130. Electrical and Lightning Injuries Flashcards

1
Q

What law describes the amount of thermal energy applied to tissue from electricity?

A

Joule’s

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2
Q

Joule’s law equation

A

P= I^2RT
p - thermal energy
I current
R is R
T is time/duration applied

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3
Q

What is current

A

flow of e down electrical gradianet
measured in amperage

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4
Q

What is the most important factor to determine degree of E transmission?

A

current

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5
Q

Ohm’s law

A

I = V/R
I is current
V is voltage, R is R

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6
Q

Ohm’s law describes

A

current’s relationship direct to voltage, inverse to R

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7
Q

Low voltage in NA

A

120-240

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8
Q

High voltage findings of injury

A

partial to full thick burn
deep tissue destruction
potential cardiac/resp arrest

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9
Q

Current types - 2 main

A

direct - flow one direction or AC - alt, cyclical at varying frequencies

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10
Q

Exposure to DC current - most common response?

A

one sharp m contraction

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11
Q

Which type of current is more dangerous?

A

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

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12
Q

What are capacitors?

A

store electirc charge in circuits
discharge from this in large burst

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13
Q

What mA can you have usual “let go” current?

A

6-9

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14
Q

What mA can you have maximum grasp and let go?

A

16

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15
Q

What mA can you have paralysis resp m

A

20

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16
Q

What mA can you vent fib?

A

100

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17
Q

What A can you have cardiac standstill and internal organ damage?

A

2

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18
Q

Lowest R of body tissues to highest

A

nerve
bl vessel
m
skin
tendon
fat
bone

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19
Q

Do burns accurately est level of injury on surface?

A

no - as blisters, decr skin R and current travels faster/further

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20
Q

Dry to wet skin change in R?

A

fold of 1000 ish - 10 000 to 1000 when wet

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21
Q

What does pathway of electrical current determine?

A

morb and mortality
“source and ground contact points”

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22
Q

Electrical current passing through a limb causes greater local tissue damage than current passing through the trunk because …

A

smaller cross sectional area limits ability to dissipate heat

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23
Q

Why does electrical current traveling through trunk cause further mortality than limb?

A

more vital organs

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24
Q

What is the flashover effect in lightning injuries?

A

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”)

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25
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.
26
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.
27
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.
28
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.
29
Conducted energy weapons mc known as ?
taser
30
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
31
Risk of taser use?
neuromuscular incapacitation - general muscle contraction
32
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
33
Delayed complications of lightning strike injuries
sepsis ARF wound infection amp
34
MC heart rhythms post electrical injury
vfib asystole
35
What are lightning strike injuries more likely to cause?
blunt injury or CP arrest from transient stunning
36
What do burns of electrical injuries look like at surface?
punctate, central depression, necrosis
37
What is an arc burn?
electrictiy jumps from skin to skin, typically across flexed area
38
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
39
Lightning strike: typical burn injury skin vs deep %
95% vs 5
40
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
41
MC cause of death from electrical injury?
C/R arrest
42
Why would resp arrest occur after a electrical injury?
tetanic paralysis of resp muscles/diaphragm or if brainstem resp centres knocked out
43
Electrocution: immediate dysthrmias common - examples
brady sinus tach afib ectopic QT prolongation can get transient STE or dep without specific area correlating
44
Lightning strike: akin to what in medicine for cardiac arrest pt?
defib
45
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
46
Head and neck injuiries - most frequent manifestion occular?
cataracts
47
Head and neck injuries: ddx occular
cataracts vitr and ant ch hemorrhage retinal detach macular lac FB coreneal or conjunctival burns
48
Head and neck injuries: what kind of hearing loss can you get?
mc snhl
49
Head and neck injuries: lips?
full thickness burn possible, particular in children
50
Head and neck injuries: do tympanic membranes commonly rupture?
yeah
51
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.
52
Injuries to the extremities in electrical injury?
M necrosis from compromised blood supply watch out for aneurysm rhabdo --> **compartment syndrome risk! fracture/bone injury
53
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
54
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
55
Keuraunoparalysis from lightning strike?
flaccid paralysis with extremities appearing cyanotic, mottled, pulseless typically prognosis is recovery within min to d
56
Electrical damage - sign m damage may cause?
myoglobinuria, renal failure life thr hyperK
57
What if you're pregnant and hit by lightning?
unclear on fetus - mat fetal monitoring
58
After hit with a taser, what do you need to find?
barb
59
<15s of taser exposure - risk of cardiac arrest?
low
60
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
61
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
62
If trop elevated in these pt, how long to watch?
12-24 hour tele and echo
63
When to monitor pt with electrical exposure for 12-24h?
high voltage electruction LOC dysrhythmia abnormal ecg
64
**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.
-
65
IN PT WHO ARE AWAKE Awake and alert, asx, had taser exposure <15s - what to tesdt?
none but careful if intox, AMS, psych condition
66
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.
67
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
68
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.
69
Remember that patients can present with __extremities per DC injury, so should not use this to cease resus
mottled/cyanotic
70
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
71
*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.
-
72
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.
73
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.
74
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.