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Electrical injury

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Electrical injury

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Electrical injury

  1. 1. QUIZ • Answers 1. C 2. B 3. A 4. D 5. D 6. B 7. C 8. B 9. A 10. D, but no cases of this being an issue. 11. C 12. B
  2. 2. CASES
  3. 3. THE ELECTRICIAN • Found unconscious near a generator. Now awake but amnesic and confused • Burns to chest and arms • VWNL • Ax? • High voltage injury likely • Transthoracic • Mx? • Resuscitate • Survey injuries, esp burns and head • Cx spine precautions and CT • ECG • UA • CK/myoglobin • IVH, targeting UO >1mL/kg/hr • NVO – compromised RUL • TF to FSH burns. Subsequent fasciotomy RUL
  4. 4. THE BLOW-DRYER BABE • Using hairdryer whilst standing on a wet floor • Felt “a shock” • R palmar erythema only • Mx? • ECG normal • Silver dressing, ADT, burns clinic FU
  5. 5. THE HAPPY CAMPERS • 3 campers • Tent struck by lightning • Cardiac arrest w 10min CPR • Bleeding ears and unable to hear • Pale, mottled, numb LLs • CPR continued and ROSC achieved despite fixed dilated pupils. In ICU, pupils returned to normal – pt did not have severe hypoxic brain injury • Ruptured TM • Keraunoparalysis
  6. 6. HOUSE, MD • Sticks knife into a power socket to see if there is an afterlife • Suffers cardiac arrest, after which he is apparently fine • Is this realistic? • Consider the path of a current – where was the “grounding”?
  7. 7. TOUCHED BY GOD • Professional storm chaser • Pulseless blue legs amongst other injuries • Started on heparin infusion on presumption of arterial thrombosis • ICH results • Keraunoparalysis • Does not require treatment and spontaneously resolves
  8. 8. HUNGRY HILLARY • Tried to get toast from toaster w knife 3mo ago. Seen in ED and essentially unhurt apart from minor R hand burn. • Now c/o entire R forearm diffuse pain, swelling, and coolness • CRPS
  9. 9. TEETHING THOMAS • Chewed electrical cord • Minor oral burns • Other considerations? • Then develops airway oedema • Eventually TF to burns unit • Represents 2 weeks later with severe labial bleeding • Eschar separation and labial artery bleeding • Should have counselled parents on haemorrhage control
  10. 10. ELECTRICAL INJURY
  11. 11. EPIDEMIOLOGY • ~25 deaths/year in Australia • Majority young men in industrial setting
  12. 12. FACTORS INFLUENCING DEGREE OF INJURY • Current, a flow of charge, measured in Amperes • Voltage, the electrical potential difference driving the flow, the energy per unit of charge • Resistance, the impedance to flow of charge • Ohm’s law: I = V/R • Current α voltage • Voltage is used to classify injuries because it is the only variable that can be reliably measured. • Current α 1/resistance • Low resistance tissues: nerve, muscle, vessels, membranes. • High resistance tissues: bone, fat, tendon • Water on skin reduces resistance 40x! • Power = VI = I2R = V2/R • Heat = Pt = I2Rt = V2t/R • Type of current • DC causes muscle spasm and throwing • AC can cause repeated spasm and grasping, depending on the frequency, leading to higher exposure time and possible dislocation • Path of current through pt. Usually to the ground. • Example: Household = 230V AC
  13. 13. MECHANISMS OF INJURY • Current itself • Thermal burns • Mechanical trauma e.g. from throwing or convulsing
  14. 14. SOURCES • >1000V • Minimum of 24hr cardiac monitoring due to dysrhythmia risk • BP monitoring due to autonomic dysfunction risk • Serial neurovascular obs • Admit cardiology or obs unless otherwise indicated by injuries • <1000V • And asymptomatic and examining normally – DC after ECG • And mild Sx with normal ECG/UA – DC after few hours’ observation • And ECG changes, LOC, injury – admit
  15. 15. LIGHTNING • Likely admission, potentially ICU or burns unit • Brief, ultra-high voltage, DC • Tends to flash over the pt and into orifices e.g. mouth and ears, rather than go through the pt • 32% mortality. Almost all from initial cardiac arrest or from resp arrest. • In event of multiple casualty, triage priority altered. First treat those who appear dead. Often respond well to CPR/defibrillation. • Morbidity is predominantly from neurologic issues. • Immediate and transient: LOC, seizure, confusion, anterograde amnesia, weakness, paraesthesia, inattention, HA, irritability • Lightning paralysis “keraunoparalysis”: LL vascular compromise and paralysis lasting a few hr only due to vasospasm and dysautonomia • Immediate and persistent: hypoxaemic or haemorrhagic injuries • Delayed: motorneurone disease-like effects • Fewer burns. More CVS, resp, neuro complications including asystolic arrest. Shockwave effect like a blast. • Otologic and ophthalmic injury common. TM rupture may be only sign of lightning in pt w collapse outdoors. • Pt can be approached immediately.
