# Burn Wound Management and Surgical Excision

## Introduction
Early excision and grafting of burn wounds has revolutionized burn care, reducing mortality and morbidity. Janzekovic introduced tangential excision in the 1970s, replacing the traditional expectant approach of waiting for eschar separation. Current standard of care: early excision within 24-72 hours for deep partial-thickness and full-thickness burns. Temporary and permanent coverage strategies are essential components of the burn surgeon's armamentarium.

## Burn Wound Assessment

### Depth Assessment Methods
Clinical evaluation: appearance, blanching, sensation, capillary refill (most common). Laser Doppler imaging (LDI): measures dermal blood flow; >95% accuracy for predicting healing potential. Indocyanine green (ICG) angiography: assesses perfusion in real time. Biopsy: gold standard but impractical for routine use.

### Burn Wound Zones (Jackson's Burn Model)

| Zone | Description | Clinical Significance |
|------|-------------|----------------------|
| Coagulation (central) | Irreversible tissue destruction; full necrosis | Non-salvageable; requires excision |
| Stasis (middle) | Compromised perfusion, potentially viable | Goal of resuscitation: salvage this zone |
| Hyperemia (outer) | Inflammatory response, increased blood flow | Usually recovers fully |

### Conversion of Burn Depth
Burn wounds may convert from partial to full thickness over 48-72 hours. Causes: inadequate resuscitation, infection, desiccation, repeated trauma, vasoconstriction. Serial assessment of burn depth is essential in the first 72 hours.

## Topical Antimicrobial Agents

### Silver Sulfadiazine (Silvadene)
Most widely used topical agent historically. Broad-spectrum (gram-positive, gram-negative, Candida). Painless on application. **Disadvantages**: pseudoeschar formation (complicates wound assessment), leukopenia (transient, reversible), may delay epithelialization in superficial partial-thickness burns. Contraindicated in sulfa allergy and near the eyes (causes argyria).

### Mafenide Acetate (Sulfamylon)
Penetrates eschar (unique advantage). Effective against gram-negative organisms including Pseudomonas. Available as cream (11%) or solution (5%). **Disadvantages**: painful on application, carbonic anhydrase inhibitor (metabolic acidosis with prolonged use), allergic rash. Preferred for deep burns, ear burns (prevents chondritis), and burns with suspected infection.

### Silver-Based Dressings
Mepilex Ag, Aquacel Ag, Acticoat (nanocrystalline silver). Sustained silver release; can remain in place for days (reduces dressing changes). Good for superficial to mid-partial-thickness burns. Reduced pain compared to daily silver sulfadiazine changes. Increasingly used as first-line for partial-thickness burns.

### Bacitracin/Polymyxin B
Used for facial burns, superficial burns, skin graft sites. Transparent; allows wound monitoring. Limited spectrum; not suitable for deep burns.

### Honey (Medical-Grade Manuka Honey)
Antimicrobial, anti-inflammatory, promotes moist wound healing. FDA-approved medical-grade preparations available. Emerging evidence supports use in partial-thickness burns.

## Surgical Excision

### Timing
Early excision (within 24-72 hours) for clearly deep burns. Delayed excision (5-7 days) when depth is uncertain (allows demarcation). Massive burns (>40% TBSA): staged excision (20% TBSA per operation to limit blood loss).

### Tangential Excision
Sequential shaving of necrotic tissue with a dermatome (Goulian/Weck knife or powered dermatome). Thin layers removed until viable tissue (punctate bleeding from dermal plexus) is reached. Preserves viable dermis → better aesthetic and functional outcome. **Advantages**: preserves residual dermis, better graft take, superior scar quality.

**Disadvantages**: significant blood loss (can lose 100-200 mL per 1% TBSA excised). Blood loss reduction: tumescent epinephrine injection (1:400,000-1:1,000,000), tourniquet for extremities, topical epinephrine/thrombin soaks.

### Fascial Excision
All tissue excised down to the investing fascia. Used for: very deep full-thickness burns, fourth-degree burns, uncertain viability of subcutaneous fat. **Advantages**: clear viable base, less blood loss than tangential excision, shorter operative time. **Disadvantages**: significant contour deformity, lymphedema, loss of subcutaneous padding, poorer cosmetic result. Reserved for life-threatening massive burns or deep electrical burns.

<image>Surgical illustration comparing tangential excision and fascial excision techniques for burn wound management. The left panel shows tangential excision with a Goulian knife sequentially shaving thin layers of necrotic burn tissue from the wound surface. Three cross-sectional views demonstrate progressive shaving: the first showing the eschar on top, the second showing a deeper layer removed revealing mottled dermis, and the third showing punctate bleeding from the viable dermal plexus indicating adequate excision depth. The right panel shows fascial excision with all skin, subcutaneous fat, and necrotic tissue removed in one pass down to the glistening white investing muscle fascia, shown in cross-section with the resulting contour defect. Labels identify the eschar, dermis, subcutaneous fat, fascia, and muscle layers in both panels, with arrows indicating the excision plane in each technique.</image>

## Wound Coverage Options

### Autograft (Permanent Coverage)
Split-thickness skin graft (STSG): most common; 10-15/1000ths of an inch. Meshed (1:1.5, 1:3, 1:4, 1:6 ratios): expands coverage area. Sheet graft: unmeshed; superior cosmetic result; used for face, hands, neck. Widely meshed grafts (>1:3) require temporary overlay (allograft or synthetic) for protection.

