Tropic Lightning: Myth or Menace?

Abstract

Lightning is one of the leading causes of death related to environmental disaster. Of all lightning fatalities documented between 2006 and 2012, leisure activities contributed the largest proportion of deaths, with water-associated, sports, and camping being the most common. Despite the prevalence of these activities throughout the islands, Hawai‘i has had zero documented lightning fatalities since weather data tracking was initiated in 1959. There is a common misconception that lightning does not strike the ground in Hawai‘i. This myth may contribute to a potentially dangerous false sense of security, and recognition of warning signs and risk factor modification remain the most important prevention strategies. Lightning damage occurs on a spectrum, from minor burns to multi-organ dysfunction. After injury, initial treatment should focus on “reverse triage” and immediate cardiopulmonary resuscitation when indicated, followed by transfer to a healthcare facility. Definitive treatment entails monitoring and management of potential sequelae, to include cardiovascular, neurologic, dermatologic, ophthalmologic, audiovestibular, and psychiatric complications.

Background

Lightning physics is complex, but all lightning begins with a thunderstorm. A thunderstorm develops when the sun heats pockets of air that cause those pockets to rise in columns which eventually form clouds. Within these clouds, layers of precipitation develop (ice, hail, rain), which based on their weights, stratify to different layers in the cloud. Rising warm air with falling ice particles results in collisions between the different particles. This creates charge, and eventually the top of the cloud becomes predominantly positive and the bottom of the cloud negative.¹ The earth is generally negatively charged, but when storm clouds roll over, the negatively charged bottom of the cloud induces the earth to take on a positive charge.^1,2 When the separation of charge becomes too much (a difference in voltage between the cloud and the ground or object exceeds 2 million volts per minute), the result is lightning.^2,3

Lightning strikes the earth approximately 8 million times a day or 100 times per second, making it one of the leading causes of weather related death in the world.³ In the United States, according to the National Oceanic and Atmospheric Administration, there were 4002 fatalities from 1959 to 2012. Climate, region, and season play a role in risk of lightning injury, as shown by the differences in incidence of lightning injury across the United States. Florida and Texas account for the most lightning fatalities (415 and 215 respectively), while Alaska and Hawai‘i (tied for 0) account for the least.⁴ Compared to last century, despite increasing population density, there are far fewer annual lightning fatalities. In the 1920s–1940s, the United States averaged around 400 lightning deaths per year. In the last 50 years there was an average of 40 deaths annually, and in the last three years, there was an average of 25 deaths annually. It is unclear why this decline is occurring, but some proposed explanations include increased urbanization, modernization of rural infrastructure and farm equipment, and increased awareness and education regarding lightning safety.^5–7

The most common lightning victim appears to be a male who is engaging in a leisure activity, particularly a water-related activity such as fishing or boating. Based on data gathered from 238 lightning fatalities occurring from 2006 to 2012, males are more likely to be victims than females (82% vs 18%); leisure associated activities are the most common (64%); water-related (36%), sports (19%), and camping (10%) made up the top three most common activities; and of water-related lightning deaths, the distribution included fishing (46%), boating (25%), beach (20%), and swimming (9%).⁸

Mechanisms of lightning injury take five different forms. A direct strike generally occurs when a person is in the open, and is the most likely to result in instantaneous death. Splash injury occurs when lightning strikes a nearby object and current jumps or “splashes” via the path of least resistance (eg, nearby victim). Contact injury occurs when a victim is touching an object that is hit by lightning. Ground current occurs when lightning strikes the ground near a victim and passes from the strike point into the victim. A fifth mechanism involves passage of lightning from the victim upward. There are also instances of blunt injury due to the sheer concussive force of the associated thunder.^1,3,9

Lightning is unidirectional and produces a massive current impulse of very short duration. The impulse can result in vaporization of skin moisture and blasting apart of clothes, rendering the victim naked. Unlike electrical injuries sustained from alternating current, the current of a lightning strike only remains internally for a very short time period, making deep tissue burns and myoglobinuric renal failure uncommon. Rather, that brief intense current may result in cardiac arrest (asystole more than ventricular fibrillation); damage to the central, peripheral, and/or autonomic nervous systems; superficial burns, ocular injuries (cataracts, corneal lesions, retinal detachment); ear injuries (tympanic membrane rupture, ossicle disruption, tinnitus); and psychological injury (fatigue, sleep disturbance, depression, memory problems).^1,3

Relevance to Hawai‘i and Asia Pacific

It is a common misconception that lightning does not strike the ground (or at all) in Hawai‘i. While it is true that lightning in Hawai‘i is far less common than on the mainland (the exact quantification remains elusive because the National Lightning Detection Network does not include Hawai‘i), there are many examples of significant lightning events on the islands. In May 2011, O‘ahu experienced a particularly impressive storm with an estimated forty thousand cloud to ground lightning strikes over a 30 hour period.¹⁰ In March 2012, lightning struck the hull of a 36 foot catamaran in O‘ahu, and the boat sank to the bottom of Keehi Lagoon Boat Harbor.¹¹ A storm in Dec 2013 on the Big Island of Hawai‘i yielded an estimated ten to twenty thousand lightning strikes.¹² No injuries were documented during any of these incidents.

