Burn Wound Assessment

Original Editor - Carin Hunter based on the course by Diane Merwarth
Top Contributors - Carin Hunter, Stacy Schiurring and Jess Bell

Burn Wound Terminology

Eschar: Eschar refers to the nonviable layers of skin or tissue indicating deep partial or full thickness injury. It is black, thick and leathery in appearance. This word is not synonymous with the word "scab".

Scab: Dry, crusty residue accumulated on top of a wound, resulting from coagulation of blood, purulent drainage, serum or a combination of all.

Pseudo-Eschar: A thick gelatinous yellow or tan film that forms with silver sulfadiazine cream combining with wound exudate. It can often be mistaken for eschar, but it can be removed with mechanical debridement.

Petechiae: Pinpoint, round spots that appear on the skin as a result of bleeding. The spots can appear red, brown or purple in colour.

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  Eschar formation over burn wound on hand

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  Eschar formation over burn wound on elbow

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  Scab

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  Pseudo-eschar formation over burn wound on hand

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  Pseudo-eschar formation over burn wound bed

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  Petechiae on back of hand

All photos used with kind permission from Diane Merwarth, PT

Classification by Depth

For an overview on wound healing, and the anatomy and physiology of the skin, please read this article.

Type	Layers Involved	Signs and Symptoms	Healing Time	Prognosis and Complications
Superficial (formerly first-degree burn)	Epidermis	Red Dry Pain No blisters	Re-epithelialisation takes 2-5 days	Heals well Repeated sunburns increase the risk of skin cancer later in life
Superficial Partial Thickness (formerly second-degree burn)	Epidermis and extends into the superficial dermis	Redness with a clear blister Blanches with pressure, but shows rapid capillary refill when released Generally moist Very painful Hair attachments are intact Wound bed pink to red	Re-epithelialisation takes 1-2 weeks	Low risk of infection unless patient is compromised No scarring typically Oedema is common
Deep Partial Thickness (formerly deep second-degree burn)	Extends into deep (reticular) dermis	Appears yellow or white. Less blanching than superficial. Sluggish capillary refill indicates vascular damage Hair attachments are intact Pain is often absent at this depth but is variable Blisters are uncommon Often moist and waxy Wound bed shades of red, yellow, white	Re-epithelialisation takes 2-5 weeks. Some require surgical closure	Scarring, contractures (may require excision and skin grafting) Oedema Circumferential burns at risk for compartment syndrome Increased risk of infection due to depth and impaired blood flow
Full Thickness (formerly third-degree burn)	Extends through entire dermis and into the hypodermis	Shades of brown, tan, waxy white, cherry red, sometimes with petechiae Appearance can vary from waxy white, leathery grey or charred black. Skin is dry, lacking in elasticity No blanching Not painful (nerve ending damage is common) Stiff and white/brown Initially painfree Hair attachments absent No blanch response indicates capillary destruction	Prolonged (months) and usually requires surgical interventions to ultimately close	Increased risk of infection due to capillary destruction Eschar, or the dead, denatured skin, is removed Results in scarring and contractures
Subcutaneous (formerly fourth-degree burn)	Destruction of dermis and hypodermis, and into underlying fat, muscle and bone	Charred with eschar Dry No elasticity Initially painfree Hair attachments absent No blanch response indicates capillary destruction	Does not heal on its own Requires surgery and reconstruction	Amputation Significant functional impairment Death

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  Superficial burn wound

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  Superficial partial burn wound

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  Superficial partial burn wound

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  Superficial partial burn wound

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  Deep partial burn wound

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  Deep partial burn wound

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  Resulting scars of a deep partial burn wound

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  Full thickness burn wound

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  Full thickness burn wound

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  Full thickness burn wound

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  Resulting scars of a full thickness burn wound

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  Subcutaneous burn wound with exposed tendon

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  Subcutaneous burn wound

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  Subcutaneous burn wound

All photos used with kind permission from Diane Merwarth, PT

Circumferential burn injury special considerations

A circumferential burn wound is typically found around an extremity or the torso and puts the patient at a significant risk for compartment syndrome. This pattern of burn injury involves deep partial thickness, full thickness, and or subcutaneous burns.

Circumferential burn injury signs and symptoms for potential compartment syndrome:

• Out of proportion pain with any movement distal to the circumferential injury.
• Diminished or lack of a pulse distal to the area of circumferential injury.
• Diminished or lack of capillary refill in the fingers and the toes. However, assessment for compartment syndrome can be limited if the injury prevents assessment of capillary refill due to extremity damage or amputation.
• A red flag sign of developing compartment syndrome is a decrease in temperature of the tissue distal to the area of circumferential injury, especially on an extremity.
• For patients with circumferential burn injuries around the torso: high concern for development of compartment syndrome if they experience difficulty breathing or an increase in difficulty breathing.

