Transcript Lightning Injuries in the Backcountry

Lightning Injuries in the
Backcountry
Remote Areas Emergency Medicine
and Survival
Content
•Lightning Fact and Figures
•Lightning Myths
•Epidemiology
•Mechanism of Injury
•Pathophysiology
•Management
•Prevention
Lightning Facts
• There are 1,800 thunderstorms on the
earth at any moment
• Equates to 16 million storms each year
• An average of 25 million strokes of
lightning from the cloud to ground every
year in the U.S.
Lightning Facts
• Lightning temps ~8,000 - 50,000° C
• Leader stroke travels one-third the speed of light
• Leader stroke est. 3-8 cm in diameter
• Lasts .01 - .001 of a second
• 10 to 200 million Volts
• Up to 200,000 amps
Lightning Facts
Lightning Facts
Lightning Facts
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Lightning can strike even if it is not raining
 Can strike in front of or behind storm
Known to strike as far as 10-25 miles from the storm
 “Bolts from the Blue”
 “Out of the Clear Blue Sky”
Can strike in sunny conditions after storm
Lightning Myths
Lightning Myths
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If it is not raining, there is no danger from
lightning
Rubber soles of boots or rubber tires on a car will
protect you from being struck by lightning
People struck by lightning carry an electrical
charge and should not be touched
Lightning Myths
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Lightning is always fatal
Lightning turns victims into “crispy critters”
Lightning never strikes the same place twice
Victims bodies remain in “suspended animation”
Lightning Myths
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If caught in a lightning storm outside, it is
better to seek shelter under an isolated or
small group of trees than to remain out in
the open.
Heat Lightning is harmless and poses no
threat to anyone
Epidemiology
Epidemiology
Epidemiology
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84% M, 16% F
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June, July, August
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Wed/Sat/Sunday
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2-6 pm
Odds of Becoming a Victim
Odds of being struck by lightning in a
given year (reported deaths + injuries)
1/700,000
Odds of being struck by lightning in
a given year (estimated total deaths + injuries)
1/400,000
Odds of being struck in your lifetime
(Est. 80 years)
1/5000
Odds you will be affected by someone being struck
(Ten people affected for every one struck)
1/500
Mechanism of Injury
• Factors determining Injury
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Type of circuit
Resistance of tissues
Amperage and voltage
Current pathway
Duration
Environmental Factors
Size of contact point
Clothing
Mechanism of Injury
Heat = current x resistance x time
Very short duration of exposure
…a “short circuit”…
Mechanism of Injury
Duration of Exposure
 Longer the contact duration, the greater the
intensity and thus increased injury
 The major difference between lightning (DC
current) and high-voltage electrical injuries
(AC current)
 Electricity takes most direct route to exit to
ground
 Lightning – “flashover” effect
 Hot Lightning – lasting up to 0.5 sec

acts like high voltage energy
Mechanism of Injury
Tissue Resistance
 Humidity affects skin moisture and thus
resistance
 Resistance drops significantly when surface is
wet
 Higher resistance can ignite clothes and cause
thermal burns
 Metal objects increase risk thermal burns
Mechanism of Injury
Tissue Resistance
• Least:
– Nerve, blood, muscle
• Intermediate:
– Dry skin
• Most:
– Tendon, fat, bone
Mechanism of Injury
•Direct Strike - most common to the head and shoulders
•Contact Injury - touching object in pathway
•Side Flash - jumps from object to victim
•Step Voltage – travels through the ground
•Blunt Injury - fractures and muscle contractions
Direct Strike
Contact Flash
Step Voltage
Pathophysiology
Clinical Presentation
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Brain, heart and skin most commonly affected
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Immediate cardiopulmonary arrest is primary
cause of death from lightning strike
Cardiopulmonary Arrest
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Effects to the respiratory center
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apnea
Effects to the conduction pathway in the heart
Asystole
 V-fib
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Spontaneous conversion to NSR may occur
MI rare
Autonomic instability
Cardiopulmonary Arrest
• Apnea persists causing hypoxia
• May outlast cardiac arrest
• May cause secondary hypoxic arrest
Skin
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Feathering burns… “Lichtenberg Figures”
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Linear burns
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Punctate burns
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Thermal burns
Feathering Burns
Linear Burn
Punctate Burns
Thermal Burns
Thermal Burns
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Skin
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2º-3º burns
Neurologic Injuries
• LOC:
– anterograde amnesia
• CNS:
– Infarction
– Hematoma
– Encephalopathy
– Degeneration
• Peripheral:
– autonomic instability
Neurologic Injuries
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Similar to after effects of electroconvulsive
therapy
Pupillary dilatation may be secondary to
autonomic injury
Intracranial bleeding, cerebral edema, seizures,
anoxia
Keraunoparalysis
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Intense vascular spasm in extremities
temporary loss of pulses
 mottling
 absence of sensation in an extremity
 usually resolves spontaneously
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Miscellaneous Trauma
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Renal…rare
Ophthalmic:
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Musculoskeletal:
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injury secondary to
trauma
cataracts less common
 entire axis injury noted  Blunt Trauma
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Otologic:
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TM rupture
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Post-Traumatic
Headaches
Management
Managing Lightning Strike
• Survey scene for safety
• Activate EMS
-depending location in the backcountry
• Move victim to safer location
• Evaluate ABCs and treat accordingly
-Use reverse triage principle
-CPR is very effective in these victims
-ACLS with good ventilation
Managing Lightning Strike
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Evaluate and treat for hypothermia and shock
Evaluate for blunt trauma and treat for fractures
Evaluate and treat for burns
Plan evacuation methods
ambulatory or litter
 air evacuation
 overnight shelter
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Long-term Management
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Survivors are an even greater tragedy!
