130. Electrical and Lightning Injuries Flashcards
What law describes the amount of thermal energy applied to tissue from electricity?
Joule’s
Joule’s law equation
P= I^2RT
p - thermal energy
I current
R is R
T is time/duration applied
What is current
flow of e down electrical gradianet
measured in amperage
What is the most important factor to determine degree of E transmission?
current
Ohm’s law
I = V/R
I is current
V is voltage, R is R
Ohm’s law describes
current’s relationship direct to voltage, inverse to R
Low voltage in NA
120-240
High voltage findings of injury
partial to full thick burn
deep tissue destruction
potential cardiac/resp arrest
Current types - 2 main
direct - flow one direction or AC - alt, cyclical at varying frequencies
Exposure to DC current - most common response?
one sharp m contraction
Which type of current is more dangerous?
AC
due to fact that amerage above so called “let-go” current will cause muscular tetanic contractions - flexor m stronger than ext so pull victim closer for prolonged exposure
What are capacitors?
store electirc charge in circuits
discharge from this in large burst
What mA can you have usual “let go” current?
6-9
What mA can you have maximum grasp and let go?
16
What mA can you have paralysis resp m
20
What mA can you vent fib?
100
What A can you have cardiac standstill and internal organ damage?
2
Lowest R of body tissues to highest
nerve
bl vessel
m
skin
tendon
fat
bone
Do burns accurately est level of injury on surface?
no - as blisters, decr skin R and current travels faster/further
Dry to wet skin change in R?
fold of 1000 ish - 10 000 to 1000 when wet
What does pathway of electrical current determine?
morb and mortality
“source and ground contact points”
Electrical current passing through a limb causes greater local tissue damage than current passing through the trunk because …
smaller cross sectional area limits ability to dissipate heat
Why does electrical current traveling through trunk cause further mortality than limb?
more vital organs
What is the flashover effect in lightning injuries?
lightning strikes involve hundreds of millions of volts, significantly more than those from elec- trical sources. In contrast, the duration of contact is drastically shorter, averaging 30 microseconds. As a result, current flow is altered, with most of the energy passing over rather than through a victim (termed the “flashover effect”)
Most unusual form of lightning?
ball
most unusual form is ball lightning, which appears as a globe, rolls along structures, and may even pass through open doors or windows.
What incr a person’s chance of being struck by lightning?
person’s chances of being struck are increased by wearing or carrying metal objects (such as golf clubs or umbrellas) or other conductors. Current from lightning may reach the body indirectly by traveling through a tree or other object (contact voltage), through the ground or even through the air from a struck object (side flash, or splash injury). Side flashes may travel as far as 30 meters.
Stride voltage definition
The risk of injury from a ground strike is increased when one con- tact point on the victim (e.g., the right foot) is closer to the strike than a second contact point (e.g., the left foot), thus creating a potential differ- ence.
How to decrease risk of stride voltage/lightning strike risk?
- Seek shelter inside an enclosed building or metal-topped automobile.
- Avoid large flat, open areas or hilltops.
- Avoid contact with metal objects and remove metal objects, such as jew-
elry or hairpins. - Avoid trees, boats, and open water.
- If caught on open ground, curl up on your side with hands and feet close
together to reduce contact points, or squat with feet together. If possible, place a rubber raincoat under your body or feet to reduce ground current effects. - If in a forest, seek shelter under a thick growth of shorter trees.
- If indoors, avoid the use of wired phones and contact with plumbing or
electrical appliances.
Conducted energy weapons mc known as ?
taser
