Burn Wound Assessment

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

Important 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

Classification by Depth

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 can extend 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 Often causes damage to the hair follicle and glandular tissue	Appears yellow or white. Less blanching than superficial. Sluggish capillary refill indicates vascular damage Hair attachments are intact Very painful to pressure and uncomfortable 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 can often affect the underlying subcutaneous tissue	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 often 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, contractures and amputation (early excision recommended)
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

The next assessment piece that I wanna talk about is looking at circumferential burn injuries. As I said earlier, any burn wound that is circumferential around an extremity or the torso that involves deep partial thickness, full thickness, or subcutaneous burns, and any combination of those three puts that patient at significant risk for developing a compartment syndrome. Just like with orthopaedic injuries, circumferential burn wounds are assessed pretty much the same way. You're looking at pain with any movement distal to that circumferential injury that is out of proportion for what you would expect with movement in that area. You're checking pulses to make sure they have a pulse distal to that area of circumferential injury. You are assessing the capillary refill in the fingers and the toes if you are able to. If the burn injury has damaged the fingers and the toes so that you can't assess capillary refill, or if they've already been amputated, then that leaves out that piece of the puzzle in assessing for compartment syndrome. You're also checking the temperature of the tissue distal to the area of the circumferential injury, especially if it's on an extremity. If it's extremely cold or has gotten colder over time, that's another red flag indicating that a compartment syndrome may be developing. You can also monitor the pressures within the compartments, if you have the tools to do so. For patients who have circumferential burn injuries around the torso, then they will experience difficulty breathing or an increase in difficulty breathing, which puts them at high concern for a development of a compartment syndrome that needs to be addressed.

Once you have assessed these symptoms and are convinced that the patient is developing a compartment syndrome, that needs to be addressed fairly urgently. It can be done at bedside with a straight incision through the eschar to allow that inelastic eschar to expand. It's better to take them to the OR if you are able to, to get a better incision, to get into the deeper fibres that can hold that compartment closed still, even once you've cut through the eschar and to control the bleeding. So as you can see in these pictures, once you have made an incision along the eschar, it will spread apart fairly widely to allow that swelling to occur, but allow the circulation to proceed through that extremity or through the trunk without being inhibited by the oedema. If you've done an escharotomy and there are still symptoms of compartment syndrome, that indicates either you needed to do an escharotomy in another area, or you didn't cut through deeply enough to allow the eschar to fully expand. And that needs to be addressed surgically as soon as possible.

Jacksons’ Burn Wound Model

Jacksons’ 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: This is the area central to the injury and is the area that experiences the greatest tissue damage. Often characterised by complete destruction of the capillaries leading to complete cell death. This is irreversible as there is no capillary refill.

• Zone of Stasis or Zone of Ischaemia: 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 vasoconstrictive mediators responding to injury. It is reversible if capillary flow can be restored.

• Zone of Hyperemia: This zone is circumferential and is characterised by the eased blood supply and inflammatory vasodilation. This tissue has a good recovery rate, as long as there are no complications, such as severe sepsis or prolonged hypo-perfusion. increased blood flow due to release of histamine.  This area will recover completely without intervention unless complications occur, characterised by superficial and superficial partial thickness burns and has a robust capillary refill.

Burn Wound Conversion

Burn Wound Conversion: This refers to the worsening of tissue damage in a superficial burn which previously was expected to spontaneously heal, but it increases in tissue depth into a deeper wound which requires excision.

Potential Causes: 

• Dessication
• Infection
• Oedema

Total Body Surface Area

The Parkland Burn Formula is the most widely used formula to estimate the fluid resuscitation required by a burns patient on hospital admission, usually within the first 24 hours. When applying this formula, the first step is to calculate the percentage of body surface area (BSA) damaged, which is most commonly done by 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 has indicated 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 palm of the patient, with the exclusion of the fingers and wrist, is approximately 1% of the patients 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.