Lightning injury

OVERVIEW

  • potentially lethal electrical injury due to lightning exposure
  • 24,000 deaths/ year worldwide

PHYSICS AND PATHOPHYSIOLOGY

Physics

  • extremely high voltage (30 millon volts)
  • high currents: 30,000 to 110,000 A
  • limited energy transfer due to extremely short duration (10-100 msec)
  • can be AC or DC current, but tetanic contractions are not seen
  • electricity travels through path of least resistance: nerves < blood < muscle < skin < fat < bone

Types of lightning injury

  • direct strike (5%)
  • contact injury (15%) – victim in contact with structure that received direct strike
  • side splash (30%) – current jumps to victim not in physical contact with structure that received direct strike
  • ground strike (50%) – current travels through the ground to the victim (strike point)

CLINICAL FEATURES

Cardiorespiratory arrest (rare)

  • immediate
  • usually asystole due to electrical insult to the myocardium, typically resolves spontaneously
  • respiratory arrest due to medullary paralysis
  • apnea is longer duration than asystole, so untreated patients may have ROSC then suffer a second hypoxic arrest

Cardiovascular

  • asystole or VF immediately
  • ECG changes such as ST elevation and QT prolongation
  • atrial fibrillation
  • cardiomyopathy
  • delayed pericarditis

Respiratory

  • blast injury
  • ARDS
  • aspiration

Neurological

  • transient, immediate
    — keraunoparalysis due to ANS-mediated vasopasm -> motor and sensory changes, cyanosis, pallor and/or pulselessness; lower limbs > upper limbs; resolves spontaneous; may mimic spinal cord injury
  • permanent, immediate
    — hypoxic encephalopathy, peripheral neuropathy, intracranial hemorrhage (especially basal ganglia, brainstem), stroke, cerebral salt wasting syndrome, traumatic injuries
  • delayed
    — progressive myelopathy (weeks-to-months; causative link to lightning strike is uncertain)

HEENT

  • eyes — cataracts, blast injury, retinal and optic nerve injury
  • ears — tympanic membrane rupture (50% – heal with conservative management), otorrhoea (suspect base of skull fracture), transient sensorineural deafness, microfractures (permanent hearing loss)

Burns

  • Lichtenberg figures — transient ferning or feathering patterns pathognomonic of lightning strike (onset <1 hour, duration <24 hours)
  • linear – “flashover” (sweat turns to steam)
  • punctate burns – multiple circular burns due to current leaving the body e.g. tip-toe sign
  • full thickness contact burns – due to fire or heated object in contact with skin (NB. deep thermal burns are rare, unlike HV electrical injuries)

Neuropsychiatric

  • functional – memory and concentration impairment
  • behavioural – depression, aggression, personality change

HIGH RISK FEATURES

  • loss of consciousness
  • focal neurological deficits
  • chest pain or dyspnea
  • pregnancy
  • burns to head, legs or to >10% BSA
  • major trauma or blast injury

INVESTIGATIONS

  • ECG
  • Echocardiogram (if high risk features)
  • CK, troponin (not prognostically important)
  • CT Head if loss of consciousness or focal deficit
  • MRI if cannot exclude spinal cord injury clinically

MANAGEMENT

Prehospital

  • ‘reverse triage’ applies as patients may appear dead (fixed dilated pupils with respiratory arrest) but develop ROSC and may make full recovery
  • all patients with high risk features should be transported to hospital; others according to comorbidities and nature of injury

Resuscitation

  • as per standard ACLS guidelines
  • despite anecdotal reports there is no reason to assume nor evidence to suggest that lightning strike victims might benefit from prolonged CPR

Specific therapy

  • treat injuries on merit
  • seek and treat complications (e.g. rhabdomyolysis)

Supportive care and monitoring

  • 24 hours cardiac monitoring if ECG changes, abnormal Echo

Disposition

  • admit all patients with high risk features to hospital
  • ECG changes or abnormal echocardiography require cardiology review and follow up
  • burns require review by burns specialist
  • visual loss or high risk features -> ophthalmology review
  • hearing impairment -> ENT review
  • functional or behavioural problems -> neuropsychiatric follow up

PREVENTION

  • “when thunder roars, go indoors” — ideally inside a large building away from metal utilities, doors and windows, otherwise in a metal-roofed vehicle with doors and windows closed (acts as a Faraday cage)
  • avoid open exposed areas, summits and ridgelines
  • avoid tall structures
  • if in a group space >20 feet (6 m) apart
  • stay indoors until 30 minutes after the last thunderclap heard (to ensure 10 mile buffer)
  • if outdoors use the ‘lightning position’ as a last resort: crouch with feet together to make one contact point, alternatively if sitting lift feet off the ground; insulate from ground if possible (e.g. sit on pack)
  • exit water and stay away from the water edge
  • be aware that lightning can strike despite clear skies (typically after a storm – ‘bolt from the blue’)
  • remove metal objects to avoid contact burns should lightning strike
  • timing thunderclaps to judge distance is unreliable (which thunderclap accounts for which lightning strike?)

References and Links

  • Davis C, Engeln A, Johnson E, McIntosh SE, Zafren K, Islas AA, McStay C, Smith W’, Cushing T; Wilderness Medical Society. Wilderness medical society practice guidelines for the prevention and treatment of lightning injuries. Wilderness Environ Med. 2012 Sep;23(3):260-9. PMID 22854068.
  • O’Keefe Gatewood M, Zane RD. Lightning injuries. Emerg Med Clin North Am. 2004 May;22(2):369-403. PMID: 15163573

CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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