lightning injuries in the backcountry remote areas emergency medicine and survival

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

info@lightning-strike.org

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