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”)