Used with kind permission from Diane Merwarth, PT

Used with kind permission from Diane Merwarth, PT

If a patient is experiencing the signs and symptoms of compartment syndrome, the medical team should be immediately alerted for further assessment and intervention. A bedside or surgical escharotomy will be needed to relieve the resulting pressures of compartment syndrome.

Blanch Test

The blanch test is similar to the capillary refill test. It is a bedside exam to assess blood flow to the capillaries of the skin. This can be performed over intact skin or in a wound bed itself.

To perform the test:

1. Gently but firmly compress the tissue to be tested until it turns white.
2. Record the time taken for the area to return to the previous colour.
3. Refill time should take 3 seconds or less. If the refill time is longer, suspect capillary damage. If there is no change in colour with applied pressure, suspect capillary destruction.

The following optional video includes a demonstration of the blanch test.

Jackson's Burn Wound Model

Jackson's Burn Wound Model is a model used to understand the pathophysiology of a burn would. This model divides the wound into three zones.

• Zone of Coagulation: (outlined in purple below) This is the central area of the injury and has experienced the greatest amount of tissue damage. It is often characterised by complete destruction of the capillaries leading to cell death. This is irreversible as there is no capillary refill.

• Zone of Stasis or Zone of Ischaemia: (outlined in green below) This area is adjacent to the zone of coagulation and as the name suggests, it is a zone in which the there is slowing of circulating blood due to the damage. These are areas of deep partial thickness burns, or burns of indeterminate depth. This zone can usually be saved with the correct wound care. Capillaries are often compromised by oedema due to hypovolemia and/or vasoconstrictive mediators responding to injury. It is reversible if capillary flow can be restored.

• Zone of Hyperaemia: (outlined in blue below) This zone is located around the edge of the previous zone and is characterised by superficial and superficial partial thickness burns and has a robust capillary refill. This is an area of increased circulation due to vasodilators, such as histamine, that are released in response to the burn injury. This tissue has a good recovery rate, as long as there are no complications such as severe sepsis or prolonged hypo-perfusion. This area will completely recover without intervention unless complications occur.

Zone of coagulation outlined in purple; zone of stasis in green; zone of hyperaemia in blue

Zone of coagulation outlined in purple; zone of stasis in green; zone of hyperaemia in blue

Burn Wound Conversion

Burn Wound Conversion: True burn wound conversion is a deterioration of the wound due to events unrelated to the initial burn injury. This refers to the worsening of tissue damage in a burn wound which previously was expected to spontaneously heal, but instead it increases in depth to a deeper wound which may require surgical intervention.

Potential Causes: 

• Dessication
• Infection
• Oedema

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  Example of wound prior to desiccation

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  Example of wound after desiccation

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  Example of wound prior to infection

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  Example of wound after infection has set in

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  Example of wound oedema in hand and fingers

All photos used with kind permission from Diane Merwarth, PT

Total Body Surface Area

Total body surface area is an important figure when applying the Parkland Burn Formula. This formula is the most widely used formula to estimate the fluid resuscitation required by a patient with a burn wound upon on hospital admission. It is usually determined within the first 24 hours of admission.

When applying this formula, the first step is to calculate the percentage of body surface area (BSA) damaged. This is most commonly calculated using the "Wallace Rule of Nines". When conducting a paediatric assessment, the Lund-Browder Method is commonly used, as children have a greater percentage surface area of their head and neck compared to an adult. The formula recommends 4 millilitres per kilogram of body weight in adults (3 millilitres per kilogram in children) per percentage burn of total body surface area (%TBSA) of crystalloid solution over the first 24 hours of care.

4 mL/kg/%TBSA (3 mL/kg/%TBSA in children) = total amount of crystalloid fluid during first 24 hours

The latest research indicates that while this method is still in use, the fluid levels should be constantly monitored, while assessing the urine output, to prevent over-resuscitation or under-resuscitation.

Calculation of Percentage Burn of Total Body Surface Area

1. The Rule of Nine
2. Lund-Browder Method
3. Palmer Method

1. The Rule of Nine

Body Part	Percentage for Rule of Nine
Head and Neck	9%
Entire chest	9%
Entire abdomen	9%
Entire back	18%
Lower Extremity	18% each
Upper Extremity	9% each
Groin	1%

2. Lund-Browder Method

3. Palmar Surface Method

The "Rule of Palm" or Palmar Surface Method can be used to estimate body surface area of a burn. This rule indicates that the patient's palm (with the exclusion of the fingers and wrist) is approximately 1% of the patient's body surface area. When a quick estimate is required, the percentage body surface area will be the number of the patient's own palm it would take to cover their injury. It is important to use the patient's palm and not the provider's palm.