Burns

A burn is a type of injury to the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of 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:

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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 Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of 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 burn Characteristics Symptoms Healing
Superficial burn (1st degree)
  • Limited to epidermis
  • No destruction of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin
  • Hyperemia (red), blanches with pressure
  • Edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
Itching to pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
  • Unscarred
  • Spontaneous recovery
Superficial partial burns (2nd degree)
  • Limited to epidermis
  • Hyperemia
  • Wet wound bed
  • Intact sensibility
  • Blistering
Severe pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
  • Usually unscarred
  • Spontaneous recovery
Deep superficial burns (2nd degree)
  • Epidermis and dermis damaged
  • Dry wound bed
  • Bright and reddened areas
Severe pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain Partial recovery with scar formation
Full-thickness burns (3rd degree)
  • Damage to all skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin layers, including superficial fascia
  • Grey-white discoloration of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the 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 Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. 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
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

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 Cell death Injurious stimuli trigger the process of cellular adaptation, whereby cells respond to withstand the harmful changes in their environment. Overwhelmed adaptive mechanisms lead to cell injury. Mild stimuli produce reversible injury. If the stimulus is severe or persistent, injury becomes irreversible. Apoptosis is programmed cell death, a mechanism with both physiologic and pathologic effects. Cell Injury and 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 Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure 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 Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation, blistering, or carbon deposits, carbonaceous sputum)
      • Carboxyhemoglobin level > 10%
      • Singed nasal hair
    • Hypoxemia despite 100% O2 
    • Respiratory distress/failure 
    • Depressed Glasgow coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. 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 Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. 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 Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain.

Partial-thickness burn management:

  • Clean and dress
  • Topical antibiotics
  • Pain medication (NSAIDs, acetaminophen Acetaminophen Acetaminophen is an over-the-counter nonopioid analgesic and antipyretic medication and the most commonly used analgesic worldwide. Despite the widespread use of acetaminophen, its mechanism of action is not entirely understood. Acetaminophen)

Full-thickness burn management:

  • Antibiotics
  • Aggressive IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids
  • Outcomes best in certified burn centers

Potential complications

  • Carbon monoxide poisoning Carbon monoxide poisoning Carbon monoxide (CO) is an odorless, colorless, tasteless, nonirritating gas formed by hydrocarbon combustion (e.g., fires, car exhaust, gas heaters). Carbon monoxide has a higher affinity to hemoglobin than oxygen, forming carboxyhemoglobin (COHb). Increased levels of COHb lead to tissue hypoxia and brain damage. 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 Nervous system The nervous system is a small and complex system that consists of an intricate network of neural cells (or neurons) and even more glial cells (for support and insulation). It is divided according to its anatomical components as well as its functional characteristics. The brain and spinal cord are referred to as the central nervous system, and the branches of nerves from these structures are referred to as the peripheral nervous system. General Structure of the Nervous System (CNS) changes ( coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma, altered mental status, seizure), cardiac ischemia, dysrhythmia.
  • Cyanide poisoning Cyanide Poisoning Hydrogen cyanide is an extremely poisonous, colorless, flammable liquid used in multiple industries and includes rubber, plastic, and household paints. Exposure to cyanide can occur via inhalation, dermal contact, or intestinal ingestion. 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 Sepsis Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. The etiology is mainly bacterial and pneumonia is the most common known source. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Sepsis and Septic Shock:
    • 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 Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension (systolic blood pressure < 90 mm Hg)  
      • Oliguria
      • Unexplained hyperglycemia
      • Thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia
      • Mental status changes
    • Management:
      • Diagnosis requires wound culture and biopsy (to determine tissue invasion depth).  
      • Causative micro-organisms usually gram-negative bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview
      • Treatment involves empiric, broad-spectrum IV antibiotics.
  • Acute respiratory distress syndrome Acute Respiratory Distress Syndrome Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Acute Respiratory Distress Syndrome ( ARDS ARDS Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Acute Respiratory Distress Syndrome):
    • 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 Ventricular fibrillation Ventricular fibrillation (VF or V-fib) is a type of ventricular tachyarrhythmia (> 300/min) often preceded by ventricular tachycardia. In this arrhythmia, the ventricle beats rapidly and sporadically. The ventricular contraction is uncoordinated, leading to a decrease in cardiac output and immediate hemodynamic collapse. Ventricular Fibrillation) and cardiac arrest Cardiac arrest Cardiac arrest is the sudden, complete cessation of cardiac output with hemodynamic collapse. Patients present as pulseless, unresponsive, and apneic. Rhythms associated with cardiac arrest are ventricular fibrillation/tachycardia, asystole, or pulseless electrical activity. Cardiac Arrest
      • Muscle injuries leading to muscle contractions
      • CNS injuries with disturbances of consciousness 
    • Severity depends on: 
      • Voltage: low < 1,000 V versus high > 1,000 V
      • Lightning
      • Duration of exposure
      • Moisture and conductivity of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the 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 Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin grafting.
    • Severe burns on arms, legs, or hands may require aggressive surgical management to remove damaged muscle or even amputation Amputation An amputation is the separation of a portion of the limb or the entire limb from the body, along with the bone. Amputations are generally indicated for conditions that compromise the viability of the limb or promote the spread of a local process that could manifest systemically. 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 Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the 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 Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and 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 Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin.
    • 𝛃 particles penetrate more (> 1 inch or 2.54 cm), usually injuring deeper layers of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin.
    • 𝛄 radiation penetrates further (> 1 foot Foot The foot is the terminal portion of the lower limb, whose primary function is to bear weight and facilitate locomotion. The foot comprises 26 bones, including the tarsal bones, metatarsal bones, and phalanges. The bones of the foot form longitudinal and transverse arches and are supported by various muscles, ligaments, and tendons. 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 Cell death Injurious stimuli trigger the process of cellular adaptation, whereby cells respond to withstand the harmful changes in their environment. Overwhelmed adaptive mechanisms lead to cell injury. Mild stimuli produce reversible injury. If the stimulus is severe or persistent, injury becomes irreversible. Apoptosis is programmed cell death, a mechanism with both physiologic and pathologic effects. Cell Injury and 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.

USMLE™ is a joint program of the Federation of State Medical Boards (FSMB®) and National Board of Medical Examiners (NBME®). MCAT is a registered trademark of the Association of American Medical Colleges (AAMC). NCLEX®, NCLEX-RN®, and NCLEX-PN® are registered trademarks of the National Council of State Boards of Nursing, Inc (NCSBN®). None of the trademark holders are endorsed by nor affiliated with Lecturio.

Study on the Go

Lecturio Medical complements your studies with evidence-based learning strategies, video lectures, quiz questions, and more – all combined in one easy-to-use resource.

Learn even more with Lecturio:

Complement your med school studies with Lecturio’s all-in-one study companion, delivered with evidence-based learning strategies.

User Reviews

0.0

()

¡Hola!

Esta página está disponible en Español.

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

Details