Skin Structure and Burns

Structure of the Skin

• The skin has two layers and is considered a complex organ.
• The epidermis is the outer, superficial layer, that provides a physical barrier.
  • It separates deeper tissues from the external environment.
  • The epidermis contains melanin, which gives skin its color.
• The dermis is the deeper layer, providing skin with elasticity and durability.
• The subcutaneous tissue lies deep to the dermis.

Definition of Burns

• Burns are traumatic injuries to the skin or other exposed tissue.
• Cell destruction occurs due to exposure to a destructive agent.
• Airways, the mouth, and the oesophagus are examples of exposed tissues other than skin.
• The extent of damage depends on the intensity and duration of exposure.

Burn Classification by Causative Agent

• Thermal burns result from exposure to heat or cold.
• Chemical burns are caused by acidic or alkaline (caustic) substances.
• Electrical burns are caused by electrical current.
• Radiation can cause burns.

Types of Thermal Burns

• Flame burns are caused by direct contact with a flame.
• Contact burns occur when tissue touches a hot solid object like a cigarette, iron, or pot.
• Scalding injuries result from contact with hot liquids through immersion, splash, or steam.
• Radiant burns are from heat emitted from a hot object without direct contact and include sunburn.
• Cold exposure or frostbite causes cell destruction via ice crystal formation.

Chemical Burns

• Damage severity depends on the substance's nature and exposure duration.
• Acids have a low pH and do less damage due to limited tissue penetration.
• Alkalis typically cause more extensive damage because of deeper tissue penetration.
  • Examples include ammonia, drain cleaners, and fertilizers.

Electrical Burns

• Electrical burns come from electrical current passing through the body, death is termed electrocution.
• These burns may be caused by lightning or live wires.
• Electricity flows from the contact point, through the body, and to an electrical ground.
• The heat generated by the electrical current causes burns to the skin as it passes.
• Arrhythmias may result when the current effects the heart.
• High voltage currents can result in death by cooking the internal organs from intense heat.

Burn Classification by Depth

• First-degree burns are superficial.
  • They only affect the epidermis.
  • Redness and pain, but no blisters are present.
  • They heal in 3-4 days without scarring.
  • An example is sunburn or a flash burn.
• Second-degree burns involve the epidermis and part of the dermis.
  • The area appears red, blistered, and may be swollen and painful.
  • Superficial partial-thickness burns heal in 2-3 weeks without scarring.
  • Deep partial-thickness burns heal in 3-8 weeks with scarring.
• Third-degree burns are full thickness burns.
  • They destroy both the epidermis and dermis.
  • These are usually white or black, and painless.
  • Skin grafting is needed because no skin regrows.

Burn Classification by Extent

• This is an estimate based on established formulae for adults and children.
• The extent of the burn determines treatment.
• The rule of nines is used in adults.

Forensic Significance of Burns

• Death from burns may be immediate or delayed.
• Carbon monoxide poisoning, airway obstruction from thermal injury, swelling of the airways, fluid loss from the burnt skin, and hypovolemic shock may cause immediate death.
• Fluid loss, infection, and ARDS (acute respiratory distress syndrome) may cause delayed death.
• Determining the cause of death starts with distinguishing if the victim was alive when the fire started.
• It is almost impossible to distinguish antemortem burns from post-mortem burns.
• Black soot particles in mouth and nostrils indicates smoke inhalation and the presence below vocal cords indicates the deceased was alive before the fire.
• High levels of Carbon Monoxide in the blood (carboxy haemoglobin) indicates the person was alive and breathing when the fire started and also it may be elevated in smokers.
• There may be patterned injuries.
• Starting a fire can try to cover foul play, or a person may die of natural causes prior to a fire.

Drowning Definition

• Drowning is death from atmospheric air being prevented from entering the lungs due to submersion in liquid.
• Complete submersion is not necessary; even the face alone submerged is sufficient.

Types of Drowning

• Wet drowning can be caused by fresh water or salt water.
  • Each water type produces a different post-mortem finding.
• In freshwater drowning, water is absorbed from the lungs into the bloodstream, causing dilution of blood.
• In saltwater drowning, water is drawn from the blood into the lung tissue.
• Asphyxia (formerly called dry drowning) is when water entering the air passages causes a reflex spasm.
  • This spasm causes a complete occlusion of the airway.
  • Water does not enter the lungs, and characteristic post-mortem findings are absent.
  • The findings of dry lungs at autopsy indicate neither that water was inhaled nor that it was not.
• Secondary drowning is death that occurs subsequent to a near-drowning.
  • It is usually due to aspiration pneumonia or a fluid imbalance.
• Cold water drowning is sudden death without the classical signs of drowning.
  • It is caused by sudden immersion in cold water where receptors in the skin induce a sudden stopping of the heart – vagal inhibition.

Post Mortem Appearance (Signs of Immersion)

• Hands and feet have corrugated or sodden skin (washer woman's skin).
  • Prolonged exposure results in detached skin of the hands and feet in a glove-like fashion.
• Goose skin appearance (cutis anserine) from contraction of muscles in the skin.
• Foam around the mouth and nostrils.
• Grass, gravel, and twigs firmly grasped in the hands (cadaveric spasm).
• Adipocere (grave wax formation).

Other Findings at Autopsy

• Heavy waterlogged lungs.
• Hyperinflated lungs similar to those of an asthmatic.
• Stomach contains liquid and foreign material (also possible if the body was immersed after death).
• Fluid in the sinuses, this is also found when a body is immersed after death.

Medicolegal Importance of Drowning

• Determine if death was caused by drowning.
  • Features supporting the cause are cadaveric spasm, froth, soggy lungs, and mud/sand in the stomach.
• Determine if the drowning was suicidal, homicidal, or accidental.
• Determine the duration of immersion.
  • After drowning, the body will sink and resurface due to putrefaction gas formation, slower in water than in air.
  • Time until reappearance depends on temperature (2-3 days in warm water or weeks in winter) and is slower in seawater.
• Distinguish antemortem injuries from injuries by wildlife, rocks, and boats while the body is in the water.

Possible Scenarios of Bodies Recovered From Water

• Died from natural disease before falling into the water.
• Died from natural disease while in the water.
• Died from injury then thrown into the water.
• Died from injury while in the water.
• Died from drowning.
• Died from effects of immersion other than drowning.