Full-thickness skin graft (FTSG): limited donor sites; used for special areas (eyelids, hands in small burns). Donor sites: thigh (most common), buttock, scalp (children — heals quickly, concealed, can be reharvested), back, abdomen. Donor site healing: 10-14 days for STSG; care with non-adherent dressings, silver-based dressings, or OpSite. Reharvesting: same donor site can be reharvested after 10-14 days (limited by dermis regeneration).

### Allograft (Cadaveric Skin — Temporary Coverage)
Human cadaveric skin, fresh or cryopreserved. Provides temporary wound coverage: dermal template, barrier function, pain reduction. Vascularizes temporarily (7-14 days) before immunologic rejection. Used as: 
Temporary coverage after excision when autograft insufficient. Overlay on widely meshed autografts. Wound bed test (if allograft takes, autograft will likely take). Must eventually be replaced with autograft. Disease transmission risk (screened but not eliminated).

### Xenograft (Porcine Skin — Temporary)
Porcine split-thickness skin. Does not vascularize; provides temporary barrier. Less expensive than allograft. Used for superficial partial-thickness burns as a biological dressing. Changed every 3-5 days until wound heals or autograft is applied.

### Dermal Substitutes

#### Integra (Bilayer Wound Matrix)
Bovine collagen and glycosaminoglycan matrix with silicone outer layer. Applied to excised wound bed. Dermal layer vascularizes over 2-3 weeks; silicone layer then removed and replaced with thin STSG (6-8/1000ths). **Advantages**: creates a neodermis; improves scar quality; reduces scar contracture; expands coverage when donor sites limited. **Disadvantages**: two-stage procedure, infection risk during incorporation phase, cost.

#### MatriDerm
Single-layer bovine collagen with elastin. Applied simultaneously with STSG (one-stage procedure). Improves scar elasticity and quality.

#### AlloDerm (Acellular Dermal Matrix)
Human-derived ADM used as a dermal template. Can be used as an overlay or placed deep to STSG.

### Cultured Epithelial Autografts (CEA)
Patient's keratinocytes harvested (skin biopsy), cultured in laboratory for 2-3 weeks. Produces thin epithelial sheets for massive burn coverage. **Advantages**: virtually unlimited supply from a small biopsy; life-saving in massive burns (>80% TBSA). **Disadvantages**: fragile (no dermal component), expensive, long culture time, poor long-term durability, high failure rate, susceptibility to shear and infection. Best used over a dermal template (Integra or allograft dermis) for improved durability.

### Spray-On Skin (ReCell)
Autologous cell suspension: skin sample processed into single-cell suspension (keratinocytes, melanocytes, fibroblasts). Sprayed onto wound surface. Treats an area up to 80x larger than donor sample. FDA-approved for acute burn wounds. Can be used alone for superficial burns or combined with meshed autograft for deeper wounds.

## Graft Fixation and Postoperative Care
Staples, sutures, or fibrin glue for fixation. Bolster dressings (tie-over or negative pressure) to ensure graft contact with wound bed. Splinting of joints in functional position. Elevation of grafted extremities.

Immobilization for 5-7 days, then gradual mobilization. First graft check at 3-5 days (earlier if concern for hematoma/seroma).

## Causes of Graft Failure
Hematoma or seroma (most common — separates graft from wound bed). Infection. Shear force (movement disrupts neovascularization). Poor wound bed vascularity (avascular tissue, eschar, fat without granulation). Systemic factors: malnutrition, immunosuppression, diabetes.

## Clinical Pearls
Early excision and grafting within 24-72 hours has been shown to reduce mortality, length of stay, and infectious complications compared to delayed excision; this is one of the most evidence-based practices in burn surgery. Tangential excision is preferred over fascial excision whenever possible; the preserved dermal elements improve long-term scar quality and reduce contracture, but blood loss must be anticipated and managed aggressively. Sheet grafts should be used on cosmetically and functionally important areas (face, hands, neck, anterior chest); meshed grafts are acceptable for concealed areas and when donor sites are limited.

Integra is a valuable tool when donor sites are limited (massive burns); it creates a neodermis that significantly improves scar quality but requires a two-stage approach and meticulous wound care to prevent infection during incorporation. The scalp is the best donor site in children: rapid healing (5-7 days), concealed by hair, and can be reharvested multiple times. Always inspect grafts at 3-5 days; accumulated seroma or hematoma beneath sheet grafts should be rolled out or aspirated with a needle to improve graft take.

## References
- Janzekovic Z. A new concept in the early excision and immediate grafting of burns. J Trauma. 1970;10(12):1103-1108.
- Herndon DN, Barrow RE, Rutan RL, et al. A comparison of conservative versus early excision therapies in severely burned patients. Ann Surg. 1989;209(5):547-553.
- Burke JF, Yannas IV, Quinby WC Jr, Bondoc CC, Jung WK. Successful use of a physiologically acceptable artificial skin in the treatment of extensive burn injury. Ann Surg. 1981;194(4):413-428.
- Greenhalgh DG, Cartotto R, Taylor SL, et al. Burn resuscitation practices in North America: results of the Acute Burn ResUscitation (ABRU) Multicenter prospective trial. Ann Surg. 2023;277(3):e512-e519.
- Holmes JH, Molnar JA, Shupp JW, et al. Demonstration of the safety and effectiveness of the RECELL System combined with split-thickness meshed autografts for the reduction of donor skin. Burns. 2019;45(4):772-782.