Electrical & Lightning Injuries

1. Electrical & Lightning Injuries Carly Thompson EM-Resident April 9, 2009

2. Electrical Injuries Definitions Epidemiology and Physics Physiologic Effects of Electricity Specific Injuries ED Management of Electrical Injuries Cases Lightning Pathophysiology of Lightning Specific Injuries: Lightning ED Management Cases Outline

3. Electric Injuries Definitions • Electric shock – response • Electrocution – death • Electrical injury – tissue damage • Electrical burn – cutaneous injury

4. 550 Electrocutions / Year in USA (1998) • 50% of low-voltage <1000 V AC no visible burns or marks • 100 Lightning Deaths / Year USA • Underestimate? • 17 000 Electric Injuries / Year USA • 300 Lightning Injuries / Year USA

5. Epidemiology 3 Groups at Risk for Electrical Injuries: • Toddlers • Adolescents • Electrical Workers (1/10 000 deaths/year) Lightning Injuries Risks: • Transportation: Car, plane, water • Storms or blue sky! Mortality: • 0.5 / million in US – 8.8 / million rural SA • 70-90% survival rate • 75% of survivors will have sequelae

6. Physics 101 • Electric flow / current = Amp • Electric potential difference = Volts • Resistance = Ohms • Conductors: high fluid, electrolyte content – nerves and blood vessels, sweaty skin, saliva, muscle • Insulators: high resistance – bone, dry skin Ohm’s Law I (Current) = V (Voltage) / R (Resistance) Current is directly proportional to potential difference, and inversely proportional to resistance. Example = Grasp 120V source, with 1000Ohms resistance = 120mAmps

7. Types of Current • What are the two types of current?

8. AC/DC How did the band AC/DC gain their name? They saw it on the back of their older sister’s sewing machine. • AC – alternating current Homes, usually 60Hz • DC – direct current Batteries, lightning

9. Physiologic Effects • Related to amount duration, type, path • Current travels along multiple paths, not only path of least resistance • Nerves and blood vessels – least resistance • Muscles have most flow due to greatest area • Nerves have higher current density -> significant injury

10. Effect of Current

11. Physics 102 • Electrical energy -> deposited as heat • Heat causes the most tissue damage Joule’s Law Energy = I2 x R x time Energy = (V2 x time) / R Therefore the heating of tissues increases according to the square of the applied voltage, and is directly proportional to the time the voltage is applied.

12. Electricity Power Line: 7620V Lines outside house: 220 / 240V Subway: 660V High Voltage Injury • >1000 V • Severe skin burns Low Voltage Injury • Cutaneous burns often minimal with household voltage, unless several secs contact • Electrical burns absent in 40% of low voltage deaths • 110V can cause V fib

13. Trivia What was AC/DC’s first album? What is considered high voltage? >1000 V

14. Cardiovascular Injuries • 1° cause of death from electrocution • Low-voltage -> v fib • High-voltage AC and DC -> transient asystole • Also: ST, PACs, PVCs, a fib, 1st / 2nd AV block • Vigorous resuscitation!!! • Victims are often young without CVD • Not possible to predict outcome based on rhythm • Vascular injury -> spasm -> delayed thrombosis or aneurysm formation, compartment syndrome

15. CNS and Peripheral Nerve Injuries • 50% have impairment (high-voltage) • Transient LOC • Agitation, confusion, • Coma • Seizures • Quadriplegia, hemiplegia, paresthesias • Aphasia, visual disturbances

16. Spinal Cord Injuries • Vertebral fractures – multilevel! • Delayed injury • ascending paralysis • complete or incomplete cord • transverse myelitis • MRI results not closely correlated to outcome

17. Eye and Ear Eye Injuries • Cataract formation weeks to years later • Retinal detachment, corneal burns, intraocular hemorrhage, intraocular thrombosis Ear Injuries • Late complications of hemorrhage into TM, middle ear, etc. -> mastoiditis, sinus thrombosis, meningitis, brain abscess • Hearing loss immediate or late

18. Cutaneous Wounds • Entry / exit wounds – painless, gray Treatment • Cleansing, Td • Silver sulfadiazine • Mafenide • Full-thickness burns – penetrates eschar • <25% BSA only – inhibits carbonic anhydrase, painful • Observe for neurovascular compromise, compartment syndrome • Splint extremities, early surgical debridement, vascular reconstruction and skin graft

