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Electrical Injuries.ppt

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Electrical Injuries.ppt

  1. 1. Electrical Injuries Stephen Hunt September 8, 2010
  2. 2. Electrical Injury <ul><li>Epidemiology </li></ul><ul><li>Mechanisms of injury </li></ul><ul><li>Associated injuries </li></ul><ul><li>Management </li></ul><ul><li>Prognosis </li></ul>September 8, 2010
  3. 3. Epidemiology: <ul><li>Account for ~ 3% all burn-related injuries </li></ul><ul><li>Estimated 3,000 annual admits to burn units </li></ul><ul><li>~ 1/3 fatal - about 1,000 US deaths annually </li></ul><ul><li>Bimodal distribution </li></ul><ul><ul><li>~1/3 children <6 yrs (electric cords & wall outlets) </li></ul></ul><ul><ul><li>~2/3 miners, construction, & electrical workers </li></ul></ul><ul><ul><li>Common cause occupational deaths </li></ul></ul><ul><li>Lightning responsible for ~300 injuries, 100 deaths </li></ul>September 8, 2010
  4. 4. Physics Review <ul><li>I = V/R (Ohm’s Law - current) </li></ul><ul><ul><li>Intensity expressed in amperes (A) </li></ul></ul><ul><ul><li>DC - lightning, rails, autos, batteries </li></ul></ul><ul><ul><li>AC - most power lines, buildings </li></ul></ul><ul><li>E = IVT (Joules law - thermal energy) </li></ul><ul><li>E = I 2 RT </li></ul>September 8, 2010
  5. 5. Mechanisms of Injury <ul><li>Direct effect of electrical current </li></ul><ul><li>Thermal burns (conversion I->E) </li></ul><ul><li>Mechanical Trauma </li></ul><ul><li>Post-trauma sequelae </li></ul>September 8, 2010
  6. 6. Direct effects of current <ul><li>I = V/R </li></ul><ul><ul><li>In general, type & extent of injury depends on current intensity (amps) </li></ul></ul><ul><ul><li>Type of current (DC vs AC), current pathway, and duration of current also influence severity of injury </li></ul></ul><ul><ul><li>As current generally not known, injuries often classified into high V ( > 1,000V) vs low V </li></ul></ul><ul><li>Cardiac, neurologic and respiratory systems most susceptible to direct effects </li></ul><ul><li>Skin is the resistor most effecting severity of injury </li></ul><ul><ul><li>Wet skin has lower R (~1K ohm) vs. dry or thick skin (>100K ohm), resulting in greater current flow </li></ul></ul>September 8, 2010
  7. 7. Thermal (Burn) Injuries <ul><li>Heat (E) = IVT = I 2 RT </li></ul><ul><li>Type & extent of injury depends on current intensity (I) </li></ul><ul><li>R varies significantly between tissues </li></ul><ul><ul><li>Tissues with high R (e.g., bone), generate more heat, resulting in osteonecrosis and deep tissue periosteal burns, esp surrounding long bones </li></ul></ul><ul><ul><li>Skin also has high R, thus entry/exit wounds </li></ul></ul><ul><ul><li>Decreasing R (e.g., wet skin) results in lower thermal injury, but higher current conductance </li></ul></ul><ul><li>Coagulation of muscle, fat, vessels (i.e., the Bovie) </li></ul><ul><li>Duration of current exposure (T) </li></ul><ul><ul><li>DC typically shorter duration, because single muscle spasm causes victim to be thrown from the source </li></ul></ul>September 8, 2010
  8. 8. Mechanical Trauma <ul><li>Trauma can result from fall or muscle contraction </li></ul><ul><li>Classic example is shock wave of lightning causing blast injuries </li></ul><ul><li>Even at low V, tetanic muscle contraction can result in bone fx </li></ul><ul><ul><li>Cord injury can result from severe muscle contraction, w/o any external signs of trauma </li></ul></ul><ul><li>Can result in vascular compromise </li></ul><ul><ul><li>Acute hypotension should always prompt search for thoracic or intra-abdominal bleeding </li></ul></ul>September 8, 2010
  9. 9. Post-trauma sequelae <ul><li>Crush injury syndrome (rhabdomyolysis, myoglobinuria) </li></ul><ul><li>Multi-organ ischemic injury 2 o /2 vascular coagulation or dissection </li></ul><ul><li>Hypovolemic shock 2 o /2 massive 3rd spacing </li></ul><ul><li>Iatrogenic injuries from acute resuscitation </li></ul><ul><ul><li>Abdominal compartment syndrome </li></ul></ul><ul><ul><li>ARDS </li></ul></ul>September 8, 2010
  10. 10. Associated Injuries I <ul><li>Respiratory System </li></ul><ul><ul><li>Suffocation 2 o /2 tetanic muscle contractions </li></ul></ul><ul><ul><li>Respiratory arrest 2 o /2 direct injury to RCC </li></ul></ul><ul><li>Cardiovascular System </li></ul><ul><ul><li>Asystole (more likely if DC or high V) </li></ul></ul><ul><ul><li>Arrhythmias (more likely AC) (~15% pts) </li></ul></ul><ul><ul><ul><li>Ventricular fibrillation most common fatal arrhythmia </li></ul></ul></ul><ul><ul><li>Myocardial necrosis (thermal effect) </li></ul></ul><ul><ul><li>Anoxic injury 2 o /2 respiratory arrest </li></ul></ul><ul><li>Neurological System </li></ul><ul><ul><li>Direct effects include LOC, autonomic dysfunction, amnesia, temp paralysis (keraunoparalysis) </li></ul></ul><ul><ul><li>Cord injury 2 o /2 spine fx 2 o /2 muscle contractions </li></ul></ul><ul><ul><li>Peripheral motor/sensory losses (long-term sequelae) </li></ul></ul>September 8, 2010
