1 Burn Classification and Severity

Classify burns by depth

Burn assessment considers depth, extent, and location. Age, associated injuries, medical conditions, and possible inhalation injury can also affect risk. A burn’s appearance may change over time, so an early estimate of depth can be uncertain.

Depth-based classifications

• Superficial burns involve the epidermis only. They are typically dry, red, blanching, and often painful, with no blisters. They are not counted in TBSA.

• Superficial partial-thickness burns involve the epidermis and superficial dermis. They are typically moist, red, blanching, often blistered, and very painful. They are counted in TBSA.

• Deep partial-thickness burns involve the deeper dermis. They are often drier and paler, with reduced blanching and sensation. They are counted in TBSA.

• Full-thickness burns involve the entire skin thickness and may extend into underlying tissue. They may be dry or leathery and appear white, brown, or black; sensation in the burned area may be reduced or absent. They are counted in TBSA.

Traditional degree labels, such as first-degree and third-degree, are still used, but depth-based terms describe the injury more specifically. In particular, “second-degree” does not distinguish superficial from deep partial-thickness injury. A full-thickness area may be painless because sensory nerves are destroyed, while nearby partial-thickness tissue can remain very painful.

When depth is uncertain, document the findings and arrange appropriate clinical assessment rather than assuming the injury is minor.

Estimate the burned body area

Total body surface area (TBSA) is the percentage of the body affected by partial-thickness or full-thickness burns. Exclude superficial burns from the TBSA estimate used for burn assessment.

Estimation methods

• The Adult Rule of Nines provides a rapid estimate using body regions in multiples of $9$. Each arm is about $9\%$, each leg $18\%$, the front torso $18\%$, the back torso $18\%$, and the head and neck $9\%$. The perineum is about $1\%$. The front and back of a region each make up half its total.

• The Lund–Browder chart adjusts body-region proportions for age. It is preferable for children because their body proportions differ from adults and change as they grow.

• The Palmar method uses the patient’s entire hand surface, including the fingers, as approximately $1\%$ TBSA. It is useful for small or scattered burns.

These methods provide estimates. Record the areas involved and the method used. Seek a more careful assessment when the estimate is uncertain or the injury may be serious.

Consider severity and referral

Burn severity is not determined by TBSA alone. Depth, location, and the patient’s overall situation also matter. For example, a smaller deep burn affecting a hand or major joint can be important because of its location and potential effect on function.

The American Burn Association (ABA) recommends immediate burn-center consultation, with consideration for transfer, for thermal burns that are full-thickness, partial-thickness and at least $10\%$ TBSA, or deep partial-thickness or full-thickness burns involving the face, hands, genitalia, feet, perineum, or a joint. It also recommends consultation for potentially deep burns of any size and for partial-thickness burns under $10\%$ TBSA.

These are referral guidelines, not a substitute for clinical judgment or a universal minor, moderate, or severe grading system. A small size alone does not rule out consultation when burn depth and location meet the guidance.

Apply the assessment principles

Apply the classifications and estimation rules to these examples:

• A moist, red, blistered, very painful burn is most consistent with superficial partial-thickness injury and is included in TBSA.

• A dry, leathery, pale area with little sensation is likely full-thickness and is included in TBSA. Clinical assessment is needed if depth is uncertain.

• If a patient has a red, painful sunburn and a separate partial-thickness burn, count the partial-thickness burn in TBSA; exclude the superficial sunburn.

• For a child, use the Lund–Browder chart because it adjusts for age-related differences in body proportions.

• If partial-thickness burns cover the entire front of one adult arm, the estimate is about $4.5\%$ TBSA: one arm is about $9\%$, and its front is half of that.

• A small deep partial-thickness burn over a major joint can still warrant burn-center consultation under ABA guidance.

• “Deep partial-thickness” is more specific than “second-degree” because the traditional degree label does not distinguish superficial from deep partial-thickness injury.