gemc: electrical and lightening injuries: resident training

Project: Ghana Emergency Medicine Collaborative Document Title: Electrical and Lightening Injuries Author(s): Rashmi Kothari, M.D. License: Unless otherwise noted, this material is made available under the terms of the Creative Commons Attribution Share Alike-3.0 License: http://creativecommons.org/licenses/by-sa/3.0/

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Rashmi U. Kothari MD Associate Professor

KCMS/MSU

BotMultichillT, Wikimedia Commons

Maksim, Wikimedia Commona 3

¨  Electrical Injuries ¡ Low Voltage ¡ High Voltage

¨  Lightening Injuries

¨  Pathophysiology ¨  Complications ¨  Management

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¨  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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¨  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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Current Strength (I)= Voltage/Resistance

Thermal Power (J)=(I)2 X Resistance X duration

Severity =(Voltage) 2 X duration Resistance

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¨ Current (Amperage) ¨ Type of current ¨ Resistance ¨ Duration of contact ¨ Voltage ¨ Pathway of current

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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) 9

¨  Which is more dangerous? ¡ AC 3X more dangerous than DC

¨  How do their mechanisms of

injuries differ? ¡ AC causes tetany ¡ DC throws you away

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¨  Source: ¡ Power lines ¡ Household current

¨  Clinical Presentation ¡ 3X more dangerous than DC ¡ Continuous tetany ¡ V-fib ¡ Contact wounds

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¨  Source: ¡ Power generating stations ¡ Long distance transmission lines ¡ Submarine cable connections ¡ Portable generators

¨  Clinical Presentation ¡ Single contraction ¡ Associated blunt trauma ¡ Arrhythmias cardiac phase dependent ¡ Entrance/Exit wounds

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¨  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 Tissues Least Nerves Blood

Mucous membranes

Intermediate Dry skin

Most Tendon

Fat Bone

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Tissue Resistance (W/cm2) Calloused hands 1-2 million Soles of feet 100-200K Other skin 10-40K Sweaty skin 2500 Bathtub 1200-1500 Mucous Membranes 100

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Injury=Voltage2 x Duration Resistance

Resistance Dry hands vs. Wet hands

2,000,000 W/cm2 è1,200 W/cm2

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¨  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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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 destruction

¨  AC increases duration due to grip strength

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¨  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 V ¡  Transformers, Power lines

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¨  Determines tissue at risk ¡ Thorax: V-fib, myocardial damage ¡ Head: resp. arrest, seizure, paralysis ¡ Eye: cataracts

Anetode, Wikimedia Commons 21

¨ Current (Amperage) ¨ Type of current ¨ Resistance ¨ Duration of contact ¨ Voltage ¨ Pathway of current

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¨  Usually minor: ¡ Tingling ¡ Local contact burns

¨  Exception: ¡  Lower resistance (moisture) ¡  Ocular involvement ¡  Oral injuries ¡  Appliance capacitor (microwave, monitor, TV) ¡  Pregnancy

Source Undetermined

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¨ Child bites electrical cord ¨ Arc burn

¡ Electricity jumps from high to low potential region

¡ High temperatures ¡ Delayed bleeding

¨ Cosmetic & Dental deformity Source Undetermined

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¨  Evaluate for any burns ¨  Cardiaorespiratory complaints

¡ ECG/monitor ¡  Isoenzymes

¨  Consider ocular involvement ¡ Ophthalmology referral

¨  Short ED observation ¨  Discharge home

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¨  Devastating burns ¨  Electrical injuries ¨  Blunt trauma ¨  Renal complications

Xy01, Wikimedia Commons

Source Undetermined

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¨  Direct contact ¡ Electrothermal heating

¨  Indirect contact ¡ Arc ¡ Flame ¡ Flash

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¨  Heating of tissue secondary to current ¡ Low voltage injuries with local burns ¡ High voltage ú Damage anywhere along current path ú Prolonged exposure due to inability to

release

7mike5000, Wikimedia Commons

Source Undetermined

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¨  Spark between unconnected objects ¨  Most destructive indirect burn ¨  Temperatures of 2,500° C

¡ Oral cord burns ¡ Lightening strikes

Achgro, Wikimedia Commons

Source: Brown Medical School

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¨  Occur when external objects catch on fire and cause the burn.

