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2009_04_09-Thompson-Electrical_and_Lightning_Injuries

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					Electrical & Lightning
        Injuries
     Carly Thompson
      EM-Resident
      April 9, 2009
                    Outline
Electrical Injuries        Lightning
• Definitions              • Pathophysiology of
• Epidemiology and           Lightning
  Physics                  • Specific Injuries:
• Physiologic Effects of     Lightning
  Electricity              • ED Management
• Specific Injuries        • Cases
• ED Management of
  Electrical Injuries
• Cases
           Electric Injuries
Definitions
• Electric shock – response
• Electrocution – death
• Electrical injury
  – tissue damage
• Electrical burn
  – cutaneous injury
• 550 Electrocutions / Year in USA (1998)
   – 50% of low-voltage <1000 V AC no visible burns or marks
• 100 Lightning Deaths / Year USA
   – Underestimate?
• 17 000 Electric Injuries / Year USA
• 300 Lightning Injuries / Year USA
                   Epidemiology
3 Groups at Risk for Electrical Injuries:
   – Toddlers
   – Adolescents
   – Electrical Workers (1/10 000 deaths/year)


Lightning Injuries
Risks:
- Transportation: Car, plane, water
- Storms or blue sky!
Mortality:
- 0.5 / million in US – 8.8 / million rural SA
- 70-90% survival rate
- 75% of survivors will have sequelae
                      Physics 101
• Electric flow / current = Amp
• Electric potential difference = Volts
• Resistance = Ohms
    – Conductors: high fluid, electrolyte content – nerves and
      blood vessels, sweaty skin, saliva, muscle
    – Insulators: high resistance – bone, dry skin
Ohm’s Law
    I (Current) = V (Voltage) / R (Resistance)
   Current is directly proportional to potential difference, and inversely
                          proportional to resistance.
Example = Grasp 120V source, with 1000Ohms resistance = 120mAmps
          Types of Current
• What are the two types of current?
                  AC/DC
How did the band AC/DC gain their name?
They saw it on the back of their older sister’s
 sewing machine.

• AC – alternating current
  Homes, usually 60Hz
• DC – direct current
  Batteries, lightning
Physiologic Effects
• Related to amount duration, type,
  path
• Current travels along multiple
  paths, not only path of least
  resistance
• Nerves and blood vessels – least
  resistance
• Muscles have most flow due to
  greatest area
• Nerves have higher current
  density -> significant injury
                   Effect of Current
Effect                        Current Path            Minimum Current
                                                        60 Hz AC
                                                        mAmp
Tingling sensation,           Through intact skin     0.5-2
   minimal perception
Pain threshold                Through intact skin     1-4
Inability to let go: tetany   From hand, through      6-22
   decreases resistance          forearm into trunk
Respiratory arrest: fatal     Through chest           18-30
   if prolonged
V Fib                         Through chest           70-4000
Ventrical asystole, if        Through chest           >2000
   current stops sinus
   rhythm may resume
                     Physics 102
• Electrical energy -> deposited as heat
• Heat causes the most tissue damage
Joule’s Law
            Energy = I2 x R x time
           Energy = (V2 x time) / R
Therefore the heating of tissues increases according to the square of
    the applied voltage, and is directly proportional to the time the
                            voltage is applied.
                      Electricity
Power Line: 7620V
Lines outside house: 220 / 240V
Subway: 660V

High Voltage Injury
• >1000 V
• Severe skin burns

Low Voltage Injury
• Cutaneous burns often minimal with household voltage,
  unless several secs contact
• Electrical burns absent in 40% of low voltage deaths
• 110V can cause V fib
                 Trivia
What was AC/DC’s first album?
What is considered high voltage?
>1000 V
Cardiovascular Injuries
•   1° cause of death from electrocution
•   Low-voltage -> v fib
•   High-voltage AC and DC -> transient asystole
•   Also: ST, PACs, PVCs, a fib, 1st / 2nd AV block
•   Vigorous resuscitation!!!
    – Victims are often young without CVD
    – Not possible to predict outcome based on rhythm
• Vascular injury -> spasm -> delayed thrombosis
  or aneurysm formation, compartment syndrome
CNS and Peripheral Nerve Injuries

• 50% have impairment (high-voltage)
  – Transient LOC
  – Agitation, confusion,
  – Coma
  – Seizures
  – Quadriplegia, hemiplegia, paresthesias
  – Aphasia, visual disturbances
         Spinal Cord Injuries
• Vertebral fractures – multilevel!
• Delayed injury
  – ascending paralysis
  – complete or incomplete cord
  – transverse myelitis
• MRI results not closely correlated to outcome
                Eye and Ear
Eye Injuries
• Cataract formation weeks to years later
• Retinal detachment, corneal burns, intraocular
  hemorrhage, intraocular thrombosis