  16. 16. TASER • High voltage, low current electricity through the target • <15sec and clinically well = NOT dangerous and pts do not require observation • All of the few deaths previously associated with taser have involved dysrhythmia-inducing drugs also
  17. 17. CHEWED ELECTRICAL CORD • Oral arc burns • Plastics/max-facs for debridement/recon/oral splinting • Risk of severe labial artery bleeding after delayed eschar separation – pts need education pre-discharge • Thinner skin in children = likely more severe injury • Risk of airway obstruction
  18. 18. SYNDROMES
  19. 19. CARDIAC • Dysrhythmia is the most common • VF at low exposures, asystole at high exposures including lightning • 4-17% of electrocutions • Esp hand-to-hand electrocution • Rarely delayed. Most cases of delayed dysrhythmia also had dysrhythmia initially. Get early ECG. • Energy levels for cardioversion are unchanged • Often respond well to defibrillation and resuscitation • Myocardial injury uncommon • Mx • Prolonged resus as pts are young and outcomes are good even if in asystole and signs of brain death may be unreliable in this group • Cardiac monitor if dysrhythmia, LOC, or >1000V • Troponin levels not well studied
  20. 20. RESPIRATORY • Respiratory failure from respiratory muscle tetany or respiratory centre injury or cardiac arrest • Mx: secure the airway
  21. 21. BURNS • Vary with voltage. Small, superficial, well demarcated for low voltage. Necrotic punctate ulceration for high voltage. • Special lightning burns: linear along fluid lines, punctate, feathering (nonserious), thermal. • Entry and exit. Often under-predict internal damage. Check head/hands/feet. • Mouth in children. • Skin flexture “kissing” burns often associated with underlying tissue damage. • Consider airway burns from coexistent smoke inhalation • Mx: • May need more IVH than formulae suggest due to concomitant rhabdomyolysis • Silver dressings • ADT • Elevate • Burns specialist
  22. 22. NEUROLOGIC • 50% incidence in high-voltage injury, likely because nerve tissue has lowest resistance. • Central: LOC, memory disturbance, weakness, spinal cord injury – ALS/TM- like, seizure, confusion, coma, aphasia • Autonomic dysfunction: dilated pupils, hypotension, hypertension, arrest, syncope, vasoconstriction, thermodysregulation, tachycardia, • Peripheral: motor and sensory, CRPS – may be delayed • Need CT to differentiate between electric and traumatic effects • Persistent: inattention, poor memory, impaired learning
  23. 23. MUSCULAR • Commonly rhabdomyolysis, coagulation necrosis, compartment syndrome from oedema • Check for myalgia • NV exam • Mx: IVH aggressively, check electrolytes <4hourly esp watching K+, UO >1mL/kg/hr, fasciotomy for compartment syndrome or ongoing myonecrosis
  24. 24. VASCULAR • Usually tunica media injury leading to aneurysm or rupture. Intimal injury leads to thrombosis. • Commonly in small arteries to muscle. Results in myonecrosis.
