Burns are typically classified by their depth into (or through) the skin.
- 1st degree: just in the epidermis
- Pink, hot, no blisters
- Like a typical sunburn
- 2nd degree: into dermis, painful, wet
- Superficial: unruptured blisters, hair & glands spared, erythematous (red) but blanch with pressure
- Deep: ruptured blisters, hair often gone, can convert to a 3rd
- 3rd degree: through the dermis aka full thickness
- Lack vascularization, dry, leathery, no sensation
Zones of a Burn
A burn isn’t a homogenous spot on the skin; more heat means more damage (who knew!)
- 40 – 44 C: enzymes malfunction, protein denature
- >44 C: damage occurs faster than the cell can handle
- Damage keeps going after the heat source is removed
- Zone of Coagulation: The cells are dead and their proteins have denatured. Denatured proteins coagulate – think fried eggs. This is what forms the eschar of the burn.
- Zone of Stasis: The cells aren’t quite dead but the blood supply isn’t the best. If the circulation gets worse (usually due to vessel constriction and thrombosis) the cells in this area will die too. This is why it can take a couple days for a burn to “declare” itself.
- Zone of Hyperemia: “Hyperemia” means an increase in blood flow, in this case because of vasodilation. The cells in this area are alive and generally recover.
The image above shows a superficial 2nd degree burn.