19. Flexor Crease Burns

20. Orthopedic Injuries / MSK • Fractures 2° to tetany, falls • Shoulder dislocation (voltages >110V) • Muscle +++heat -> periosteal burns, osteonecrosis • Severe arterial spasm -> compartment syndrome • Muscle breakdown -> rhabdomyolysis -> myoglobinuria and renal failure

21. Blast and Inhalational Injuries Blast Injuries • Strong blast pressure -> head injury, mechanical trauma, arterial air emboli Inhalational Injuries • Ozone -> mucous membrane irritation, decreased pulmonary function, pulmonary hemorrhage, edema • Carbon monoxide, etc. assoc. with fires

22. GI Injuries • Suspect in patients with burns of abdo wall, or trauma • Lethal injuries – reported only at autopsy • Gastric ulcers – Curling’s ulcers • Fluid resuscitation -> abdominal compartment syndrome with restrictive surface burns

23. DIC • May be due to thermal injury or tissue necrosis • Low-grade DIC from hypoxia, vascular stasis, rhabdomyolysis, release of procoagulants • Tx: eliminate precipitating factor by early surgical debridement • FFP or cryo as needed

24. Oral Burns • Children • Unilateral • Lateral commissure, tongue, alveolar ridge • Systemic complications rare • Vascular injury to labial artery • Severe bleeding 10% cases • Occurs 5 days – 2 weeks when eschar separates

25. Oral Burns Treatment • Admission – monitoring • Outpatient – reliable parents, who can be shown how to control bleeding, consideration? • Saline rinses, swabs to debride necrotic tissue • Petrolatum-based Abx for soothing effect • Specialty consultation – splinting / surgical procedures to prevent deformity and dysfunction

26. Tasers • Sinusoidal electrical impulses 10-15Hz • High voltage 50 000V for Taser • Low Amps and low average energy • 2001-2007 245 deaths after Taser Injuries • R on T phenomenon -> v fib • Pacemaker or ICD malfunction • Death more likely with concomitant drug use (PCP, cocaine), trauma from struggle, preexisting CAD • Ocular injuries • Other: burns, lacs, rhabdo, testicular torsion, miscarriage

27. Accident Scene: Rescuer Safety Downed Power Lines • Electrocution possible, recommend 9m away (3m may be enough) • Reapplication of voltage may occur -> jumping power lines Victims • Victims in contact with source may be “active” • Voltage >600V -> dry wood, rubber boots may conduct electricity • Persons inside vehicle in contact with power line, likely to be killed if they step out

28. ED Treatment Resuscitation • ABCs as per trauma • ACLS • Spinal immobilization • Careful physical exam! Investigations • Labs: High-voltage, extensive burns, evidence of systemic injury • CBC, lytes, Cr, BUN, CK, serum / urine myoglobin • Imaging as indicated, clear spines

29. ED Treatment Fluid Resuscitation • Fluid requirements > Parkland’s formula • Visible damage < internal damage! • Initial fluid bolus: 20-40mL/kg/ 1st hr • Considerations: • Fluid load to prevent rhabdomyolysis • Avoiding over-resuscitation in patients with restrictive burns on abdomen -> prevent compartment syndrome

30. Disposition Admission: • In contact >600V • Symptoms (CP, palp, LOC, confusion, weakness, dyspnea, abdo pain) • Signs (weakness, burns with subcut damage, vascular compromise) • Ancillary changes (ECG, CK, myoglobinuria) • Cardiac monitoring: If ECG abnormal No Admission: • Household voltage injury 100-220V in adult + • Neglibible risk for delayed arrhythmias + • Asymptomatic, normal ECG and normal exam -> d/c

31. Electric Injury in Pregnancy • Increased rate of fetal damage or loss after apparent harmless contact • Monitor x 4 hours in women >20-24 weeks GA • Monitor >24 hours if LOC, ECG abN, hx of CVD • Fetal ultrasonography at presentation, then at 2 weeks • No proof that monitoring or tx can influence outcome

