Burns are injuries to the skin and underlying tissues caused by thermal, chemical, electrical, radiation, or mechanical agents. The injury leads to protein denaturation , increased vascular permeability , loss of intravascular fluids, and edema.
Etiology of Burns
- Thermal: Flame, hot liquids, steam
- Chemical: Acids, alkalis, vesicants
- Electrical: Low voltage (<1000V), high voltage (>1000V), lightning
- Mechanical: Friction burns
- Radiation: UV light, ionizing radiation
- Frostbite: Cold-induced tissue injury
Persons at Risk
- Extremes of age: Children <4 years, elderly >50 years
- Impaired protective ability: Alcoholics, diabetics, paraplegics, psychiatric patients, convulsives
- Environmental hazards: Unsafe storage of petrol, paraffin use, smoking in bed, working near electric wires
- Innocent bystanders: Accidental exposure
Skin Anatomy & Function
| Layer | Description & Components | Function |
|---|---|---|
| Epidermis | Outermost layer; stratified epithelium. Contains: | Barrier to microbes, toxins; retains water & electrolytes |
| - Stratum corneum (dead, cornified cells) | Cell renewal via Malpighian layers | |
| - Malpighian layers (germinal basal cells, stratum spinosum & granulosum) | ||
| Dermis | Dense connective tissue with collagen, elastic fibers, blood vessels, nerves | Structural support; blood supply; thermoregulation; sensation |
| Divided into papillary (superficial) and reticular (deeper) dermis | ||
| Subcutaneous tissue | Areolar and adipose tissue, skin appendages, variable thickness | Insulation, cushioning, fat storage |
Functions of the Skin
- Protect against microorganisms
- Shield from UV radiation
- Vitamin D synthesis
- Thermoregulation and water retention
- Cosmetic function & identity (fingerprints)
Pathophysiology of Burns
- Tissue injury → release of vasoactive substances (prostaglandins, histamine, leukotrienes, oxygen radicals) →
- Increased capillary permeability → fluid shifts → edema , hypovolemia , decreased cardiac output → shock
- Compensatory mechanisms: sympathetic stimulation → tachycardia, vasoconstriction → reduced skin, muscle, gut perfusion
- Severe burns: myocardial depression (due to TNF-alpha), hemolysis , acute renal injury (from hypoperfusion or myoglobinuria)
- Pulmonary complications from bronchoconstriction mediated by histamine, serotonin
- Increased evaporative water loss → dehydration and hypothermia
Classification of Burns
1. According to Cause
| Type | Features, Examples & Management |
|---|---|
| Thermal | Flames, hot liquids (>45°C), steam. Most common cause. |
| Chemical | - Acids: Coagulative necrosis; superficial damage; burning stops early; flush with water for 1-2 hours. |
| - Alkalis: Liquefactive necrosis; deep damage; prolonged reaction; flush extensively; do NOT neutralize. | |
| - Extravasation injuries from drugs (cytotoxics, potassium, bismuth) cause tissue necrosis; stop infusion & dress locally. | |
| Electrical | Low (<1000 V), high (>1000 V), very high voltage (lightning). Cause entry/exit wounds, deep tissue damage, arrhythmias, rhabdomyolysis → myoglobinuria → renal failure. |
| Frostbite | Cold-induced tissue freezing injury. |
| Mechanical | Friction burns from skin scraping against rough surfaces. |
| Radiation | UV light, ionizing radiation causing cellular damage. |
2. According to Depth
| Degree | Tissue Involved | Appearance | Clinical Features | Healing & Scarring |
|---|---|---|---|---|
| 1st degree | Epidermis only | Red, dry, painful, no blisters | Tender, hypersensitive | Heals in days, no scarring |
| 2nd degree (superficial) | Epidermis + upper 1/3 dermis | Red, moist, blistered | Very painful | Heals in 2-3 weeks, minimal scarring |
| 2nd degree (deep) | Epidermis + deeper dermis (lower 2/3) | Pale, dry, less painful | Reduced sensation | Longer healing, hypertrophic scars possible |
| 3rd degree | Full thickness (epidermis + dermis) | White, leathery, dry, insensate | No pain (nerve destruction) | Requires grafting, scars inevitable |
| 4th degree | Full thickness + underlying tissues (muscle, bone) | Charred, black | No sensation | Amputation often required |
Additional Notes on Specific Types
Chemical Burns
- Acids: Cause coagulation necrosis → limits depth.
- Alkalis: Cause liquefactive necrosis → deeper and more severe damage.
Electrical Burns
- May cause compartment syndrome → may require fasciotomy.
- Fluid resuscitation guided by urine output; monitor for myoglobinuria (dark urine).
- Arrhythmias may occur; ECG monitoring mandatory.
Management Principles
- Stop the burning process : Remove patient from source; remove contaminated clothes.
- Fluid resuscitation : Guided by burn extent and urine output (Parkland formula for thermal burns, adjust for electrical burns).
- Pain control: Analgesics (opioids as needed).
- Wound care: Clean, sterile dressings; debridement when indicated.
- Prevent infection: Topical antimicrobials; tetanus prophylaxis.
- Supportive care: Maintain thermoregulation, nutrition, and monitor for complications.
- Surgical: Skin grafting for deep burns; fasciotomy if compartment syndrome suspected.
