Post on 17-Dec-2015
transcript
Investigation of Traumatic Deaths
Ch 4
Pages 43-58
Terminology – Part 1
Mechanism of Death - biochemical and/or physiological abnormality produced by the cause of death which is incompatible with life
Manner of Death – one of the four ways death can be caused; natural, accidental, suicidal, or homicidal.
Liver mortis – the postmortem reddish discoloration of the body due to the settling of red blood cells due to gravity
Algor mortis – the postmortem cooling of the body. Lacerations – injury produced by blunt instruments; characterized by
surface abrasion, bridging vessels, and nerves with irregular margins. Exsanguinations – death after a significant amount (usually half or more)
of blood is lost. (Bleeding to death) Contusion – bruise; leakage of the blood from damaged blood vessels into
tissues. Hematoma – a tumor of blood caused by leakage from damaged blood
vessels; it contains enough blood to form a blood filled space.
Part 2 Handgun – firearm designed to be fired by the hand Shotgun – smoothbore firearm designed to be fired from the shoulder Contact wounds – a skin injury produced by a weapon in contact
with or a fraction of an inch from the skin when discharged. Explosion – sudden conversion of potential energy to kinetic energy
accompanied by physical destruction of the container or structure via a high pressure wave front.
Stippling – disposition of fragments of powder into the skin as the result of a gunshot wound of relatively close range; also called powder tattooing.
Intermediate range gunshot wounds – firearm wound that shows stippling, but no smoke; generally indicates a distance of a few millimeters to a meter from skin to gun muzzle at the time of discharge.
Distant wound – firearm wound that lacks stippling, smoke, or soot. Indicates a distance of 1 meter or more at the time of discharge.
Shored exit wounds – a bullet exit wound that has many characteristics of a distant entrance wound. Caused by the supporting or shoring the skin as the bullet exits.
Yawing – deviation of a bullet from the longitudinal axis of its flight. Ethanol – ethyl alcohol or beverage alcohol found in beer, wine, and liquors. Depressant – drug that reduces excitability and calms a person Stimulant – drug that produces a temporary increase of functional activity or
efficiency Ventricular Fibrillation – uncoordinated non-propulsive quivering of the
heart often produced by heart attack; also by low voltage electrocution. Asphyxia – the interruption of oxygen to the brain. Ligature – a device, similar to a tourniquet, usually of thread or string, tied
around a limb, blood vessel or similar to restrict blood flow.
Introduction
The purpose of investigating a death is to determine its cause and manner. Forensic pathologist
must be able to support his/her conclusions
Cause and Mechanism of Death
1. The Cause of Death is the disease or injury that initiated the lethal chain of events that led to death. The underlying cause
2. The Mechanism of Death is a biochemical or physiological abnormality produced by the cause of death. A contributory factor
3. Injury takes precedence over disease in determining cause of death.
Manner of death
4. The manner of death is defined as the fashion in which the cause of death came to be:Natural (caused solely by disease)AccidentalHomicide } all involve traumaSuicide
Time of Death
5. When a person dies the following can be used to determine time of death: Rigor mortis – stiffening of the muscles due to the
chemical reaction of glycogen (~4 hrs, lasts 24-36 hrs)
Liver mortis – discoloration of the body due to the settling of the red blood cells (w/in min.- becomes fixed in 12 hrs, disappears in 36)
Algor mortis – is the cooling of the body (1.5°C per hour for the first 8 hours at room temp)
Classification of Traumatic Deaths
*Trauma- a body wound or shock produced by sudden physical injury, as from violence or accident.
6. Traumatic deaths may be classified as: -Mechanical -Thermal -Chemical -Electrical
7. Surgeons typically classify trauma as penetrating (stab wound) or non-penetrating (collisions).
Sharp
Blunt
Non-firearm
FirearmLow
High
8. Asphyxia, death caused by interference of oxygen to the brain,can overlap all classes of traumatic deaths.
Ex: mechanical asphyxia – strangulation
Chemical asphyxia – cyanide poisoning
electrical asphyxia - electrocution
Mechanical Trauma 1. Mechanical trauma occurs when applied physical force exceeds
the tensile strength of the tissue to which the force is applied.
