gemc: electrical and lightening injuries: resident training
TRANSCRIPT
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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