Project: Ghana Emergency Medicine Collaborative
Document Title: Electrical and Lightening Injuries
Author(s): Rashmi Kothari, M.D.
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ELECTRICAL &
LIGHTENING INJURIES
Rashmi U. Kothari MDAssociate Professor
KCMS/MSU
BotMultichillT, Wikimedia Commons
Maksim, Wikimedia Commona
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Goals Electrical Injuries
Low VoltageHigh Voltage
Lightening Injuries
Pathophysiology
Complications Management
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Importance Electrical burns:
1000 deaths annually 4-6.5% of all burn admissions Almost all involve litigation (negligence,
product liability, workmen’s compensation)
Lightening Injuries: 50-300 deaths annually 4-5 X as many lightening strikes 2nd leading cause of weather related deaths
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Vocabulary
Voltage: electrical pressure in a circuit
Resistance: tissues resistance to flow of electrons
Current: amount of energy in a circuit
Current = Voltage/Resistance
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Pathophysiology
Current Strength (I)= Voltage/Resistance
Thermal Power (J)=(I)2 X Resistance X duration
Severity =(Voltage) 2 X durationResistance
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Factors Affecting Injury
Current (Amperage) Type of current Resistance Duration of contact Voltage Pathway of current
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Current*(amount of energy in
circuit)Physical Effect Milliamperes
(mA)Tingling 1-4
Let go current
Children 4
Women 7
Men 9
Freezing to circuit 10-20
Thoracic muscle tetany 20-50
Ventricular fibrillation 60-120*at 50-60 Hz (frequency of household AC current)
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Why does AC vs DC current matter?
Which is more dangerous?AC 3X more dangerous than
DC
How do their mechanisms of injuries differ?AC causes tetanyDC throws you away
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Alternating Current
Source:Power linesHousehold current
Clinical Presentation3X more dangerous than
DCContinuous tetanyV-fibContact wounds
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Direct Current Source:
Power generating stationsLong distance transmission linesSubmarine cable connectionsPortable generators
Clinical PresentationSingle contractionAssociated blunt traumaArrhythmias cardiac phase dependentEntrance/Exit wounds
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Resistance
Amount tissue resists flow of electrons
resistance the greater potential to convert electric energy to heat energy
Tissue resistance changes with charring
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Resistance of Body TissuesLeastNervesBlood
Mucous membranes
IntermediateDry skin
MostTendon
FatBone
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Skin Resistance
Tissue Resistance (W/cm2)
Calloused hands 1-2 millionSoles of feet 100-200KOther skin 10-40KSweaty skin 2500Bathtub 1200-1500Mucous Membranes 100
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Injury=Voltage2 x Duration Resistance
ResistanceDry hands vs. Wet hands 2,000,000 W/cm2 1,200
W/cm2
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2 case scenarios Child puts key in socket
110V AC current Dry skin (10-40K W/cm2 ) current = 2.75-11 mA
Child in tub, key in socket 110V AC current Wet skin (1,200-1,500 W/cm2 ) current =73-92 mA
Injury=(V)2 X t
R
Chris Phan, Flickr
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Current*Physical Effect Milliamperes
(mA)Tingling 1-4
Let go current
Children 4
Women 7
Men 9
Freezing to circuit 10-20
Thoracic muscle tentany 20-50
Ventricular fibrillation 60-120
*at 50-60 Hz (frequency of household AC current)
2.75-11
73-92
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Duration of Contact
duration destruction
AC increases duration due to grip strength
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Voltage Difference in electrical potential
between two points Low Voltage <500-1000 V
24 V=Long distance communication lines
65 V Telephone lines 110-220 V Household current
High Voltage >500-1000 VTransformers, Power lines
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Current Pathway
Determines tissue at riskThorax: V-fib, myocardial damageHead: resp. arrest, seizure,
paralysisEye: cataracts
Anetode, Wikimedia Commons
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Factors Affecting Injury
Current (Amperage) Type of current Resistance Duration of contact Voltage Pathway of current
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Low Voltage Injuries
Usually minor:TinglingLocal contact burns
Exception:Lower resistance (moisture)Ocular involvement Oral injuriesAppliance capacitor (microwave, monitor,
TV)Pregnancy
Source Undetermined
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Oral Low Voltage Injuries
Child bites electrical cord Arc burn
Electricity jumps from high to low potential region
High temperaturesDelayed bleeding
Cosmetic & Dental deformitySource Undetermined
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40 y.o. touches an extension cord & feels shock & tingling
Evaluate for any burns Cardiaorespiratory complaints
ECG/monitorIsoenzymes
Consider ocular involvement Ophthalmology referral
Short ED observation Discharge home
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High Voltage Injury Devastating burns Electrical injuries Blunt trauma Renal
complications
Xy01, Wikimedia Commons
Source Undetermined
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Electrical Burns
Direct contactElectrothermal heating
Indirect contactArcFlameFlash
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Electrothermal Burns
Heating of tissue secondary to currentLow voltage injuries with local
burnsHigh voltage
Damage anywhere along current path
Prolonged exposure due to inability to release 7mike5000,
Wikimedia Commons
Source Undetermined
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Arc Burns
Spark between unconnected objects
Most destructive indirect burn Temperatures of 2,500° C
Oral cord burnsLightening strikes
Achgro, Wikimedia Commons
Source: Brown Medical School
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Flame Burns
Occur when external objects catch on fire and cause the burn.
