Death or severe injury caused by electric shock passing through the body is known as Electrocution. Electric burns are a kind of thermal injury. The tissue damage associated with an electric injury occurs when electric energy is converted to thermal energy or heat. Accidental death due to electric currents was not reported until 1879.
The direct current is comparatively less dangerous than the alternative current. The AC between 40 to 150 cps is most dangerous. A current of 50- 80 mA of AC can be fatal within seconds whereas 250 mA DC is non-fatal. The cause of death in electrocution is ventricular fibrillation, tetanic asphyxia, respiratory arrest, cardiac arrest, cerebral anoxia, burns, secondary injuries sustained. When high voltage current is passed through the body, death happens due to arching of electric current or due to ignition of clothes.
When electric current passes through the body it can cause injuries like contact injury, spark burn injury, flash burns. The point of contact acts as the entry site for the current. In some cases, we can observe the entry and exit wound, and sometimes it cannot be seen because of the larger acting surface and low resistance exhibited by the body. Tissue temperature is a critical factor in determining the magnitude of tissue injury before the current ceases.
Features of Electrocution
- The appearance of an areola or pale halo around the electric mark is due to the arteriolar spasm because of the direct effect of current on vessel wall musculature. It is considered as pathognomonic of electrical damage.
- If it is due to direct contact then there are chances of the electric conductor to leave its impression or pattern or shape on the skin. This will help in identifying the causative appliance.
- Metallic traces in the electric mark can be seen because when an electric current passes from a metal conductor, electrolysis occurs due to which the metal ions get deposited in the skin and subcutaneous tissue at the point of entry. They combine with tissue anions and form metal salts. They can be visible to the naked eye as a bright green imprint otherwise they can be detected by chemical, histological, histochemical, or spectroscopic examinations.
Lesion Produced by Electrocution
1. COLLAPSED BLISTER: This occurs when the epidermis or the epidermal-dermal junction splits due to the steam produced when the tissue fluid heats up when the skin offers resistance to the heat produced while the electric current passes through the skin. When current ceases, the blister cools and collapses which appears circular, producing a raised gray or white ring or margin with an umbilicated center.
2. EXOGENOUS BURNS: This occurs in burns due to high voltage current, usually when the clothes get ignited.
3. ENDOGENOUS BURNS: These are also known as Joule burns. This is a contact injury when the electric conductor is in contact for a prolonged period, it leaves a brownish color on the skin. This can be seen at the site of the entry of current.
4. EXIT MARKS: They appear to be grayish-white circular spots. They are firm to touch and do not have inflammatory reactions. It may look like a punctured or lacerated wound. If the exit wound is on the feet, the shoe may get torn and the sole of the feet will be lacerated.
5. SPARK LESION: When the contact is not firm and there is a small gap between the conductor and the skin, the current jumps the gap as a spark. This causes lesions as the outer skin keratin melts and fuses into hard brownish nodules with a surrounding areola or pale halo.
6. CRATER LESION: When the voltage of the current is low or medium a crater is formed which is round/oval, shallow, electric mark bordered by a ridge of the skin of about 1 to 3 mm height.
The appearance of electric lesions depends on the density of the current passage in terms of skin area and the conductivity of the skin which mostly varies based on the moisture content of the tissue.
The factors that influence the appearance of these electric marks are voltage, ampere, resistance, nature of the current, duration of the current, alertness of the person, point of entry, earthing, area of contact. Internal examination of the body of a person who died due to electrocution will reveal congested organs, pulmonary edema, petechial hemorrhages over the pericardium, pleura, or brain.
Most of the deaths due to electrocution are accidental and most of the fatalities occur while working. Cases of suicide and homicide are also reported. In some countries, judicial electrocution is used for death execution. It is also used for child abuse.
Low voltage currents are employed as a method to torture a person in custody. The features and the injuries help to understand the cause of death.