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