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ENVIRONMENTAL DEATHS. ELEMENTS. DROWNING. QUESTIONS: WAS VICTIM ALIVE OR DEAD WHEN IMMERSED ? ANY PRIMARY INJURY PRIOR TO SUBMERSION? IF DEATH WAS DUE TO DROWNING,IS IT ACCIDENT,SUICIDE OR HOMICIDE. DROWNING. DEATH due to Cerebral Anoxia - PowerPoint PPT Presentation
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ENVIRONMENTAL DEATHS
ELEMENTS
DROWNING
• QUESTIONS:
• WAS VICTIM ALIVE OR DEAD WHEN IMMERSED ?
• ANY PRIMARY INJURY PRIOR TO SUBMERSION?
• IF DEATH WAS DUE TO DROWNING,IS IT ACCIDENT,SUICIDE OR HOMICIDE
DROWNING
• DEATH due to Cerebral Anoxia
• Voluntary Breath-Holding eventually overcome by Involuntary Urge to Breathe
• LARYNGOSPASM in “Dry-Drowning”
• If no laryngospasm,large volumes of fluid are inhaled and swallowed---may continue until respiration ceases
DROWNING
• Hypoxia ---- Anoxia --- Brain Death
• Conciousness lost within 3 minutes
• Agonal Period -- vomiting (aspiration ), defaecation,urination,seminal emission
Freshwater Drowning
• Hypotonic
• Large volumes of water pass through the alveoli and increase the blood volume
• Haemolysis
• Pulmonary Surfactant denatured
Freshwater Drowning
• Hypotonic
• Large volumes of water pass through the alveoli and increase the blood volume
• Haemolysis
• Pulmonary Surfactant denatured
Saltwater Drowning
• Hypertonic
• Plasma drawn into alveoli by osmosis
• Decreased Blood Volume
• Haemoconcentration
• Raised Blood Electrolytes
• Dilutes and washes away Pulmonary Surfactant
Loss of Pulmonary Surfactant
• Leads to Alveolar Collapse
• Reduced Lung Compliance
• Severe Ventilation/Perfusion Mismatch
• Hypoxia
Near-Drowning
• First 24 hours after rescue
• Sudden Cerebral Oedema is a major cause of death
Near-Drowning
• Survival beyond 24 hours after rescue
• May be Concious or Unconcious
• May develop Pulmonary Oedema,Haemoglobinuria,Cardiac Arrythmia,Pneumonitis,Fever,Sepsis
• Cerebral Hypoxia----convulsions,amnesia,confusion,coma
ICY WATER
• Survival possible after prolonged submersion
• “DIVING REFLEX”---Bradycardia,intense Vasoconstriction (except Brain and Heart)
WARM WATER
• Irreversible Cerebral Anoxia in 3-10 minutes
DROWNING
• AUTOPSY FINDINGS:
• Findings are variable
• Plume of frothy fluid in mouth and airway
• Water in stomach
• Evidence of Cerebral Oedema
• The above are seen only in cases where body is recovered soon after drowning
DROWNING
• AUTOPSY FINDINGS:
• “Washerwoman changes”
• Affects skin of hands and feet
• Skin becomes shrivelled and pale within 1-2 hours
• Feature of Immersion---Not of Drowning
• Non-specific---cf wet clothing,mud etc.
Laboratory Tests for Drowning
• Diatoms --- Unicellular Algae• Present in water,soil,atmosphere• If circulation, enter lungs and other organs• Bone Marrow---Femoral• Digested with enzymes or detergents,obtain
centrifuged pellet• Compare with water sample• Reliability Questionable
Body in Water
• After death the body sinks• Only moves if strong currents• Injuries---may scrape rough surfaces• Animal Predation---fish,crabs,turtles• Putrefaction----Body rises• Obese-----rise sooner• Putrefaction---signs of drowning absent,ID a
problem
Bathtub Deaths
• Adults---- Cardiac Disease,Epilepsy,Intoxication (alcohol or drugs) are major factors
• Homicide is rare---may be pulled by feet
• Young children---if left unattended,may drown accidentally or rarely may be drowned by siblings
Hot-tubs,Spas,Heated Whirlpools
• Young Children---hot water,if submerged likely to develop anoxic brain injury rapidly
• Adults—Alcohol,Drugs
• Adults---Vasodilation,Stand Up,experience Postural Hypotension
HYPOTHERMIA
• Below 35 degrees (Celsius)
• Mild---- ----34 to 35
• Moderate—30 to 34
• Severe------below 30
HYPOTHERMIA
• INFANTS---Body Surface Area
• Wet
• Elderly
• Alcohol and Drugs
• Injury or Immobility
• Mental Impairment
HYPOTHERMIA
• COMPLICATIONS
• Pancreatitis
• G-I mucosal ulcers
• Pneumonia
• Acute Tubular Necrosis
• Myocardial Fibre Necrosis
HYPOTHERMIA
• PARADOXICAL UNDRESSING
• Hallucinations
• Feel Warm
• “Hide and Die”---found under bed,in wardrobe etc.
