When lightning strikes: tips for emergency management

Dr. Robert McMickle, an emergency physician at Harbor UCLA Medical Center in Los Angeles, delves into the topic of lightning injuries.

Clinical case: a lightning in a park during a thunderstorm

Some people are spending the afternoon in a park when a thunderstorm breaks out. As it starts to rain, a group of four people decide to hide under a tall tree. They notice intermittent flashes of lightning, but the situation does not seem to be getting worse. As they are planning to leave the park, the tree is struck by lightning and the group is hit by a side splash of electricity. When the first rescuers arrive, all four are breathless and pulseless. A 30-year-old woman can be resuscitated, although she goes into cardiac arrest again for 10 minutes on the way to the hospital. She recovers again (ROSC), while the other three members of the group fail to be resuscitated.

Background

Lightning is not an uncommon environmental cause of injury and death worldwide. Approximately 24,000 fatal accidents occur each year and almost ten times as many accidents in which people are struck and survive. In the United States, there are about 400 lightning injuries and 40 deaths per year, and most lightning strikes occur from May to September in the afternoon or early evening hours in states near the Gulf of Mexico¹.

Lightning carries an impressive amount of energy (30-110 thousand amperes) and voltage (10 million volts) that is delivered in a massive pulse within a few milliseconds. For reference, a typical household current measures 110-120 volts and 15 amperes, and a typical power line can deliver >7,000 volts. Lightning is neither direct nor alternating current, but rather a massive pulse of electrons moving in one direction^1,2.

The temperature is usually around 8,000°C, but it can reach 50,000°C and can therefore cause significant thermal burns¹.

Mechanism of the discharge^1,2

Direct strike (5%): lightning makes direct contact with subjects, most commonly fatal.
Contact injury (15%): lightning strikes an object that the victim holds or touches directly with a direct current flow.
Side splash (30%): lightning strikes an object (e.g. a tree, pole, building) and the current 'jumps' towards the victim.
Ground current (50%): the current passes through the ground and reaches the victim, whose body has less resistance than the ground.
Blunt trauma: secondary to the force wave generated by the lightning.
Electrical flux: lightning that rises to the sky and discharges a charge that passes over the victim, not as powerful as lightning from the sky.

Pathophysiology

Injuries occur through a variety of mechanisms and can affect all organs.

Effect of electric current on tissues: follows the path of least resistance (nerves > blood > muscles > skin > fat > bones).
Mechanical trauma: debris, falls, shocks.
Conversion of electrical energy into thermal energy, resulting in burns.

Effects on the cardiovascular system

Cardiopulmonary arrest is the most common cause of death and is most frequent with direct hits.
A second cardiac arrest due to continuous paralysis of the medullary respiratory centre and continuous apnoea can occur if respiratory support is not initiated in a timely manner.
Ventricular dysrhythmias, asystole, QT prolongation (asystole is more common than ventricular dysrhythmias).

Effects on the pulmonary system

Apnoea may persist after return of spontaneous circulation (ROSC), so early and continuous ventilation is important to prevent secondary cardiac arrest from hypoventilation.

Effects on the skin

90% of victims suffer superficial skin burns.
Lichtenberg figures (pathognomonic fern or feather pattern on the skin, shown below), due to 'electron rain' on the skin leading to red blood cell overflow, usually resolve in <24 hours.
Flash burns, punctuated burns, full thickness burns (<5%), contact burns.

Neurological effects

Intracranial haemorrhage in the basal ganglia and brainstem.
Keraunoparalysis - stunned or transient quadriplegia (lower limbs > upper limbs) secondary to overstimulation of the autonomic nervous system. Usually resolves within a few hours without treatment, but may take up to 24 hours.
Fixed, dilated pupils may be present in the absence of irreversible brain damage (NOT used to prognosticate or declare death).

Other effects

Cataracts (may occur weeks to years after injury).
Optic neuritis.
Vitreous haemorrhage, retinal and optic nerve injury.
Perforated tympanic membranes (present in 50-80% of victims).
Neurosensory damage to the acoustic nerve.
Compartment syndrome, rhabdomyolysis.
Posterior dislocation of the shoulder^1-3.

Assessment

A thorough head-to-toe physical examination is crucial to assess the presence of trauma, burns and other injuries.

An ECG is generally recommended in all patients, although it may reveal transient changes that eventually resolve.
Consider electrolytes, kidney and liver function, CK and urine examination.
Laboratory tests and workup are at the physician's discretion, although a low threshold is recommended to assess for rhabdomyolysis, compartment syndrome and to perform advanced neuroimaging such as noncontrast brain CT.
Troponin testing should be based on patient presentation and should not be performed routinely.
For patients with confusion or altered mental status, a CT brain scan without contrast should be performed.
Other imaging examinations should be based on the history and examination (e.g. extremity X-ray for trauma, abdominal CT scan for evaluation of intestinal contusions and haemorrhage).

