, which may differ from initial formula calculations. All patients undergoing formal fluid resuscitation should have a urinary catheter inserted for accurate measurement of hourly urine output. Specifically, urine output is an easily observable parameter, and approximately 0.5 to 1 mL of urine per hour per kilogram of the patient's weight is considered a marker of successful resuscitation; similarly, 30 to 35 mL/hour for average-sized adults is also within acceptable range [19]. Hourly urine output for pediatric patients should be in the range of 1 to 2 mL/kg/hour.

The authors' preferred formula in the management of severe burn injury is the Parkland formula, which uses a factor of four for calculating initial fluid resuscitation needs: 4 mL of intravenous fluid for every kilogram of the patient's weight multiplied by the total percent TBSA (not including epidermal [superficial burns]) (figure 3). Of this volume, one-half is given in the first eight hours after burn injury, and the remaining one-half over the subsequent 16 hours. Initiation of the specific rate per the formula is used; fluid boluses are not indicated unless there are other hemodynamic indications. It is important to note that the formula includes time from burn injury. Any fluid given before the calculation is made should be subtracted from the expected volume to be given in the first eight hours; otherwise, higher volumes than necessary may be administered. Fluid calculations should also be adjusted once TBSA assessments are made by more experienced personnel; specifically, the TBSA reported by emergency medical services is often incorrect.

The fluids used in the Parkland formula included crystalloid, specifically Lactated Ringer's (LR) solution, as well as albumin infusion both at a particular time and specific rate. The original Parkland formula accounted for a predictable timing of albumin bolus at the conclusion of a 24-hour resuscitation period at a rate of (0.1 cc) x (TBSA) x (kg). The occurrence of fluid creep (resuscitation volumes that exceed those predicted) has led to some alteration in this method, specifically using colloid infusion as a means of "rescue therapy" or a way to halt or decrease fluid creep [20]. The administration of colloid, specifically albumin, during the initial resuscitative phase was evaluated in the past, but studies were small, and results and recommendations have been conflicting [21]. Contemporary studies have proposed reevaluation of plasma administration for burn resuscitation. Plasma was previously avoided due to the risk of transmission of bloodborne disease, cost, and risks of transfusion-related reactions (ie, transfusion-related acute lung injury, transfusion-associated circulatory overload, allergy) [22].

Fluid creep refers to fluid resuscitation volumes that exceed those predicted by the Parkland formula, specifically in larger TBSA burns [23]. Colloid infusion may help decrease the complications of fluid creep, even if the specific cause is not addressed. In one systematic review, a meta-analysis of four trials, mean load (volume [mL]/percent TBSA/weight [kg]) 24 hours following burn injury was lower for hyperosmotic fluid compared with isosmotic fluid (LR) without altering renal function or mortality [24]. The hyperosmotic fluids included hypertonic saline, or LR plus albumin, fresh frozen plasma, or hydroxyethyl starch. Additional trials are needed to determine whether any of the hyperosmotic fluids result in better outcomes than the others. However, it should be noted that among 25 trials in a separate systematic review, hydroxyethyl starch increased the risk of death compared with crystalloid (risk ratio 1.10, 95% CI 1.02-1.19) [25].

Some degree of early fluid restriction, especially with close goal-directed therapy, can also help decrease the incidence of fluid creep. Some examples of colloid use to help decrease the incidence and impact of fluid creep include:

●Adherence to the original Parkland formula with a routine colloid bolus at the completion of a 24-hour crystalloid fluid resuscitation [20].

●Initiation of resuscitation with albumin at 12 hours post-burn when fluid requirements exceed 120 percent of normal [26].

●Use of 5% albumin infusion in any patient whose 24-hour fluid resuscitation requirements are projected to exceed 6 mL/kg/% TBSA [27].

Responders to fluid resuscitation are those patients in whom urine output remains within the acceptable range during the first 24 hours, while nonresponders are those who fall short of this expectation or are oliguric. It is important to identify these nonresponders early because there is a potential tendency to increase the hourly resuscitation volume, which may lead to significant pulmonary and cardiac consequences without any additional benefit. While some patients may adhere to their calculated 24-hour fluid resuscitation volumes with expected urine output, some may have higher- or lower-than-expected urine output. Both scenarios require specific attention.