HYPERTHERMIA
• MILDER FORMS
• Heat Cramps---salt depletion---treat with Rest in cool environment and salt replacement
• Heat Exhaustion---loss of salt and water---treatment is similar
HYPERTHERMIA
• Defined as Core Temp above 40.5 deg C
• HEAT STROKE
• Life – Threatening
• Direct thermal tissue injury
• 41deg C--- Mortality 75%
• Factors---Alcohol,Drugs,Obesity
HYPERTHERMIA
• HEAT-STROKE
• Classic--- Elderly in prolonged heatwaves
• Exertional--- Young--- Extreme Exertion---eg seen in Athletes,Military Recruits,Labourers
HYPERTHERMIA
• HEAT-STROKE----SIGNS & SYMPTOMS
• Hyperthermia• Hot, Dry skin• CNS dysfunction---
nausea,vomiting,cramps,dyspnoea• Above 42.4 deg---Vasodilation and
Circulatory Collapse
HYPERTHERMIA
• HEAT-STROKE• In Survivors---Late Complications• Pneumonia• Acute Tubular Necrosis• Adrenal Haemorrhage• Hepatic Necrosis• Myocardial Necrosis• DIC
LIGHTNING
• Cloud to Ground Strikes usually• Most are NEGATIVE---5% are Positive• High-Voltage, Direct Current• Direct Strike--- Lightning Bolt• Indirect Strike---Side-Flash eg Tree—
current arcs to person standing nearby------or Conduction through intermediary objects eg telephone wires, waterpipes
LIGHTNING
• CLOTHING DEFECTS• Rips,tears,burns --- person may be NUDE• Singeing of body hair• Skin Burns--- jewellery,buckles,zips• Tympanic Membrane rupture• Lichtenberg Figure—fern-like red mark on skin---
1 to 24 hours• Death due to immediate Cardiopulmonary Arrest• Secondary traumatic injuries-----eg falls
ELECTROCUTION
• OHM’S LAW---------- C = V/R• Current (Amperage ) most important• 1mA---- tingle• 5mA----muscle tremor• 15mA---muscle contraction--hold-on effect• 40mA---possible loss of conciousness• 75-100mA– Ventricular Fibrillation• 2Amps----Cardiac Arrest
ELECTROCUTION
• LOC may not be immediate• Low-Voltage eg domestic- --burns in 50%• Firm Contact--- crater with white edges• Loose Contact---yellow spark burn• Exit---may get a burn eg soles of feet• If exits over broad area,may be no burn• Burns may be hidden—eg mouth or lips• Prolonged Contact---severe burns
ELECTROCUTION
• HIGH VOLTAGE
• Burns in virtually all cases
• May be severe---tissue charring
• Flash burns—multiple,small,pitted burns as current dances over large area of body
• Heat may cause explosive injuries---loss of limbs,rupture of viscera
ELECTROCUTION
• DOMESTIC SUPPLY
• IN IRELAND & UK
• Voltage sufficient to cause “hold – on” effect
• Frequency of Current likely to cause cardiac arrest
ELECTROCUTION
• SKIN OFFERS GREATEST RESISTANCE
• Dry skin more resistant than wet skin
• Thick skin more resistant than thin skin
• Clothing--- rubber boots and gloves can insulate
ELECTROCUTION
• CURRENT FLOW
• Different paths depending on entry and exit sites
• If path involves heart or brain,a fatal outcome is more likely
ELECTROCUTION
• CAUSE OF DEATH• Low-voltage• Must be direct contact between victim and
electrical circuit• Ventricular Fibrillation is main cause• If low current but long contact time,death
may be due to muscle paralysis and asphyxia
ELECTROCUTION
• CAUSE OF DEATH
• High-voltage
• Respiratory Arrest or
• Electrothermal Injuries
ASPHYXIA
• INADEQUATE OXYGENATION OF TISSUES:
• SUFFOCATION
• STRANGULATION
• CHEMICAL ASPHYXIA
ASPHYXIA
• SUFFOCATION• Failure of Oxygen to reach blood• Environmental—closed chamber eg Silo (CO2),
Hold of Ship (N2)• Smothering---mechanical obstruction of nose &
mouth---eg plastic bags,burial,gagging,• In Infants--- pillows or pinching nose & clamping
mouth
ASPHYXIA
• CHOKING
• Blockage of Internal Airways
• Blockage of posterior pharynx and larynx by food or foreign object
• Children------ Toys
• Adults ---- factors include Alcohol,Senility,Mental Retardation
ASPHYXIA
• FOOD ASPIRATION
• Rare as a genuine cause of death
• Agonal aspiration common
• Occurs in context of severe CNS depression
• ACUTE EPIGLOTTITIS
ASPHYXIA
• MECHANICAL ASPHYXIA
• Syn. Traumatic Asphyxia
• Pressure on chest & abdomen restricts respiratory movement and inspiration
• Scenarios—car-jack,burial,cave-ins,crowd crushes and stampedes
• May be no internal injuries
ASPHYXIA
• MECHANICAL ASPHYXIA• OVERLAYING of INFANTS---
indistinguishable from SIDS• Positional Asphyxia—eg suspended upside-
down,crucifiction,wedged between furniture,infants wedged in cots
• SIGNS---deep congestion of face & neck,petechiae,scleral haemorrhages
ASPHYXIA
• CHEMICAL ASPHYXIA
• Carbon monoxide—accidental,suicidal
• Hydrogen cyanide---mostly suicidal
• Hydrogen sulphide---accidental,affect workers in sewer plants and cess-pools
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