It is estimated that a lightning flash occurs approximately 8 million times per day throughout the world. Most strikes are benign and cause little damage to property and physical structures; however, when lightning strikes a person or group of people, it is a significant medical and potentially traumatic event that could lead to immediate death or permanent disability. By understanding some basic physics of lightning and pathophysiology of injuries associated with lightning strikes, EMS providers will be better prepared to identify assessment findings, anticipate complications and provide effective emergency care.
Lightning strikes are one of the top three causes of death associated with a natural or environmental phenomenon and are the second leading cause of storm-related deaths in the United States. According to the National Oceanic and Atmospheric Administration's (NOAA) National Weather Service publication, Storm Data, there are on average 62 reported deaths per year due to lightning strikes in the U.S. Since there is no standardized reporting system and most of the data is collected from newspaper accounts of lightning-strike injuries and deaths, the average is thought to be low. The National Weather Services estimates it is closer to 70. Of those people struck, it is believed that only 10% are killed; the remaining 90% suffer some type of acute or permanent disability.
Most lightning-strike injuries occur between May and September, with the highest incidences in June, July and August. Approximately one-third of strike injuries are work related, one-third occur during recreational or sports activities, and one-third as a result of other situations, such as being struck while indoors or on the telephone.
Although one of the safest places to be during lightning is indoors in a substantial improved structure with electrical wiring and plumbing, do not assume that all lightning-strike patients will be found outdoors. If lightning strikes the structure or a nearby object, the electrical energy can be transmitted through plumbing fixtures like a sink, shower or toilet, and electrical devices that are hard-wired to the structure, such as computers, phones and electronic games. The incidence of lightning -strike injuries increased among emergency services call-takers and dispatchers when they began using headsets that were hard-wired into radio consoles. A person talking on a landline telephone is also at risk of being struck, as the electrical energy is transmitted through the phone line and receiver being held to the ear. Although phone lines are grounded, the extremely high electrical energy associated with a lightning strike overwhelms the ground, which provides little or no protection. Acoustic injury from the loud crack of static electricity has been reported in people using a portable phone with a hard-wired base during lightning. Cell phones pose no increased risk, other than promoting inattention to the weather and surroundings.
It is often thought that a shelter will provide adequate protection against a lightning strike. Unfortunately, this is not true. A shelter may protect against rain and wind, but seeking protection in one may actually increase the risk of being struck by indirectly increasing the height surrounding the individual.
Cars, buses and other vehicles surrounded by metal provide a safe shelter against lightning. A common misconception is that the rubber tires of a vehicle provide the protection; however, the power of a lightning strike easily overwhelms the little protection offered by the tires. It is the metal structure that allows the energy to be dispersed along the outside of the vehicle and keep the occupants inside safe from injury, providing they are not in contact with electrical devices like the radio or the metal of the car itself.
Males are approximately five times more likely to be struck, injured and killed by lightning. The highest incidence of lightning strikes occurs in children younger than age 16 and adults between 26 and 35 years. This is due primarily to their involvement in outdoor work-related, sports and recreational activities.
It is estimated that 90% of the time the lightning strike involves only one patient. The most common cause of death due to lightning strike is immediate cardiac arrest. If a patient who has been struck by lightning is not pulseless or apneic upon your arrival, it is likely that he or she will survive the strike injuries. Thus, when performing triage at a multiple-casualty lightning-strike incident, the patients in respiratory and cardiac arrest should be treated first.
PHYSICS OF A LIGHTNING STRIKE
It is often thought that certain individuals attract lightning, or that having metal on their person will attract it. There is no evidence to suggest either is true. Individuals who are more likely to be struck by lightning put themselves in high-risk situations that increase their chance of being struck, such as being outdoors during a lightning storm. Metal on a person's body will conduct electricity once struck, and will likely cause a burn due to the extreme heat; however, it does not serve as a lightning rod or attraction unless it increases the height of the person, such as a metal umbrella, pole or other object carried over the head. A person who is the only object in the middle of a flat surface is also at greater risk of being struck. This may occur on a golf course, football field, or while hiking in the flat open tundra on a mountain.
Lightning results from transfer of an electrical charge. When warm low-pressure air rises through high-pressure air, an electrical potential is created, causing the inferior aspect of the cloud to become negative as the ground remains positive. The static energy generates lightning channels that are either dissipated within the cloud or extend downward toward the ground. Objects on the ground send positively charged strokes upward to meet the downward negatively charged stroke. If the downward stroke, termed a stepped leader, contacts an upward stroke, the lightning channel is completed and a downward moving lightning strike is observed. Even though not all of the positively charged upward strokes result in a true observed lightning strike, they contain enough electrical energy to cause potential injury.
Lightning is not classified as alternating current (AC) or direct current (DC). It falls in its own category due to its unique characteristics and is often referred to as a cosmic direct current. It is clear, though, that the current associated with a lightning strike is massive. Lightning current can range from 100 million to 2 billion volts with an amperage as high as 200,000. Its contact temperature may be as high as 15,000 to 60,000 degrees Fahrenheit; the duration of a strike may be as short as 1/100th to 1/1,000th of a second. This extremely short duration of exposure explains why lightning strikes produce minimal internal and external burn injury.
