Only 3 factors predispose to a lightning hit:
- height of an object
- "pointiness", which is not a factor with people.
Note: Whether it is metal or not does not matter.
The physics of lightning is incredibly complex and substantially different from the physics of generated electricity. . It can generate a direct electrical current of over 10 million volts, lasting only 10 -100 milliseconds.
The mortality from a lightning strike is around 10% in developed countries.
- Direct strike (often fatal)
- Contact injury - victim is in contact with structure that receives a strike
- Side flash - lightning arcs from a nearby object onto the victim
- Ground current – lightning spread through the ground from the strike site onto the victim
- Blast injury – primary blast injuries may result in injury to major organs and eardrum; secondary blast injury occurs when the victim is thrown a distance resulting in trauma.
The most serious complications of lightning strike are cardiac arrhythmias and respiratory arrest.
- The most common arrhythmia post lightning is asystole – in this situation, survival can be up to 50% if early bystander CPR is commenced.
- Respiratory arrest may also occur due to transient paralysis of the medullary respiratory centre – ventilatory support is important during this time as the length of unsupported apnoea is a major determinant of survival.
- Fixed dilated pupils may be a transient direct result of the strike and should not be used to guide resuscitation in this circumstance.
Other cardiovascular effects range from benign ECG changes through to VF or asystole – the ECG may show ST changes, QT prolongation, AF or other effects. Delayed pericarditis is also possible
Lightning strikes are primarily a neurologic injury that affects all 3 components of the nervous system: central, autonomic, and peripheral.
It is common for the person to have anterograde amnesia or confusion. Other effects include loss of consciousness, possible intracranial haemorrhage, strokes, seizures and peripheral nerve injuries.
A particular injury that is unique to lightning is keraunoparalysis – this is a transient paralysis of one or more limbs, with the limb appearing cold, pale and mottled. It is thought to be due to vasospasm and should resolve within 6-24 hours – if not, then other causes should be sought.
The vast majority of lightning energy flashes around the person's body surface with only brief contact with skin and, in most instances, the contact is too brief to burn the skin substantially. Entry and exit are inappropriate terms to apply to lightning injuries.
Injury from a direct strike only affects a small percentage of patients and electrical, thermal or mechanical effects from surrounding strikes make up the rest. Internal burns are rare.
When burns do occur, they are usually superficial, or result from contact with hot objects or fire from resulting from the strike. In some cases classical ferning occurs, as illustrated below. This is due to electron showers over the skin, and is not a true burn - it should resolve within 24 hours.
Source: Dr John Mackenzie
Internal burns are rare.
Eye injuries like retinal detachment or optic nerve injury may occur – cataracts are a common delayed effect.
Ears are also often affected with tympanic membrane rupture in 50%, tinnitus and sensorineural deafness resulting.
Workup is related to the presentation and what you find, not because it is a lightning strike. For example, you should assess all patients post strike as a potential trauma
Perform ECG as directed by physical findings. Many changes may be observed on the ECG, but the most commonly reported change is QT prolongation, which generally resolves over several months and does not commonly require treatment. Cardiac markers are often elevated and hence difficult to interpret.
Further testing depends upon the clinical circumstance. It may include echocardiogram if the ECG is abnormal; CT brain if there was LOC at the time or persistent focal neurological deficits; MRI if concern about spinal cord injury.
Treatment relates to the complications such as seizures, chest pain, and other symptoms.
In multi-casualty situations, “reverse triage” applies – CPR should be given to those without signs of life first due to the potential chance for good recovery. Usual ACLS guidelines should be followed.
Admission for the vast majority of lightning strikes is not required – admit if high risk features present.
High Risk Features
- Direct strike
- Loss of consciousness
- Focal neurological deficits
- Chest pain or dyspnoea
- Pregnancy (high risk of fetal mortality)
- Burns to head, legs or to >10% BSA
- Major trauma or blast injury
Myths about Lightning
- Victims remain charged after the strike and should not be touched.
- Lightning never strikes twice in the same place.
- Lightning always strikes the tallest object.
- Lightning only occurs where there are storm clouds overhead or when it is raining.
Further References and Resources
Wilderness Medical Society. Wilderness medical society practice guidelines for the prevention and treatment of lightning injuries 2012