Sharp Force Injury Injuries received from sharp implements (knives, swords, axes) Produces incised wounds Most common cause of death is exsanguination (bleed to death)
Blunt Trauma Most common cause of death is damage to the brain Produces lacerations, contusion, and hematomas
Firearm injury Most common suicidal and homicidal wounds in the US Classified based on the type of firearm and the wounds
Other Blunt Force injury Motor vehicle collision, falls, (accidental) Homicidal – lethal head injury
Incised wounds – Sharp force injury
This is a single-edge blade stab wound in which there is a "hilt" mark at the left. The sharp blade edge is at the right. [Image contributed by Todd Grey, MD, University of Utah]
Seen in this clay model is the pattern of a stab wound from a double edge knife on the left and a single edge knife on the right.
Blunt Trauma Wounds – Lacerations, Contusions, Hematomas
Here is a very superficial laceration of the forehead. Note that the skin surface is broken. There are some small tags of skin where the surface was irregularly torn.
Firearm Wounds
Types of Firearms Gunpowder propelled
(rare) Smokeless powder
(nitrocellulose) Handguns Shotguns
Types of wounds Diameter of the projectile or bullet The velocity of the projectile Penetrating (has and entrance
wound, but not exit) Perforating (has an entrance and
an exit wound) Proximity to the gun at time of
discharge Contact Stippling Distant wound Shored exit wounds Yawing
Firearm wounds
This is an contact gunshot entrance wound. Since the barrel contacts the skin, the gases released by the fired round go into the subcutaneous tissue and cause the star-shaped laceration. Note also the grey-black discoloration from the soot, as well as the faint abrasion ring. [Image contributed by Todd Grey, MD, University of Utah]
An abrasion ring, formed when the force of the gases entering below the skin blow the skin surface back against the muzzle of the gun, is seen here in this contact range gunshot wound to the right temple. [Image contributed by Todd Grey, MD, University of Utah]
This is a contact range gunshot entrance wound with grey-black discoloration from the burned powder.
The right diagram illustrates the basic differences between the skin appearance of a contact, close (intermediate), and distant (indeterminant) range gunshot wound. The appearance of the wounding characteristics in the skull is shown in the lower diagram in which there is bevelling of the skull outward away from the direction of origin of the bullet
This is an intermediate range gunshot entrance wound in which there is powder "tattooing" around the entrance site.
With a contact or very close range gunshot wound, it is possible to have blood spatter as well as sooting on the hand of the person firing the weapon.
Chemical Trauma
Deaths from trauma include deaths that result from the use of drugs or poisons
The most common drug – ethanol Longest history of
abuse
Alcohol.. Nervous system
depressant Slows reactions to the
brain At .25 gram percent /
go into coma Eventually breathe so
slowly they pass out
Other drugs of abuse….
Barbiturates, diazepams, and opiates Produce increasing
degrees of coma followed by cessation of breathing
Exceptions: Marijuana – not
known to have produces an overdose death
Cocaine – is a stimulant and may result in seizures, and uncontrolled quivering of the heart
CO Poisoning
Carbon Monoxide Odorless, colorless, explosive gas
Co kills by asphyxiation – cuts off oxygen to the brain
Binds to the hemoglobin 300 times more strongly than oxygen
Blood levels above 20% may prove fatal
cherry red coloration of skin
autopsy specimen showing brain discoloration
Cyanide Poisoning
Interferes with the oxygenation of the brain Available as the sodium or potassium salt
that is used in electroplating and metal polishing
Smells like almonds
Thermal Trauma
Exposure to excessive heat or coldHypothermiaHyperthermia
Diagnoses requires the absence of other causes of death
Thermal burns are localized woundsCause death when complications arise
Electrical Trauma
The passage of electricity through a person may cause death when the heart experiences ventricular fibrillation
Asphyxias
Drowning- death by asphyxiation of water or other liquid Fluid is in the lungs Diatoms may also be
present
Manual strangulation – with the hands
Ligature strangulation – with a rope/cord/wire
Most common findings fracture of the thyroid
cartilage Hemorrhage of the neck
muscles Presence of a furrow in the
neck Petechial hemorrhaging