Lightning Injury

Lightning injury is trauma caused by a lightning strike. Peak current is 20,000 to 50,000 amperes, but contact lasts only milliseconds, so deep burns and muscle destruction are much less common than in high-voltage industrial injury. The current usually flashes over the surface of the body.

Mechanisms

• Direct strike (3 to 5%)
• Side flash from a nearby object (about 30%)
• Ground current (about 50%, the commonest and affecting many victims)
• Contact injury (touching an object that is struck)
• Upward streamer and blast effect (barotrauma and thrown victim)

Deaths number about 6000 a year worldwide, with an overall mortality of 10 to 30% and high morbidity (up to 70% of survivors have lasting problems). Most deaths follow immediate cardiac arrest (asystole, which often reverts spontaneously because the heart has automaticity). Respiratory arrest from medullary paralysis persists, so hypoxia can cause secondary ventricular fibrillation if ventilation is not supported.

Complications: cardiac arrest, tympanic membrane rupture (about 50%), cataracts and retinal injury, autonomic dysfunction, seizures, keraunoparalysis (transient limb paralysis with vasospasm), fractures and blunt trauma, neuropsychological sequelae (memory loss, personality change, chronic pain, sleep disturbance and post-traumatic stress) and fetal loss.

• Lichtenberg figures (transient fern-like or feathery erythema, pathognomonic but present in a minority), linear and punctate burns
• Loss of consciousness, confusion and amnesia
• Keraunoparalysis: cold, pale or mottled, pulseless limbs with weakness and paresthesia, which recover within hours
• Tympanic membrane rupture, hearing loss, tinnitus and visual disturbance
• Fixed dilated pupils from autonomic injury (not a sign of death)
• Chest pain, palpitations, hypotension and arrhythmia
• Red flags: cardiac or respiratory arrest, altered consciousness, severe blunt injury, pregnancy and several victims at the scene

1. Primary survey with reverse triage, since apparently dead victims have the best chance of survival if treated first.
2. 12-lead ECG and monitoring: transient QT prolongation, ST elevation, arrhythmia.
3. Blood tests: creatine kinase, myoglobin, creatinine, electrolytes, troponin (limited specificity) and blood gases.
4. Imaging: CT head and cervical spine when consciousness is altered or trauma is possible, plus radiographs for fractures.
5. Otoscopy and audiometry, and eye examination with fluorescein and fundoscopy.
6. Echocardiography for persistent chest symptoms or hypotension, and compartment pressure checks when limbs swell.
7. Fetal assessment in pregnancy.

Differentials: high-voltage electrical injury, blunt trauma, primary arrhythmia, seizure and intoxication.

1. Scene safety: a victim carries no charge, so rescuers can approach, but should avoid ongoing storm danger by moving to shelter.
2. Reverse triage: resuscitate those in cardiac or respiratory arrest first, before those who are breathing.
3. Cardiopulmonary resuscitation: begin at once, give prolonged ventilatory support (respiratory arrest outlasts cardiac arrest, so continued ventilation prevents secondary arrest) and continue resuscitation longer than usual, since good outcomes follow prolonged efforts. Defibrillate ventricular fibrillation and tachycardia, and give standard drugs (epinephrine 1 mg IV every 3 to 5 minutes).
4. Airway: intubate for coma or ongoing respiratory failure, with cervical spine protection.
5. Fluids: do not give routine large volumes, since burns are usually minor. Titrate crystalloid to a urine output of 0.5 to 1 mL/kg/h. When myoglobinuria is present, give lactated Ringer solution 200 to 500 mL/h to keep urine output at 1 to 2 mL/kg/h until clear.
6. Monitoring: continuous ECG for 24 hours in symptomatic patients and anyone with abnormal ECG, loss of consciousness or chest pain.
7. Burns and wounds: clean and dress, and tetanus toxoid 0.5 mL IM if not immunized. Fasciotomy only for proven compartment syndrome.
8. Keraunoparalysis: supportive care, warming and reassurance. Pulses return within hours.
9. Eyes and ears: topical chloramphenicol 0.5% four times daily for corneal injury with cycloplegia, keep the ear dry for tympanic perforations (most heal in 4 to 6 weeks), and give antibiotics only for infection. Later cataract surgery.
10. Analgesia: paracetamol 1 g orally every 6 hours, and morphine 0.05 to 0.1 mg/kg IV for severe pain.
11. Pregnancy: fetal monitoring and obstetric review.
12. Neuropsychological care: neurorehabilitation, cognitive assessment and psychological support.

Prevention: stop outdoor activity when thunder is heard (flash to bang under 30 seconds) and wait 30 minutes after the last thunder, seek an enclosed building or a hard-topped vehicle, avoid trees, open fields, water and metal objects, and crouch with feet together if stranded. Follow-up at 3 to 6 months with eye, hearing and neurocognitive review.