Lightning Injuries

An expert panel from last year’s Wilderness Medical Society Annual Meeting have produced Guidelines for the Treatment and Prevention of Lightning Injuries.  Of course, there is not a great deal of high quality evidence in this area but the guidelines are a good summary of expert opinion.

To provide guidance to clinicians about best practices, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for the treatment and prevention of lightning injuries. These guidelines include a review of the epidemiology of lightning strikes and recommendations for the prevention of lightning strikes, along with treatment recommendations organized by organ system. Recommendations are graded based on the quality of supporting evidence according to criteria put forth by the American College of Chest Physicians.

Here are some of the key points:

An estimated 400 lightning strikes occur annually in the United States, with a lifetime risk of lighting strike estimated at 1 in 10, 000.  Most victims are males between the ages of 20 and 45.

There are four types of lightning injury

1. Direct strike – rare, caused by uninterrupted connection between the lightning bolt and the individual
2. Contact injury – when a persons is in contact with object struck by lightning
3. Side splash – the current follows the path of least resistance and “splashes” from a nearby object to the victims body
4. Ground current – the lightning travels through the ground from the strike point to the recipient

Prevention

When thunder roars, go indoors

In the wilderness setting, leave high risk areas such as ridgelines, summits, ski-lifts, water or isolated trees.  Relying on timing lightning flashes with thunderclaps may engender a false sense of security. Individuals should instead rely on observing signs of impending storms and seeking cover accordingly. Individuals should wait a minimum of 30 minutes after hearing the last thunderclap before resuming outdoor activity.The safest shelters are buildings or hard-topped vehicles.  In the wilderness, possible shelters include deep caves, dense forests or deep ravines.

When lightning strike is imminent, sit or crouch with knees and feet close together to create only one point of contact with the ground.  Hmmm, and cross your fingers?

In a mountain climbing environment, tie off individually and discard metal items to avoid contact burns.

Injuries and Treatment

Cardiac

The mechanism of sudden death from lightning strike is simultaneous cardiac and respiratory arrest. Death is rare should a victim survive the initial lightning strike.

Asystolic arrest classically occurs due to simultaneous depolarization of all myocardial cells, although ventricular fibrillation may also occur.  The medullary respiratory centre remains paralysed after return of  cardiac automaticity, so a second cardiac arrest may result if ventilation is not supported.  For this reason, those patients without vitals signs or spontaneous respirations should take priority.

Resuscitation should follow basic and advanced life support algorithms.  In fact, mortality from cardiac arrest due to lightning strike has a lower mortality than cardiac arrest in the general population.

Direct strikes are more likely to cause cardiac arrest.  Other types of strikes may cause transient ECG abnormalities.

Patients with any of the following high risk indicators for lightning strike should have a screening ECG and echocardiography.

• Suspected direct strike
• Loss of consciousness
• Focal neurologic complaint
• Chest pain or dyspnea
• Major trauma defined by Revised Trauma Score
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• Cranial burns, leg burns or burns 10% TBSA
• Pregnancy

Neurologic

Neurologic injuries are common and may include transient loss of consciousness, headache, weakness, confusion and memory loss.Keraunoparalysis is transient paralysis after lightning strike and is thought to be caused by overstimulation of the autonomic nervous system leading to vascular spasm.Typically lasting several hours, the affected limbs exhibit pulselessness, pallor or cyanosis, and motor and sensory loss.  Spinal injury must be excluded, particularly if paralysis continues despite resolution of vascular symptoms. 

Lightning strike may also cause hypoxic encephalopathy, intracranial heamorrhage and a multitude of delayed neurological syndromes.

Dermatologic

The pathognomonic Lichtenberg figures are a “ferning” pattern on the skin usually occurring within an hour of lightning strike and resolving within 24 hours.  No treatment is required.

Lightning strike can cause linear burns from sweat vaporization, punctate burns from current exiting deep tissues, and full-thickness burns from contact with  heated objects.

 Others

• Cataracts comprise the majority of eye injuries, and can occur between 2 days and 4 years after lightning strike.
• Tympanic membrane rupture is common, and can occur from a combination of blast trauma and electrical injury.
• Abnormalities in memory and concentration
• Depression, sleep disturbances,  emotional lability, and aggressive behavior.