Lightning injury


Lightning injuries are injuries caused by a lightning strike. Initial symptoms may include heart asystole and respiratory arrest. While the asystole may resolve spontaneously fairly rapidly, the respiratory arrest is typically more prolonged. Other symptoms may include burns and blunt injuries. Of those who survive about 75% have ongoing health problems as a result, such as cataracts and hearing loss. If death occurs it is typically from either an abnormal heart rhythm or respiratory failure.
Lighting injuries are divided into direct strikes, side splash, contact injury, and ground current. Ground current make up about half of cases and occurs when the lightning strikes nearby and travels to the person through the ground. Side splash makes up about a third of cases and occurs when lightning strikes nearby and jumps through the air to the person. Contact injury occurs when the person is touching the object that is hit. Direct strikes make up about 5% of injuries. The mechanism of the injuries may include electrical injury, burns from heat, and mechanical trauma. Diagnosis is typically based on history of the injury and examination.
Prevention includes avoiding being outdoors during a thunderstorm. If avoiding being outdoors is unavoidable crouching low is recommended. When indoors the use of devices connected to electrical outlets and contact with water is not recommended. Among those who appear in cardiac arrest and have no central pulse, cardiopulmonary resuscitation should be started. In those who have a central pulse but are not breathing artificial ventilation, such as mouth to mouth, is recommended.
It is estimated that lightning injuries occur 240,000 times a year with 24,000 deaths. Areas with mountainous terrain and moisture-heavy airflow, such as Central Africa, have the highest rates of lightning strikes. Among pregnant women who are hit by lightning, the death of the baby occurs in about half. In the United States about 1 in 10,000 people is hit by lightning during their lifetime. Males are affected 4 times more often than females. The age group most commonly affected is 20 to 45 years old.

Signs and symptoms

Common injuries caused by lightning include: muscle pains, broken bones, cardiac arrest, confusion, hearing loss, seizures, burns, behavioral changes, and ocular cataracts. Loss of consciousness is very common immediately after a strike.
Lighting burns result from energy caused by lightning strikes, and are characterized by a unique pattern of skin lesions. These tree-like lesions resemble feathering or ferning, and are also called “Lichtenberg figures". The marks are formed when capillaries beneath the skin rupture due to the electrical discharge and they usually appear "within hours" of the strike though they tend to disappear within a few days. They also generally occur on the upper body. The brief duration of the exposure frequently limits the damage to the outer layer of skin.
The intense heat generated by a lightning strike can burn tissue, and cause lung damage, and the chest can be damaged by the mechanical force of rapidly expanding heated air.
Just as heat can cause expanding air in the lungs, the explosive shock wave created by lightning can cause concussive and hearing damage at extremely close range. Other physical injury can be caused by objects damaged or thrown by the lightning strike. For example, lightning striking a nearby tree may vaporize sap, and the steam explosion often causes bark and wood fragments to be explosively ejected.
Lightning strikes can also induce a transient paralysis known as keraunoparalysis. Signs and symptoms of keraunoparalysis include lack of pulse, pallor or cyanosis, and motor and sensory loss in the extremities. However, keraunoparalysis usually resolves within a few hours.

Pathophysiology

Although the current flow of a lightning strike occurs only over a short period, the current has an extremely high voltage of some 30 million volts. Lightning is neither a DC or an AC current but best described as a unidirectional massive current impulse of electrons.
Lightning strikes are grouped in four categories: direct strikes, side splash, contact injury, and ground current.
Lightning injury may occur by these electrical mechanisms or by secondary blunt trauma as a result of the strike.

Diagnosis

Diagnosis is typically based on history of the injury and examination.

Prevention

Preventing lightning injury involves avoiding being outdoors during a thunderstorm. While no place is entirely safe from lightning strikes, seeking a substantial shelter or an enclosed all-metal car is recommended. If being outdoors is unavoidable, staying away from metal objects, tall structures, and open, exposed areas is strongly suggested. When there is risk of imminent lightning strike, crouching low with one's knees and feet together can be used, however this is typically used as a last resort since this position can be difficult to maintain for an extended period of time. For large groups of people, it is recommended that individuals spread out to avoid mass casualties. When indoors, the use of devices connected to electrical outlets and contact with water is not recommended.

Treatment

Immediate

The most critical injuries are cardiac arrest and respiratory failure. This will often require prompt emergency care. It is safe to provide care immediately, as the affected person will not retain an electrical charge after the lightning has struck.
Many people who are unconscious and appear lifeless die of suffocation. Chances of survival may be increased if cardiopulmonary resuscitation is started immediately, and continued without interruption until the brainstem recovers.

Long-term

A complete physical examination by paramedics or physicians may reveal ruptured eardrums. Ocular cataracts may later develop, sometimes more than a year after an otherwise uneventful recovery. Long-term injuries are usually neurological in nature, including memory deficit, sleep disturbance, chronic pain, and chronic dizziness.

Prognosis

The mortality rate for lightning strike is approximately 10%. Survivors of lightning strike may suffer long term injury or disability.

Epidemiology

It is estimated that lightning injuries occur 240,000 times a year with 24,000 deaths. Among pregnant women who are hit by lightning, the death of the baby occurs in about half. In the United States about 1 in 10,000 people is hit by lightning during their lifetime. Males are affected 4 times more often than females. The age group most commonly affected is 20 to 45 years old.