electrical injuries, atmospheric lightening, heat & cold disorders dr. shiuli, forensic medicine...

Dr. Shiuli, Forensic Medicine & Toxicology, KGMU.

ELECTRICAL INJURIES, ATMOSPHERIC LIGHTENING,HEAT & COLD DISORDERS

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


• Path of current• Duration of current

Q = I2 X R X t



Cause of death

Low voltage (household) current• Ventricular fibrillation High voltage (industrial) current• paralysis of respiratory center• Electro thermal injury


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


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


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


• 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


Atmospheric discharge of electricity

Lightening


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


Mechanism of lightening injuries Electrical injury• Direct strike• Splash injuries• Contact injury• Ground current Mechanical effects Burns


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.


• 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


• Mechanical lesions Internal • Brain – congestion, edema, hemorrhages• Lungs – congested, patchy hemorrhages• Muscles – necrosis• Spinal cord – damage • Eyes & Ears – cataracts, corneal edema,

tympanic membrane perforation


Deaths due to cold and heat


Heat disorders

Predisposing factors Hot and humid conditions Clothing Drugs Diseases Obesity Alcohol


1. Heat edema

- Mild form- Dependant soft tissue swelling

Peripheral vasodilatation

Pooling of interstitial fluid


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


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.


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


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


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


Cerebellar dysfunction, clouding of senses

convulsions Delirium Speech difficulties Coma


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


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


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.


o Trench foot (immersion foot)- Caused by prolonged exposure- Affected part becomes numb, blue/red

and may swell- Advanced conditions – blisters or open

sores


o Chillbains (pernio)- Redness and inflammation of skin- Acral ulcers- Due to constriction of capillary beds in

skin

electrical injuries, atmospheric lightening, heat & cold disorders dr. shiuli, forensic medicine...

Documents