Burns

A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Management is greatly dependent on the extent of surface area affected and the depth of the burns. Management involves fluid resuscitation, adequate analgesia, and appropriate wound care with the goal of preventing opportunistic infection.

Last update:

Table of Contents

Share this concept:

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on email
Share on whatsapp

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

Table: Degrees of thermal burns
Degree of burnCharacteristicsSymptomsHealing
Superficial burn (1st degree)
  • Limited to epidermis
  • No destruction of skin
  • Hyperemia (red), blanches with pressure
  • Edema
Itching to pain
  • Unscarred
  • Spontaneous recovery
Superficial partial burns (2nd degree)
  • Limited to epidermis
  • Hyperemia
  • Wet wound bed
  • Intact sensibility
  • Blistering
Severe pain
  • Usually unscarred
  • Spontaneous recovery
Deep superficial burns (2nd degree)
  • Epidermis and dermis damaged
  • Dry wound bed
  • Bright and reddened areas
Severe painPartial recovery with scar formation
Full-thickness burns (3rd degree)
  • Damage to all skin layers, including superficial fascia
  • Grey-white discoloration of skin
  • No blisters
Painless because nerve endings have been destroyed
  • Skin regeneration no longer possible
  • Need excision and grafting
Full-thickness/eschar burns (4th degree)
  • Involves muscles, tendons, or bones
  • Leather-like
  • Charring of tissue
Painless
  • Skin regeneration no longer possible
  • Need excision and grafting

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.
Table: Classification of burn severity into mild, moderate, and severe
MildModerateSevere
Children< 5% TBSA5%–10% TBSA> 10% TBSA
Adult< 10% TBSA10%–20% TBSA> 20% TBSA
Elderly< 5% TBSA5%–10% TBSA> 10% TBSA
All< 2% full thickness2%–5% full thickness, high voltage, inhalation, circumferential, comorbid disease> 5% full thickness, high voltage, inhalation, circumferential, comorbid disease
DispositionOutpatientAdmissionBurn unit

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.

References

  1. Orgill DP, Solari MG, Barlow MS, & O’Connor NE. (1998). A finite-element model predicts thermal damage in cutaneous contact burns. J Burn Care Rehabil.
  2. Lee RC, Zhang D, & Hannig J. (2000). Biophysical injury mechanisms in electrical shock trauma. Annu Rev Biomed Eng.
  3. Brent J. (2013). Water-based solutions are the best decontaminating fluids for dermal corrosive exposures: a mini review. Clin Toxicol (Phila).
  4. Barnett GC, West CM, Dunning AM, Elliott RM, Coles CE, Pharoah PD, & Burnet NG. (2009). Normal tissue reactions to radiotherapy: towards tailoring treatment dose by genotype. Nat Rev Cancer.
  5. Coeytaux K, Bey E, Christensen D, Glassman ES, Murdock B, & Doucet C. (2015). Reported radiation overexposure accidents worldwide, 1980-2013: A systematic review. PLoS One.

🍪 Lecturio is using cookies to improve your user experience. By continuing use of our service you agree upon our Data Privacy Statement.

Details