¨  Most commonly, clothes

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¨  Current flashes over the body, rather than going through the tissues

¨  Seen primarily in lightening injuries.

Source Undetermined

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¨  Head ¨  Cardiac ¨  Skin ¨  Extremities ¨  Neurological

7mike5000, Wikimedia Commons

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¨  Common point of contact ¨  Burns ¨  Blunt trauma ¨  Cataracts

¡ Days, weeks, months ¡ Complete eye exam ¡ Outpatient Ophthalmology

Batholith, Wikimedia Commons EyeMD,

Wikimedia Commons

Source Undetermined 33

¨  Arrhythmias ¡ V-Fib or Asystole ¡ Sinus Tach/ A-fib/BBB

¨  ECG changes

¡ ST elevation ¡ Prolonged QT

¨  AMI ¡ Rare ¡ Elevation of CPK & CPK MB%

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¨  Common contact sites ¡ Head/hands/heels

¨  Internal flow of current ¡ Deep muscle injury ¡ Can’t estimate damage

from surface burn

Guyprocter, Wikimedia Commons

Magnus Manske, Wikimedia Commons

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¨  Damage distant to skin burns ¨  Arterial injury

¡ High flow è delayed injury

¨  Venous injury ¡ Slow flow è acute thrombosis & edema

¨  Severe muscle necrosis ¡ Fasciotomy ¡ Rhabdomyolysis

¨  Kissing burns Source Undetermined

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¨  Transient loss of consciousness ¨  Concussive type symptoms

¡ Difficulty concentrating ¡ Dizziness ¡ Flat affect

¨  Spinal Injuries ¡ Fractures/ligamentous injuries

Source Undetermined

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¨  Immediate ¡  Weakness/parasthesias within hours ¡  Lower extremity >upper extremity ¡  Good prognosis

¨  Delayed ¡ Days to years ¡ Ascending paralysis/ALS/Transverse

myelitis ¡ Motor>sensory ¡ Poor prognosis

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¨  Current impulse ¨  High voltage/Short duration

¡ Very minimal skin damage ¡ Flash over

Maksim, Wikimedia Commons

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¨  Direct strike ¡ Orifice entry

¨  Contact ¡ Side flash, “splash” ¡ Ground current or step voltage ¡ Blunt trauma

Ambika Kilaparthi, Flickr

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¨  Enters eyes, ears, mouth ¨  High incidence of:

¡  cataracts/uveitis/detached retina/optic atrophy

¡  ruptured TM/hearing loss, tinnitus, vertigo

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object è person è ground

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Source Undetermined

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¨  Thrown 2° to massive contraction of current passing through body

¨  Air superheats then quickly cools è explosive force

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¨  Cardiovascular ¡  Cardiac arrest 2° electrical shock or

vascular spasm ¡  Respiratory arrest > Cardiac arrest

¨  Skin ¡ <5% deep burns ¡ Linear lesions ¡ Punctate lesions ¡ Feathering ¡ Thermal

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Source Undetermined

Source Undetermined

Source Undetermined 46

¨  Extremities ¡ Transient vasospasm ¡ Cold, blue, mottled, pulseless ¡ Resolves within hours

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¨  Common ¡ LOC, confusion, antegrade amnesia ¡ Paresthesias

¨  Less common ¡  ICH, seizure, paraplegia ¡ Delayed muscle atrophy

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¨  Keraunoparalysis ¡ 2/3 of patients ¡ Extremities mottled, cold, blue ¡ Legs>arms ¡ Transient (clears w/in hours) ¡ Vascular spasm & sympathetic instability

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¨  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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¨  ABC ¨  Fluids & foley

¡ Urine output 0.5-1.0 cc/kg/hr ¡ Heme in urine 1-1.5 cc/kg/hr

¨  Cardiac monitor/ECG ¨  Trauma Evaluation ¨  Labs

¡ CBC & CMP ¡ Serum Myoglobin, U/A

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¨  Trans-abdominal current ¡ Hepatic, lipase, PT/PTT

¨  Altered MS ¡ CT head

¨  Cardio-respiratory complaints ¡ Troponin, CPK with Isoenzymes ¡ Poor correlation: CPK MB, Angio, echo,

thallium studies with AMI

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¨  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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¨  Inhospital ¡ Trauma ¡ Burns/Plastics

¨  Outpatient ¡ Ophthalmology ¡ Neurology

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