Transcript Electrical & Lightning Injuries

Electrical & Lightning
Injuries
Carly Thompson
EM-Resident
April 9, 2009
Outline
Electrical Injuries
• Definitions
• Epidemiology and
Physics
• Physiologic Effects of
Electricity
• Specific Injuries
• ED Management of
Electrical Injuries
• Cases
Lightning
• Pathophysiology of
Lightning
• Specific Injuries:
Lightning
• ED Management
• 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,
minimal perception
Pain threshold
Through intact skin
0.5-2
Through intact skin
1-4
Inability to let go: tetany From hand, through
decreases resistance
forearm into trunk
Respiratory arrest: fatal Through chest
if prolonged
6-22
V Fib
Ventrical asystole, if
current stops sinus
rhythm may resume
70-4000
>2000
Through chest
Through chest
18-30
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
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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:
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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
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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
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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
current range
10 million – 2 billion V; 600-70 000 V; <1000 A
20 000 – 200 000
A
<600 V; usually < 20-30
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
uncommon, renal
failure rare
Myoglobinuria and renal
failure common
Myoglobinuria and renal
failure occasionally
Fasciotomy and
amputation
Rarely necessary
Relatively common
Sometimes necessary
Blunt injury
Explosive effect with
shock wave
Being thrown from
current source or
falls
Tetanic contraction or
falls
Immediate cause of
death
Prolonged apnea
Apnea
V Fib
Mechanism of Injury
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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:
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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 fullthickness
• 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
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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!