●In a patient with excess urine output, consideration may be made to decrease the hourly fluid resuscitation to help prevent unnecessary volume overload. Some possible etiologies of this supraoptimal response may be due to an overestimation of either TBSA or burn depth. (See 'Burn wound characterization' above.)

●A patient with suboptimal urine output may benefit from intermittent increases in hourly resuscitation volume as long as there is a parallel increase in urine output. However, close attention is mandatory to avoid excessive increases without a comparable response to urine output; these specific nonresponders are candidates for earlier continuous renal replacement therapy. (See "Continuous kidney replacement therapy in acute kidney injury".)

Initial wound care and dressings — Ultimately, the management of deep burn injury requires excision of the eschar; any local therapy applied before excision occurs is unlikely to have significant effect. Specifically, while antibiotic-impregnated or silver-containing products are useful in superficial burns after cleansing/debridement [28], the thick eschar of deep partial-thickness and full-thickness burns prevents penetration of the compounds, and they are generally not indicated. Ultimately, the eschar must be removed before any dressing can be effective, and therefore dry gauze is sufficient on unexcised eschar, with plans for excision as soon as possible. Wound management following burn wound excision and dressings following skin grafting are discussed below. (See "Topical agents and dressings for local burn wound care" and 'Post-excision dressings' below and 'Graft dressings' below.)

For deep partial-thickness or full-thickness burns associated with escharotomies, saline-moistened gauze should be placed within the incisions to prevent desiccation of the subcutaneous tissue. Similarly, exposed tendon, bone, and muscle should also be kept moist. (See "Basic principles of wound management", section on 'Wound dressings'.)

Burn wound care is routinely accomplished in the burn unit, often in a special treatment room, but in some burn centers, the initial wound care is completed in the operating room with general endotracheal anesthesia. For patients who are not undergoing general anesthesia, analgesia for the burn wound cleansing can be achieved with intravenous administration of narcotics and anxiolytics (eg, morphine and benzodiazepines) with timed oral narcotics (ie, hydrocodone) within 30 minutes prior to cleansing. These medications are started just shortly beforehand when the patient and personnel are ready to proceed. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications" and "Procedural sedation in children: Approach".)

Once analgesia is achieved, cleaning deep burn wounds with sterile saline or Dakin’s solution (0.025% sodium hypochlorite) is generally sufficient to remove debris [29]. Scrubbing with povidone/iodine solution (Betadine), chlorhexidine (Peridex), or other agents is not typically necessary [30]. (See "Topical agents and dressings for local burn wound care".)

EARLY BURN EXCISION — Deep burn injuries require excision of burn eschar to provide an appropriate wound bed for eventual autografting, prevent burn wound sepsis, and simplify dressing changes [31,32]. Based upon small randomized trials and observational studies [33-38], we suggest early burn wound excision, which removes ischemic, necrotic, and potentially infected tissue, rather than awaiting eschar separation (see 'Efficacy' below). Following burn wound excision, skin/soft tissue coverage can be performed concurrently if adequate tissue is available. At other times, temporary wound dressings or other alternatives (eg, skin substitutes) are needed until more definitive reconstruction can be accomplished. (See "Topical agents and dressings for local burn wound care" and 'Burn wound closure' below.)

Prior to the recognition that early excision reduced burn wound mortality and complications, burn eschar was left undisturbed until it spontaneously separated from the underlying wound bed, revealing granulation tissue suitable for grafting. Burn wound sepsis was a common consequence due to the prolonged process. While topical agents applied to the eschar were used as a means to control the level of bacterial colonization, these were essentially ineffective since the typical agents (eg, mafenide acetate, aqueous silver nitrate solution, silver sulfadiazine) do not penetrate the eschar [39-45]. (See 'Initial wound care and dressings' above and "Topical agents and dressings for local burn wound care" and "Burn wound infection and sepsis".)

Hemodynamic and resuscitative parameters must be under control for the patient to tolerate general anesthesia and the stress of excision and grafting, including what is often large blood volume loss during and after excision of large total body surface area (TBSA) burns. (See "Anesthesia for patients with acute burn injuries".)