A lightning strike will suddenly heat the air around it, resulting in the rapid expansion of air, which creates an explosive effect. Because the strike is of such a short duration, the air rapidly cools and an implosion also occurs. Not only does this result in thunder, it may propel a person in the immediate area and cause blunt trauma. If thunder is heard, lightning has occurred in the area and is close enough to cause injury.
Lightning can strike as much as 10 to 12 miles ahead of a thunderstorm, with a clear blue sky and no rain present. This is commonly referred to as anvil lightning, or a bolt from the blue. Don't rule out a potential lightning-strike injury when the scene does not present with the typical characteristics of a thunderstorm. When conducting the scene size-up, be aware of scene safety issues and the potential for lightning as the mechanism of injury and nature of illness if there is a thunderstorm in the area.
PATHOPHYSIOLOGY OF LIGHTNING INJURIES
Some EMS providers believe that a lightning-strike injury results in severe burns. Due to the extremely short duration of contact with the electrical current, most of the energy flashes over the body and causes only superficial burns. Thus, both external and internal burns are usually not a significant consideration in lightning-strike injuries. Lightning strikes can produce both medical dysfunction and traumatic injuries. The central, autonomic and peripheral nervous systems are quite sensitive to the electrical energy producing neurologic and autonomic disturbances manifested as acute and chronic complications. Cardiopulmonary and vascular complications can also occur from the strike.
The sudden discharge of electrical energy causes muscles to contract forcefully, which may cause the victim to fall to the ground or be thrown several yards. The rapid heating and cooling of the air around the strike causes an abrupt change in pressure, creating an explosion and implosion that may also propel the victim. These pressure changes may result in barotrauma (trauma related to a sudden change in pressure). All of these mechanisms contribute to blunt trauma to the victim, causing possible head, spine, pelvic, extremity, soft tissue and organ injury. This is why lightning-strike victims may be both trauma and medical patients, and you must consider a thorough physical assessment, a high index of suspicion for traumatic injuries, and spinal immobilization in your patient management.
Lightning strikes disrupt the normal function of the central, autonomic and peripheral nervous systems, which may lead to acute or chronic complications. Central nervous system dysfunction may cause simple confusion, an altered mental status or coma, headache, personality change, seizures and cognitive disability. Autonomic nervous system disruption shuts down the vital function of the cardiac and respiratory center. It may also produce sympathetic nervous system-induced vasoconstriction with resultant hypertension and mottling of extremities. Chronic pain and sensory disturbances may result from peripheral nervous system effects.
Cardiopulmonary arrest, although rare, is usually the cause of death from a lightning strike. Lightning energy acts as a massive defibrillation, depolarizing the myocardium and producing a period of asystole. The massive electrical energy also causes a dysfunction in autonomic nervous system control of cardiac rhythm and respirations, resulting in prolonged respiratory arrest while no longer providing cardiac conduction stimulation. The inherent automaticity of the cardiac conduction system often restores a perfusing rhythm; however, the lack of autonomic nervous system stimulation keeps the patient in respiratory arrest. Persistent apnea causes the patient's contracting myocardium to become severely ischemic and acidotic, leading to a secondary cardiac arrest. Ventricular fibrillation is frequently the pulseless rhythm associated with the secondary cardiac arrest.
An extremely short duration of contact and a flashover of electrical current usually produce only superficial burns. Deeper burns from the electrical current are rare; however, if they're present, suspect internal organ and tissue damage as well. Partial thickness and full thickness burns may occur from metal (coins, belt buckles, hair pins, golf cleats) heating to extreme temperatures, retaining the heat and prolonging the duration of exposure to cause deeper dermatologic burns.
Typical burn patterns that may be seen in a lightning strike are:
- Linear burns (appear as lines on the body and occur from sweat or rainwater running down the body, and being heated and vaporized due to the extreme temperature of the lightning)
- Punctuate burns (appear as cigarette burns)
- Feathering or pathognomonic fernlike patterns (due to electron shower)
- Thermal burns (usually as a result of heated metal on the body).
It is imperative that you approach the lightning-strike victim as both a medical and trauma patient in your assessment and management. The patient may have suffered a burn as a result of the strike; however, it is usually not your primary concern or a major injury. If you fail to focus on the potential medical and trauma conditions caused by lightning energy, the patient's survival may be severely impacted. Any patient struck by lightning needs to be transported to an appropriate medical facility for further evaluation.
If multiple victims are struck by lightning, conduct your triage in a reverse manner from what you would normally do in a multiple-casualty incident. The strike victims who are not in cardiac arrest, provided they are breathing spontaneously, will almost always survive. Immediate resuscitation of respiratory and cardiac arrest patients is the most important factor to their survival. When performing your initial triage, lightning-strike patients who are apneic or in cardiac arrest will receive priority emergency care. Those with adequate cardiac or respiratory function will be considered a lower priority for treatment and transport.
