Electrocution

RUCHIT PATELSecond M.B.B.S.

Government medical college Bhavnagar

Electrocution is death caused by electric shock, electric current passing through the body.

The word is derived from "electro" and "execution", but it is also used for accidental death.

The word is also sometimes used to describe non-fatal injuries due to electricity.

Electrical injuries can be Trivial or fatal Observable or inconspicuous or absent

High voltage –more than 1000v Low voltage – less than 600v

AC – 60 Hz DC-

battery current-

High voltage electrocution – extensive burns, therefore, little difficulty for

forensic pathologists for diagnosis.

But serious problem in Low voltage household AC current- die with little

or no visible injury (35-50% no electrical burns)

DEATHS due to LOW VOLTAGE ELECTROCUTION (DOMESTIC)

1. Incidence SL - Not frequent

Time of the year – more when hot Less clothes and barefooted, More sweat and less resistance

2. Circumstances1) Accidental- most.

2) Suicidal – rare,

3) Homicidal- usually in bathtubs.

4) Sexual – electrode is fixed at anus or penis.

5) Judicial (Electrical chairs)- as capital punishment started in New York in 19th century. Still used in some states of USA. 2000v with 10 amp PM- marked, burns on skin and tissues.

3 elements required simultaneously for electrocution

Electrical source Current pathway through the body Grounding

No harm if well insulated from ground, eg. Birds sit on high tension wires with no effect.

Effects of current depends on the amount of amperes.

If 1mA- felt (tingling of the fingers) If 5mA-

tetanic contractions and hence grab the power conductor (no-let-go threshold),

hence increase the duration of contact and die.

15mA- control over muscles is lost

If 50mA- loss consciousness, severe muscles contractions, hence can lead to traumatic asphyxial and

even fractures in bones.

If 70mA- fatal

Predisposing factors of domestic electrocution

1. electrical appliance attached to electrical circuit,

2. AC> DC (6:1)

3. Voltage

4. Amperes (I)

5. Resistance (R)– if increase-

increase local injury due to more heat generation, but decrease the entry of ampere amount and decrease fatality.

If decrease- decrease local injury due to less heat generation but increase the entry of amperes and hence the fatality.

6. Duration of contact If prolong- severe injuries If short- less injuries

7. Surface area of contact

8. Pathway of current through the body. a. hand to hand or b. hand, heart and feet, c. hand, chest wall and feet, d. hand brain and scalp etc

When current flows through the body, it takes the shortest and least resistance pathway.

If Hand to head –current goes through brain – respiratory centre paralysis (can die immediately),

If Hand to leg – current goes through heart- ventricular fibrillation (need few seconds of contact to die), loose

consciousness in 10 –15 seconds, as the brain has oxygen reservoir for 10- 15 seconds, with out cardiac output. Therefore can cry out for help or shout, some times can disconnect by him.

If Hand to hand – current goes through chest wall muscles, resulting continuous contractions or spasms of inter costal muscles

and diaphragm - leading to traumatic asphyxia (need several minutes of contact to die)

Clinical features Depends on

amount of Ampere and the pathway within the body, Complications

Amount of Amperes depend on

1. Skin resistance- Insulating effect of skin eg. Dry thick skin (palm or sole) - 1 million ohms.

Dry normal skin – 100,000 ohms.Moist thick skin (palm or sole) – 1000 ohms,Moist normal skin – 100 ohms.

2. Also depends on clothing-eg, rubber gloves or boots act as insulators, hence protective.

3. Complications 1. Blood and blood vessels

less resistance Heat of the current cause

Break up RBC and WBC Activate platelets Damage endothelium of Blood vessels

If survive Can cause thrombosis of the BVs eg. Right brachial A.

2. Bones If high voltage- fractures due to forceful muscles

contractions

Cutaneous Injuries & Burns Extensive flash and flame burns

Hemodynamic, autonomic, cardiopulmonary, renal, metabolic and neuroendocrine responses

Nervous System Loss of conciousness, confusion & impaired recall

Peripheral motor & sensory nerves deficits.

Seizures, visual disturbances & deafness.

Hemiplegia, quadriplegia, spinal cord injury.

Transient paralysis, autonomic instability.

Respiratory System

Direct injury to the respiratory control center cause cessation of respiration or suffocation.

secondary to tetanic contractions of the respiratory muscles.

Acute respiratory dysfunction syndrome secondary to

- Ischemia- Aggressive fluid resuscitation - Ventilator-associated pneumonia

Other Systems Kidneys susceptible to anoxic/ischemic injury.

Release of myoglobin & creatinine phosphokinase renal tubular damage renal failure

Fractures.

Transient autonomic disturbances fixed pupils may be perceived as severe brain injury or even death.

Temporary sensorineural hearing loss.

Mechanisms of death- 1. If current travel through brain/ spinal cord

brain centres paralysed and die. if interferes with respiration, asphyxial death

2. If current travel through heart VF and cardiac arrest, even with ventricular fibrillation and die

even with 120v for split of a second. 3. If current travel through the chest wall

Direct paralysis of chest muscles – asphyxial death (traumatic asphyxia)

PM findings

Usually reveals no specific results some times can cause cadavaric spasm

(instantaneous rigor mortis) of affected body part.

Examination of clothing- burns

Post-mortem findings Depend on ........ 1. Thermal effect

( mainly due to resistance( R) – cause local burns.

2. Electrical effect (mainly due to current (Amperes) –

cause death

Entry wounds1. Joule burns- contact is needed.

Due to cooking effect on tissues. Elevated crater with charred centre. It is the collapsed blister.

May be patterned entry wound. Surrounded by Pale peripheral halo and further

surrounded by red halo. Blood pushed out due to heat.

2. Spark burns – contact is not needed. If there is a gap between the conductor and the body, there can be arcing

3. Odour - Fresh burns have a characteristic odour - burnt cork.

Joule and spark burns

4 Arcing of eyes and face– it is erythema of the face with burns of the eye lashes. (this is due to radiant heat released from current.

Severe thermal denaturation of the collagen- stains blue with haematoxylin.

Internal findings Pulmonary and cerebral oedema (increase

weight) - due to VF or asphyxiation. Visceral petechiae- asphyxiation Muscle damage and fractures- Some times

muscle contractions could lead to muscle damage and fractures.

Exit wound- Usually a split. Usually on soles. (if the exit site is wet, there may be no exit injury)

Thank You !