  11. 11. Associated Injuries II <ul><li>Skin (~57% low V fatalities; ~96% high V fatalities)* </li></ul><ul><ul><li>Superficial, partial or full thickness thermal burns </li></ul></ul><ul><ul><li>Degree of external injury can underestimate internal injury & vice-versa </li></ul></ul><ul><li>Muscle </li></ul><ul><ul><li>Necrosis 2 o /2 severe contraction or thermal injury </li></ul></ul><ul><ul><li>Compartment syndrome 2 o /2 edema from deep injury & 3rd spacing </li></ul></ul><ul><li>Skeletal </li></ul><ul><ul><li>Osteonecrosis 2 o /2 thermal injury </li></ul></ul><ul><ul><li>Fx 2 o /2 muscle contraction or blunt trauma </li></ul></ul>September 8, 2010 *Wright, et al, J Foren Sci, 1980
  12. 12. Associated Injuries III <ul><li>Renal </li></ul><ul><ul><li>Pigment-induced renal failure </li></ul></ul><ul><ul><li>Hypovolemia 2 o /2 3rd spacing can lead to prerenal </li></ul></ul><ul><li>GI </li></ul><ul><ul><li>Injury rare, most commonly “Curler’s ulcers” </li></ul></ul><ul><li>HEENT </li></ul><ul><ul><li>Cataracts can develop up to 2 years after </li></ul></ul><ul><ul><li>Hearing loss from 8th nerve injury </li></ul></ul><ul><li>Damage to any organ system 2 o /2 blunt trauma </li></ul><ul><li>Damage to any organ system 2 o /2 vascular damage </li></ul>September 8, 2010
  13. 13. Associated Injuries September 8, 2010 Koumbourlis, Crit Care Med 2002
  14. 14. Lichtenberg Figures <ul><li>Rare pathognomonic “flower-like” branching skin lesions in persons struck by lightning </li></ul><ul><li>Caused by “flashover” effect of non-penetrating current </li></ul><ul><li>Rapidly fade, not typically serious </li></ul>September 8, 2010
  15. 15. Management I <ul><li>Standard ABCDEs of any major trauma </li></ul><ul><li>Pulmonary </li></ul><ul><ul><li>Low threshold for intubation, as respiratory failure common </li></ul></ul><ul><li>Cardiac </li></ul><ul><ul><li>Serial monitoring if high V, abnormal ECG, LOC, respiratory arrest, or PMH of CV dysfunction </li></ul></ul><ul><li>Neuro </li></ul><ul><ul><li>C-spine and log-roll precautions; CT head & spine often warranted </li></ul></ul><ul><ul><li>Thorough serial neurological exams, as vessel coagulation can result in late sequelae </li></ul></ul>September 8, 2010
  16. 16. Management II <ul><li>Musculoskeletal </li></ul><ul><ul><li>Thorough evaluation for fractures </li></ul></ul><ul><ul><li>Serial evaluations of limbs for compartment syndrome requiring emergent decompression </li></ul></ul><ul><ul><li>Even in absence of compartment syndrome, persistent aciduria or myoglobinuria may require limb amputation </li></ul></ul><ul><li>Skin </li></ul><ul><ul><li>Early debridement and later reconstruction </li></ul></ul><ul><ul><li>Antibiotic prophylaxis (controversial) </li></ul></ul><ul><li>Renal </li></ul><ul><ul><li>Fluid resuscitation key, as 3rd spacing common & myoglobinuria 2 o /2 rhabdomyolysis can cause ARF </li></ul></ul>September 8, 2010
  17. 17. <ul><li>GI </li></ul><ul><ul><li>Ulcer prophylaxis, as gastric ulcers (Curling’s ulcers) can develop </li></ul></ul><ul><ul><li>Ileus uncommon, but should prompt evaluation for other injury </li></ul></ul><ul><li>Serial evaluation of liver, pancreatic, & renal function for traumatic/anoxic/ischemic injury </li></ul><ul><li>Judicious management of fluid and electrolytes to avoid acidosis and compartment syndromes </li></ul>Management III September 8, 2010
  18. 18. Prognosis <ul><li>Highly variable, depending on severity of both initial injury and subsequent complications </li></ul><ul><li>High morbidity/mortality in patients with multisystem organ failure </li></ul><ul><li>Advances in surgical interventions (early excision, fasciotomy, skin grafts, etc…) have improved </li></ul>September 8, 2010
  19. 19. References <ul><li>DM Mozingo & BA Pruitt. 1998 . Electric Injury. in Fundamentals of Surgery, 1st ed, JE Niederhuber, pp 194-195. </li></ul><ul><li>DS Pinto & PF Clardy. 2007 . Environmental electric injuries. Up-to-Date, accessed 06/01/2007. </li></ul><ul><li>TN Pham & NS Gibran. 2007 . Thermal & Electrical Injuries. Surg Clin N Am 87:185-206. </li></ul><ul><li>AC Koumbourlis. 2002 . Electrical Injuries. Crit Care Med 30:S424-S430. </li></ul><ul><li>C Spies & RG Trohman. 2006 . Electrocution & Life-Threatening Electrical Injuries. Ann Intern Med 145:531-537. </li></ul>September 8, 2010

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