Scene safety is a major consideration for EMS personnel. If the storm clouds producing lightning are still in the area, or if you hear thunder, you are also at risk. If outdoors, move the patient into an improved structure or into the ambulance as quickly as possible to reduce your risk of being struck. Keeping in mind that lightning strikes are traumatic events and can produce blunt trauma, be sure to take the necessary spinal immobilization precautions prior to moving the patient.
Other emergency care includes:
- Take manual in-line spinal stabilization.
- If clothing is burning or smoldering, put out the fire and immediately cool the burning area with water.
- Remove smoldering or hot jewelry or metal, or cool with water.
- Assess and manage the airway.
- If the patient is apneic or has an inadequate respiratory rate or tidal volume, immediately begin positive pressure ventilation.
- Administer supplemental oxygen guided by a continuous SpO2reading.
- Place the patient on a continuous ECG monitor and manage any dysrhythmias according to your protocol.
- Initiate an intravenous line of normal saline and run it based on the patient's blood pressure, heart rate and signs of perfusion. However, be cautious when assessing signs of perfusion due to the arterial spasm that may produce mottled and cold extremities. Since lightning typically produces only superficial burns and not internal tissue and organ damage, there is no real concern for myoglobinuria and the need to infuse fluid aggressively.
- Dress wounds or burns.
- Immobilize any suspected fractures.
- Provide complete spinal immobilization or rule out spinal injury according to your protocol.
Mechanism of Lightning Strikes
There are five different mechanisms by which a person may be struck by lightning:
- Ground current or ground strikeoccurs when the lightning strikes a distance away from the victim and spreads out across the ground, energizing it and eventually striking the victim. This is the most common type of mechanism and accounts for close to half of strikes. If the victim's legs are spread, the energy may travel up one leg and down the other. This is referred to as step voltage. The further the victim is away from the strike zone, the less energy and injury can be expected.
- Side flash or side splashis the mechanism in approximately 30% of injuries, occurs when the lightning strikes an object and splashes or jumps to the victim.
- Upward leader strikeresults from the positive ground current moving upward without contact with the downward stroke. Up to one-quarter of injuries result from an upward leader mechanism.
- Direct strikeis the most dangerous because the victim's body is the point of contact for the strike's full electrical charge. Keep in mind that the short duration of the strike may only cause superficial external injury, but the electrical charge may result in significant nervous system disruption and dysfunction. This is a relatively uncommon mechanism accounting for up to 5% of injuries.
- Contact strike, which is the least common (1%–2%), results from a person being in contact with an object that is struck.
If the patient is in respiratory arrest, aggressive airway management, ventilation and oxygenation are necessary to prevent the patient from deteriorating to a lethal cardiac rhythm. If the patient does deteriorate to cardiac arrest or is found in cardiac arrest, perform resuscitation, including defibrillation for ventricular fibrillation, as you would normally do according to your protocol.
CEU Review Form Lightning-Strike Injuries (PDF)Valid until May 2, 2008
Dr. Mary Ann Cooper, Professor, Departments of Emergency Medicine and Bioengineering, Director of Lightning and Electrical Injury Research Program at the University of Illinois at Chicago, and attending physician in the Electrical Trauma Program at the University of Chicago and University of Illinois at Chicago, is a recognized leader in studying lightning-strike injuries. Most of the information in this article is taken from her years of investigation and published work in this area.
Bjerke HS. Lightning Injuries. www.emedicine.com/med/topic2796.htm. June 19, 2006.
Cooper MA. Lightning Injuries. www.emedicine.com/emerg/topic299.htm. January 7, 2008.
Cooper MA, Andrews CJ, Holle RL. Lightning Injury. Wilderness Emergencies. CV Mosby, 2006.
Cooper MA. Lightning injuries: Prognostic signs for death. Ann Emerg Med 9(3):134–138, March 1980.
Cooper MA. Medical Aspects of Lightning. National Weather Service. www.lightningsafety.noaa.gov/medical.htm.
Marx JA, Hockberger RS, Walls RM. Rosen's Emergency Medicine: Concepts and Clinical Practice, 5th ed. St. Louis: Mosby, Inc., 2002.
Part 10.9: Electric Shock and Lightning Strikes. Circulation 112:IV—154—IV155, 2005.
Joseph J. Mistovich, Med, NREMT-P, is a professor and chair of the Department of Health Professions at Youngstown (OH) State University, author of several EMS textbooks and a nationally recognized lecturer.
William S. Krost, BSAS, NREMT-P, is an operations manager and flight paramedic with the St. Vincent/Medical University of Ohio/St. Rita's Critical Care Transport Network (Life Flight) in Toledo, OH, and a nationally recognized lecturer.
Daniel D. Limmer, AS, EMT-P, is a paramedic with Kennebunk Fire-Rescue in Kennebunk, ME. He is the author of several EMS textbooks and a nationally recognized lecturer.