32. Electric Injury in Children • Children with only hand wounds from outlet, but no cardiac or neurologic involvement can be d/c home with wound care • Consider admission if equivocal home safety or reliability • Guidelines for ECG in children: • Tetany • Decreased skin resistance by water or burns • Unwitnessed event • Guidelines for cardiac monitoring x 24 hours: • Past cardiac hx • LOC • Voltage >240V • Abnormal ECG

33. Cardiac Monitoring in Children Bailey et al. (2000). Experience with guidelines for cardiac monitoring after electrical injury in children. Am J Emerg Med; 18(6):671-5. • July 1994 – June 1998 • Tertiary pediatric teaching hospital • 224 cases • Cardiac monitoring on 13% (all normal) • No morbidity 0/172 patients • No mortality 0/224

34. Case 1 • 30 yo M electric worker • Found down at steel plant • Thermal burn – lateral head • Presenting in asystolic arrest What do you do? How long do you continue treatment?

35. Case 1 Cont’d Thoughts . . . • Resuscitation as per ACLS • Spinal precautions • Vigorous resuscitation as patient is young and otherwise healthy, heart may spontaneously regain automaticity Conclusion . . . • 45 minutes in ED resuscitation – no cardiac activity • Code called

36. Case 2

38. Summary: Electrical Injuries • Low-voltage <600V -> may be D/C if asymptomatic • Immediate cause of death: V Fib • Children: oral burns – consider labial artery bleed ? admission • High-voltage >1000V -> admit for observation and cardiac monitoring • Asystole, treat cardiac arrest vigorously • Deep tissue destruction with high fluid needs • Myoglobinuria and renal failureis common • Trauma: thrown • Immediate cause of death: Apnea

40. Trivia • Name a team, a song and a runner who all have something in common with lightning. Tampa Bay Lightning Lightning Crashes – Live Usain “Lightning” Bolt http://www.youtube.com/watch?v=GIKYWlAPHVQ

41. Pathophysiology • Different injury pattern, severity, tx • Lightning = extremely high-voltage DC • Brief, intense, thermal radiation producing rapid heating and expansion of surrounding air • Flashover = less likely to cause internal cardiac injury or muscle necrosis • TM perforation, internal contusion, tear clothing, melt metal, intense photic injury

43. Mechanism of Injury • Direct strike – direct contact • Side flash – hits nearby object • Contact strike – hits object being held • Ground current – through ground • Upward streamer – weak streamer

44. Cardiac Injury • Htn, tachycardia – sympathetic activation • Depolarization -> sustained asystole • Other: • global myocardial contractility depression • coronary artery spasm • pericardial effusion • atrial and ventricular arrhythmias • ECG: acute injury – ST elevation, long QT, T wave inversion (neurologic injury) • MI is unusual • Cardiac automaticity may return spontaneously

45. Respiratory Issues Respiratory arrest • Due to paralysis of medullary resp centre • Critical prognostic factor

46. Neurologic Injury • Common Injuries: • ALOC • Temporary lower extremity paralysis • Seizures • Lethal injuries: heat-induced coagulation of cortex, epidural / subdural, ICH • Autonomic dysfunction: mydriasis, anisicoria • Immediate and transient effects: • LOC, confusion, amnesia, paralysis - keraunoparalysis • Delayed and progressive effects: • Seizures, spinal muscular atrophy, ALS, parkinsonian syndromes, progressive cerebellar ataxia, myelopathy with paraplegia or quadriplegia, chronic pain

47. Neurologic Injury Indications for CT: • Coma • ALOC • Persistent headache • Confusion

48. Neurologic Injuries Spinal Cord Injuries • Fractures may be caused by tetany, falls, secondary trauma • Maintain spinal precautions • Image entire column due to multilevel fractures

49. Neurologic Injuries Ocular • Lightning-induced cataracts • Also: hyphema, vitreous hemorrhage, abrasions, uveitis, retinal detachment or hemorrhage, optic nerve damage Auditory • TM rupture • Strike along phone: persistent tinnitus, sensorineural deafness, ataxia, vertigo, nystagmus

50. Cutaneous Injuries • Lictenberg Figures • Superficial ferning • Disappear in 24 hours • Pathognomonic for lightning strike