Transcript Classification of Trauma

Classification of
Trauma
Types of Trauma
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Mechanical
Chemical
Thermal
Electrical
Medical doctors and surgeons may classify
wounds differently than medical examiners
and forensic pathologists
Mechanical Trauma
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Occurs when the force exceeds mechanical or
tensile strength of that tissue
Resulting from sharp or blunt force
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Size, shape, and kind of wound may allow the forensic
pathologist to determine if a sharp or blunt object caused
it
Judicious interpretations and caution are required
because of the flexible nature of many of the body’s
tissues and the variability of the violent force
Death from blunt and sharp trauma results from
multiple processes
Mechanical Trauma: Sharp Force
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Refers to injuries caused by sharp
implements, such as knives, axes, or ice
picks
Takes significantly less force for a
sharpened object to cut or pierce tissue
than what is required with a blunt object
Produce incised wounds – more depth
than length or width
Mechanical Trauma: Sharp Force
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Sharp objects produce incised wounds a wound that has more depth than
length or width
Sharp trauma most commonly causes
death from a fatal loss of blood
(exsanguination) when a major artery of
the heart is damaged
Mechanical Trauma: Blunt Force
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Caused by dull or non-sharpened
objects, such as baseball bats, bricks,
or lamps
Blunt objects produce lacerations, or
tears in the tissue, typically the skin
Blunt trauma causes death most often
when the brain has been severely
damaged
Mechanical Trauma: Blunt Force
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Contusion – an accumulation of blood in the
tissues outside the normal blood vessels and
is most often the result of blunt impact
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The blood pressures the tissues enough to break
small blood vessels in the tissues, and they leak
blood into the surrounding area
The pattern of the object may be transferred to the
skin and visualized by the blood welling up in the
tissues
An extreme contusion, a hematoma, is a blood tumor,
or a contusion with more blood
Mechanical Trauma: Blunt Force
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Gunshot wounds – the projectile from a
discharged firearm produces a special
kind of blunt force trauma
There are 4 major classes of gunshot
wounds
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Contact (entrance)
Intermediate (entrance)
Distant (entrance)
Shored exit
Mechanical Trauma: Blunt Force
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Contact (entrance) – distance is 0
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Blackening of the skin; lacerations from escaping
muzzle gases; bright red coloration of the blood in
wound from carbon monoxide gases reacting to
hemoglobin in blood (carboxyhemoglobin)
Intermediate (entrance) – 0.5cm-1m
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Unburned gunpowder penetrate skin and burns it,
causing small red dots called stippling; the stippling
pattern enlarges as the muzzle-to-target distance
increases
Mechanical Trauma: Blunt Force
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Distant (entrance) – >1m
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Speed of gunpowder is insufficient to cause stippling
at this distance; lack blackening: no
carboxyhemoglobin; circular defect with abraded rim;
distance intermediate
Shored exit
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Skin is supported or shored by some material, such
as tight clothing, wall board, or wood, as bullet exits;
may look very similar to entrance GSW except pattern
of shoring material (such as the weave of cloth) may
be transferred to skin as it expands when bullet exits
Chemical Trauma
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Damage and death that results from the
interaction of chemicals with the human
body
This is the domain of the forensic
toxicologist (discussed later)
If the damage from chemicals is external
(acid or alkaline burns) then it is still the
responsibility of the pathologist
Thermal Trauma
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Extreme heat or cold also may produce
death
Hypothermia – too much exposure to cold
Hyperthermia – exposure to excessive heat
Either condition can interfere with the
normal physiological mechanisms that keep
body temperature at about 98°F/37°C
Thermal Trauma
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In both cases, the forensic pathologist may
encounter few signs at autopsy that will
indicate either of those mechanisms; more
commonly, external or environmental
factors, as well as what is not found, may
lead to this determination
Thermal Trauma
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Individuals in a vulnerable state of health –
the sick, the very elderly, or the very young
– most often succumb to hypo- or
hyperthermia
Other factors may contribute, such as
alcohol, which reduces sensitivity to cold
and dilates (opens) the blood vessels,
speeding the cooling of the body
Thermal Trauma
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Hyperthermia deaths are common in
elderly people in northern cities and infants
left in automobiles during the summer
The inside temperature of a closed car in
the sun can exceed 140°F/60°C and can
be fatal to an infant in 10 minutes
Thermal Trauma
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Thermal burns tend to be localized; persons who die in a fire
do so generally because of a lack of oxygen (asphyxia) and
the inhalation of combustion products, like CO
The level of CO in the tissues can determine whether the
person was alive or dead when the fire burned him or her
A body from a burned building with 1 or 2% CO is presumed
to have been dead (or at least not breathing) at the time the
fire started.
True deaths from thermal injuries do occur due to either
massive tissue damage and/or swelling of the airway,
causing suffocation
Electrical Trauma
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Electricity can cause death by a number of means
Circuits of alternating current (AC) at low voltages
(<1,000V) that cross the heart cause ventricular
fibrillation, a random quivering that does not pump
the blood through the body properly
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A person in ventricular fibrillation for even a few minutes
cannot be resuscitated
The heart fibrillates because the current is acting like a
(faulty) pacemaker
AC in the US alternates from positive to negative at 3,600
times/minute and at 2,500 times/minute in Europe; the
heart can beat only about 300 times/minute maximum
Electrical Trauma
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At high voltages, the amount of current
causes the heart to stop beating (it
becomes defibrillatory) pushing the heart
into tetany, a sustained contraction that is
broken only when the circuit is broken
Although the heart will generally start
beating normally again, high voltages
produce severe burns and cellular damage
within a fraction of a second