Lightning in the Hawaiian Islands is referenced in Hawaiian mythology. Pele is not only the goddess of fire, wind, and volcanoes, but also lightning. In one story, Pele disguises herself and enters a store. She approaches a Chinese proprietor and asks for a cup of coffee. When the proprietor refuses, Pele unleashes lightning, causing the store to burn down and killing the proprietor inside.¹³

Aside from stories of Pele's vengeance, Hawai‘i has had no official documented lightning fatalities since storm data tracking was initiated in 1959. Hawai‘i is ranked last (tied with Alaska) in the least lightning fatalities per year (zero), and an estimated 0.1 injuries from lightning per 1 million people per year.⁴

The scarcity of lightning injuries may engender a false sense of security. Hawai‘i is home to recreational activities (eg, water sports, camping, hiking, sporting events) at the highest risk for lightning injury. Therefore, individuals and providers should remain knowledgeable regarding recognition, prevention, and treatment strategies.

Example Case(s)

In July 2013, a 47-year-old man was inside his home in Maui during Hurricane Flossie. He was washing dishes, and when he reached to turn on the faucet, he saw a blue streak connecting the faucet to his hand. The shock sent him to his knees, but shortly after, he was able to walk to the living room to tell his wife what had happened. He reported hand numbness for five minutes. His wife took his pulse, estimated at 180, and subsequently called 911.^14,15

Treatment in Resource-Constrained Environments

Recognition: The “30-30 Rule” is still often utilized, but may not be the current best practice. This rule suggests that if less than thirty seconds passes between seeing lightning and hearing corresponding thunder, then an individual should seek a safer location.¹⁶ Although easy to remember, practice guidelines now express concern that this rule may instill a false sense of security. A safer approach suggests that if lightning is seen or thunder is heard, an individual is already at greater risk for lightning injury and precautions should be initiated regardless of time separation. Lightning is always associated with a thundercloud, but has been known to strike as much as 10 miles from the periphery of a storm. Therefore, lightning injury can still be sustained after a storm has passed or even in sunny conditions, and individuals should wait at least 30 minutes from the most recent thunder clap or lightning sighting before resuming activities. Signs of a more imminent strike include static electricity, nearby crackling, funny smells, or even “St. Elmo's fire” (ie, a blue haze around a person or object).⁵

Prevention: No location is absolutely safe from lightning. Large structures and fully enclosed metal vehicles offer more protection than small open structures. Even while inside a structure, injury can occur with contact to conducting materials, as in the case example above (the victim touched his faucet). Individuals should avoid touching metal during thunderstorms, to include plumbing, telephones, and electronics. Areas to avoid would include open fields, tall structures (eg, flagpoles, trees), or being near or in water (eg, oceans, beaches, pools). Efforts should focus on fleeing these areas, however if this is not possible and signs of imminent strike are present (as explained above), individuals should take the lightning position as last resort. This position involves insulating oneself from the ground and minimizing points of contact. For instance, crouch with feet together on a nonmetal surface (eg, sleeping bag, backpack, etc). Time spent in this position should be limited if access to more definitive safety is possible.⁵

Treatment: Most victims survive lightning injury if they receive timely medical treatment. The most likely cause of death from a lightning strike is cardiac arrest, and therefore if the victim is not breathing or without a pulse, advanced cardiac life support (ACLS) should be initiated as soon as possible with the following considerations: (1) patients struck by lightning do not carry electrical charge, and it is therefore safe to touch them, (2) caution must be exercised when running to save a lightning victim, as the rescuer is often putting themselves at risk (there is no explicit evidence that suggests lightning does not hit the same place twice, and in fact, it often does), (3) ventilation must often be supported, as respiratory arrest due to suppression of the medullary respiratory center as well as thoracic muscle spasm may persist despite return of spontaneous circulation , and (4) even if appearing dead (fixed and dilated pupils), or the interval between injury and resuscitation has been prolonged, lightning patients have been known to respond to resuscitation. For this reason, if multiple victims are present, “reverse triage” should be initiated, where those patients who are not breathing or are without a pulse should actually be treated first.^1,3,5,9

