How to Accurately Assess Burn Depth and Calculate TBSA: A Detailed Resource for Medical Students

Introduction

Burn injuries are among the most severe types of trauma, often resulting in significant morbidity and mortality. Accurate assessment of burns is crucial for determining the appropriate treatment and predicting outcomes. This guide will provide a detailed overview of how to assess burns, including the classification of burn depth, the calculation of total body surface area (TBSA) affected, and the identification of potential complications. This content is crafted to enhance your understanding and improve patient care.

1. Understanding Burn Mechanisms

Burns can be caused by various mechanisms, including:

• Thermal Burns: Caused by direct contact with flames, hot liquids, or objects.
• Chemical Burns: Result from exposure to corrosive substances.
• Electrical Burns: Occur when electrical current passes through the body.
• Radiation Burns: Typically caused by prolonged exposure to ultraviolet light or ionizing radiation.

Understanding the mechanism of injury is essential, as it influences the burn's depth and the appropriate treatment approach.

2. Classification of Burn Depth

Burns are classified into different categories based on their depth, which is critical for determining the severity and treatment. The depth of the burn is directly related to the temperature and duration of exposure.

• Superficial Burns (First-Degree): Affect only the epidermis. The skin is red, painful, and dry without blisters. An example is sunburn.
• Partial-Thickness Burns (Second-Degree): Involve the epidermis and part of the dermis. These burns are further divided into superficial and deep partial-thickness burns.
  • Superficial Partial-Thickness Burns: Characterized by redness, blistering, and severe pain. The affected area is typically moist and blanchable.
  • Deep Partial-Thickness Burns: Extend deeper into the dermis, leading to a pale appearance, less blanching, and reduced pain due to nerve damage.
• Full-Thickness Burns (Third-Degree): Extend through the entire dermis and potentially into underlying tissues. The skin may appear white, charred, or leathery. There is no sensation in the burn area due to nerve destruction.
• Fourth-Degree Burns: Involve deeper tissues, including muscles, tendons, and bones. These burns are life-threatening and often require extensive surgical intervention.

3. Assessment of Burn Surface Area (TBSA)

The total body surface area (TBSA) affected by burns is a critical factor in determining fluid resuscitation and overall management. Various methods are used to estimate TBSA:

• The Rule of Nines: This method divides the body into regions, each representing 9% (or a multiple thereof) of the TBSA. For adults, the head and neck are 9%, each arm is 9%, each leg is 18%, the anterior trunk is 18%, the posterior trunk is 18%, and the perineum is 1%.
• Lund and Browder Chart: This chart is more accurate, especially in children, as it accounts for changes in body proportion with age. It provides a detailed breakdown of TBSA percentages for different body parts based on the patient’s age.
• Palmar Method: This method estimates that the palm of the patient's hand (including fingers) represents approximately 1% of TBSA. It is useful for assessing smaller or scattered burns.

4. Initial Assessment and Stabilization

The initial assessment of a burn patient follows the principles of Advanced Trauma Life Support (ATLS). The primary survey includes:

• Airway Management: Assess for inhalation injury, which is a common complication in burn patients, especially with facial burns or exposure to smoke. Signs include hoarseness, stridor, and soot in the oropharynx. Early intubation may be necessary.
• Breathing and Ventilation: Evaluate respiratory function and look for signs of respiratory distress. Consider escharotomy if circumferential chest burns restrict breathing.
• Circulation with Hemorrhage Control: Establish IV access, ideally with large-bore cannulas, and begin fluid resuscitation. Monitor for signs of shock, and initiate the Parkland formula for fluid replacement (4 mL of Lactated Ringer’s solution per kg body weight per percentage TBSA burned).
• Disability (Neurological Status): Assess the patient’s neurological status using the Glasgow Coma Scale (GCS). Burns, especially electrical, may cause neurological deficits.
• Exposure and Environmental Control: Completely expose the patient to assess the full extent of burns while preventing hypothermia. Warm the patient as needed.