Early burn wound excision and closure alone does not eliminate the hypermetabolic response [46,47]. (See "Hypermetabolic response to moderate-to-severe burn injury and management".)

Efficacy — Early excision of necrotic tissue and closure of the burn wound was one of the greatest advancements in the treatment of patients with severe burn injuries and is a mainstay of modern therapy [37,38].

In an early single-institution review of 1103 patients, mortality declined significantly from before to after early eschar excision and burn wound closure was standardized as practice (24 to 7 percent; 1974 to 1979-1984) [37]. The mortality reduction was independent of burn size, patient age, and sex. The most dramatic reduction in mortality occurred in older patients with massive burn injuries. In a later meta-analysis of four trials (490 patients), there was a nonsignificant trend toward lower mortality in patients managed with early excision compared with conservative treatments consisting of dressing changes, and placement of skin grafts following eschar separation (relative risk [RR] 0.72; 95% CI 0.52-1.01). Patients in the early excision group had greater transfusion requirements (standard mean difference [SMD] 1.65; 95% CI 0.51-2.80), but hospital length of stay was shorter (SMD -8.89; 95% CI -14.28 to -3.50). The trials included in the meta-analysis were generally low quality (high risk of bias).

For some anatomic sites, such as the hand, optimal management remains debated [48,49]. (See "Primary operative management of hand burns".)

Timing — Excision should ideally be within 24 to 72 hours of the burn injury, but whether this is feasible depends heavily on the condition of the patient in that time frame. The ideal timing to grafting is immediate if the wound bed can be appropriately prepared. In a review evaluating burn wound care in 3561 burn patients over a 14-year period, significant decreases in mortality (9.8 versus 7.3 percent) and length of hospital stay (23 days in 1979 to 14.2 days in 1990) were correlated with a decrease in the surgery interval (14.8 days in 1979 to 6.1 days in 1990) [50]. The surgery interval reflected the rapidity with which the surgical team was able to close the burn wound.

For small TBSA wounds, excision and grafting can be performed within this time frame, but for large TBSA burns, hemodynamics and progress with resuscitation must be taken into account before subjecting the patient to the acute blood loss expected during the burn wound excision procedure.

Techniques — The thick eschar that characterizes deep burn injury requires complete excision to create a wound bed appropriate for the acceptance of autografts or other biologic dressings. Most described techniques for surgical excision of deep burn injuries involve sharp debridement and excision, typically with an excision knife or other cutting instrument (ie, dermatome), but other methods are being developed as alternatives.

Tangential excision — Tangential excision is the most common technique and involves sequential debridement of burned tissue until a layer of viable, vascularized tissue is encountered [51]. Tangential excision may suffice for superficial partial-thickness burn wounds, whereas for deep partial-thickness and full-thickness burn wounds, full-thickness excision is required to assure an adequate tissue bed to accept an autograft.

Sharp — A sharp handheld instrument is usually used. One of these is the Humby knife, which is a long, guarded blade that can be adjusted to the depth of excision needed [52]. Another instrument is the Goulian-Weck dermatome. Both apply pressure against the burn wound to assure sequential excision of even depths of tissue. The instrument is guided across the burn eschar in a back-and-forth motion with downward pressure and little forward force to produce a smooth excision. Care must be taken as too great a pressure will lead to uneven excision, potential excision of otherwise viable tissue, or inadvertent excision deeper than was planned [53].

Excision to an easily identified fascial plane is typically reserved for very large, deep, and life-threatening burn wounds; invasive burn wound sepsis; or when the patient is unlikely to tolerate the very large blood volume loss of tangential excision. The main drawback is permanent loss of cutaneous sensation and development of lymphedema with the excision of viable subcutaneous tissue and lymphatics [54,55]. In addition, fascial excision leads to notable tissue depression with unaesthetic contour deformities.

Hydrosurgery — Another technique for burn wound excision that can be applied to partial thickness burns uses high-pressure water jets to debride necrotic tissue (eg, Versajet [51,56,57]). Proponents of hydrosurgery have noted that it can help preserve dermal tissue, which should reduce scarring [58,59]. One randomized trial has reported encouraging results; however, additional larger trials with longer term follow-up are needed before making a recommendation for routine use. Availability of this technology may be limited.

