Burns

Overview

Definition

Burns are acute traumatic injuries to the skin or underlying tissue caused by exposure to thermal energy, chemicals, electrical discharge, or radiation.

Epidemiology

• Incidence of fire-related injuries worldwide is 1.1 per 100,000:
  • 85,000 emergency department visits/year in the United States
  • Most are minor, only 2% cover > 40% total body surface area (TBSA).
• Cause 34,000 deaths/year: 
  • Fatality directly correlated with % surface area burned
  • ½ of patients with 60%–70% surface area burns die.
• Different etiology based on age:
  • Scalding with hot liquid more common in children
  • Flame burns more common in adults

Etiology

• Heat
• Electric
• Chemical
• Radiation

Classification

Burns are described using 2 identifiers—degree and severity:

1. Degree: depth of burn on body
2. Severity: % of TBSA burned

Thermal burn degree

Burn severity

To determine the severity of the burn, calculate the percentage of TBSA injured:

• A patient’s hand is approximately 1% of TBSA.
• Use the rule of 9s in adolescents and adults.
• Modified rule of 9s applies to patients under 15.

Thermal Burns

Pathophysiology

Burns occur due to direct contact with:

• Flames
• Heated objects
• Steam
• Hot water

Skin has low heat conductivity, so most thermal burns only involve the epidermis.

Injured areas can be subdivided into 3 zones, like a bullseye:

1. Zone of coagulation and necrosis:
   • Innermost zone
   • Irreversible cell death and damage
2. Zone of ischemia:
   • Decreased circulation
   • Tissue may progress to necrosis.
3. Zone of hyperemia:
   • Vasodilation
   • Usually heals without long-term complications

Management

• Airway, breathing, and circulation (ABC) assessment
• Administer high-flow oxygen via non-rebreather mask and keep saturation > 92%.
• Consider early endotracheal intubation with evidence of airway or lung compromise due to fire: 
  • Signs of inhalational injury:
    • Soot around mouth 
    • Stridor (high-pitched inspiratory sound because air is being forced through a very narrow opening)
    • Burns on face (loss of eyebrows, oropharyngeal inflammation, blistering, or carbon deposits, carbonaceous sputum)
    • Carboxyhemoglobin level > 10%
    • Singed nasal hair
  • Hypoxemia despite 100% O₂ 
  • Respiratory distress/failure 
  • Depressed Glasgow coma scale (GCS)
• Fluid resuscitation:
  • Prevention of hypovolemia and tissue hypoperfusion is the major goal.
  • Always establish 2 large-bore intravenous (IV) lines.
  • Calculated using Parkland formula: volume = 4 mL of fluid x body weight (kg) x % TBSA:
    • Example: 70-kg male experiences deep partial-thickness burns to the entire left leg. IV volume = 4 mL x 70 kg x 18 TBSA = 5,040 mL.

Superficial burn management

Superficial burn management consists of non-steroidal anti-inflammatory drugs (NSAIDs) and cold packs for pain.

Partial-thickness burn management:

• Clean and dress
• Topical antibiotics
• Pain medication (NSAIDs, acetaminophen)

Full-thickness burn management:

