ELECTOCUTION

Dr. Nouh Hamdan

INTRODUCTION

 Definition:

It’s the INJURY which results from passage of a

substantial electrical current through the tissues.

The injury could be skin lesions, organ damage and

death.
 Deaths caused by electrocution are infrequent.

 Usually are accidents.

 Suicides rare and homicides even rarer.

 Between 2007-2011, the number of electric
deaths per million inhabitants was:
 In Sweden : 0.6
 Denmark: 0.3
 Finland: 0.3
 Norway: 0.2

Kinnunen, Minna (2013). "Electrical accident hazards in the Nordic countries", Tampere University of
Technology
 Data from the National Traumatic Occupational
Fatality (NTOF) surveillance system indicated
that an average of 6,359 traumatic work-related
deaths occurred each year in the United States
from 1980 through 1989; an estimated 7% of
these fatalities were due to electrocutions.
ELECTRICAL CONSIDERATIONS
 Direct current:
 Unidirectional
 circuits and batteries
 medical defibrillation
 Alternating Current

 Bidirectional (alternating back and forth)

 Household electricity
 60 Htz means it alternate 60 times a second.
 Generated by magnet spinning
ALTERNATING VS DIRECT CURRENT
 AC is more dangerous than DC.

 4-6 times more likley to cause death

 a current of 50–80 mA a.c. can be fatal in seconds,

whereas 250 mA d.c. for the same time is often
survived.

 BUT WHY ?
 ‘hold-on’ effect

 results from tetanoid muscle spasm and prevents the

victim from releasing the live conductor.
 the time of contact
 the risk of cardiac & resp. arrest
 Can begin at current as low as 9-10 mA
 AC is also much more likely than DC to cause
cardiac arrhythmias.

 The passage of a.c. at 100mA for only one-fifth of a

second is likely to cause ventricular fibrillation and
arrest. High amperage d.c. (above 4A) may even
cause an arrhythmic heart to revert to sinus rhythm,
as in medical defibrillation.
 Ohm’s Law:

 A=V/R
 Current measured by Ampere
 Voltage
 Resistance(Ohm)
 Current:
 quantity of electricity flowing through an object.
 It’s the most important factor in electrocution

AMPERE EFFECT
1 mA Tingle
5 mA Tremor
15-17 mA Contracture of muscles (no let go )
50 mA Contracture of all muscles (resp. paralysis & death
if sustained)
75-100 mA Ventricular fibrilation (m.c)
~1 A & higher Ventricular arrest
 The usual frequency of a.c. is 50 cycles/second
(cps),

 AC between 40 and 150 cps is most dangerous in

terms of ventricular fibrillation.

 Above 150 cps, fibrillation is progressively less.

 at 1720 cps the heart is 20 times less likely to

fibrillate than at 150 cps
 Voltage:
 the difference in electric potential energy between
two points per unit electric charge

 Residential voltage in the U.S. & Europe is

approximately 110–120 V.
 Residential voltage in the Jordan is approximately
220 V.
 High-voltage lines in suburban and urban areas are
approximately 7500–8000 V.
 Most fatalities occur with the domestic voltage of
240 V.

 It is uncommon to encounter deaths at less than

100V.
 Report case :
 Polson (1963) has reported a fatality at 24 V in a man
pinned beneath an electrical vehicle for several
hours.

 This case emphasizes the importance of the time

element in electrical injury.
 For electrocution from low-voltage (110–120 V)
household current, there must be direct contact
with the electrical circuit.

 with death primarily caused by ventricular

fibrillation.
 In high-voltage accidents, direct contact with the
wire is not necessary.
 As the body approaches the highvoltage line, an
electric current (arc) may jump from the line to the
body.

 Death from high-voltage electrocution is usually

caused by either the electrothermal injury
produced by the current, or respiratory arrest.
The temperature generated by an arc current can
be as high as 40,000ºC
 Resistance:
 The major barrier to an electrical current is the skin.

 R. of skin depend on:

1. thickness of the keratin-covered epidermis
2. dryness or dampness of the skin
PHYSICAL FACTORS
 The severity of tissue damage ‘including death’ is
directly related to a number of physical factors,
including:
 Current
 Voltage
 Resistant
 time
 Pahtway of the current:

 The current enters at one point (most often a hand)

and then leaves the body at an exit point, usually to
the earth or the neutral conductor of the electricity
supply.
 The pathway of the current will depend mainly on
the relative resistance of various potential exit
points.

 It tends to take the shortest route between entry and

best exit, irrespective of the varying conductivity of
different internal tissues
 three major events
may occur, which are
a threat to life:
1. The most common is the passage of a current
across the heart.
 usually when a hand is brought into contact with a
live conductor, and the body is earthed either
through the feet or the opposite hand.

 claimed that the most dangerous is contact with the

right hand and exit through the feet, as this causes
the current to pass obliquely along the axis of the
heart.
  The fatal process is a cardiac dysrhythmia, usually a
ventricular fibrillation ending in asystole.