In a within-patient trial, among 137 patients who required split-thickness skin grafting, the burn wound in one area was excised with hydrosurgical techniques, and in another area conventional debridement was performed using a Weck knife [60]. At 12 months, Patient and Observer Scar Assessment Scale (POSAS) observer total item score, which judges vascularity, pigmentation, thickness, relief, pliability, and surface area, was significantly lower for hydrosurgically debrided wounds (mean difference -0.16, 95% CI -0.25 to -0.06), as was observer overall opinion score (mean difference -0.22, 95% CI -0.34 to -0.09). Patient total item score was also lower (mean difference -0.29, 95% CI -0.49 to -0.09), but patient overall opinion score was not. Among patients who noticed a difference, twice as many judged the hydrosurgically debrided area to be better or much better at 12 months; however, one-fourth of patients saw no difference. Histologically, significantly more dermis was preserved with hydrosurgery. Complication rates did not differ between both treatments.

Others — Various types of selective enzymatic debridement have also been used [61]. As an example, NexoBrid (EDNX) has specific debriding enzymatic activity that is derived from bromelain raw material extracted from pineapple plant stems [62]. In one randomized controlled clinical trial, NexoBrid significantly reduced the time from injury to complete debridement, need for surgery, area of burn excised, and need for autografting [63].

Hemostasis — Tangential excision is traumatic and associated with significant blood loss as excision continues until a layer of viable, bleeding tissue is encountered. Blood loss can be lessened with the use of tourniquets on extremities and topical hemostatic agents on the wound bed. Tumescent solution with epinephrine can also be used before eschar and donor site excision to decrease bleeding [54].

●Tourniquets for extremity burns – The use of tourniquets, with or without Esmarch bandages, has been used in the excision of deep partial- and full-thickness burns of the extremities to help reduce blood loss [64]. Tourniquets are used only when grafting is anticipated immediately after excision and does not affect graft take. It is unnecessary for staged procedures where excision and grafting are separated temporally. One drawback to tourniquet use during excision is that exsanguination of an extremity limits capillary bleeding, which is useful as a marker to distinguish viable from nonviable tissue, which could lead to excessive tissue excision [65]. As with tourniquets used in other surgical procedures, tourniquet time should be limited; approximately 30 minutes is an acceptable duration.

●Topical hemostatic agents – Fibrin sealants have been used in burn operations for both their hemostatic and adhesive properties, and often in combination with tourniquet exsanguination of the extremities. [66-69] (See "Skin autografting", section on 'Graft placement and fixation' and "Fibrin sealants".)

Post-excision dressings — Following excision, if grafting will not take place immediately, a variety of tropical antimicrobial agents and dressings can be used. Examples include Conformant, Acticoat, Aquacel Ag, or warm bacitracin-soaked mesh dressings [55]. The choice can be made based on cost, availability, frequency of dressing changes, and provider familiarity. Depending on the dressing used, these can be left in place from three to seven days postoperatively. (See "Topical agents and dressings for local burn wound care", section on 'Antimicrobial agents'.)

BURN WOUND CLOSURE

Timing to grafting — Burn wounds are considered closed when autografts have been placed and healed. Early wound closure is associated with decreased severity of hypertrophic scarring, joint contractures, and stiffness and promotes faster rehabilitation [48,70-73]. (See "Hypertrophic scarring and keloids following burn injuries".)

Closure of the burn wounds within the first five days is optimal, which is achievable with immediate grafting after burn wound excision (or shortly thereafter), but burn wound coverage may not always be achievable expeditiously, or with complete success. Although the sooner the better, physiologic and hemodynamic instability can compromise skin graft take and the status of the patient.

●For small TBSA (total body surface area) burns, grafting can follow excision in the same operative setting.

●For large TBSA burns (>60 percent), the ideal timing is the same, but grafting is often delayed due to lack of donor sites. When necessary, later excision and grafting is reasonable [74]. (See 'Managing large burn wounds' below.)

Autografting — For deep burn injuries that are less extensive, autografting may provide adequate coverage. (See "Skin autografting".)

Autografts include split-thickness skin and full-thickness skin transferred from a donor site to a recipient site. Autografts are harvested from healthy, uninjured skin.