Ear Injuries
• Late complications of hemorrhage into TM,
  middle ear, etc. -> mastoiditis, sinus thrombosis,
  meningitis, brain abscess
• Hearing loss immediate or late
            Cutaneous Wounds
• Entry / exit wounds – painless, gray

Treatment
• Cleansing, Td
• Silver sulfadiazine
• Mafenide
   – Full-thickness burns – penetrates eschar
   – <25% BSA only – inhibits carbonic anhydrase, painful
• Observe for neurovascular compromise, compartment
  syndrome
• Splint extremities, early surgical debridement, vascular
  reconstruction and skin graft
Flexor Crease Burns
    Orthopedic Injuries / MSK
• Fractures 2° to tetany, falls
• Shoulder dislocation (voltages >110V)
• Muscle +++heat -> periosteal burns,
  osteonecrosis
• Severe arterial spasm -> compartment
  syndrome
• Muscle breakdown -> rhabdomyolysis ->
  myoglobinuria and renal failure
  Blast and Inhalational Injuries
Blast Injuries
• Strong blast pressure -> head injury, mechanical
  trauma, arterial air emboli

Inhalational Injuries
• Ozone -> mucous membrane irritation,
  decreased pulmonary function, pulmonary
  hemorrhage, edema
• Carbon monoxide, etc. assoc. with fires
               GI Injuries
• Suspect in patients with burns of abdo
  wall, or trauma
• Lethal injuries – reported only at autopsy
• Gastric ulcers – Curling’s ulcers
• Fluid resuscitation -> abdominal
  compartment syndrome with restrictive
  surface burns
                    DIC
• May be due to thermal injury or tissue
  necrosis
• Low-grade DIC from hypoxia, vascular
  stasis, rhabdomyolysis, release of
  procoagulants
• Tx: eliminate precipitating factor by early
  surgical debridement
• FFP or cryo as needed
Oral Burns
• Children
• Unilateral
  – Lateral commissure, tongue, alveolar ridge
• Systemic complications rare
• Vascular injury to labial artery
  – Severe bleeding 10% cases
  – Occurs 5 days – 2 weeks when eschar
    separates
Oral Burns
Treatment
• Admission – monitoring
• Outpatient – reliable parents, who can be shown
  how to control bleeding, consideration?

• Saline rinses, swabs to debride necrotic tissue
• Petrolatum-based Abx for soothing effect
• Specialty consultation – splinting / surgical
  procedures to prevent deformity and dysfunction
                      Tasers
• Sinusoidal electrical impulses 10-15Hz
• High voltage 50 000V for Taser
• Low Amps and low average energy
• 2001-2007 245 deaths after Taser
Injuries
• R on T phenomenon -> v fib
• Pacemaker or ICD malfunction
• Death more likely with concomitant drug use (PCP,
   cocaine), trauma from struggle, preexisting CAD
• Ocular injuries
• Other: burns, lacs, rhabdo, testicular torsion,
   miscarriage
  Accident Scene: Rescuer Safety
Downed Power Lines
• Electrocution possible, recommend 9m away (3m may
  be enough)
• Reapplication of voltage may occur -> jumping power
  lines

Victims
• Victims in contact with source may be “active”
• Voltage >600V -> dry wood, rubber boots may conduct
  electricity
• Persons inside vehicle in contact with power line, likely
  to be killed if they step out
                ED Treatment
Resuscitation
• ABCs as per trauma
• ACLS
• Spinal immobilization
• Careful physical exam!

Investigations
• Labs: High-voltage, extensive burns, evidence of
  systemic injury
• CBC, lytes, Cr, BUN, CK, serum / urine myoglobin
• Imaging as indicated, clear spines
             ED Treatment
Fluid Resuscitation
• Fluid requirements > Parkland’s formula
• Visible damage < internal damage!
• Initial fluid bolus: 20-40mL/kg/ 1st hr
• Considerations:
  – Fluid load to prevent rhabdomyolysis
  – Avoiding over-resuscitation in patients with
    restrictive burns on abdomen -> prevent
    compartment syndrome
                  Disposition
Admission:
• In contact >600V
• Symptoms (CP, palp, LOC, confusion, weakness,
  dyspnea, abdo pain)
• Signs (weakness, burns with subcut damage, vascular
  compromise)
• Ancillary changes (ECG, CK, myoglobinuria)
• Cardiac monitoring: If ECG abnormal

