Electrical Injuries/Burns

1. Electrical Injuries/Burns Case-Based Presentation 5 February, 2009

2. When is electricity not your friend?

3. 45 year-old man encountered in an alley behind an apartment building after a passer-by heard a loud “bang.” • EMS notes: patient found in tree alongside powerline, next to 20-foot metal ladder (fallen over). • Pair of shoes noted to be hanging from line by their laces. • 2 blocks from hospital: rapid transport.

4. Initial assessment • Paitent initially GCS E3 V3 M5 per EMS. • Now in full c-spine (sort of) with GCS E2 V2 M5. • VS: HR 120 reg, BP 110/50, RR 30, SpO2 92% on high-flow O2 by NRM. • Attempt by ER doc to examine patient elicits movement of head and all extremities as pt struggles against tape and straps. • Right hand is mangled beyond recognition.

5. What are the mechanisms of electrical injury? • Direct and indirect.

6. 1. What are the mechanisms of electrical injury (direct and indirect)?

7. 4 causes of damage: 1) direct effect of current on body tissues, leading to asystole, ventricular fibrillation, or apnea; 2) blunt mechanical injury from electrocution, resulting in muscle contraction or falling; 3)conversion of electrical energy to thermal energy, resulting in burns; and 4) electroporation

8. Electroporation: defined as the creation of pores in cell membranes by means of electrical current disrupts cell membranes and leads to cell death without clinically significant heating

9. Electrocution • Direct • 10 determinant of damage caused by direct effects of electricity is the amount of current flowing through the body • other factors include voltage, resistance, type of current, current pathway, and duration of contact with an electrical source

11. High or Low Electrical shocks of 1000 V or more are classified as high voltage household electricity has 110 to 230 V, and high-tension power lines are more than 100000 V. Lightning strikes are can produce 10 million V or more High-voltage electrical shocks are expected to result in more severe injury per time of exposure

12. Burns 4 groups: electrothermal burns, arc burns, flame burns, and lightning injuries. Electrothermal burns are the classic injury pattern and create a skin entrance and exit wound High voltage can cause much more damage to deeper tissues than to skin

13. Respiratory • Respiratory arrest may result • Multiple reasons Noemie will elaborate on later • lung damage is rarely seen but blunt trauma may be present if falls

14. Cardiovascular • Arrhythmias • Sudden cardiac death due to ventricular fibrillation is more common with low-voltage AC, • asystole is more frequent with electric shocks from DC or high-voltage AC • fatal arrhythmias are more likely by horizontal current flow (hand to hand); • current passing in vertically(from head to foot) more commonly causes myocardial tissue damage

15. 10% to 46% of survivors experience other arrythmias most common arrhythmias are sinus tach and PVCs, but V tach and afib have been reported nonspecific ST–T-wave abnormalities are common and usually resolve spontaneously

16. Conduction Abnormalities • Sinus brady and high-degree AV block have been reported. • Electrical injury caused by AC seems to have a predilection for the SA and AVnodes

17. Musculoskeletal Bone has the highest electrical resistance and experiences the most severe electrothermal injuries, including periosteal burns, destruction of bone matrix, and osteonecrosis Forceful tetanic contractions or falls can cause fractures and large-joint dislocation

18. Electrothermal injury of the musculature may manifest as edema formation and tissue necrosis and may lead to the compartment syndrome and rhabdomyolysis

19. Neurologic can damage the central and peripheral nervous system Loss of consciousness, generalized weakness, autonomic dysfunction, respiratory depression, and memory problems are frequent manifestations Don’t forget about blunt trauma

20. Keraunoparalysis is a specific form of reversible, transient paralysis that is associated with sensory disturbances and peripheral vasoconstriction and is seen in some patients following lightning injury

21. Lightning Strikes 150 to 300 deaths annually in the USA causes cardiac and respiratory arrest, resulting in a 25% to 30% mortality rate Lots of volts but short time according to Joule’s law, the amount of energy delivered may be less than with other high-voltage electrical injuries because of the short exposure

22. rarely sustain extensive tissue destruction or large cutaneous burns; cardiac arrest is usually asystole, with frequent spontaneous restoration of a rhythm respiratory arrest is often prolonged, and without vent support, apnea results in hypoxia-induced vfib

23. Lichtenberg figures are pathognomonic skin manifestations in persons struck by lightning

24. What are the most common causes of electrical injury?

25. 1000 people die of exposure to electricity annually in the USA age distribution of patients who are electrocuted is bimodal; the first peak occurring in children younger than 6 yrs, and the second occurs in persons in young adulthood

26. In children usually occurs at home associated with electrical and extension cords (in about 60–70%) and with wall outlets (another 10–15%) Most deaths in adults due to electrocution are work related (5–6% of all workers’ deaths) Miners and construction workers account for most of these cases, with rates of 1.8 to 2.0 deaths per 100 000 workers

27. Yoan • Noemie

28. Evaluation of Our Patient • Paramedics report that he was initially not moving much beyond shallow respirations. • (protective when slung over a branch 15 feet above asphalt) • However, his overall LOC has deteriorated somewhat. • His clothes are cut off, revealing extensive burnt skin from the remains of his right hand, along his arm, involving his torso and left thigh.