Typically, autografts for the extremity and torso burns are split-thickness skin grafts (STSGs). Common donor sites include the thigh, abdomen, and buttocks. The scalp is also a reliable donor site with rapid healing, particularly in children, allowing for multiple or more frequent harvests from the same site [75]. STSGs are expanded by meshing (picture 1) according to the area of skin needed. Meshed STSGs can stretch to cover large surface areas but consequently have a higher risk of contraction compared with full-thickness skin grafts (FTSGs), which are not meshed. Nonmeshed (ie, sheet grafts; STSG or FTSG) can be used for smaller burns or cosmetic areas (eg, hands, face). STSGs are harvested with a Zimmer dermatome, which provides a specific uniform thickness. Harvesting the epidermis and a superficial portion of the dermis leaves the remaining epidermal appendages intact to regenerate the epidermal layer, allowing reharvesting at a later time [54]. The ideal wound bed for STSGs is dominated by red granulation tissue, no visible tendon or bone, no obvious sloughing or exudate, no residual necrotic tissue, and no local signs of soft tissue or systemic infection [76]. STSGs can be fixed to the wound bed using fibrin sealants, staples, sutures, or surgical glue. STSGs will quickly adhere to a properly prepared wound bed with revascularization usually occurring between three and five days [77]. (See "Fibrin sealants" and "Skin autografting", section on 'Split-thickness skin grafting'.)

FTSGs are also harvested from a healthy area of tissue but include both the dermal and epidermal layers of skin. These are harvested via surgical excision and are taken from areas of redundant tissue or skin (to facilitate primary closure) like the groin or lower abdomen, or above the supraclavicular space for facial or neck recipient sites to improve color and texture match. The tissue is excised and stripped of any adipose tissue, which is poorly vascularized and, if not properly removed, can compromise engraftment. FTSGs are generally sutured to the prepared wound bed. FTSGs are obviously smaller than STSGs and are only used to address small cosmetic areas due to limited stretch but have a lower rate of contracture. (See "Skin autografting", section on 'Full-thickness skin grafting'.)

Managing large burn wounds — Managing large deep burns (TBSA >60 percent) becomes particularly challenging regarding timing and type of grafting (see 'Timing to grafting' above). In addition, for larger TBSA burns, planning includes prioritizing specific areas for patients who are expected to have a prolonged hospital course. Specifically, prioritizing excision and grafting of areas critical for central venous access, arterial lines, and tracheostomy and gastrostomy sites may be indicated when long-term airway and nutritional supplementation are anticipated [54]. Ultimately, the order of excision and prioritization depends on many factors but overall is aimed at optimizing outcomes.

With the goal of full coverage of the wound, any available unburned skin must be harvested judiciously, but large TBSA deep burns limit the availability of non-burned skin that can be harvested for autograft coverage. (See 'Autografting' above.)

Options for expanding coverage for burn wound closure in the patient with a large TBSA deep burn injury include wide meshing, using the Meek technique, temporary coverage using xenografts or allografts, reharvesting donor sites, and using cultured skin alternatives.

●For large burn wounds, meshed grafts (1:1.5, 1:2, 1:3) are primarily used [78]. The larger the mesh ratio, the larger the surface area the meshed autograft can cover. As an example, a 1:1.5 mesher increases the surface area of the autograft by 50 percent. While meshing facilitates burn wound closure, it may lead to suboptimal cosmetic results due to the healed appearance of the meshed skin. (See "Skin autografting", section on 'Graft meshing'.)

●The Meek technique is a method of skin graft expansion that builds upon the postage stamp technique [79,80]. Skin is harvested from healthy donor sites and divided into 196 micrografts that are placed onto the prepared wound bed using a cork carrier. These micrografts, or skin islands, effectively help cover much larger areas than the additive area of the individual small sizes would suggest [81]. (See "Skin autografting", section on 'Graft meshing'.)

●Donor sites, which are very superficial partial-thickness injuries, will heal within two to three weeks, after which they can be reharvested. Until additional donor tissues are available, staged burn wound excisions are temporarily covered using skin substitutes [36,82,83]. Allografts (human cadaveric origin) or xenografts (porcine origin) can be used as temporary bridges for coverage. (See "Skin substitutes", section on 'General properties and application'.)

