Burn wound depth assessment & classification

Accurate classification of burn depth is essential to determine the healing potential and the need for surgical treatment. Accurate classification may be difficult as most burns are not uniform; they comprise deep and superficial components. Furthermore, burns are dynamic and can develop into deeper wounds. Some burns may require several days to develop before a final assessment can be performed.

The depth of the burn can only be estimated. Only by means of Laser Doppler Imaging (LDI), 48 hours after burning, a more precise measurement of the depth is possible.

However, this method is only available in specialized burn centers. In general practice, the medical history and physical examination are the cornerstone of the classification of burn wound depth.

In addition to the primary and secondary survey, it is important to carry out a full assessment of the burn wound to determine its extent and depth.

Classify the depth of the burn wound

You need to know the depth of the burn wound in order to determine its potential to heal and plan any surgical treatment.

It may be difficult to classify burn depth accurately, as most burns are not uniform; they comprise deep and superficial components. Burns are also dynamic and can develop into deeper wounds. Some burns may require several days to develop before a final assessment can be performed.

During the secondary survey, you can only estimate the depth of the burn by taking a medical history and performing a physical examination. A more precise measurement is possible 48 hours after burning, using Laser Doppler Imaging (LDI). However, this method is only available in specialized burn centers.

Take a medical history

The burn-specific history can indicate the depth of the burn before you examine the wound.

  1. Etiology – the agent that caused the burn, such as hot fat or a gas explosion.
  2. Intensity – the temperature, viscosity or concentration of the agent.
  3. Quantity – a larger volume (pot of tea) can cause a deeper burn than a smaller volume (cup of tea) of the same agent.
  4. Duration – in contact burns and chemical burns, long exposure may cause a deep burn even if the temperature or concentration is low.
  5. First aid – was sufficient cooling applied after a thermal burn, or was the wound rinsed after a chemical burn?
Layers of the skin. Epidermis, dermis and subcutis

Assess the depth, appearance and healing of the burn wound

Assess the depth, appearance and healing of the burn wound. The depth of the wound affects the appearance and expected healing time.

DepthAppearanceHealing
Superficial 1
First degree burn 2
Epidermal burn 3
Red and dry
No blisters
Positive capillary refill
Supple
Painful
Within a few days
(5-10 days)
Superficial partial thickness
Second degree burn – superficial
Dermal burn – superficial (IIA)
Pink/red shiny
Moist
Blisters
Positive capillary refill
Supple
Very painful
Within one to two weeks
(<14 days)
Deep dermal partial thickness
Second degree burn - deep
Dermal burn – deep (IIB)
Mottled pink/red with white spots
Ruptured blisters
Capillary refill present but delayed or absent in some parts
Supple to stiff
Pain moderate to absent
Healing from islands of epithelium and border of the wound takes over two weeks
(14-17 days)
Full thickness
Third degree burn
Dermal burn - deep
White/yellow/brown/black/red
Dull surface
No blisters or blisters attached to the wound
Capillary refill negative
Leathery
Pain absent
No spontaneous healing
Full thickness with involvement of underlying tissues
Fourth degree burn
Subdermal burn
Comparable to aspects of full thickness burn
After debridement: exposed subcutis, muscles or bone tissue
No spontaneous healing
1 The classification by Shakespeare is applied
2 Classification in degrees
3 Classification of Derganc

Fourth degree burns

Burns can be even deeper than full thickness depth. In burn wound classification the term fourth degree burn is often used. The tissues below the skin such as fascia, muscle and bones can be affected.

Physical examination of the burn wound

Do a physical examination to reveal more important information to determine the depth of the burn injury. Remove all clothes to reveal hidden burns.

Assess these five points during examination:

  1. Color and aspect of the burn – A moist, pink surface indicates a superficial burn wound. If the surface is dry and dull or mottled, the burn is estimated to be deep dermal partial thickness to full thickness.
  2. Blisters – Blisters can be filled with fluid, lie loosely on the burn, or even be firmly attached to the wound. Blisters may be absent after removal of clothing or cooling with water.
  3. Capillary refill – Investigate the whole surface area of the burn. Always wear disposable gloves. An absent capillary refill indicates a deep burn. Remember that the wound is heterogeneous and can have various superficial and deep areas. In general, the central part of the burn wound is the deepest.
  4. Suppleness – The suppleness of the wound may vary from supple, like normal skin, to stiff, like leather. Note that edema can alter the suppleness.
  5. Pain – Pain level may vary from severe, in superficial burns, to almost absent, in deep burn wounds. Remember that deep burn wounds always have a border of a superficial burn wound.

Be aware of the following points

The initial diagnosis of the depth of the burn can be inaccurate. Always check again yourself.

An epidermal burn is not a wound, but an inflammation reaction of the skin.

Erythema observed during first examination may alter to blister formation. When this is present, the diagnosis must be changed from an epidermal burn to a superficial dermal burn.

In chemical burns, physical examination will fail you. These burns are very unpredictable.

If a deep dermal partial thickness burn wound is not healed after three to four weeks, the diagnosis must be altered to a full thickness burn. At this point, surgery is often required.

Estimate the extent of the burn injury (TBSA)

General principles

It is essential to estimate the extent of a burn wound accurately in order to guide therapy and to determine whether transfer to a burn center is necessary.

Epidermal burn wounds (i.e. erythema only) are not included in the assessment of TBSA burned. Be aware that the percentage of TBSA in small burn wounds may easily be overestimated and the percentage of TBSA of large burns easily underestimated.

TBSA = Total Body Surface Area

Palm method

Use the palm method for burn wounds with an assumed TBSA of <10%. Make sure the palm of the patient is used as a reference, not the palm of the clinician. The entire palmar surface of the patient’s hand including the closed fingers is 1% TBSA in both adults and children.

Palm method to determine TBSA

Use the palm method for burn wounds with an assumed TBSA of <10%. Make sure the palm of the patient is used as a reference, not the palm of the clinician. The entire palmar surface of the patient’s hand including the closed fingers is 1% TBSA in both adults and children.

Rule of Nines

Use the rule of nines for burn wounds with an assumed TBSA of >10%. Make sure the rule of nines is adjusted to the age of the patient.

Age of patientHead %TBSAEach arm %TBSAEach leg %TBSAAnterior trunk %TBSAPosterior trunk %TBSA
0-1 years18914  
1-10 yearsSubtract 1% per year above age 19Add 0.5% per year above age 1  
Adult99181818

Lund & Browder

The Lund and Browder chart can be used to estimate an assumed TBSA of >10%. This method is more accurate and more detailed than the rule of nines, but it requires an advanced clinician. Make sure the Lund and Browder chart is adjusted to the age of the patient.

Area0 years151015adult
A ½ of head9.58.56.5 5.5 4.53.5
B ½ of one thigh2.753.254 4.25 4.54.25
C ½ of one leg2.52.52.7533.253.5

Burn wound depth assessment & classification

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