No Admission:
• Household voltage injury 100-220V in adult +
• Neglibible risk for delayed arrhythmias +
• Asymptomatic, normal ECG and normal exam -> d/c
    Electric Injury in Pregnancy
• Increased rate of fetal damage or loss after
  apparent harmless contact
  – Monitor x 4 hours in women >20-24 weeks GA
  – Monitor >24 hours if LOC, ECG abN, hx of CVD
  – Fetal ultrasonography at presentation, then at 2
    weeks
• No proof that monitoring or tx can influence
  outcome
        Electric Injury in Children
• Children with only hand wounds from outlet, but no
  cardiac or neurologic involvement can be d/c home with
  wound care
• Consider admission if equivocal home safety or reliability
• Guidelines for ECG in children:
   – Tetany
   – Decreased skin resistance by water or burns
   – Unwitnessed event
• Guidelines for cardiac monitoring x 24 hours:
   –   Past cardiac hx
   –   LOC
   –   Voltage >240V
   –   Abnormal ECG
 Cardiac Monitoring in Children
Bailey et al. (2000). Experience with guidelines for
  cardiac monitoring after electrical injury in
  children. Am J Emerg Med; 18(6):671-5.
• July 1994 – June 1998
• Tertiary pediatric teaching hospital
• 224 cases
  – Cardiac monitoring on 13% (all normal)
  – No morbidity 0/172 patients
  – No mortality 0/224
                    Case 1
•   30 yo M electric worker
•   Found down at steel plant
•   Thermal burn – lateral head
•   Presenting in asystolic arrest

What do you do?
How long do you continue treatment?
              Case 1 Cont’d
Thoughts . . .
• Resuscitation as per ACLS
• Spinal precautions
• Vigorous resuscitation as patient is young and
  otherwise healthy, heart may spontaneously
  regain automaticity

Conclusion . . .
• 45 minutes in ED resuscitation – no cardiac
  activity
• Code called
Case 2
  Summary: Electrical Injuries
• Low-voltage <600V -> may be D/C if
  asymptomatic
  – Immediate cause of death: V Fib
  – Children: oral burns – consider labial artery bleed
     ? admission
• High-voltage >1000V -> admit for observation
  and cardiac monitoring
  –   Asystole, treat cardiac arrest vigorously
  –   Deep tissue destruction with high fluid needs
  –   Myoglobinuria and renal failureis common
  –   Trauma: thrown
  –   Immediate cause of death: Apnea
                 Trivia
• Name a team, a song and a runner who all
  have something in common with lightning.

          Tampa Bay Lightning
          Lightning Crashes – Live
          Usain “Lightning” Bolt
 http://www.youtube.com/watch?v=GIKYWl
 APHVQ
           Pathophysiology
• Different injury pattern, severity, tx
• Lightning = extremely high-voltage DC
• Brief, intense, thermal radiation producing
  rapid heating and expansion of
  surrounding air
• Flashover = less likely to cause internal
  cardiac injury or muscle necrosis
• TM perforation, internal contusion, tear
  clothing, melt metal, intense photic injury
Factor                     Lightning               High-Voltage AC            Low-Voltage AC
Current Duration           1-3ms                   Often brief 1-2s, may be   Prolonged
                                                       prolonged
Typical voltage and        10 million – 2 billion V; 600-70 000 V; <1000 A    <600 V; usually < 20-30
   current range               20 000 – 200 000                                  A
                               A
Current characteristics    Unidirectional (DC)     Alternating (AC)           Alternating (AC)
Current pathway            Skin flashover          Horizontal or vertical     Horizontal or vertical
Tissue damage              Superficial, minor      Deep tissue destruction    Sometimes deep tissue
                                                                                 destruction
Initial rhythm in arrest   Asystole                Asystole > V fib           V fib
Renal involvement          Myoglobinuria is        Myoglobinuria and renal    Myoglobinuria and renal
                              uncommon, renal         failure common             failure occasionally
                              failure rare
Fasciotomy and             Rarely necessary        Relatively common          Sometimes necessary
   amputation
Blunt injury               Explosive effect with   Being thrown from          Tetanic contraction or
                              shock wave               current source or          falls
                                                       falls
Immediate cause of         Prolonged apnea         Apnea                      V Fib
   death
          Mechanism of Injury
•   Direct strike – direct contact
•   Side flash – hits nearby object
•   Contact strike – hits object being held
•   Ground current – through ground
•   Upward streamer – weak streamer
                 Cardiac Injury
• Htn, tachycardia – sympathetic activation
• Depolarization -> sustained asystole
• Other:
  –   global myocardial contractility depression
  –   coronary artery spasm
  –   pericardial effusion
  –   atrial and ventricular arrhythmias
• ECG: acute injury – ST elevation, long QT, T
  wave inversion (neurologic injury)
• MI is unusual
• Cardiac automaticity may return spontaneously
         Respiratory Issues
Respiratory arrest
• Due to paralysis of medullary resp centre
• Critical prognostic factor
               Neurologic Injury
• Common Injuries:
   – ALOC
   – Temporary lower extremity paralysis
   – Seizures
• Lethal injuries: heat-induced coagulation of cortex,
  epidural / subdural, ICH
• Autonomic dysfunction: mydriasis, anisicoria
• Immediate and transient effects:
   – LOC, confusion, amnesia, paralysis - keraunoparalysis
• Delayed and progressive effects:
   – Seizures, spinal muscular atrophy, ALS, parkinsonian
     syndromes, progressive cerebellar ataxia, myelopathy with
     paraplegia or quadriplegia, chronic pain
          Neurologic Injury
Indications for CT:
• Coma
• ALOC
• Persistent headache
• Confusion
         Neurologic Injuries
Spinal Cord Injuries
• Fractures may be caused by tetany, falls,
  secondary trauma
• Maintain spinal precautions
• Image entire column due to multilevel
  fractures
           Neurologic Injuries
Ocular
• Lightning-induced cataracts
• Also: hyphema, vitreous hemorrhage,
  abrasions, uveitis, retinal detachment or
  hemorrhage, optic nerve damage

