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
How does a taser work?
hand held unit with 2 barbs and connecting cable that are deployed up to 25 feet
delive a 5s burst of E
Risk of taser use?
neuromuscular incapacitation - general muscle contraction
How does electrical injury cause injury on a clellular evel?
damage to membrane and alers its solubility, so lyte abnormality occurs
–> eventually irreversible cell damage and death
Delayed complications of lightning strike injuries
sepsis
ARF
wound infection
amp
MC heart rhythms post electrical injury
vfib
asystole
What are lightning strike injuries more likely to cause?
blunt injury or CP arrest from transient stunning
What do burns of electrical injuries look like at surface?
punctate, central depression, necrosis
What is an arc burn?
electrictiy jumps from skin to skin, typically across flexed area
What kind of burns can electrical injury pt get?
catch fire themself - thermal injury
\flash burn by brief strong light
cutaneous burn across chest and upper abdo and bad as transthoracic current concerning
Lightning strike: typical burn injury skin vs deep %
95% vs 5
Typical pattern of burn from Lightning strike?
fernlike/erythematous straks of first degree burn “Lichtenberg figures”
deeper if wearing metal at that site of contact
maybe you catch on fire too
MC cause of death from electrical injury?
C/R arrest
Why would resp arrest occur after a electrical injury?
tetanic paralysis of resp muscles/diaphragm or if brainstem resp centres knocked out
Electrocution: immediate dysthrmias common - examples
brady
sinus tach
afib
ectopic
QT prolongation
can get transient STE or dep without specific area correlating
Lightning strike: akin to what in medicine for cardiac arrest pt?
defib
Lightning strike: what might actually cause death from cardiopulmonary arrest
myocardial cells only briefly stunned
if hits medulla its probably central apnea and might last longer than cardiac stanstill –> hypoxia
Head and neck injuiries - most frequent manifestion occular?
cataracts
Head and neck injuries: ddx occular
cataracts
vitr and ant ch hemorrhage
retinal detach
macular lac
FB
coreneal or conjunctival burns
Head and neck injuries: what kind of hearing loss can you get?
mc snhl
Head and neck injuries: lips?
full thickness burn possible, particular in children
Head and neck injuries: do tympanic membranes commonly rupture?
yeah
Head and neck injuries: other effects of inner ear?
hearing loss, tinnitus, vertigo, and nystagmus.
Specific injuries include avulsion of the mastoid process, ossicle dam- age, rupture of the Meissner membrane, and strial degeneration.
Injuries to the extremities in electrical injury?
M necrosis from compromised blood supply
watch out for aneurysm
rhabdo –> **compartment syndrome risk!
fracture/bone injury
Injuries to the nervous system in electrical injury?
altered mental status
seizure
coma
sleep/anxiety disturbances
Brain - cerebral infarction, ICH
Delayed and chronic manifestations include ascending paralysis, transverse myelitis, and amyotrophic lateral sclerosis (ALS). Peripheral neuropa- thies are a common result, most often involving the median an
Lightning strike injury - specific neuro sequelae?
apnea
skull fracture
ICH and extra cerebral hematomas
cerebral edema nad elevated ICP
later:
cerebellar ataxia
horner
cognitive dsyfunction
FN palsy
neuritiss
neuralgia
Keuraunoparalysis from lightning strike?
flaccid paralysis with extremities appearing cyanotic, mottled, pulseless
typically prognosis is recovery within min to d
Electrical damage - sign m damage may cause?
myoglobinuria, renal failure
life thr hyperK
What if you’re pregnant and hit by lightning?
unclear on fetus - mat fetal monitoring
After hit with a taser, what do you need to find?
barb
<15s of taser exposure - risk of cardiac arrest?
low
Findings suggestive of a lightning strike - pt “unknown” into resus: will see…
Clothing wet from rain
Tears or disintegration of clothing
Multiple victims
Typical arborescent pattern of erythema or superficial linear or punctate burns
Tympanic membrane injury
Cataracts, especially in a younger patient
Magnetization of metallic objects on the body or clothing Electrocardiographic changes
Recommended labs/tests for electrical injury?
ECG
CBC
Chem10
trop and myoglobin
urine analaysis for myoglobinuria
intra abdo suspected - LFT and LE
radiograph if painful limb
CT if concern for further trauma brain, pelvis, thoracic, etc
If trop elevated in these pt, how long to watch?
12-24 hour tele and echo
When to monitor pt with electrical exposure for 12-24h?
high voltage electruction
LOC
dysrhythmia
abnormal ecg
**The Wilderness Medical Society has recommended that an electrocar- diogram (ECG) be obtained on lightning strike victims with high-risk indicators, such as suspected direct strike, loss of consciousness, focal neurologic complaint, chest pain or dyspnea, associated traumatic inju- ries, pregnancy, or burns of the cranium or legs or on more than 10% of the total body surface area.
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IN PT WHO ARE AWAKE Awake and alert, asx, had taser exposure <15s - what to tesdt?
none
but careful if intox, AMS, psych condition
Low-voltage electrical injuries associated with minimal signs and symptoms generally require only local wound treatment and patient reassurance. The treatment of other patients is directed at the …
organ systems involved.
Patients who present in cardiopulmonary arrest should be resusci- tated, regardless of cardiac rhythm, because favorable outcomes have been documented even with patients presenting in __
asystole
Specific monitoring helpful to electrical injury patients?
usual abc
Intravenous crystalloid fluids are given to maintain adequate urine output (over 100 mL/hr in adults and 1.5 to 2 mL/kg/hr in young children). Serum potassium levels should be closely monitored in patients with acute renal injury or myoglobinuria.
Remember that patients can present with __extremities per DC injury, so should not use this to cease resus
mottled/cyanotic
What patients in ED from lightning strike injury do not require treatemtn?
no sx or signs
inlcyding minor first. degree burns
only if ecg shows abn
*Lightning strikes can result in a spectrum of peripheral and central neurologic injuries, including pupils that are fixed and dilated in the absence of irreversible brain injury. This factor should be kept in mind when deciding when to discontinue resuscita- tive efforts in patients who present in cardiac arrest.
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Lightning strikes can cause extensive catecholamine release or autonomic stimulation, resulting in transient hypertension and tachycardia that can be treated with …
with β-adrenergic blockers and hydralazine or with alpha-2 adrenergic
agonists such as clonidine, to reduce adrenergic excesses.
Peds pt. dispo
Pediatric patients with oral electric injuries are usually hospitalized for hydration, wound and pain management, and plastic surgery con- sultation. Patients with minor burns confined to the oral commissure can be discharged with close follow-up but should be provided with information regarding the possibility of delayed labial artery bleeding, which can be managed by the parents with direct wound pressure and return visit instructions.
Taser exposure dispo
For patients who have had CEW exposure for greater than 15 sec- onds, there is limited experience and no clear guidelines exist, so an observation period of 6 to 8 hours is a reasonable approach.
