What is the classification of burns based on depth and extent of injury?

Classification of Burns

Burns are classified by depth into superficial (first-degree), superficial partial-thickness (second-degree superficial), deep partial-thickness (second-degree deep), and full-thickness (third-degree) injuries, with extent measured by total body surface area (TBSA) using the Lund and Browder chart. 1, 2

Classification by Depth

Superficial Burns (First-Degree)

• Involve only the epidermis with intact skin appendages 3
• Present with erythema, pain, and no blistering 3
• Heal spontaneously within days without scarring 3
• Require only simple first-aid measures and over-the-counter analgesics 3

Superficial Partial-Thickness Burns (Second-Degree Superficial)

• Extend into the superficial dermis while preserving most skin appendages 3, 4
• Characterized by blistering, intense pain, and moist, pink appearance 3
• Heal within 2-3 weeks with minimal scarring if properly managed 3
• Require advanced wound dressings to maintain moist environment 3

Deep Partial-Thickness Burns (Second-Degree Deep)

• Destroy epidermis and deeper dermal structures including most skin appendages 5, 3
• Appear white or mottled, with decreased sensation and blanched appearance 2
• Require immediate referral to burn specialist for possible early tangential excision 3
• Cannot heal without severe scarring due to destruction of regenerative elements 5

Full-Thickness Burns (Third-Degree)

• Involve complete destruction of epidermis and entire dermis 3, 4
• Present as leathery, white, brown, or charred tissue with no sensation 3
• Mandate automatic referral to burn center regardless of size 3
• Require surgical excision and skin grafting for closure 5

Classification by Extent (TBSA)

Measurement Method

• Use the standardized Lund and Browder chart for both adults and children, as it accounts for age-related body proportion differences 1, 2
• The "rule of nines" is less accurate and should be avoided to prevent inappropriate fluid resuscitation 2

Severity Criteria in Adults

Major burns requiring burn center referral include: 1, 2

• TBSA > 20% (any depth)
• Deep burns > 5% TBSA
• Smoke inhalation injury
• Deep burns in function-sensitive areas (face, hands, feet, perineum) regardless of size
• High-voltage electrical burns

Moderate burns requiring burn center evaluation include: 1

• TBSA 10-20% with age > 75 years
• Deep burns 3-5% TBSA
• Superficial burns in function-sensitive areas
• Low-voltage electrical or chemical burns (e.g., hydrofluoric acid)
• Severe comorbidities with any significant burn

Severity Criteria in Children

All pediatric burns requiring burn center referral include: 1, 2

• TBSA > 10% (any depth)
• Deep burns > 5% TBSA
• Age < 1 year with any burn
• Smoke inhalation injury
• Deep burns in function-sensitive areas (face, hands, feet, perineum, flexure lines)
• Any circular burns
• Any electrical or chemical burn

Critical Location-Based Classification

Function-Sensitive Areas

Burns in these locations automatically elevate severity regardless of TBSA: 1, 2, 6

• Face: Risk of airway compromise, cosmetic disability, requires specialized burn center care 6
• Hands: Risk of permanent functional disability, requires immediate specialist referral 2
• Feet: Ambulation concerns, requires specialist evaluation 1
• Perineum: High infection risk, requires burn center management 1
• Flexure lines/skin folds: Risk of contractures in children 1

Circular Burns

• Deep circular burns create compartment syndrome risk requiring urgent escharotomy within 48 hours 1
• Thoracic circular burns compromise ventilation and cardiac output 1
• Limb circular burns cause acute ischemia with downstream necrosis 1
• Escharotomy should only be performed at burn centers except when immediate transfer is impossible 1

Common Pitfalls to Avoid

• Never delay specialist referral for partial-thickness or full-thickness burns in function-sensitive areas, as this leads to permanent functional impairment and increased mortality 2, 6
• Do not use the "rule of nines" for TBSA estimation, as it leads to inaccurate fluid resuscitation 2
• Recognize that children have four times higher burn incidence than adults and require lower TBSA thresholds for burn center referral 1
• Direct admission to burn centers improves survival compared to sequential transfers through non-specialized facilities 1, 2, 7