Electrocution (Electrical Injuries): Symptoms, Types, Causes of Death, Joule Burns and Flash Burns

Electrocution is the very destructive form of injuries resulting from high voltage current passing through the body. The severity of electrical Injuries varies from a transient unpleasant sensation due to brief contact with low-intensity household current to instantaneous death and massive injury from high-voltage electrocution.

Severity and type of electrical injury depends on various factors -

(1) Type of current - Alternative current (A.C) is more dangerous than the Direct current (D.C) because A.C have "hold on effect" when a person touches A.C source his hand muscles undergo tetanus spasms and he is unable to release the source until the supply is turned off. A.C also causes ventricular fibrillation and cardiac arrest. High voltage D.C. is used in defibrillator

(2) Pathway of Current - If Person's right hand is in contact with the source of current then current passes obliquely through heart and exit through feet and chances of death are more because it causes cardiac arrhythmia.
   Sometimes current passes across the chest and abdominal wall which results in respiratory paralysis.

(3) Duration of Flow-  It is directly proportional to the severity of the injury.

(4) Amount of current - The amount of current is expressed as Ohm ’s law:  I  =  V/R,  where  ‘I’  is current  (amperes  [A]),  ‘V’ is voltage (volts  [V]) and  ‘R’ is resistance (ohms).  The flow of the current is great, voltage is high or if resistance is low. Electrocution is rare at <  100  V almost deaths occur at > 200 V. Amperage is more important, as it indicates the actual intensity/amount of electricity which passes through the body.



Effects due to Passage of Electricity -

(1) Local Effects:-

1. Burns and Blisters - These are seen on skin and termed as joule burns. It is seen as puckering of skin around the edges of the electrical burn and the red line is absent around the lesion and it is also not seen at the point of entry and exit of electrical current.

Joule burns- These blisters are produced due to heat generated within the tissues and termed as endogenous burns. Joule burns are characteristics of electrical burn. These are rounded or oval marks irregular in shape 1-1.5 cm in diameter and seen at the point of entry of electrical current.


2. Flash or Spark burn/crocodile skin - High voltage current can jump across the air. If the gap between source and skin is very small (few millimeters) then current reaches to skin and produces very high temperature and causes the outer skin keratin to melt over small areas. On cooling, melt keratin fuses to form hard multiple brownish nodules and look like crocodile skin. The current jumps the gap like spark that's why it is called spark burn/flash burns.

3. Wounds - lacerated and punctured wounds With contusions of margins.

4. Metallic luster - the heat generated at the site of entry may cause atomization of the metallic wire which may give a metallic luster.

(2) Systematic Effects:-

Shock, headache, aphasia, vertigo, hemiplegia, optic atrophy, suspended animation like state

Cause of Death -

  • Ventricular Fibrillation
  • Paralysis of respiratory muscles
  • Secondary causes like infections, septicemia
  • Effects on brain stem

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