  25. 25. ORTHOPAEDIC • Highest resistance. Generates high heat when current passes. • Osteonecrosis, periosteal burns, matrix breakdown • Trauma from throwing, convulsions, shockwaves. Posterior shoulder dislocation common. • Mx: as trauma patient
  26. 26. OCULAR AND OTOLOGIC • Ophthalmologic • Corneal commonest. Erosion, keratitis, scarring • Cataract – may be delayed and pts w high voltage injury ought to be warned, hyphaema, vitreous haemorrhage, optic neuropathy • Hearing impairment • Conductive from TM rupture, esp in lightning strike due to shockwave • Sensorineural from cochlea electrocution
  27. 27. GASTROINTESTINAL • Rare • Curling’s ulcers in pt w >30% BSA burns. Mx: PPI. • Ileus • Vascular insufficiency
  28. 28. PREGNANCY • Burns = uteroplacento blood flow changes and dysfunction can occur, abruption, abortion, oligohydramnios, growth retardation, • CTG/FHR/USS • Obstetric consultation • Most have good outcome if low voltage and not transuterine shock
  29. 29. CLINICAL APPROACH
  30. 30. HISTORY • Source and voltage and type of current. Specificity is key as capacitors and transformers in household appliances can alter the voltage substantially compared to housing mains voltage. • Other risk factors in pts w low-voltage exposure • Duration of contact • Water involvement • Spasmic injury • Transthoracic • PMHx: cardiac • Tetanus immunity
  31. 31. EXAMINATION • Entry and exit burns • High voltage pts • Ophthalmic including fundoscopy for haemorrhage and optic neuropathy • Otoscopy for TM rupture • Neurovascular of extremities
  32. 32. INVESTIGATIONS • Only ECG needed if asymptomatic and low voltage injury • ECG • FBC, UEC, • Coag, G+H if trauma • CK. Need serial if elevated as this predicts mortality, LOS, risk of amputation. • Trop – unclear utility and should DW cardiology • Imaging as for trauma pt • UA for Hb/myoglobin. If positive, send urine for microscopy ?RBC vs myoglobin.
  33. 33. MANAGEMENT • Resuscitation • Triage arrested casualties first • Prolonged CPR indicated – young pts w good outcomes • Secure airway against burns and in event of resp arrest • Neurologic death difficult to determine • Treat as trauma • Cx spine needs to be cleared • Image if any neuro issue to distinguish electric and trauma effects • Eyes and ears are particularly vulnerable • Burns management including DTPa • Cardiac monitor if LOC, ECG change, and transthoracic or >1000V exposure • NV monitoring • IVH for rhabomyolysis and burns • Titrate to UO rather than using a formula
  34. 34. KEY POINTS • Avoid being electrocuted on scene • Do not withdraw resuscitation too early • Signs of death are unreliable in this patient group • Treat as trauma • High voltage DC and lightning injury pts are often thrown violently • High voltage AC pts may have violent muscle spasm • Internal injury may be severe despite only minor burns in pts with high voltage exposure • ECG for all patients • Cardiac monitor pts w LOC, ECG change, and transthoracic or >1000V exposure • Frequently need aggressive IVH due to burns and rhabdomyolysis • UO target 1-1.5mL/kg/hr rather than burns formulae • Monitor neurovascular status of involved extremities regularly due to high risk of compartment syndrome, vasospasm, and neurologic effects. • Counsel pts about delayed effects • CRPS, inattention, STML, weakness, paraesthesia, depression, cataract
  35. 35. REFERENCES • Environmental and weapon-related electrical injuries - UpToDate • Electrical Injuries: A Review For The Emergency Clinician - Emergency medicine practice 2009 • Lightning and Electrical Injuries . Christopher B. Colwell. Emergency medicine. 2nd ed. 2013. • Chapter 218: Electrical and Lightning Injuries. Caitlin Bailey. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e. • https://lifeinthefastlane.com/ccc/electrical-injury/
  36. 36. MISCELLANY • Man electrocuted arm to arm • Intact NV obs initially. Later develops compartment syndrome. • LITFL info • Tintinalli info starting from prehosp care section

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