Burn Injuries

Introduction

Burn injuries can result from a variety of sources, each producing different clinical presentations and physiological effects. The severity depends on multiple factors including the cause, depth, duration of exposure, and extent of injury. Pediatric patients under 5 years old and older adults are at significantly higher risk of mortality.

Patient age, preexisting medical conditions, use of protective equipment, and skin thickness all influence burn severity. In many cases, it can be difficult to fully determine the exact mechanism, exposure time, and force involved.

Airway compromise, hypoxia, and respiratory distress are common risks, especially in enclosed-space fires where toxic gases can accumulate. Certain burn patterns—particularly scalds or contact burns in children, elderly individuals, or those with disabilities—may raise concern for possible abuse. Irregular injury patterns or burns involving the genital, thigh, or buttock regions should prompt further investigation.

Anatomy and Physiology of the Skin

The skin plays a critical role in maintaining homeostasis by regulating temperature, preventing fluid loss, and providing sensory feedback. It also serves as a barrier against environmental threats such as heat, ultraviolet radiation, mechanical injury, chemicals, and pathogens.

Skin Layers

Epidermis
The outermost layer of skin acts as the primary protective barrier against microorganisms, dehydration, and physical injury. It contains layers of continuously regenerating cells along with melanocytes, which produce pigment that provides varying levels of UV protection.

Dermis
Located beneath the epidermis, the dermis is a strong and elastic layer composed of connective tissue, collagen, and elastin. It contains blood vessels, nerve endings, sweat glands, hair follicles, and sebaceous glands.

Subcutaneous Layer
The deepest layer consists mainly of adipose tissue, which provides insulation, cushioning, and energy storage.

Types of Burns

Thermal Burns

Thermal injuries occur when skin is exposed to temperatures generally above 111°F or when heat transfer overwhelms the body’s ability to dissipate energy.

Severity depends on temperature, exposure time, and heat intensity—the higher the heat and longer the exposure, the deeper the injury.

• Flame burns often produce deep tissue injury and may be associated with inhalation damage.
• Scald burns from hot liquids are commonly seen in children and vulnerable adults and can affect large surface areas, especially when clothing traps heat. Oils and grease may cause deeper injury due to prolonged adherence.
• Contact burns occur from direct contact with hot surfaces and are often limited in depth due to reflex withdrawal.
• Steam burns may appear minor externally but are frequently associated with airway involvement.
• Flash burns result from brief exposure to intense heat and vary widely in severity depending on energy source.

Chemical Burns

The extent of injury depends on the chemical type, concentration, temperature, exposure duration, and tissue penetration depth.

• Acids typically cause coagulation necrosis, limiting deeper tissue spread.
• Alkalis/bases tend to penetrate deeper and cause liquefactive necrosis with more extensive damage.
• Oxidizers generate heat during reaction and may cause systemic toxicity.
• Phosphorus compounds may ignite on contact with air and produce systemic poisoning.
• Vesicants cause blistering and may lead to airway injury if inhaled.

Inhalation Injuries and Toxic Exposure

Burn patients exposed to smoke or chemicals may develop rapid airway compromise.

Symptoms include coughing, wheezing, hoarseness, stridor, and upper airway swelling. Hot gases and particulates may damage both upper and lower airways.

Smoke inhalation effects:

• Thermal injury
• Hypoxia
• Systemic toxicity
• Airway inflammation

Carbon monoxide poisoning:

Carbon monoxide displaces oxygen from hemoglobin and binds with high affinity (over 200 times stronger than oxygen). Even small exposures can significantly impair oxygen delivery.

Pulse oximetry may appear falsely normal in CO poisoning. Specialized CO-oximetry devices are required for accurate detection.

Severe exposure (around 50% CO levels) can be fatal.

Indicators of Airway Injury

• Hoarseness or voice changes
• Facial or nasal hair singeing
• Facial burns
• Carbonaceous sputum
• Confined-space fire exposure
• Rapidly developing airway edema

Chemical Inhalation Effects

The solubility of a chemical determines symptom onset:

• Highly soluble agents cause immediate airway irritation and swelling
• Moderately soluble agents produce delayed but progressive symptoms
• Poorly soluble agents may cause deep lung injury and delayed pulmonary edema

Electrical Injuries

Electrical burns often produce significant internal injury with minimal external signs.

Severity depends on current strength, tissue resistance, and exposure time. Entry and exit wounds may be present, though the exit wound is often more extensive.

Electric current typically follows pathways such as nerves, blood vessels, and muscles, resulting in deep tissue destruction.

Types of electrical injury:

• True electrical injury: entry/exit burns with internal tissue damage
• Arc flash injury: high-temperature electrical arc causing thermal burns
• Flame injury: clothing or environment ignited by electricity

Electrical injuries can cause cardiac arrhythmias, respiratory arrest, neurological dysfunction, seizures, and muscle paralysis.

