Skin Structure, Function, and Burns

Pathophysiology of Burns

• Severe burns can lead to circulatory failure (shock), widespread inflammation, and immunosuppression.
• Extent of tissue damage determines the prognosis.

Functions of Human Skin

• Acts as a barrier, protecting tissues from external pathogens.
• Regulates body temperature.
• Provides sensation (tactility).
• Prevents water loss.

Layers of the Skin

• Epidermis: The thin, outermost layer exposed to the environment, consists of stratified epithelial cells.
  • Uppermost cells are dead and sloughed off.
  • Contains specialized cells called keratinocytes, which contain keratin protein.
• Dermis: Contains capillaries, nerve fibers, and fibroblasts.
  • Nerve fibers connect to nociceptors (pain receptors).
  • Hair follicles, sweat glands, and sebaceous glands are present in the dermis.
• Hypodermis: Not technically part of the skin but lies below the dermis; contains fat cells (adipocytes).
• Below the hypodermis is the muscle fascia, and then bone.

Causes of Burns (Thermal Injuries)

• Physical factors: Fire/flame, heat sources, electric sources, UV radiation.
• Chemical factors: Acids and alkaline agents.
• Contact with hot water causes scalding.
• Extreme cold can cause frostbite.

Degrees of Burns

• First-Degree Burns: Superficial, affecting only the epidermis.
  • Sunburn is a common example.
  • Heals quickly.
  • Usually dry lesions.
  • Blisters are rare, may appear after 24-48 hours if present.
• Second-Degree Burns: Affect the epidermis and dermis, classified by depth:
  • Superficial (Partial Thickness): Affects the upper portion of the dermis.
    • Red in color due to preserved vasculature.
    • Blanching is observed when pressed (turns white due to blood supply).
    • Painful due to intact nerve fibers.
    • Immediate formation of wet blisters with fluid leakage from capillaries.
  • Deeper (Partial Thickness): Affects a major part or the entire dermis thickness.
    • Whitish lesions due to destroyed vasculature.
    • Pain is usually absent due to destroyed nerve fibers.
    • Healing leads to scarring.
• Third-Degree Burns: Extends beyond the dermis, affecting the hypodermis, muscle, and fascia.
  • No pain due to destroyed nerve fibers.
  • No blanching.
  • Lesion is whitish or charred (blackish), with a leathery texture.
  • Diagnosis typically relies on clinical features (skin blanching, wetness, pain).

Wallace Rule of Nines

• A chart used to estimate the total body surface area (TBSA) affected by burns
• Involves multiples or factors of nine
• Clinically important for determining treatment decisions
• Burns affecting more than 20% of TBSA are considered major burns.

Complications of Burns

• Systemic Effects: alterations in fluid balance, hyperkalemia, myocardial depression, myoglobinuria.
  • Fluid shifts: Intravascular fluid moves into the interstitium causing edema and hypovolemic shock (burn shock).
    • Reduced plasma oncotic pressure due to capillary leakage.
  • Hyperkalemia: Damaged cells release potassium causing increased potassium levels.
    • Can cause arrhythmias.
  • Myoglobinuria: Presence of myoglobin in the urine due to muscle damage.
    • Myoglobin can cause acute renal failure.
  • Renal insufficiency can occur due to decreased perfusion to the kidneys.
  • Monitor urine output to gauge patient prognosis: Oliguria indicates severe shock.
  • Stress response triggers the release of hormones like cortisol and catecholamines.
  • Stomach ulcers, specifically Curling ulcers, may occur.
• Immunosuppression: Patients become susceptible to infections.
  • Open lesions allow easy entry for pathogens..

Capillary Seal

• Restoration of capillary integrity through proper treatment and fluid administration.
• Capillaries stop leaking, increasing urine output.

Acute Burn Injury Systemic Response

• Acute burn injury leads to a systemic response releasing inflammatory mediators
• Direct tissue injury occurs
• Capillary Permeability Increases
• Blood Viscosity Increases
• Tissue Ischemia results from decreased pertusion
• Endothelial cell injury
• Leukocyte Recruitment
• Multiple Organ Damage leads to decreased cardiac output
• Acidosis and organ failure

Explore skin's layers (epidermis, dermis, hypodermis), its function as a protective barrier with roles in temperature regulation and sensation, and pathophysiology of burn injuries.