BURNS
Definition
Tissue injury caused by thermal, radiation, chemical, or
electrical contact resulting in protein denaturation, loss of
intravascular fluid volume due to increased vascular
permeability and oedema.
Incidence
100% about 1/3 of whom require admission
Etiology
Chemical, Thermal, Electrical, Mechanical, Radiation, Frost
bite
Persons at Risk of burns
1.Extremes of age - the very young (<4yrs) or very old
(>50yrs)
The higher death rate in infants results from a number of
factors.
First, the body surface area in children relative to body
weight is much greater than in adults. Therefore, a burn of
comparable surface area has a greater physiologic impact on
a child.
Second, immature kidneys and liver do not allow for
removal of a high solute load from injured tissue or the rapid
restoration of adequate nutritional support.
Third, the incompletely developed immune system
increases susceptibility to infection.
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,2.Those whose ability to protect themselves is impaired or
prone to accidents Alcoholics, Sick, paraplegics ,diabetics,
psychiatric patients and patients of convulsive disorders
3.The unlucky - Innocent bystander
4.The careless - Storing petrol in the house, adding paraffin to
a lit stove, smoking in bed, working close to high tension
electric wires
Skin Anatomy and Function
Skin is the largest organ of the body.
It is 0.25 m2 in children and 1.8m2 in adults.
It has 3 major tissue layers.
Epidermis
The outermost layer, the epidermis, is composed of
stratified epithelium.
Epidermis has two components, an outer layer of
anucleate cornified cells (stratum corneum) that covers
inner layers of viable cells (Malpighian layers) from which
the cornified surface cells arise by differentiation.
The stratum corneum acts as a barrier to impede the
entrance of microorganisms and toxic substances while
allowing the body to retain water and electrolytes.
Malpighian layers provide a continuous production of
cornified cells.
Malpighian layers can be further subdivided into the
germinal basal cell layer, stratum spinosum, and stratum
granulosum
Dermis(corium)
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, Beneath the epidermis is the dermis, which is composed of
a dense fibroelastic connective-tissue stroma containing
collagen and elastic fibers and an extracellular gel termed
ground substance.
The dermal layer contains an extensive vascular and
nerve network, special glands, and appendages that
communicate with the overlying epidermis.
The dermis is divided into two parts.
a) The most superficial portion, the papillary dermis, is molded
against the epidermis and contains superficial elements of the
microcirculation of the skin. Within the papillary dermis, dermal
elevations indent the inner surface of the epidermis
b) In the reticular portion of the dermis, collagen and elastic
fibers are thicker and greater in number. Fewer cells and less
ground substance are found in the reticular dermis than in the
papillary dermis
Subcutaneous tissue The third layer of skin is subcutaneous
tissue, which is composed primarily of areolar and fatty
connective tissue.
This layer shows great regional variations in thickness and
adipose content.
It contains skin appendages, glands, and hair follicles
Functions of skin
1.Protect entry of micro-organism
2,.Protect against UV light
3.Vitamin D synthesis
4. Homeostasis-Thermoregulation and prevent excess water
loss
5.Cosmesis ,beauty and identification-finger prints
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, Pathophysiology of Burns
-Tissue damage due to above agents leads to release of
vasoactive substances e.g. prostaglandins, histamines,
oxygen radicals, leukotrienes & platelet activating factors
-This causes microvascular instability with increased
capillary permeability for the first 24-36hrs fluid shift to
extravasular compartment and oedema.
- This leads to decreased right atrial filling pressures
decreased CO and Shock.
-The body tries to compensate for these physiological
changes by
Increased peripheral resistance (sympathetic stimulation)
Tachycardia
Decreased capacitance of great vessels
If the process goes uncorrected;
Cardiac output is diverted to vital tissues reducing
perfusion of skin, muscle & gut - Skin feels cold & clammy
Reduced renal perfusion lead to acute RE
-Irreversible shock occurs as an end stage with falling BP,
CO & PR
-In patients with serious burns, release of catecholamines,
vasopressin, and angiotensin causes peripheral and
splanchnic bed vasoconstriction that can compromise in-
organ perfusion
-Myocardial contractility also may be reduced by the
release of inflammatory cytokine TNF-alpha
-In deep third-degree burns, hemolysis may be encountered,
necessitating blood transfusions to restore blood loss
-A decrease in pulmonary function can occur in severely
burned patients without evidence of inhalation injury from the
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