Lightning and Electrical Injuries - Presented at the Sept 9th PETOS
Cases of electrical injury tend to follow these patterns:
- Young children: electrical cords or outlets
- Adolescents: high-voltage injuries from climbing trees or power lines
- 2:1 male to female ratio in kids, 90% male in adults
- >50% of lightning injuries occur during outdoor recreational activities
The amount of current flowing through the body determines the severity of the injury. Tissues with higher resistance (skin, bone, fat) tend to heat up and coagulate. Lower resistance tissues (nerves and blood vessels) transmit current. Dry skin has greater resistance than wet skin; lower voltage applied to wet skin can generate more current.
AC and DC Currents
- Alternating current (AC) is found in most homes. It is cyclical and alternates at 60 cycles per second. AC repetitively stimulates muscle contraction causing victims to grasp the source which leads to a longer duration of exposure.
- Direct current (DC) has a flow that remains constant. Examples are batteries, railway tracks, and car electrical systems. DC current causes a single muscle spasm that throws the victim from the source. While injuries are of shorter duration there is a higher likelihood of trauma.
Lightning Injuries
- High voltage >1000 V (power lines 100,000 V) and lightning voltages exceed 10 million V.
- Lightning strikes during thunderstorms kill more Americans each year than hurricanes or tornadoes.
- Contrary to the saying, lightning can, and often does, strike the same place twice!
- Lightning incidents often involve more than one victim. Ground current may spread the electricity to a group of people seeking shelter.
- 10-30% of those struck by lightning die; 75% of survivors have permanent disabilities.
- Most lightning-associated deaths occur within one hour of injury and are related to fatal arrhythmia or respiratory failure.
Lightning injury is caused by unidirectional massive current exposure (similar to DC) that lasts from 1/10 to 1/1000 of a second. Peak temperatures rise to 30,000 Kelvin (5x hotter than the sun). Rapid heating of the surrounding air generates a shock wave which causes mechanical trauma to the body. It is difficult to predict the course of current flow and the extent of injury. Surface findings often underestimate the extent of tissue damage.
Organ Involvement in Lightning Injury and Treatment Tips
Cardiac
- Massive direct current shock can depolarize the entire myocardium.
- Autonomic stimulation and catecholamine surge have additive effects on the heart and rhythm. Asystole is a common presenting rhythm. V-fib and V-tach are also common as is QT prolongation.
- Spontaneous return of sinus rhythm has been noted after asystole.
- Respiratory paralysis lasts longer and the return of spontaneous rhythm may degenerate to v-fib due to hypoxia. So, in lightning strikes with multiple casualties, treat the patients without signs of life first. Lightning strike victims who do not sustain cardiac arrest generally survive without intervention. We also recommend prolonged CPR even with asystole as the initial rhythm.
Neurologic
- Damage to the central and peripheral nervous system
- LOC, weakness/paralysis, respiratory arrest/depression, autonomic dysfunction
- Keraunoparalysis = specific to a lightning injury with blue, mottled extremities (LE>UE), thought to be due to vascular spasm
- Hypoxic encephalopathy, ICH, cerebral infarction, spinal fractures. Remember spinal precautions!
- Ruptured TM, optic nerve injury, cataracts. Fixed and dilated pupils may NOT reflect severe brain injury.
Skin- Superficial burns are common (>85%), deep burns cause about 5%. This is due to the short duration of contact.
- Flashover effect is when the current travels on the surface of the skin and is discharged to the ground (looks like a feather or a fern).
- Punctate burns are multiple small, cigarette-like burns.
- Linear burns (where sweat or water accumulate).
- Burns can occur from metal objects touching skin.
- The Parkland formula should NOT be used in lightning burns. Surface burns in electrical injuries may grossly underestimate the extent of internal injury. Utilize aggressive fluid resuscitation especially if there are signs of muscle necrosis. Fluid resuscitate for hypotension in transport.