Most commonly, clothes
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Flash Burns Current flashes over the body,
rather than going through the tissues
Seen primarily in lightening injuries.
Source Undetermined
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Electrical Injuries by Body Site
Head Cardiac Skin Extremities Neurological
7mike5000, Wikimedia Commons
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Head Strikes
Common point of contact Burns Blunt trauma Cataracts
Days, weeks, monthsComplete eye examOutpatient Ophthalmology
Batholith, Wikimedia CommonsEyeMD,
Wikimedia Commons
Source Undetermined
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Cardiovascular
ArrhythmiasV-Fib or AsystoleSinus Tach/ A-fib/BBB
ECG changesST elevationProlonged QT
AMIRareElevation of CPK & CPK MB%
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Skin
Common contact sitesHead/hands/heels
Internal flow of currentDeep muscle injuryCan’t estimate damage from surface burn
Guyprocter, Wikimedia Commons
Magnus Manske, Wikimedia Commons
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Extremities Damage distant to skin burns Arterial injury
High flow delayed injury Venous injury
Slow flow acute thrombosis & edema
Severe muscle necrosisFasciotomyRhabdomyolysis
Kissing burns Source Undetermined
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Nervous System
Transient loss of consciousness Concussive type symptoms
Difficulty concentratingDizzinessFlat affect
Spinal InjuriesFractures/ligamentous injuries
Source Undetermined
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Neurologic Injuries Immediate
Weakness/parasthesias within hoursLower extremity >upper extremityGood prognosis
DelayedDays to yearsAscending
paralysis/ALS/Transverse myelitisMotor>sensoryPoor prognosis
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Lightening Injuries
Current impulse High voltage/Short
durationVery minimal skin damageFlash over
Maksim, Wikimedia Commons
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Mechanism of Lightening Injuries
Direct strikeOrifice entry
ContactSide flash, “splash”Ground current or step
voltageBlunt trauma
Ambika Kilaparthi, Flickr
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Orifice Entry
Enters eyes, ears, mouth High incidence of:
cataracts/uveitis/detached retina/optic atrophy
ruptured TM/hearing loss, tinnitus, vertigo
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Splash Injury
object person ground
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Step Voltage
Source Undetermined
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Blunt Trauma
Thrown 2° to massive contraction of current passing through body
Air superheats then quickly cools explosive force
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Lightening Injuries
CardiovascularCardiac arrest 2° electrical shock or
vascular spasmRespiratory arrest > Cardiac arrest
Skin<5% deep burnsLinear lesionsPunctate lesionsFeatheringThermal
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Skin LesionsSource Undetermined
Source Undetermined
Source Undetermined
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Extremities
ExtremitiesTransient vasospasmCold, blue, mottled,
pulselessResolves within hours
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Nervous System
CommonLOC, confusion, antegrade
amnesiaParesthesias
Less commonICH, seizure, paraplegiaDelayed muscle atrophy
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Nervous System
Keraunoparalysis2/3 of patientsExtremities mottled, cold, blueLegs>armsTransient (clears w/in hours)Vascular spasm & sympathetic
instability
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3 y.o. bites electrical cordpresents with oral burn
Evaluate for other injuries Other burns Ocular involvement
Admission Pain or poor oral intake Poor compliance or follow-up
Discharge home Educate parents regarding bleeding Burns follow-up Dental referral ±Plastics referral ±Ophthalmology referral
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37 yo touched high voltage power line
ABC Fluids & foley
Urine output 0.5-1.0 cc/kg/hrHeme in urine 1-1.5 cc/kg/hr
Cardiac monitor/ECG Trauma Evaluation Labs
CBC & CMPSerum Myoglobin, U/A
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Ancillary Tests
Trans-abdominal currentHepatic, lipase, PT/PTT
Altered MSCT head
Cardio-respiratory complaintsTroponin, CPK with IsoenzymesPoor correlation: CPK MB, Angio,
echo, thallium studies with AMI
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Admission Criteria for ECG Monitoring
Status post arrest Concomitant severe injuries Loss of consciousness Suspicion of conductive
injury Abnormal ECG or
dysrhythmia History of CAD Significant CAD risk factors Chest pain
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Consultants Inhospital
TraumaBurns/Plastics
OutpatientOphthalmologyNeurology