On-site management

In contrast to most mass casualty incidents, where apnoeic and non-ambulatory patients are considered 'waiting' to succumb to their severe injuries and should not be prioritised in a situation of limited resources, the concept of 'reverse-triage' is of crucial importance and should be used in mass casualty events with relief.

This scheme identifies victims who appear to be in cardiac and respiratory arrest and prioritises their treatment, as they can have good results if identified and treated immediately. Victims who are unresponsive, not breathing or gasping are immediately given CPR and assisted breathing. If a pulse is obtained, continue to provide assisted ventilation to prevent 'secondary cardiac arrest' due to inadequate ventilation. Those who survive the initial stroke rarely die before or after arrival at hospital^1,2, although up to 77% of victims do not respond to CPR. If victims do not regain a pulse within 20-30 minutes of starting CPR, it is reasonable to discontinue resuscitation efforts⁴. Remember to also consider hypothermia before discontinuing efforts.

When patients arrive, aggressive resuscitation is recommended for those in cardiac arrest, as lightning-induced cardiac arrest has a better prognosis. Hypotension is not typical and suggests another injury. After ROSC, hyperthermia should be avoided.

General guide for management in the emergency room

Intravenous fluid resuscitation is recommended for unstable patients.
There are no reports in the literature on the use of mannitol-induced diuresis, urine alkalinisation or aggressive fluid resuscitation.
In hypertensive or normotensive patients, fluid restriction is recommended due to the risk of underlying cerebral oedema.
Fasciotomy is generally not necessary, as the intense vascular spasm typically resolves on its own.
Prophylactic antibiotics are not indicated unless there are other complicating conditions (e.g. open fractures).
Update tetanus vaccination if indicated.
Burns are generally too superficial to require treatment with topical agents⁴.

The best treatment is prevention

Seek shelter in a large enclosed indoor structure or a fully enclosed metal-roofed vehicle; even small structures such as golf huts and shallow caves can be energy capacitors for lightning.
The flash-bang rule helps to estimate the distance to an observer. Count the seconds between the flash of lightning and the bang of thunder. The time in seconds/5 = approximate number of kilometres.
Rule of 30-30: when observing lightning, count the time until you hear a clap of thunder and if the time is less than 30 seconds, seek shelter and wait 30 minutes from the time of the last flash or thunder before leaving.
If you are in a group, distribute people to avoid side splashes.
Avoid singularly tall structures such as trees or isolated flat areas.
Assume the 'lightning stance' if you are in an exposed area and cannot retreat (squat with feet together with heels touching or sit cross-legged preferably on a mat, rucksack or other conductive surface).

General provisions

High-risk characteristics warranting observation and/or admission for telemetric monitoring

Direct hit
Loss of consciousness
Focal neurological deficit
Chest pain
Dyspnoea
Major trauma
Cranial or significant burns
Pregnancy (fetal mortality approaching 50%)¹

In all other patients, discharge is safe if the patient has normal vital signs, appears well and has no other injuries requiring hospitalisation.

Myths about lightning

Lightning can strike twice in the same place, and often does.
Lightning often strikes outside thunderstorms (up to 1/3 of the time).
Lightning leaves no residual charge on victims and does not cause 'internal burns'.
Rubber tyres do not provide 'insulation' in a car, but the metal spreads the current around the occupants to the ground.
Personal items such as watches, mobile phones and jewellery do not 'attract' lightning. Metal objects do not 'attract' lightning, but conduct it, so it is best to stay away from metal fences, poles and steps⁵.

Main take-aways

Lightning injuries occur through a variety of mechanisms (side splashes, direct hits, currents, etc.) and affect almost all body systems.
Lightning injuries can be immediate or delayed; a thorough examination from head to toe, including a thorough neurological examination, is important to account for all injuries and determine long-term outcomes.
Lightning burns are often superficial and do not need to be treated with specific intravenous fluid protocols, which may worsen cerebral oedema if present.
Reverse triage in mass casualty situations.
Admission for high-risk features.
There are many myths and legends about lightning.
Prevention is crucial: no one can be completely safe during a thunderstorm unless they are in a large enclosed structure or in a fully enclosed vehicle with a metal roof.

References

References: Della-Giustina D, Ingebretsen R, eds. Advanced Wilderness Life Support : Prevention, Diagnosis, Treatment, Evacuation. Wilderness Medicine Society; 2011:122-132.
Jensen JD, Thurman J, Vincent AL. Lightning Injuries. [Updated 2021 Jul 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441920/
Kaji A, Pedigo RA. Emergency Medicine: Board Review. Elsevier; 2022.
Cooper, MA., Andrews, CJ., Holle, RL., Blumenthal, R., Navarrete Aldana, N. Lightning-Related Injuries and Safety. In: Auerbach P, ed. Auerbach’s Wilderness Medicine. Elsevier; 2017:71-117.
US Department of Commerce NOAA. Lightning myths. National Weather Service. https://www.weather.gov/safety/lightning-myths. Published April 20, 2018. Accessed February 15, 2022.
McMickle RJ. Lightning Strike Injuries. emDOCs. Aug 29th 2022