Treatment in Non-Austere Environments

In absence of cardiopulmonary arrest from the initial lightning strike, dying from lightning is a rare occurrence. Unfortunately, of the 70%–90% of people who survive lightning injury, many may still have permanent disability afterward.³ Getting struck by lightning can cause derangement in multiple organ systems, particularly related to cardiovascular, neurologic, dermatologic, eye, ear, and psychiatric manifestations. Recognition of high risk is therefore important when determining need for closer monitoring. These factors include suspected direct strike, any loss of consciousness, focal neurologic complaints, chest pain, dyspnea, major trauma, cranial burns, leg burns or burns greater than 10% of total surface body area, or pregnancy.^1,5

Lightning causes massive simultaneous depolarization of the myocardium as well as possible muscle paralysis of chest wall muscles and suppression of medullary respiratory center. Additional cardiopulmonary manifestations from lightning strikes may include atrial fibrillation, elevated cardiac enzymes, cardiomyopathy, and ECG changes (ST elevation and QT prolongation). As discussed above, this emphasizes the importance of initial implementation of ACLS. Once resuscitation is achieved, high-risk patients should be admitted to the hospital for cardiac monitoring (at least 24 hours), screening ECG, and echocardiography.^1,5

Neurologic injury due to lightning strike varies widely in severity. Most sustained neurologic injuries are transient, and include loss of consciousness, headaches, paresthesias, confusion, seizures, and memory loss. Another phenomenon of neurologic lightning injury is known as keraunoparalysis which is a transient paralysis of limbs thought secondary to massive overstimulation of the autonomic nervous system. Subsequent vascular spasms may be accompanied by pulselessness, cyanosis, and motor/sensory deficits. Close monitoring for compartment syndrome should occur, but most instances of keraunoparalysis resolve spontaneously after several hours. Direct lightning strikes are associated with intracranial hemorrhage, cerebral infarctions, and hypoxic encephalopathy (often secondary to cardiopulmonary arrest). Delayed neurologic symptoms following lightning strike (eg, progressive myelopathy) are also possible, which would warrant close follow up with a neurologist to establish a long term treatment plan.^1,3,5

Whereas the American Burn Association recommends referral to a burn center for affected patients, generally, burns sustained after lightning injury are more superficial, less severe, and quickly healing when compared to high-voltage electrical burns. In order to avoid contact burns after initial strike, metal objects (eg, jewelry) should be promptly removed. Internal burns resulting in underlying muscle damage, compartment syndrome, and rhabdomyolysis are less common, however, suspicion should remain, particularly in a hypotensive patient. Hypotensive patients require fluid resuscitation as well as thorough evaluation for potential internal trauma caused by the concussive force of the lightning injury. Full thickness burns are generally seen in areas of skin that had contact to metal objects or synthetic melted materials. Full thickness burns requiring grafting are generally uncommon in lightning injury, and patients with superficial burns that involve less than 20% of total body surface area have been shown to heal relatively quickly.^1,3,5

Otologic and ophthalmologic findings after lightning injury are also well documented. Blast overpressures from lightning may result in tympanic membrane rupture and temporary deafness. Small perforations can be managed conservatively with bed rest and head elevation to prevent perilymph leakage. More severe injuries such as sensorineural deafness, vestibular injury, or complex perforations will likely require specialized care. The most common eye injury from lightning is cataracts which may occur soon after injury, or sometimes as late as four years after initial insult. Prompt referral to an ophthalmologist is always indicated in survivors of lighting injury, both for potential intervention (eg, steroids), as well as for closer evaluation of other potential injuries (eg, corneal burns, intraocular hemorrhage, uveitis, orbital fractures).^1,3,5

Psychological and neurocognitive sequelae of lightning injury are often delayed. Depression, changes in behavior, impaired memory, and difficulty with assimilation of new information have all been described in post-lightning strike syndrome. The highest recovery rates are seen within the first year after injury, with mild improvement after three years. Antidepressants have been found to be useful, but any dysfunction after three years is thought to be chronic, requiring long-term management.¹

Conclusion

In answering the question, “Tropic lightning: myth or menace?” the answer is neither. Lightning in Hawai‘i, while less common compared to the mainland, does occur and has the potential to be just as dangerous. The lack of documented lightning fatalities in Hawai‘i should not be construed to mean that lightning does not strike the ground, and the population should be educated regarding lightning safety.

Disclosure

The author reported no conflicts of interest.

Disclaimer

The views expressed in this abstract/manuscript are those of the author and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the US Government.