Allografts may be more effective than xenografts. Allografts have also been used over micrografts to help secure autografts in place and to cover donor sites between harvests. Allografts are available in various sizes and can be meshed similarly like autografts. The use of allografts may help decrease wound size, which in turn can decrease the area of skin that is ultimately harvested for burn wound closure. Although considered temporary, some incorporation of allografts can be expected. When the wound bed is ready for autografting, the allografts are removed. While not considered permanent, some adherence and incorporation into the wound bed could be expected, which can be associated with a moderate-to-significant blood loss. Less-incorporated grafts can essentially be peeled from the wound bed.

●Cultured skin alternatives, including cultured epithelial autografts (CEAs) and cultured skin substitutes (CSSs), have also be used.

•CEAs are prepared from cultured keratinocytes from a full-thickness tissue sample of healthy, unburned skin. The cells are prepared and harvested and within a few weeks are readied for transplant [84,85].

•CSSs are prepared from epidermal keratinocytes and dermal fibroblasts attached to collagen-glycosaminoglycan substrates [86]. The addition of cultured epidermal melanocytes has restored skin pigmentation in preclinical models.

Graft dressings — Immobilization (ie, extremity splints, bedrest) is advocated to prevent shearing of the skin grafts until fully adherent, which can take up to five days. Tie-over bolster dressings are helpful for securing skin graft dressings on the trunk or near joints by placing nonabsorbable sutures around the wound and tying them to each other across the wound. This provides gentle pressure to help prevent shearing and promote immobility of the graft for engraftment to occur.

Negative pressure wound therapy (NPWT) can be used to help keep the graft in place while potentially allowing for earlier or more liberal mobilization but is used at the discretion of the burn surgeon. While challenging to place and manage, negative pressure dressings are not limited by the size or location. NPWT helps decrease graft loss [87] and improves the qualitative appearance of STSGs [88]. (See "Skin autografting", section on 'Graft immobilization'.)

Extremity dressings can be secured with gauze wraps, and extremity elevation helps prevent edema. Casts or splints over joints and extremities help prevent shearing or graft migration, especially during the first eight hours. After adherence to the wound bed, various dressings can be applied over skin grafts depending on the type of skin graft and site. (See "Skin autografting", section on 'Limb immobilization and elevation' and "Skin autografting", section on 'Recipient site dressings and care'.)

Donor site dressings — The ideal dressing applied to the donor site protects the wound and promotes epithelialization. The specific dressing used depends on its location. (See "Skin autografting", section on 'Donor site dressings and care'.)

COMPLICATIONS — Burn-wound-related complications include burn wound infection and sepsis, graft failure, and conversion of split-thickness donor sites to full-thickness wounds. Inadequate eschar excision, placement of grafts on ill-prepared tissue beds, shearing and suboptimal graft immobilization, uncontrolled local and systemic infections, shock, and poor postoperative wound care can all contribute to these problems. (See "Overview of complications of severe burn injury".)

Burn wound infection — Burn wound infections are associated with significant complications that increase morbidity and mortality in burn patients [39]. Similar to the assessment of burn wound depth, typical detection of the beginning of a local infection is based on a daily inspection by an experienced physician. The diagnosis of burn wound infection depends on a tissue biopsy demonstrating a bacterial count of at least 10⁵ per 1 cm² (1 g) of burn tissue [89-91].

The treatment of infected unexcised burn wounds is excision. Topical antimicrobial therapy is first-line treatment for infection involving excised burn wounds and grafted areas in the absence of systemic signs. If signs of systemic infection are present, an empiric intravenous antibiotic regimen tailored to the institution's susceptibility patterns is indicated and discussed separately.(See "Burn wound infection and sepsis".)

Graft failure — The rate of graft failure for split-thickness sheet and meshed grafts for burn injury is approximately 5 percent [92]. Failure of engraftment is more often a result of an inadequately prepared wound bed than an inadequately prepared skin graft. Both local and systemic factors influence the rate of successful skin grafting [93]. (See "Risk factors for impaired wound healing and wound complications".)

