Estimation of Depth of Burn Injury:

A thermal injury is described as partial thickness or full thickness, depending on the depth  and  severity of tissue damage

a) First Degree Burns affecting  the epidermal layer  is  characterized  by  erythema due  to vascular response  in  the  sub papillary vessels. Edema occurs  in  the  basal layer irritating the nerve ending at  this  level and causing discomfort. 

b) Second Degree Bums which  involve from one half  to seven eights of  the dermal  layer.  It is subdivided  into superficial partial thickness and deep partial thickness. In superficial partial thickness bum,  the surface may  be covered with blisters of varying size. The  removal of  blister reveals  the skin beneath it which  is weeping, glistering bright pink or red and exquisitely sensitive to touch, temperature and air  flow. The deep partial thick-ness bum destroys the entire thickness of the epidermis including dermal papillae leaving intact the sweat glands and  hair follicles from which epithelial elements cover the wounds. 

c) Third  Degree Full thickness injury involves all  the epidermis and dermis. The burnt skin  is hard and  dry,  tan or  fawn  colored  and  after exposure  to air  it  becomes parchment like and translucent with thrombosed vessels visible underneath. Children less than  4  years of age have a higher mortality as compared  to older patients with similar  injury. Their response to stress  is  limited and smaller body mass equipped with low protein and fat stores  is  unable  to cope with hypermetabolism.