Notes
1) Introduction: definition and variety of burns – contact burn, burn produced by flame, kerosene oil, petrol, explosion, microwaves, corrosive substances, etc
2) Degree of burn and rules of nine: divided into 3 degree by Wilson
a) epidermal or first degree burn – affected part erythematous
- may form blister
-singeing of hair
b) dermo-epidermal or second degree burn – skin destroyed with destruction of dermal appendage
- tissue necrosis present
-affected area appears shriveled, depressed
-heals by scar formation
c) deep burn- more severe form of burn
-destruction of skin, subcutaneous tissue, muscles and even bones
3) Postmortem appearances: clothes, external and internal
4) Scalds: injury from liquid above 60℃ or from stem.
Introduction
A burn is an injury which is caused by application of heat (by conduction or radiation) or chemical substances to the external or internal surfaces of body, which causes destruction of tissues. Radiation causes damage through conversion of infrared frequencies into thermal heat on absorption at the skin surface. The minimum temperature for producing burn is 44℃ for an exposure of about 5 to 6 hours. At 65℃, two seconds are sufficient are to produce a burn. . In contact burn there is physical contact between the body and a hot object, like heated solid or molten metal, it produce blister with erythema. Flame burn produce vesication but singeing of hair and blackening of skin are always present.
Burns produced by kerosene or petrol are usually severe and produce sooty blackening of the parts and have characteristics odour. Burns produced by explosion are very extensive and produce blackening and tattooing of the skin. Microwave burns are well-demarcated, full thickness burns without charring.
Degree of burn and rules of nine
Burn is divided into 3 degree. The precise depth of a burn can be measured by a high frequency ultrasound device. In first degree or epidermal burn, affected part is erythematous due to capillary dilation and transudation of fluids into tissue causing swelling. A split may occur in the epidermis or at the dermal-epidermal junction to form blisters containing gas and proteinaceous fluid. Burns are very painful and repair is complete without scar formation. In dermo-epidermal or second degree burn, whole thickness of skin is destroyed with destruction of dermal appendages. The central zone of necrosis is surrounded by first degree burn or hyperemia or both. These burns appear as shriveled, depressed area of coagulated tissue, bordered by reddish blistered skin. Heals by scar formation and may produce disfigurement or impaired function.
Pain and shock are greater than first degree burn. In third or deep burn, there is a gross destruction not only of skin and subcutaneous tissue, but also of muscles and even bones. Nerves endings are also destroyed. Appears similar to those of second degree burn, but in a more severe form. The burnt part is completely charred.
The effects of burns depend on the surface area of the body involved. The estimation of surface area of the body involved is usually worked out by Wallace rules of nine, 9% for the head and neck; 9% for each upper limb; 9% for front of each lower limb; 9% for back of each lower limb; 9% for the front of chest; 9% for the back of chest; 9% for the front of abdomen and 9% for the back of abdomen. The remaining one percent is for external genitalia.
Postmortem appearances
In any case of burns postmortem signs of burns will be present. Clothes should be removed carefully and examined for the presence of kerosene, petrol and other such inflammable and combustible substances. Keys, metallic rings, ornaments, etc., worn on the body should be removed and preserved. It may be useful in establishing identity. Face usually distorted, swollen with tongue protruded out. Skin finding depend on the type of the burn. Radiant heat produce whitish color, highly heated solid objects produce Blister and reddening or roasting and charring, Explosions in coal mines or by gun-powder produce blackening of the parts. Kerosene oil burns produce characteristic odor and sooty blackening of the parts. Hair they undergo singeing. The singed hair looks curly and is highly fragile. Pugilistic attitude (Boxer’s attitude, Fencing attitude) a condition wherein the body assumes a rigid position with the limbs flexed and resembles a boxer in defending. All the four limbs are flexed with closed fist, body is bent forward and skin is tense, leathery, hard and frequently shows splitting.
Skull bones may be fractured and burst open due to intense heat. Brain and meninges are congested and heat hematoma present. Larynx, trachea and bronchial tubes contain carbon and soot particles and mucosa is congested with frothy mucous secretions. Pleura are congested and inflamed with serous effusion. Lungs are congested and edematous. Heart chamber are full of blood, cherry red in colour due to inhalation of carbon monoxide. Stomach and intestines may contain carbon impregnated mucous membrane. It may be red. Curling ulcer may be present in duodenum.
Scalds
A scald is an injury which results from the application of liquid above 60℃ or from stem. The destruction does not extend as deeply as in burns. Water at 70℃ can cause full thickness scald of skin in one second of contact. It resembles a first degree dry bur but the shape of scald tends to be different. Severity depends on duration of contact with skin and temperature of fluid. Redness appears at once and blister formation takes place in few minutes. There is reddening and swelling of papillae in the floor of blister. The blister fluid contains white and red cells. A postmortem blister does not show hyperemia in the surrounding area and the floor is not red. Scalds show soddening and bleaching but do not singe the hair. There are 3 degree of scalds namely erythema by vasoparalysis, blister formation due to increased permeability of capillaries and necrosis of the dermis. The injury due to scald is limited to the area of contact. Scalds usually occurs accidentally due to bursting of hot water bottles, bursting of boilers, splashing of fluids from cooking utensils, etc