electrical injuries, atmospheric lightening, heat & cold disorders dr. shiuli, forensic medicine...
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
ELECTRICAL INJURIES, ATMOSPHERIC LIGHTENING,HEAT & COLD DISORDERS
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Injuries produced by electricity Depends on:• Nature of current In India, the domestic supply is 220-240
volts AC at 50 Hz• Amperage vs voltage• Amount of current A = V/R
Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
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• Path of current• Duration of current
Q = I2 X R X t
Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Cause of death
Low voltage (household) current• Ventricular fibrillation High voltage (industrial) current• paralysis of respiratory center• Electro thermal injury
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Post Mortem findings
External • Electric entry marka. Joule burn produced in low voltage currents Appearance:- Crater, 1-3 cm in diameter with a ridge
around circumference- Charring - Metallization
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Histology: - Micro blisters - Electric channels – cells separated in the
form of sharp slits- Palisading and streaming of nuclei- Collagen stains blue in ordinary H&E
stain
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
b. Flash/spark burn Produced in high voltage currents, when
sparking occurs between conductor and victim
Crocodile skin – high temperatures causes keratin of skin to melt over multiple areas
Arc eye – superficial and painful keratitis
c. Electric splits Point of entry shows laceration
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
• Exit mark- Where the body was earthed- More damage than entry Internal • Congestion of all organs• Petechial hemorrhages along the line of
passage of current• Brain – irregular tears and fissures• Zenker’s degeneration• Bone pearls
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Atmospheric discharge of electricity
Lightening
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Electrical discharge is between a negatively charged cloud and a positively charged object on earth - negative lightening
5% of lightening flashes are from positively charged clouds - positive lightening
Temperature – about 50,000*C Amperage – 12,000 to 200,000 amperes Voltage – equivalent to 1 million volts DC
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Mechanism of lightening injuries Electrical injury• Direct strike• Splash injuries• Contact injury• Ground current Mechanical effects Burns
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Post Mortem appearance
Clothes • Torn, burnt, may be stripped off• Melting belt knuckles and zippers External• Endogenous burns – due to heat
generated within the body. • Tip toe sign – small, circular, full
thickness burns involving the sides of the soles of the feet and the tips of toes.
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
• Arborescent burns – irregular, superficial, thin, tortuous markings on skin resembling the pattern of a fern or tree
- Seen in 20% to 33% cases- Not associated with burning- No pathological changes- Disappear in 1-2 days in survivors• Exogenous burns
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
• Mechanical lesions Internal • Brain – congestion, edema, hemorrhages• Lungs – congested, patchy hemorrhages• Muscles – necrosis• Spinal cord – damage • Eyes & Ears – cataracts, corneal edema,
tympanic membrane perforation
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Deaths due to cold and heat
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Heat disorders
Predisposing factors Hot and humid conditions Clothing Drugs Diseases Obesity Alcohol
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
1. Heat edema
- Mild form- Dependant soft tissue swelling
Peripheral vasodilatation
Pooling of interstitial fluid
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
2. Heat rash (prickly heat)
- rash on anterior surface of elbows, posterior surface of knees, sternum , clavicle, waistP
rolonged sweating with no evaporation
Periductal edema d/t NaCl
Inflammation of sweat gland
Rash
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
3. Heat cramps (miner’s cramps)
Common in manual laborers, miners, athletes, tennis players, runners
Drinking large quantities of water only after sweating lowers the effective salt concentration
Sudden onset, flushed face, dizziness, headache, vomiting, paroxysmal cramps in muscles of hands, calves, feet, thighs and abdomen.
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
4. Heat syncope (heat collapse)
Intense peripheral vasodilatation leading to peripheral pooling and hypotension
Precipitating factors
•Sudden change – most imp.•Prolonged standing
Symptoms
•Fainting & giddiness•Blurring of vision•Epigastric distress•Nausea
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
5. Heat exhaustion
Severe dehydration after a huge amount of sweat loss
Most commonly encountered clinically Both water and salt depleted
circulatory deficiency Thermoregulation is maintained Symptoms- fever, nausea, fatigue,
muscle aches If left untreated may progress to heat
stroke
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
6. Heat stroke (heat hyperpyrexia)
Complete breakdown of thermoregulatory mechanism, complete loss of sweating and temperature >41*C
sudden onset with sudden collapse and loss of consciousness
Cramps, dizziness, excessive thirst, headache, weakness, nausea & vomiting, staggering gait
Skin dry and flushed, cessation of all sweating
Temp>42*C, BP↓, tachycardia
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Cerebellar dysfunction, clouding of senses
convulsions Delirium Speech difficulties Coma
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Cold injuries
Hypothermia core temp falls below 35*C First stage- Core tem 35-32*C Second stage- Core temp 32-26*C- Temp regulation lost below 30*C- Patient depressed, lethargic, drowsy- Muscles stiff, red patches on skin, edema
of face
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Third stage- Core temp < 26*C- Death ensues if this temp maintained for
24 hrs Cause of death failure of vital centers – d/t anoxia Cessation of heart function – d/t atrial
and ventricular fibrillation
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
Local effectso Frost bite- Characterized by freezing of tissues- Temp below 0*C- Bluish black discoloration of fingers, toes
or nose, ears & face- Microscopically, damage of endothelial
cells, leakage of serum into tissues.
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
o Trench foot (immersion foot)- Caused by prolonged exposure- Affected part becomes numb, blue/red
and may swell- Advanced conditions – blisters or open
sores
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Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.
o Chillbains (pernio)- Redness and inflammation of skin- Acral ulcers- Due to constriction of capillary beds in
skin