Post on 06-Jan-2018
description
FORENSIC PATHOLOGY
ELECTROCUTION
ELECTROCUTION
• Virtually all accidents– Alternating currents
• Most common type found in homes in the US– Low (<600 V)– High (>600-750 V)
• Amperage is most important factor in the current flow
A = V/R
ELECTROCUTION
• Voltage– Household – 110V
• Must directly touch electrical circuit• Death mainly by ventricular fibrillation
– High voltage lines – 8000 V• Electric current may jump (arc)• Death mainly by electrothermal injury or
respiratory arrest
ELECTROCUTION
• Resistance– Mainly by skin
• Dry skin has resistance of 100,000 ohms
• Dry calloused skin has resistance of 1,000,000 ohms
• Moist skin has resistance of 1,000 ohms
• Wet skin has resistance of 100 ohms
• Mechanism of Death– Minimal perceptible amperage
= 1mA– 5 mA will produce tremors in
muscle– 15 mA causes contractions– 50 mA causes respiratory
paralysis and death– 75 mA causes ventricular
vibrillation– 1 A causes ventricular arrest
ELECTROCUTION
• Judicial execution– High voltage currents
• Produces– 3rd degree burns– Brain temperature up
to 63°C
ELECTROCUTION
• Electroconvulsive “shock” Therapy– May cause fracture of
bones• Due to muscle
contractures• Most common are T12
and L1 vertebrae along with scapular fractures bilaterally
ELECTROCUTION
• Muscle Contraction– Back and neck arch backward– Arms rotate inward, elbows flex and hands
form fists– Hips and knees lock straight and feet extend– Individuals may grasp and continue to do so
ELECTROCUTION
• Autopsy Findings– High Voltage
• Electrical burns over body– Low Voltage
• Electrical burns at point of entry or exit• May have no electrical burns if minimal resistance
to flow– Bathtub
• Muscle Contraction
ELECTROCUTION
• Low Voltage Burns– Most often on palms of hands and tips of
fingers– Erythematous or blistering– Chalky white lesions– Raised borders with central crater– Yellow or black discoloration at burn site
ELECTROCUTION
• A typical electrical burn consists of a round, oval or elongated crater.
• Base of wound is dark brown.
• Ridge of elevated skin on margin
ELECTROCUTION
ELECTROCUTION• If victim survives for
short period of time after contact there may be a collection of foam in air passages.
ELECTROCUTION
• High Voltage Burns– Charring of body– Current runs through intermediary object
• Burns are large and irregular• Chalky white• Raised borders and central crater• Yellow black discoloration at burn site• Massive tissue destruction• Organ rupture
ELECTROCUTION
• Manner of Death– Usually all accidental– May be sexual in nature– Suicides and homicides are rare
• Ground-Fault Current Interrupters (GFCI)– Circuit is broken if amperage increases by 5 mA
ELECTROCUTION
• Lightning– Charged undersurface of a thunder cloud
• Virtually always Negative• Electrical charge to the ground
– Direct Strike• May injure or kill person
– Side flash• Hits an object and ricochets
ELECTROCUTION• Side-Flash Strike
– Clothing torn, shoes burst, hair seared, burned on skin from zipper or other metal objects
– Entrance and exit burns– Rupture of tympanic
membrane– Death by cardiopulmonary
arrest or thermal injury• Injury to cardiac and respiratory
centers of brain
ELECTROCUTION
• Aborescent Lightning injury– Fern-like pattern– Lichtenberg figures– Appears within 1h of lightning injury and fades within
24h– Not burns
• May be due to a positively charged lightning bolt• May be due to flashover by positive discharge over skin• Really don’t know what causes this pattern