lightning injuries in the backcountry remote areas emergency medicine and survival
TRANSCRIPT
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 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 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 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
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
84% M, 16% F
June, July, August
Wed/Sat/Sunday
2-6 pm
Odds of Becoming a Victim
Odds of being struck by lightning in a given year (reported deaths + injuries)
1/700,000Odds of being struck by lightning in a given year (estimated total deaths + injuries)
1/400,000
Odds of being struck in your lifetime 1/5000(Est. 80 years)
Odds you will be affected by someone being struck 1/500(Ten people affected for every one struck)
Mechanism of Injury• Factors determining
Injury– Type of circuit– Resistance of tissues– Amperage and voltage– Current pathway– Duration– Environmental Factors– Size of contact point– Clothing
Heat = current x resistance x time
Very short duration of exposure…a “short circuit”…
Mechanism of Injury
Mechanism of InjuryDuration 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 InjuryTissue 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
Brain, heart and skin most commonly affected
Immediate cardiopulmonary arrest is primary cause of death from lightning strike
Cardiopulmonary Arrest
Effects to the respiratory center apnea
Effects to the conduction pathway in the heart Asystole V-fib
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
Feathering burns… “Lichtenberg Figures”
Linear burns
Punctate burns
Thermal burns
Skin
Feathering Burns
Linear Burn
Punctate Burns
Thermal Burns
Skin 2º-3º burns
Thermal Burns
Neurologic Injuries• LOC:
– anterograde amnesia• CNS:
– Infarction– Hematoma– Encephalopathy– Degeneration
• Peripheral:– autonomic instability
Neurologic Injuries
Similar to after effects of electroconvulsive therapy
Pupillary dilatation may be secondary to autonomic injury
Intracranial bleeding, cerebral edema, seizures, anoxia
Keraunoparalysis
Intense vascular spasm in extremities temporary loss of pulses mottling absence of sensation in an extremity usually resolves spontaneously
Miscellaneous Trauma
Renal…rare Ophthalmic:
cataracts less common
entire axis injury noted
Otologic: TM rupture
Musculoskeletal: injury
secondary to trauma
Blunt Trauma 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
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
Long-term Management
Survivors are an even greater tragedy! ~ 70% Long-Term Medical
Problems ~ 30% Suffer Debilitating
Problems
Elusive Data - 40-70% Under-Reported
Support group is recommended
Lightning Strike and Electric Shock Survivors
International
www.lightning-strike.org
1-910-346-4708 Jacksonville, NV
Lightning Safety
STAY INDOORS!
Lightning Safety If you can see lightning or hear
thunder, activate your safety plan.
Resume activities only when lightning and thunder have not been observed for 30 minutes.
If you can see it (lightning), flee it; if you can hear it (thunder), clear it.
Lightning Safety 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.
Lightning Safety
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
Lightning Safety
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
Convertibles or canvas type (soft) tops offer no protection
Lightning Safety
If you remain outdoors Stay away from rivers, lakes, or other
bodies of water
Be aware of the potential for flooding in low-lying areas
NEVER stand under an isolated tree
Lightning Safety Stay away from tall trees
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 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
Stay low (crouch) in a ditch or depression a low area, ravine, or foot of a hill.
DO NOT lie flat on ground Conductors should be removed from
body communication devices with antennas
Lightning Safety
In the mountains
On by noon, off by two
Move off ridges and summits -
descend
Get below tree line into a grove of
small trees
Stay clear of cave entrance and walls
Avoid rappelling when lightning
imminent
Lightning Safety Boating Safety
First, make sure your boat is properly grounded.
Secondly, stop using anything that could be a potential lightning rod. Fish later.
Thirdly, get below deck if possible. Don’t touch the mast or any metal objects. Water conducts electricity across its surface.
Swimming during a thunderstorm is not safe.
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™
Portable lightning/ storm detector Four ranges
20-40 miles 8-20 miles 3-8 miles 0-3 miles
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
http://www.lightningsafety.com http://www.lightningsafety.noaa.gov http://www.marinelightning.com