2.  Assessment of Depth & Size 

There are three categories of second degree burns typically used to characterize the depth of injury. Each corresponds with healing time, treatment modalities, and outcomes.

• Superficial Second Degree Burn

Involves entire epidermis to basement membrane and no more than the upper third of dermis. Rapid re-epithelialization occurs in 1 to 2 weeks. Because of a large number of remaining epidermal cells and good blood supply, there is a very small zone of injury or stasis beneath the burn eschar.

• Mid Second Degree Burn (Mid-Dermal)

Destruction of the epidermis occurs to the basement membrane plus the middle third of dermis. Re-epithelialization is much slower (2-4 weeks) due to fewer remaining epidermal cells and less blood.  More collagen deposition will occur, especially if not closed by 3 weeks.  This depth of wound has a significant risk of conversion.  The zone of stasis is much larger than in the superficial second-degree injury because of less blood flow and more initial injury to the remaining epidermal cells.

• Deep Second Degree Burn (Deep-Dermal)

Involves the entire epidermis and at least two-thirds of the dermis, leaving very little dermis and epidermal cells to regenerate. Spontaneous healing is very slow (4-12 weeks).  Sharp debridement is usually needed to remove eschar.  Scarring is usually severe if not skin grafted and there is a high risk of infection.  Inflammation induced conversion to a full-thickness burn is common.  Function of a re-epithelialized deep, second-degree burn is poor due to fragility of the epidermis and the rigidity of the scar-laden dermis.

Full Thickness or Third Degree Burn

Both layers of the skin are completely destroyed. There are no remaining epidermal cells. Fibroblasts will migrate into the tissue below the burn and deposit viable scar tissue. Wounds can partially heal by contraction (2 to 3cm.) but any significant burn will require excision and skin grafting (usually split thickness skin graft).

Assessment of Burn Size

An easy way to determine the percent (%) of the body which has been burned is to use the diagram below (Figure 1) where specific body parts are described as percent of total body surface.

Common Characteristics of Burn Injury

Hot Liquids

Short exposure

Long exposure

Superficial or mid 2^o

Deep 2^o, 3^o (full thickness)

Severe

minimal

wet, pink blisters

wet, dark red

Flames

Flash exposure

Superficial to mid 2^o, 3^o

(full thickness)

Severe

minimal

wet, pink blisters

dry, white, waxy or brown, black lathery

Chemicals

Acids, alkali

Deep 2^o to 3^o (full thickness)

Severe

light brown to light gray