2. Less often, the passage of a current across the

chest and abdomen.
 may lead to respiratory paralysis from spasm of the
intercostal muscles and diaphragm.
3. Rarely, the current passes through the head
and neck
 usually in circumstances when the head of a worker
on overhead power lines comes into contact with the
conductor.
 In such instances, there may be a direct effect on the
brainstem so that cardiac or respiratory centres are
paralysed.
MODE OF DEATH
1. Cardiac arrhythmias, usually ventricular
fibrillation ending in arrest. (m.c).
2. Respiratory arrest (2nd but far less common).
3. Unknown
 electrical deaths are not observed, the person being
found dead later
4. non-electrical trauma
 injury from falls and other associated trauma.
 Especially in industrial accidents
 suffer violent muscular spasms that may lead to
fractures and other serious injury.
THE CUTANEOUS ELECTRIC
MARK
 Entry site of the current
 The point of contact on the body surface may leave
skin lesions, which are either called ‘electrical burns’
or ‘electrical marks’, “Joule burn”

 Exit site
 Where the body was earthed or grounded
 fatal electrocution may occur with no skin mark
whatsoever, making the diagnosis entirely
dependent upon the circumstances of the death.

 Example: electrocution in the bath, why ?

 the large surface area for entry.
 low skin resistance caused by the water.
 An electrical mark may not be externally obvious,
as the current can be applied to:
 the genitals, anus or abdomen in sexual perversions
 through the mouth, especially in children.
 Infants may place a live plug between their lips and
sustain electrical burns on the tongue or buccal
mucosa.
 When a current passes, there may or may not be
a visible lesion, depending upon:

 the density of the current passage in terms of skin

area.

 the conductivity, usually varying with the moisture

content.
 The skin lesion is a thermal burn from heating of
the epidermis and dermis as the current passes.

 Theoretically, the heat generated can be

determined from the formula :
 GC = C2R/4.187
GC is the heat in gram calories per second
 C is the current in amperes

 R the resistance in ohms.

 The temperature in the tissues directly under the
contact point can easily reach 95°C.

 Tissue damage can occur within 25 seconds when

the temperature reaches a mere 50°C.
 Collapsed blister:
 The collapsed blister is
often annular
 producing a raised grey
or white ring with an
umbilicated centre.
 The mark sometimes
reproduces the shape of
the conductor
 Sparked lesion:
 When the time has been prolonged, the voltage is
high, or the conductor is large, the burn may be
correspondingly severe with:
 large areas of peeled blistered skin.
 charred keratin.
 a mixture of hyperaemia, deep scorching and shed
epidermis.
 deep muscle damage and cooking of the tissues.
 Multiple electrical
burns on a hand, with
blisters showing the
typical pale raised
margins and areas of
peeling epidermis.
There is a blackening
from metallization as
the current was
passing for several
hours; the victim was
an electrician who fell
into an air-
conditioning plant
 Crocodile-skin effect:
 In high-voltage burns
 caused by arcing of the current over a considerable
distance
 A characteristic feature of the electric mark
(pathognomonic), which is the most useful
indicator of the nature of the lesion, is the
common occurrence of an areola of blanched skin
at the periphery.
 Presumably because of arteriolar spasm from the
direct effects of the current on vessel wall
musculature.
 Often there is a hyperaemic border outside the
blanching, though reddening may also be seen
inside the pale zone, as the outermost rim of the
heated burn area.
 Occasionally, an alternating spectrum of blister
reddening- pallor-reddening can be observed
centrifugally from the centre of the lesion.
Exit marks :

Itis grayish white circular spots, firm to touch

& free from inflammatory reaction .

The wound of exit may show splitting of skin in

form of puncture or lacerated wounds instead of
formation of blisters as in entry wound.
PATTERNED ELECTRIC MARKS
 Electric conductor may leave its impression or
pattern on the skin, From the pattern of
electrical injury

 These marks may be useful when the pathologist

tries to reconstruct the events.
METALLIC TRACES IN
ELECTRICAL MARKS
 When a current passes from a metal conductor
into the body, a form of electrolysis occurs so that
metallic ions are embedded in the skin and even
in the subcutaneous tissues.

 These can be gross and observed directly on the

skin
 Can be invisible to the eye, but detectable by
chemical, histochemical and spectrographic
techniques.
 They persist for some weeks during life and resist
a moderate amount of post-mortem change.

 In high-voltage contacts, the skin of a wide area

may be brown or greyish, partly from heat
effects, but partly from metallization
 Can be detected by:
 Scanning microscope.
 Chemical tests for metallic deposits.
AUTOPSY
 External appearance:
 Skin lesions.
 The body is pale or slightly congested.

 Internally:
 Congested lung
 Petechiae on epicardiam, pleura and intracerebral

 Laboratory findings, Electron microscopy,

Histochemical .
LIGHTNING

 Lightning deaths cannot be other than

accidental.
 Cutaneous marks may be present:
 ‘fern-like’ or ‘arboresque’ pattern, also referred to as
‘Lichtenberg’ ( less common).
 Irregular red marks, often linear first-degree burns,
may follow skin creases, especially if damp from
sweating. These marks may be many inches long and
generally follow the long axis of the body towards the
ground.
 Frank blistered or charred burns are also present in
some cases.
 The clothing may be torn off.

 Metal objects in the pockets may be fused or

Magnetized.

 Burns on the skin may be adjacent to metal

objects in or on the clothing.
 There is often a smell of burning about the body
and its clothing.

 The hair may be scorched.

 there is often a head injury, caused either by the

lightning strike itself or by falling to the ground.
 Thank you