Local factors of the burn wound that are associated with decreased split-thickness skin graft survival include:

●Inadequate vascularity, such as the presence of unvascularized bone or tendon

●Inadequate hemostasis, such as a hematoma or seroma under the graft, which is a major cause [94]

●Excessive mobilization

●Areas of high contact or friction, such as the back, anorectal area, and genitalia

●Local tissue hypoxia caused by smoking or previous radiation

Systemic factors may decrease the survival of split-thickness skin grafts much in the same way that wound healing, in general, is affected. These include:

●Advanced patient age

●Malnutrition

●Comorbidities that impact wound healing such as diabetes and immunosuppression

●Glucocorticoid use

●Hemodynamic instability can lead to graft failure and donor site conversion. In particular, one study found that vasopressin used in the treatment of shock in burn patients was associated with both [95].

The main factor that prevents a complete take of full-thickness skin grafts is the lack of initial adhesion to the recipient site due to the presence of a hematoma or seroma that inhibits revascularization. Even small perforations in the full thickness may not be sufficient to drain accumulating fluid. The same local and systemic factors that decrease the survival of split-thickness skin grafts also decrease the survival of full-thickness skin grafts.

Donor site conversion — Harvested skin taken with excess pressure of the dermatome or at a significant thickness may become a full-thickness injury. Some have advocated returning spare harvest skin to donor sites, possibly with additional meshing, as a method to help decrease wound morbidity and healing time [78].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Care of the patient with burn injury".)

SUMMARY AND RECOMMENDATIONS

●Most large total body surface area (TBSA) deep burn injuries (full thickness, deep partial thickness) will require admission to a burn intensive care unit. Such burn injuries are associated with large fluid resuscitation expectations, which can lead to airway compromise and the need for intubation. (See 'Introduction' above and 'Initial care' above.)

●While cleansing, debridement, and topical wound care is generally sufficient for healing of superficial burns (epidermal [superficial], superficial partial thickness), deep burns (deep partial thickness, full thickness, or deeper) require surgery. Deep burn wounds are considered closed when autografts have been placed and healed, which requires an appropriately prepared wound bed. (See 'Early burn excision' above and 'Burn wound closure' above.)

●For deep burn injuries, we suggest early excision (within three days from injury), which removes ischemic, necrotic, and potentially infected tissue, rather than awaiting eschar separation (Grade 2C). Early burn wound excision may reduce mortality, and it shortens hospital stay. However, hemodynamic and resuscitative parameters must be under control to tolerate an often large blood loss. (See 'Efficacy' above and 'Timing' above.)

●Using tourniquets and topical hemostatic agents during tangential excision of burn wounds can help reduce blood loss and the need for transfusion. An alternative surgical debridement method is fascial excision, which has the advantage of less blood loss, but increased morbidity related to excision of subcutaneous tissue and accompanying lymphatics. (See 'Techniques' above and 'Hemostasis' above.)

●We suggest definitive burn wound coverage (autografting) at the time of burn wound excision, if possible (Grade 2C). Burn wound closure (ie, autografts have been placed and have healed) within the first five days is optimal, but this is often difficult to achieve in patients with extensive burns, or with concurrent traumatic injuries. Excised deep burn wounds that are not immediately grafted can be covered with allografts or other skin substitutes. Early wound closure is associated with decreased severity of hypertrophic scarring, joint contractures, and stiffness, and promotes faster rehabilitation. (See 'Burn wound closure' above.)

●Large TBSA burns limit the availability of non-burned skin that can be harvested for immediate coverage. Strategies to manage large TBSA burns include (see 'Managing large burn wounds' above):

•Meshing split-thickness skin grafts

•Using the Meek technique

•Reharvesting donor sites

•Using allografts as temporary coverage, until donor sites are ready for reharvesting

•Using cultured skin alternatives (eg, cultured epithelial autografts, cultured skin substitutes)

●Immobilization of the grafted sites is important to prevent shearing of the grafts they adhere to. Negative pressure wound therapy can be used to help keep the graft in place while potentially allowing for earlier or more liberal mobilization. (See 'Graft dressings' above.)

●Complications of burn wound care include ischemia from inadequate escharotomy, burn wound infection and sepsis, graft failure, and conversion of split-thickness donor sites to full thickness injuries. The rate of graft failure for split-thickness grafts in burn injury is approximately 5 percent. (See 'Escharotomy' above and 'Complications' above.)