Lightning Injuries

Lightning strikes involve extremely high energy delivered over milliseconds and can mimic blast injuries.

Immediate effects may include cardiac and respiratory arrest. The heart may spontaneously restart, but respiratory failure can still occur without intervention.

Prevention includes avoiding open areas, tall conductive objects, and seeking shelter in fully enclosed structures during storms.

Radiation Burns

Radiation injuries may occur in industrial, medical, or accidental exposure settings.

• Alpha radiation is blocked by skin
• Beta radiation can penetrate superficial skin layers
• Gamma radiation penetrates deeply through tissue and materials

Symptoms may develop hours to days after exposure. Acute radiation syndrome can affect the GI, neurological, and hematologic systems.

Severe early vomiting indicates high exposure and worse prognosis.

Burn Classification

Zones of Injury

• Zone of coagulation: central irreversible tissue damage
• Zone of stasis: at risk for progression to necrosis
• Zone of hyperemia: outer area likely to recover

Burn Depth

First-degree burns

• Epidermis only
• Red, dry, painful, no blistering
• Heals within days

Second-degree burns (partial thickness)

• Epidermis + part of dermis
• Blistering, pain, and blanching present
• May heal with scarring

Third-degree burns (full thickness)

• Complete destruction of epidermis and dermis
• Skin may appear leathery, charred, or waxy
• No sensation in central area due to nerve destruction

Circumferential Burns

These burns encircle limbs or torso and may restrict circulation or breathing due to swelling. They are considered high risk and require urgent transport.

Burn Severity Classification (Adults)

Severe burns include:

• 10% TBSA full-thickness
• 30% TBSA partial-thickness
• Burns to face, hands, feet, airway, or genitals
• Electrical or chemical burns
• Inhalation injuries
• Significant trauma or comorbidities
• Age extremes (<5 or >55)

Moderate burns: intermediate TBSA involvement without high-risk features
Minor burns: limited surface area involvement and superficial injury

Burn Shock

Burn injury can cause systemic fluid shifts leading to hypovolemia, electrolyte imbalance, and cardiovascular instability.

The body compensates with tachycardia and vasoconstriction, but worsening capillary leakage leads to shock progression. Metabolic and inflammatory mediators further intensify the injury response.

TBSA Estimation (Rule of Nines)

Adults

• Head: 9%
• Each arm: 9%
• Front torso: 18%
• Back torso: 18%
• Each leg: 18%
• Genitalia: 1%

Children/Infants

Head proportion is larger, while lower extremities are smaller compared to adults.

Prehospital Burn Management

Airway Priority

Burn patients are classified into:

• Immediate airway failure
• Impending airway compromise
• At-risk airway
• No current airway threat

Early airway protection is critical because edema can rapidly obstruct ventilation.

Fluid Resuscitation

Patients with burns >20% TBSA require aggressive fluid replacement due to massive fluid shifts and capillary leakage.

The Parkland formula estimates 24-hour fluid needs:

$4mL\times \text{weight (kg)}\times \mathrm{\%}TBSA$4mL×weight (kg)×%TBSA

• First half given in first 8 hours
• Remaining half over next 16 hours

Over- or under-resuscitation both carry risks, especially in children and elderly patients.

Pain Management

Burn injuries often require significant analgesia due to intense pain and high metabolic demand. Opioids such as morphine or fentanyl are commonly used per protocol.

Burn Center Referral Criteria

Includes:

• Significant partial or full-thickness burns
• Burns involving critical anatomical areas
• Electrical or chemical burns
• Inhalation injury
• Complex comorbid conditions
• Pediatric or elderly high-risk patients

Specific Burn Care

• Thermal burns: cover with appropriate dressings; prevent heat loss
• Superficial burns: cool water application; avoid ice or ointments
• Partial-thickness burns: cooling, elevation, blister protection
• Full-thickness burns: dry sterile dressings and rapid transport

Chemical and Special Burn Care

• Immediate decontamination is essential
• Remove contaminated clothing
• Irrigate thoroughly with water
• Maintain warmth after decontamination
• Brush off dry chemicals before irrigation when applicable

Electrical and Radiation Management

• Treat life-threatening conditions first
• Monitor for arrhythmias and neurological injury
• Avoid spinal movement when indicated
• Decontaminate radiation exposure appropriately and prevent secondary contamination

Burn Recovery Phases

• Acute resuscitation (0–72 hrs): airway, fluids, stabilization
• Early wound care (1–7 days): debridement and closure planning
• Definitive closure (1–6 weeks): grafting and wound coverage
• Rehabilitation phase: mobility, function, and reintegration