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:
- Degree: depth of burn on body
- Severity: % of TBSA burned
Thermal burn degree
Degree of burn | Characteristics | Symptoms | Healing |
---|---|---|---|
Superficial burn (1st degree) |
| Itching to pain |
|
Superficial partial burns (2nd degree) |
| Severe pain |
|
Deep superficial burns (2nd degree) |
| Severe pain | Partial recovery with scar formation |
Full-thickness burns (3rd degree) |
| Painless because nerve endings have been destroyed |
|
Full-thickness/eschar burns (4th degree) |
| Painless |
|
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.
Rule of 9s in adolescents and adults used to determine the TBSA of burn
Image by Lecturio.Rule of 9s in children used to determine the TBSA of burn
Image by Lecturio.
Infants’ and children’s heads and legs account for a larger and smaller proportion of TBSA, respectively, when compared with adults. As infants and children grow, the percent represented by these areas changes to more closely resemble adults.
Area A represents 8.5% TBSA in a 1-year-old, 6.5% in a 5-year-old, 5.5% in a 10-year-old, and 4.5% in a 15-year-old.
Area B represents 3.25% TBSA in a 1-year-old, 4.0% in a 5-year-old, 4.5% in a 10-year-old, and 4.5% in a 15-year-old.
Area C represents 2.5% TBSA in a 1-year-old, 2.75% in a 5-year-old, 3.0% in a 10-year-old, and 3.25% in a 15-year-old.
Mild | Moderate | Severe | |
---|---|---|---|
Children | < 5% TBSA | 5%–10% TBSA | > 10% TBSA |
Adult | < 10% TBSA | 10%–20% TBSA | > 20% TBSA |
Elderly | < 5% TBSA | 5%–10% TBSA | > 10% TBSA |
All | < 2% full thickness | 2%–5% full thickness, high voltage, inhalation, circumferential, comorbid disease | > 5% full thickness, high voltage, inhalation, circumferential, comorbid disease |
Disposition | Outpatient | Admission | Burn unit |
Superficial burn
Image: “Sunburn Skin Red Flushed Dermatology Burned” by Hans Braxmeier. License: Public domain.Superficial partial-thickness facial burns caused by the rapid passage of a fireball following a petrol explosion in a confined space
Image: “Burn injury and explosions: an Australian perspective” by Greenwood JE. License: CC BY 2.0.Deep partial-thickness burn
Image: “Major-2nd-degree-burn” by Westchaser. License: Public domain.Full-thickness burns
Image: “Burn injury and explosions: an Australian perspective” by Greenwood JE. License: CC BY 2.0.
Related videos
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:
- Zone of coagulation and necrosis:
- Innermost zone
- Irreversible cell death and damage
- Zone of ischemia:
- Decreased circulation
- Tissue may progress to necrosis.
- 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)
- Signs of inhalational injury:
- 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
- Thermic:
- 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
- Damage to tissue caused by:
- 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
- Remove chemical:
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
- 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.
- Lee RC, Zhang D, & Hannig J. (2000). Biophysical injury mechanisms in electrical shock trauma. Annu Rev Biomed Eng.
- Brent J. (2013). Water-based solutions are the best decontaminating fluids for dermal corrosive exposures: a mini review. Clin Toxicol (Phila).
- 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.
- 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.