Transcript Accidents in home and environment

Accidents in home and environment
Accidents in home and environment
Accidents in home
and environment
Cold
Heat
Electricity
Accidents in home and environment
Electricity
1 Domestic – 110-240 v
2 Industrial – 440-22000 v
3 Lightning – 106-1012 v
Accidents in home and environment
Electricity
Variables in electric shock
Variables in the current
Direction
Resistance
Frequency
––current
depends
upon
Voltage – of
low
voltage or
domestic current
alternating
amperage
50 cps
or ac
Hertz
high
voltage
or industrial current
direct
contact
60 cps
dc orhigh
Hz voltage or lightning
extremely
area involved
Accidents in home and environment
Electricity
Variables in electric shock
Variables in the contact
Resistance of area in contact – wet or dry
Duration of current flow
Pathway of current in the body
Extent of area involved
Accidents in home and environment
Accidents in home and environment
High voltage burns
Accidents in home and environment
High voltage burns
Accidents in home and environment
High voltage burns
Accidents in home and environment
Automobile burns
Accidents in home and environment
Automobile burns
Accidents in home and environment
Low voltage
burns
High voltage
burns
Accidents in home and environment
Accidents in home and environment
High voltage burns
Accidents in home and environment
Lightning
Accidents in home and environment
Lightning
Accidents in home and environment
Hazards in the bath room
Accidents in home and environment
• Electrical burns can be usefully divided into;
• Flash burns – typically superficial
• Contact burns – may be negligible surface burning but
deeper tissue damage due to the conduction of
electricity through tissue plains. These burns can be
further divided into high tension or voltage and low
tension/ voltage burns.
• Electrical conduction through tissues causes damage
due to the conversion of electrical energy to thermal
energy, the amount of which is dependant upon tissue
resistance and the potential difference across it.
• Local injury is seen at the points of current entrance and
exit (often the hands and the feet, where the body has
been ‘earthed’ or grounded). In the case of high voltage
injuries the burn may be caused by the conversion of
electrical to thermal energy at the air interface adjacent
to the body (Cooper 2003 p.191).
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Accidents in home and environment
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• The passage of current through the body may also induce
cardiac arrhythmias, hence the need to admit and observe all
victims of electrical injury (Britto et al 1999 pp.112-113).
• Low voltage/ tension burns are caused by domestic and light
industrial supplies of 240V and 415V respectively. Contact
skin burns are seen at both entrance and exit points, and
should be closely looked for. Full thickness burns with deeper
structure involvement may be seen ( Greaves et al 2001
p.214, Barret and Herndon 2001 pp. 14-16).
• High voltage/ tension burns may be associated with massive
tissue destruction at entry and exit points leading to muscle
contractures requiring fasciotomies and possibly amputations.
There can also be secondary ignition of clothing resulting in
extensive cutaneous burns of a lesser degree.
Accidents in home and environment
Current
•
Thermal energy generated
is proportional to the
square of the current,
the resistance and the
duration of exposure
(Joules Law). As the
current is increased there
is the sensation of
tingling (<0.5 mA), pain
(5 mA), involuntary
muscle contraction/ hand
spasm etc (10 - 16 mA),
loss of consciousness (40
mA), and death (50 - 80
mA).
Accidents in home and environment
Voltage
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Skin provides resistance to
current flow, causing
electrical energy
conversion to thermal
energy. The greater the
thickness of keratin the
greater the resistance.
Sweating however
reduces resistance.
Accidents in home and environment
Time
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1st degree burns may
occur with low
voltage contact of a
few seconds, whilst
the longer the
contact, the more
severe the burn and
the greater the risk
of arrhythmias
developing
Accidents in home and environment
Type of
current
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AC is more
dangerous than
DC (at the same
voltage)
Accidents in home and environment
Route of the
current
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Passage of current
through the chest
is associated with
an increased
mortality
(arrhythmias)
compared with
passage through
the limbs
Accidents in home and environment
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• Low voltage electrical injuries are typically
shallow craters with blistering (often surrounded
by a rim of hyperaemia). Prolonged contact can
result in higher degrees of injury.
• At higher voltages, more extensive burn wounds
are seen, and often no contact is required due to
the phenomenon of ‘arcing’. Temperatures can
reach 2500°C and this causes keratin to melt,
producing a brown nodule (Cooper 2003 p.193,
Knight 1999 p.322, Family Practice Notebook
2003).
• Severe ‘flashover’ burns can also result from
high voltage sources
Accidents in home and environment
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• Lightening strikes can characteristically
give rise to a patterned surface burn,
resembling a feather or a fern
('Lichtenberg figure'). However, they are
frequently absent, and so collateral
evidence is often required when
diagnosing this type of injury.
Accidents in home and environment
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