5. Detailed Burn Evaluation

After the initial stabilization, a more thorough burn assessment should be conducted:

• Location and Distribution of Burns: Document the precise location of burns on a body map. Pay special attention to critical areas such as the face, hands, feet, genitalia, and major joints, as these may require specialized care.
• Burn Depth Estimation: Determine the depth of each burn using clinical assessment. Palpation can help differentiate between superficial and deeper burns based on texture and capillary refill.
• Inhalation Injury: Evaluate the airway for signs of inhalation injury, such as carbonaceous sputum, facial burns, or singed nasal hairs. Consider bronchoscopy if inhalation injury is suspected.
• Associated Trauma: Look for additional injuries, especially in cases of explosion or falls. Burns can be accompanied by fractures, head injuries, or internal trauma.

6. Complications to Watch For

Burns can lead to numerous complications that require prompt recognition and management:

• Infection: Burn wounds are highly susceptible to infection. Signs include increased pain, redness, swelling, purulent discharge, and systemic signs such as fever.
• Hypovolemic Shock: Large burns can cause significant fluid loss, leading to shock. Early and adequate fluid resuscitation is crucial to prevent this life-threatening complication.
• Compartment Syndrome: This is a potential complication of circumferential burns, especially on the limbs. It occurs when increased pressure within a closed muscle compartment reduces blood flow, leading to ischemia. An escharotomy may be required to relieve pressure.
• Hypermetabolic Response: Severe burns trigger a hypermetabolic state, leading to increased energy expenditure, muscle wasting, and delayed wound healing. Nutritional support and metabolic monitoring are essential.
• Acute Kidney Injury: Fluid shifts, dehydration, and rhabdomyolysis (particularly in electrical burns) can lead to acute kidney injury. Monitor urine output and serum creatinine levels closely.
• Respiratory Complications: Inhalation injury, pulmonary edema, and acute respiratory distress syndrome (ARDS) are potential complications. Mechanical ventilation may be necessary.

7. Special Considerations in Pediatric and Elderly Patients

• Pediatric Patients: Children have thinner skin, making them more susceptible to deeper burns. They also have a larger TBSA relative to body mass, leading to higher fluid requirements. Special attention must be given to fluid resuscitation and monitoring for hypoglycemia.
• Elderly Patients: The elderly are at higher risk of complications due to pre-existing comorbidities, thinner skin, and a reduced ability to withstand stress. Fluid management should be cautious to avoid fluid overload, and care should be taken to prevent hypothermia.

8. Long-Term Management and Rehabilitation

Burn management extends beyond the initial treatment and requires long-term care to address complications and promote recovery:

• Wound Care: Burn wounds require meticulous care to prevent infection and promote healing. This may involve debridement, application of topical antimicrobials, and dressing changes. Skin grafting may be necessary for extensive full-thickness burns.
• Physical Therapy: Early mobilization and physical therapy are essential to prevent contractures and maintain function, especially in burns over joints.
• Psychological Support: Burn injuries can have significant psychological impacts, including post-traumatic stress disorder (PTSD), anxiety, and depression. Psychological support and counseling are important aspects of comprehensive burn care.
• Scar Management: Hypertrophic scars and keloids are common in burn patients. Treatments include pressure garments, silicone gel sheets, and possibly surgical interventions.
• Social and Occupational Reintegration: Long-term rehabilitation includes assisting patients in returning to their normal activities, work, and social interactions. This may involve vocational training and support services.

9. Emerging Technologies and Advances in Burn Care

Recent advancements in burn care are improving outcomes and reducing recovery times:

• Biological Skin Substitutes: Innovations in skin substitutes, such as bioengineered skin and stem cell therapy, offer new possibilities for treating severe burns.
• Telemedicine: The use of telemedicine in burn care allows specialists to provide remote consultations, improving access to expert care in underserved areas.
• Advanced Wound Dressings: Modern wound dressings, such as hydrocolloids, foam dressings, and silver-impregnated dressings, are enhancing wound healing and reducing infection rates.
• Rehabilitation Robotics: Robotic-assisted rehabilitation is emerging as a tool for enhancing physical therapy outcomes in burn patients.

Conclusion

Assessing burns is a complex process that requires a thorough understanding of burn classification, TBSA calculation, initial stabilization, and ongoing management. By following the guidelines outlined in this article, healthcare professionals can provide optimal care to burn patients, improving their chances of recovery and reducing the risk of complications.