• Antibiotics
• Aggressive IV fluids
• Outcomes best in certified burn centers

Potential complications

• Carbon monoxide poisoning:
  • Can be seen in patients who have been in fires
  • Causes cellular asphyxia by displacing O₂ from hemoglobin 
  • Signs and symptoms:
    • Elevated carboxyhemoglobin 
    • Oxygen saturation unreliable to rule out CO toxicity, use co-oximeter.
  • Management:
    • 1st-line treatment: 100% O₂ (via mask or endotracheal tube)
    • Consider hyperbaric oxygen if carboxyhemoglobin > 25%, central nervous system (CNS) changes (coma, altered mental status, seizure), cardiac ischemia, dysrhythmia.
• Cyanide poisoning:
  • Lethal complication in some closed-space fires
  • Formed when plastics burn
  • Exposure via inhalation
  • Signs and symptoms: Suspect in any burn patient with lactic acidosis.
  • Management: Treat with sodium thiosulfate, nitrites, and hydroxocobalamin.
• Sepsis:
  • Patients with large-surface-area burns at high risk for severe infection
  • Signs and symptoms:
    • Temperature < 36.5°C (97.7°F) or > 39°C (102.2°F) 
    • Tachycardia, tachypnea 
    • Refractory hypotension (systolic blood pressure < 90 mm Hg)  
    • Oliguria
    • Unexplained hyperglycemia
    • Thrombocytopenia
    • Mental status changes
  • Management:
    • Diagnosis requires wound culture and biopsy (to determine tissue invasion depth).  
    • Causative micro-organisms usually gram-negative bacteria
    • Treatment involves empiric, broad-spectrum IV antibiotics.
• Acute respiratory distress syndrome (ARDS):
  • Diffuse interstitial lung damage
  • Caused by:
    • Direct damage from heat inhalation
    • Large volumes of fluid given to patients with significant burns 
  • Signs and symptoms:
    • Worsening hypoxia
    • Worsening chest X-ray with infiltrates
  • Management:
    • Monitor breathing status.
    • Intubate if necessary.

Other Types of Burns

Electrical burns

• Pathophysiology:
  • Body tissues are poor conductors.
  • Electrical energy converts to thermal energy.
• Symptoms:
  • Thermic:
    • Local burns
    • Skin injuries can occur at entry and exit of current.
  • Electrical:
    • Cardiac arrhythmia (ventricular fibrillation) and cardiac arrest
    • Muscle injuries leading to muscle contractions
    • CNS injuries with disturbances of consciousness 
    • Muscle injuries leading to muscle contractions
  • Severity depends on: 
    • Voltage: low < 1,000 V versus high > 1,000 V
    • Lightning
    • Duration of exposure
    • Moisture and conductivity of skin
• Management:
  • ABC assessment
  • IV access, cardiac monitoring, and measurement of oxygen saturation
  • Minor burns managed by topical antibiotics and dressings.
  • More severe burns may require surgery or skin grafting.
  • Severe burns on arms, legs, or hands may require aggressive surgical management to remove damaged muscle or even amputation.

Chemical burns (acid and alkali)

• Pathophysiology:
  • Damage to tissue caused by:
    • Alteration of pH
    • Direct toxic effects on metabolic processes
  • Amount of damage determined by:
    • Nature of chemical (e.g., acidic versus basic)
    • Concentration
    • Duration of exposure
    • More extreme pH = more severe injury
• Management:
  • Remove chemical: 
    • Rinse skin under running water for 10–20 minutes (exceptions include dry lime, phenols, and elemental metals).
    • In case of chemical contact with eyes, rinse eyes continuously for ＞20 minutes.
  • Consider treating for effects of systemic absorption of chemicals.
  • Chemical burns almost always require hospitalization: 
    • Difficult to remove 100% of chemical
    • Continue to damage tissue slowly

Radiation burns

• Definition: damage caused by ionizing radiation (most common example is sunburn)
• Pathophysiology: Depth and severity of injury is dependent on type of radiation, distance from source, and duration of exposure:
  • 𝝰 particles cannot penetrate far, injuring upper layers of skin.
  • 𝛃 particles penetrate more (> 1 inch or 2.54 cm), usually injuring deeper layers of skin.
  • 𝛄 radiation penetrates further (> 1 foot or 30 cm) causing deeper tissue injury and acute radiation syndrome.
  • Neutron radiation can cause severe tissue damage.
• Extent of cutaneous damage based on dose of radiation:
  • ≥ 3 gray (Gy): hair loss
  • ≥ 6 Gy: erythema
  • > 10 Gy: dry desquamation
  • > 15 Gy: moist desquamation
  • > 20 Gy: cell death
• Management:
  • Decontamination and safeguarding care personnel from radiation 
  • Management of radiation burns mirrors that of thermal burns.