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~ 70% Long-Term Medical Problems
~ 30% Suffer Debilitating Problems
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Elusive Data - 40-70% Under-Reported
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Support group is recommended
Lightning Strike and Electric Shock
Survivors International
[email protected]
 www.lightning-strike.org
 1-910-346-4708
 Jacksonville, NV
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Lightning Safety
 STAY
INDOORS!
Lightning Safety
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If you can see lightning or hear thunder, activate
your safety plan.
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Resume activities only when lightning and thunder
have not been observed for 30 minutes.
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If you can see it (lightning), flee it; if you can hear it
(thunder), clear it.
Lightning Safety
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These are some key facts to remember about
lightning safety:
No place in the out of doors or the wilderness is
absolutely safe from lightning.
 The safest location is inside a substantial building,
away from all windows and doors.
 The next best location is inside a hard top
automobile with windows rolled up.
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Lightning Safety
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Indoor Lightning Safety
Avoid using telephone (remember the wires)
 Avoid using water – sink, tub, etc. (plumbing)
 Unplug appliances (remember the wires)
 Inner rooms are the best
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Lightning Safety
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Vehicles: car, bus, etc.
close windows
 keep hands on lap it’s not the rubber tires that make a
vehicle safe; it’s the metal cage
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Convertibles or canvas type (soft) tops offer no
protection
Lightning Safety
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If you remain outdoors
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Stay away from rivers, lakes, or other bodies of water
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Be aware of the potential for flooding in low-lying
areas
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NEVER stand under an isolated tree
Lightning Safety
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Stay away from tall trees
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keeping twice as far away from a tree
as it is tall to minimize a side strike
and step voltage.
Avoid being the tallest object
around
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Get as low as you can but do not lie
prone on the ground
Lightning Safety
• Stay away from natural lightning rods and
tall structures such as:
– towers
– tall trees
– telephone poles/lines
– tents with metal supports
Lightning Safety
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Stay low (crouch) in a ditch or depression
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a low area, ravine, or foot of a hill.
DO NOT lie flat on ground
Conductors should be removed from body
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communication devices with antennas
Lightning Safety
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In the mountains
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On by noon, off by two
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Move off ridges and summits - descend
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Get below tree line into a grove of small trees
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Stay clear of cave entrance and walls
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Avoid rappelling when lightning imminent
Lightning Safety
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Boating Safety
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First, make sure your boat is properly grounded.
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Secondly, stop using anything that could be a potential
lightning rod. Fish later.
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Thirdly, get below deck if possible. Don’t touch the mast
or any metal objects. Water conducts electricity across its
surface.
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Swimming during a thunderstorm is not safe.
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Wear life vest at all times
Indications of Imminent
Lightning
• Crackling noise or ozone smell
• Hair may stand on end
• St. Elmo’s fire
Detection Equipment
Sky Scan™
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Portable lightning/ storm detector
Four ranges
20-40 miles
 8-20 miles
 3-8 miles
 0-3 miles
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Strike Alert™
•LED and alarm
sound warnings:
•<6 miles
•6-12 miles
•12-24 miles
•20-40 miles
ThunderBolt™
• Provides three warning methods:
•Audible, LED and text
•Three models
•Max detection is 75 miles
Resources
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http://www.lightningsafety.com
http://www.lightningsafety.noaa.gov
http://www.marinelightning.com