William T. Hark, MD
Approximately 100 to 600 people die annually in the United States as a result of lightning. Serious injuries are caused in about 1,000 to 1,500 persons each year. This produces a 25 to 32% mortality rate. Of the survivors, 74% sustain permanent injuries. There are more deaths caused by lightning than any other natural phenomena including floods, hurricanes and tornadoes. These deaths are less well publicized because they are individuals or small groups and not associated with large-scale property damage. People with outdoor occupations or hobbies including storm chasers are at greatest risk. Although no storm chaser has been killed or seriously injured, the risk remains.
The current in a lightning bolt is as high as 30,000 Amperes with 1,000,000 or more Volts. The short duration of about 1-100 milliseconds limits, but doesn’t prevent injury. There are several mechanisms of lightning injury. The most severe is a direct strike, either on the victim or on some object the victim is holding such as a golf club, tripod or umbrella. A “side flash” occurs when lightning hits a nearby object and jumps to the victim. Ground current injures the victim when lightning strikes the ground nearby and it spreads to the person. Rarely, people maybe injured or killed indoors while using the telephone or taking a shower. Burns may occur from jewelry, clothing or other heated material. Finally, blunt injury and trauma may occur secondary to the shockwave from a lightning strike or from a resulting fall.
Lightning can affect all organ systems, especially the cardiovascular system. The primary cause of death following lighting strike is cardiopulmonary arrest. Changes in the heart rhythm (asystole or heart stoppage) may occur, but the heart will usually quickly resume its normal rhythm. EKG abnormalities are common but generally resolve. A paralysis of the respiratory center is more common and can last much longer than the stoppage of the heart. If artificial respiration is not immediately initiated, the person will die of hypoxia or lack of oxygen. Vascular instability is another type of lightning injury which results in cold, pulse less and mottled extremities. This condition usually resolves over several hours.
Central nervous system injuries are common. Transient confusion, paralysis and amnesia are likely. Coagulation of the brain, subdural hematomas or collections of blood surrounding the brain, and bleeding within the brain are possible with direct strikes. Swelling of the brain is another outcome. There may be global brain damage and neurologic devastation secondary to anoxic brain injury if respiratory arrest is not immediately treated. Paresthesias (pins and needles sensations) may affect areas of the victim’s body. Possible chronic sequelae include amnesia, movement disorders, dementia and decreased reflexes. Paraplegia can be secondary to brain or spinal cord injury from lightning strikes. There may also be neuropsychiatric complications such as depression, anxiety, memory deficits, and post-traumatic stress disorder.
Burns are another possible effect of lightning. Most lightning burn victims have first or second degree burns. Third degree or full-thickness burns are much less common but can occur associated with metal objects such as jewelry. Lighting can also produce a reddish-brown feathery skin lesion which disappears in a few days. This is an inflammatory response rather than a burn.
About one half of all lightning victims will have some type of eye damage, usually corneal injury. The most common serious eye injuries are cataracts which can occur from a few days to several years after the lightning strike. Other eye injuries include retinal bleeding, retinal detachment and optic nerve degeneration. There may also be transient autonomic nerve disturbances which can result in dilated or contracted pupils even without concurrent head injury. The ears are also commonly affected with over 50% of lightning victims having ruptured ear drums. Transient hearing loss and tinnitus affect most survivors of lightning strikes. Chronic ear infections and partial hearing loss occur in 47% of patients with initial ear injury. Vertigo or dizziness has also been reported.
The victim of lightning strike may have injury either directly from the lightning strike or from being thrown by the blast. Contusions and fractures may occur along with muscle and ligament tears. In rare cases, a compartment syndrome or swelling within section of an extremity may result from lightning damage requiring a surgical release to prevent further tissue destruction.
Avoidance and prevention are the best means of lightning safety. Total avoidance is clearly impossible for storm chasers but risks can be minimized. A good description is given by Dr. Charles Doswell III in his essay on chaser safety. Lighting has about a 50 yard search radius on the ground in an area that a strike will occur. It can strike as much as 10 miles from the rain of a thunderstorm and even when the storm appears to be dissipating. It usually seeks the tallest objects in that area. While chasing, the safest place to be is inside a vehicle with a solid metal top. Outside, don’t be the highest object around or be connected or near anything taller than the surrounding objects. Examples include lone or small groups of trees, power poles, and antennas. Hill tops and exposed areas have great visibility but are dangerous. Holding metal objects such as golf clubs, antennas or umbrellas can increase risk by increasing one’s effective height. Being under a developing rain shaft near a thunderstorm is particularly risky. One should also avoid leaning on metal vehicles or being near metal fences which lead toward the storm. If one feels one’s hair stand on end, immediately crouch on the balls of one’s feet with head down while not touching the ground with one’s hands. The potential victim should not lie flat on the ground. A lightning strike is imminent and this position helps minimize height and exposure to ground current. Usually lightning gives no warning and the sign of hair standing on end is not a reliable warning signal. Some chasers recommend using a tall metal object to produce a "cone of protection." Presumably, lightning will strike the metal object instead of the surrounding ground or storm chasers. The cone extends from the top of the object to the ground in a circle and it starts at an angle of 45 degrees from vertical. Unfortunately, with objects taller than 30 meters, the size of the cone's maximal ground radius will remain fixed at about 30 meters. Of course, this is not perfect, and there are no good scientific studies of the safety of this "cone of protection."
The main cause of death is cardiopulmonary arrest. Most victims survive if they receive prompt cardiopulmonary resuscitation. Among storm chasers groups, at least two members should be trained in basic life support or CPR. Two are necessary since a single trained person may be the one struck. Lightning danger and the need for CPR is another reason not to chase alone and CPR is something everyone should know even if not a storm chaser. Storm chasers should also have a CPR mask available and easily accessible in their vehicles. These masks are used for mouth-to-mouth respiration. They are cheap ( about $3.00 to $12.00) and aid in hygiene and in prolonged artificial respiration. If a group of persons are victims of a lightning strike, the normal mass casualty triage protocols are reversed. In this situation, those that appear “dead” should be immediately attended and CPR begun. The person who is moving around or screaming will almost always survive and should not require immediate attention if there are others who appear dead. CPR should be started on those not breathing or without a pulse before an ambulance is called. After a lightning strike, the heart will often resume beating while the respiratory drive will be paralyzed for hours. Prompt CPR may prevent secondary hypoxia, brain damage and death. Artificial respiration may need to be continued for hours but can result in a good outcome. Resuscitation in lightning victims has a higher success rate, even after prolonged administration of CPR. It should be noted that the presence of dilated pupils should not be used as an indication of brain damage because these findings can be induced by the lighting strike without head injury. The victim should also be kept immobilized if not in immediate danger because of the possibility of cervical spinal injury. Finally, lightning victims do not carry an electrical charge and can be touched immediately following a strike.
Lighting is a continuing risk to storm chasers. This risk can be minimized with some simple safety measures but not eliminated completely. In the event of a lightning injury, immediately attention and CPR to those that appear “dead” can give them the greatest chance of full recovery. Discussing safety and first-aid including CPR should be done prior to storm chasing to minimize the time before CPR is begun in the rare event of a lightning strike leading to cardiac or pulmonary arrest.
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