30. Airway Issues

31. Breathing • How might his initial assessment (on scene) have been clouded by his electrical injury? • What are the effects of electrocution on skeletal and respiratory muscles?

32. “Keraunoparalysis” • 2dary to massive catecholamine release • Typically after lightening injury • Clinical manifestation • Paraplegia/quadriplegia • Autonomic instability • Hypertension • Peripheral vasospasm • Mydriasis and anisocoria • Resolves within a few hours Critical Care Clinics 1999;15(2)

33. Respiratory failure • Usually no specific injury from the electric current to the lung or airways • Causes of respiratory arrest: • Blunt trauma • Injury to the respiratory control center as a result of electrical current through the brain • Spinal cord injury C4 to C8 (hand-to-hand) leads to indefinite refractory state of the NMJ • Tetanic contractionsuffocate

34. Skeletal system • Current: • DC: causes single muscle contraction • AC: causes repetitive tetanic muscle contractionprolonged electrical exposure • Muscle: • Tissue necrosis • Can lead to compartment syndrome and rhabdo

35. Skeletal System • Bone has the highest resistancehighest electrothermal injuries • Periosteal burns • Osteonecrosis • Long bone fractures from muscle contraction

36. Initial management goals

37. In the field: • Provide a safe environment; disconnect electricity if necessary. • ABCs • Arrhythmia management as per ACLS guidelines. • may also cause fixed dilated pupils due to autonomic effects; do not cease resusc. • Immobilize C-spine and splint other fractures prior to transfer.

38. In the E.R. • Aggressive fluid resusc. for significant electrical injury through large bore IV. • Less fluid usually required for lightning injury. • Complete Hx, including nature of electrical contact, voltage, duration of contact, and any resulting fall have obvious implications. • Complete Px looking for associated (esp. spinal cord) injuries, as well as entry, exit wounds, and blunt thoracic and abdominal trauma.

39. After initial resuscitation: • Most common complication is cardiac arrhythmia. Although most run a benign course, particularly with transthoracic injuries, cardiac monitoring for up to 24 hours is appropriate. • R/O spinal cord, C-spine injury with appropriate imaging. • Keep this in mind in event of impaired motor function.

40. Serial evaluation of liver, pancreatic,and renal function for traumatic and anoxic/ischemic injury (in case of cardio-respiratory arrest), supplemented by appropriate imaging studies (e.g., CT or abd. U/S) as necessary. • CT scan of the head is indicated in all severe cases of lightning injury, of injuries due to a fall, and if there are persistent abnormal findings in the neurologic examination. • Evaluation of the limbs for compartment syndrome that may require fasciotomy (rare in lightning injury). • Nutritional support due to increased energy expenditures. • Ophthalmologic and otoscopic evaluation (injury common in cases of lightning injury).

41. Fluid resuscitation • Any concerns about crystalloid volume?

42. Fluid Management Traditional formulas use %BSA

43. How do you estimate BSA in Electrical Injuries • Often see superficial burns • Rule of 9’s, but not the full story • Not able to asses internal burns along path of electricity • Often extensive internal organ injury • Third spacing is often significant and ongoing

44. So how do you decide how much fluid to give? • Titrate to normal urine output (0.5 cc/kg/hr) • How much is too much? • Klein et al. • 5ml/ % BSA = increased pneumonia + death • Compartment syndromes • Abdominal • Extremity • Ocular Physicians tend to over resus follow BP, unwilling to decrease when good U/O

45. Which fluid to give? • Crystalloid • Hypertonic saline • Increased risk of renal failure • Colloid • No benefit over crystalloid, may increase ARDS • Mannitol • Bicarb

46. Fluid Resuscitation • In high voltage injury, risk of rhabdo is high. • Maintain u/o 70-100 cc/h until clear of pigment, then 50 cc/h. • Alkaline diuresis with intravenous sodium bicarbonate may improve clearance of myoglobin. • Osmotic diuresis with mannitol can be tried in patients who have increased pigment. • If compartment syndrome has been excluded, early amputation may be necessary when there is persistent myoglobinuria. • The fluid requirement is approximately 1.7 times the calculated fluid requirement for the percentage of body surface area burnt by standard formulas. • Because of large fluid shifts, close monitoring of electrolytes is also necessary with replacement as needed.

47. Later, in ICU • His spine imaging is clear. • Seen by plastics, who plan to take him to OR within 24 hours. • VS after volume resus: • HR 110, BP 115/65, RR 18 on PSV FiO2 .35 • U/O approx 1 cc/kg/hr • Requiring MS and midaz to allow for ventilation. • Admission labs come back…

48. Labs • 7.20/30/90/18 • CBC: Hb 110 • ‘lytes: K+ 4.8 • PAG: 18 • Lactate: 6 • Cr: 95 • CK: 500

49. Exam • GCS 3, sedated/ventilated. • HR 110 BP 100/50 RR 24 SpO2 98% on FiO2 0.4. Afebrile. • Right arm is more swollen and tense than it was downstairs. • Peripheral pulse no longer palpable.

50. What is the cause of his lactic acidosis? DDx? • Marios