USMLE Guide: Burns

Introduction

Burns are common injuries encountered in clinical practice, and it is crucial for medical professionals to have a solid understanding of their assessment, classification, and management. This USMLE guide aims to provide a comprehensive overview of burns, including their pathophysiology, classification, initial management, and potential complications.

Pathophysiology

Burns result from the exposure of the skin or other tissues to thermal, chemical, electrical, or radiation sources. Understanding the pathophysiology of burns is essential to assess their severity accurately and guide appropriate management.

• Thermal burns: caused by contact with hot objects, flames, scalding liquids, or steam.
• Chemical burns: result from exposure to corrosive substances such as acids, alkalis, or strong irritants.
• Electrical burns: occur when electrical current passes through the body, causing deep tissue injury.
• Radiation burns: caused by exposure to ionizing radiation, such as in radiation therapy.

Classification

Burns are classified based on their depth and extent, which directly influence prognosis and management decisions.

1. Superficial burns (1st degree):

   • Involves the epidermis only.
   • Presents with erythema, pain, and mild edema.
   • Examples include sunburns and mild scalds.
   • Heal within 3-7 days without scarring.

2. Superficial partial-thickness burns (2nd degree):

   • Involves the epidermis and superficial dermis.
   • Presents with erythema, blistering, pain, and moderate edema.
   • Examples include scalds and flash burns.
   • Heal within 1-3 weeks and may cause minimal scarring.

3. Deep partial-thickness burns (2nd degree):

   • Involves the epidermis and deep dermis.
   • Presents with erythema, blistering, pain, moderate edema, and mottled appearance.
   • Examples include scalds, flames, and contact burns.
   • Healing takes more than 3 weeks and usually causes hypertrophic scarring.

4. Full-thickness burns (3rd degree):

   • Involves the entire dermis and potentially underlying structures.
   • Presents with leathery eschar, pale or black appearance, numbness (due to nerve damage).
   • Examples include flames and high-voltage electrical burns.
   • Require surgical intervention (excision and grafting) for healing.

Initial Management

Prompt and appropriate management of burns is crucial for optimizing outcomes. The initial management steps include:

1. Ensure scene safety: Remove the patient from the source of the burn and extinguish flames if present. Take precautions for chemical or electrical burns.

2. Primary survey: Assess and stabilize the patient's airway, breathing, and circulation (ABCs). Administer supplemental oxygen if necessary.

3. Stop the burning process: Remove smoldering clothes, jewelry, or any source of ongoing heat.

4. Assess burn depth and extent: Perform a thorough physical examination to determine the classification and severity of the burn. Consider the "rule of nines" or Lund-Browder chart to estimate the total body surface area (TBSA) involved.

5. Fluid resuscitation: Calculate the Parkland formula (4 mL × body weight in kg × %TBSA burned) to estimate fluid requirements for the first 24 hours. Administer crystalloid solutions (e.g., lactated Ringer's) following fluid resuscitation protocols.

6. Wound care: Cleanse the burn wound with mild soap and water or sterile saline. Apply sterile dressings to minimize infection risk and fluid loss.

7. Tetanus prophylaxis: Administer tetanus toxoid if the patient has an incomplete or uncertain vaccination history.

Complications

Burns can lead to various complications, including:

• Infection: Monitor for signs of wound infection (e.g., increasing pain, erythema, pus). Administer prophylactic antibiotics if necessary.
• Inhalation injury: Suspect inhalation injury in patients with burns involving the face, singed nasal hair, hoarseness, carbonaceous sputum, or respiratory distress. Consider intubation and early transfer to a burn center.
• Compartment syndrome: Vigilantly monitor for signs of compartment syndrome, especially in circumferential burns. Prompt escharotomy or fasciotomy may be necessary.
• Hypertrophic scarring and contractures: Aggressively manage wounds to minimize scarring. Physical therapy and splinting may be required to prevent contractures.
• Long-term psychological effects: Burns can have significant psychological impacts. Provide emotional support and consider referral to mental health professionals when needed.

Conclusion

Understanding the pathophysiology, classification, initial management, and potential complications of burns is essential for medical professionals. By familiarizing yourself with this