Transcript Slide 1
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 2. The Mechanism of Death is a biochemical or physiological abnormality produced by the cause of death. A underlying cause 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) Accidental Homicide Suicide } all involve trauma Time of Death 5. When a person dies the following can be used to determine time of death: 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 Rigor 12 hrs, disappears in 36) mortis – is the cooling of the body (1.5°C per hour for the first 8 hours at room temp) Algor 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 Sharp Blunt Non-firearm Low Firearm High -Electrical 7. Surgeons typically classify trauma as penetrating (stab wound) or non-penetrating (collisions). 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 Blunt Trauma Most common cause of death is damage to the brain Produces lacerations, contusion, and hematomas Firearm injury Injuries received from sharp implements (knives, swords, axes) Produces incised wounds Most common cause of death is exsanguination (bleed to death) 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 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. 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] 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 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 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 starshaped 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] 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 abuse history of 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: – not known to have produces an overdose death Cocaine – is a stimulant and may result in seizures, and uncontrolled quivering of the heart Marijuana 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 cold Hypothermia Hyperthermia Diagnoses requires the absence of other causes of death Thermal burns are localized wounds Cause 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