Auditory
• TM rupture
• Strike along phone: persistent tinnitus,
  sensorineural deafness, ataxia, vertigo,
  nystagmus
         Cutaneous Injuries
• Lictenberg Figures
  – Superficial ferning
  – Disappear in 24 hours
  – Pathognomonic for
     lightning strike
         Cutaneous Injuries
• Flash burns: erythema
• Punctate burns: cigarette burns <1cm full-
     thickness
• Contact burns: metal close to skin
• Superficial erythema and blistering burns
• Linear burns: <5cm wide in skin fold
• Entrance and exit wounds - rare
              Rescuer Safety
• Beware of the “lightning strike” victim that may
  truly be the victim of knocked down power lines

• Look for evidence of lightning: hx of electric
  storm, blast effect, torn clothing, melted objects,
  melted nylon cloths, burned vegetation

• Triage: Those who are sickest – treat first!
           ED Management
• ABCs, IV, O2, monitor
• Hypotension is an unexpected finding – warrants
  investigation
• Careful exam for secondary injuries, burns,
  current path
• Labs: CBC, lytes, BUN, Cr, glucose, CK, urine
  for myoglocin
• ECG
• Imaging as indicated
              Disposition
• Admission for observation recommended
• No neuro injuries, normal ECG, monitoring
  -> may consider d/c home
• Neurologic and ophthalmic referral
  recommended
    Pregnancy Considerations
• Fetal injury and death more common even
  after little or no maternal injury (amniotic
  fluid)
  – Review: 11 women who survived lightning
  – 5 cases of fetal or neonatal death
  – Abruption can occur
• Ultrasonography recommended
• Maternal uterine activity and fetal HR
  monitor x 4 hours
                  Case 3
You are working at Foothills one stormy
 afternoon, and there is a soccer game
 going on at McMahon Stadium . . .

You get a patch . . .
32 German Soccer Players Get
         “Zapped”
               3 Patients
• Patient 1: Full cardiac and respiratory
  arrest. Apparently a direct strike. Has
  Lichtenburg figures.

• Patient 2: Altered, shallow breathing,
  mottled, deformity to R femur.

• Patient 3: Complaining of paralysis to
  legs, flash burns to torso.
            Case 3 Cont’d
• How do you triage these patients?

• In contrast to multiple victim events
  caused by mechanical trauma . . .
• Persons with lightning injury who appear
  dead (resp +/- cardiac arrest) should be
  treated first!!!
    Summary: Lightning Injuries
•   Lightning is extremely high-voltage DC
•   CV: Causes asystole in arrest
•   Neuro: Apnea from medulla injury,
•   MSK: Explosive effect of shock wave
•   Cutaneous: Lichtenberg figures
•   Tx: ABCs, treat sickest first (even ?dead!)
•   Get ocular and neuro assessment
•   Admission for observation
         Thanks!
Thanks also to Marc Francis and
James Huffman for pictures and
            cases!

				
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