Lightning Injuries Douglas Eyolfson, MD, FRCP(C) Department of Emergency Medicine Seven Oaks General Hospital

Objectives l Epidemiology of lightning injuries l Properties of lightning l Patterns of injury l Treatment

Mr. A. l 54 year old male, post-lightning strike l Golfing, took refuge under shelter l Lightning struck center support l Unresponsive for ~ 2 minutes l Paramedics: alert, oriented, no complaints l Vital signs WNL l Monitor: NSR

Lightning Injuries l ~100 strikes/sec (~8 million/day) worldwide l Canada » injuries/year »60-70 deaths/year l Under-reported l Sports and transportation common settings l ~1/350,000 chance l Injuries different from artificial electricity

Lightning: A Primer

Levels of Electrical Exposure l Long distance lines: 24 V l Telephone lines: 65 V l Household circuits: 110 V l Stoves, dryers: 220 V l House power lines: 220 V l Subway third rails: 600 V l Residential trunk lines: 7000 V

Effects of Electricity l 1-5 mA: Tingling sensation l 5-10 mA: Pain l mA: Tetany, sustained grip l mA: Thoracic & diaphragmatic tetany l mA: Respiratory arrest l mA: V-fib l 2-5 A: Cutaneous burns l 5-10 A: Asystole

Low-Voltage AC l <600 V, <20-30 A, prolonged l V-fib commonest arrhythmia l Minor burns, occasionally deep tissue destruction l Myoglobinuria and renal failure occasionally l Tetanic contraction, falls

High-Voltage AC l ,000 V, <1000 A, 1-2 sec. l Asystole, V-fib l Burns, deep tissue destruction l Myoglobinuria l Renal failure l Musculoskeletal injury (thrown from source, falls)

Properties of Lightning l Voltage: ~20,000-2 billion l Current: ~20, ,000 amps l Unidirectional current l Speed 0.5 C l Duration ~1-3 msec l Temperature ~ 8,000-30,000 o C

Injuries: Lightning vs Artificial l Current pathway l Burn characteristics l Arrthythmias l Deep tissue injury l Blunt trauma l Cause of death

Current Pathway l Artificial –hand-hand –hand-foot –deep tissue/organ involvement l Lightning –flashover –internal organs often spared

Lightning Strikes l Direct »most serious l Side Flash l Contact Strike l Ground Current l Stride Potential (Step Voltage)

Cardiovascular Injuries l Sustained asystole –direct current depolarization –secondary to apnea l Acute MI –coronary vasospasm –direct myocardial damage –myocardial contusion (blunt trauma)

Respiratory Injuries l Prolonged apnea –paralysis of medullary respiratory centre l Pulmonary edema l ARDS l Pulmonary contusion

Neurologic Injuries l Heat-induced cortical coagulation l Epidural/subdural hematomas l Intraventricular hemorrhage l Paralysis of respiratory center l Keraunoparalysis

Dermatologic Injuries l Lichtenberg figures l Burns –8,000-30,000 o C –moisture becomes steam l Flash burns l Contact burns (keys, coins, jewelry) l Usually superficial

Renal Injuries l Less common than with AC l AC: sustained tetanic contraction and heating of muscle l Lightning: short duration current l Renal damage <6%

EENT Injuries l Ocular injuries >50% –cataracts –retinal hemorrhage –retinal detatchment –hyphema l Otologic –tympanic membrane rupture >50%

Misdiagnosis l CVA l Seizure disorders l CNS trauma l Toxic ingestion/envenomation l MI/arrhythmias l Assault

Prehospital Management l Lightning strikes twice in the same place l Safety of rescue personnel & bystanders l Evacuate all nonessential personnel l Multiple casualties may be present l Vital signs may be absent l Institute rapid triage

Standard Triage l Mass casualty incident l Multiple patients, limited resources l Concentrate resources where benefit most likely l Apparently dead and imminently dead unlikely to survive -----> lowest priority

Lightning Incident Triage l Reverse triage l Arrest most commonly due to asystole and/or apnea -----> transient l Vital signs present -----> likely to survive l Apparently dead most likely to benefit from ALS l Highest priority to victims without vital signs

Initial Prehospital Treatment l Institute CPR in victims without vital signs l Establish IV, fluid resuscitation rarely required l Be aware of other traumatic injuries l C-spine precautions

Emergency Department Treatment l ACLS/ATLS principles l Aggressive resuscitation l Hypotension: search for occult hemorrhage l Head-toe exam for associated injuries l Monitoring if unresponsive period l Usually admit for observation

Prevention l Anticipate (hot, humid days) l Remain indoors, seek shelter l Keep distance from water l If outside, remove metal objects l Stop all machinery l Groups should separate l Keep low

Prevention