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Electrical Injuries - CLINICAL


  History:

Due to multiple causes in electrical injury cases, the history can be either very obvious or extremely subtle.

  • Lightning:

    Patients who come to the ED are generally observed to have been struck by lightning with the characteristic flash and boom. Usually they are rendered unconscious or arrest and history must be obtained from bystanders.

  • Low Voltage Alternating Current:

    Low voltage is 780 volts or less, the sort of voltage encountered in domestic and industrial wiring. Injury from Low Voltage AC can be subcatergized into those with and those without cardiac/respiratory arrest and/or loss of consciousness.

    • Low Voltage Without Loss of Consciousness and/or Arrest:

      Typically these patients are infants and young children who bite into appliances cords. The circuit is generally restricted to the mouth. The adult will almost always be able to relate that the child was found with the cord in his or her mouth. Older children and adults may be injured this way while working on electrical appliances or home electrical circuits, when the circuit does not involve the heart or brain.

    • Low Voltage With Loss of Consciousness and/or Arrest:

      The presentation may be so subtle, that the correct diagnosis may be missed. Always be alert to the possibility that a sudden arrest might be the result of an electric circuit. Rescue workers, co-workers, family and friends should be queried about this possibility.

  • High Voltage Alternating Current:

    These cases involve voltages higher than 780. Generally, the injuries are so characteristic that history taking is less important than in low voltage injuries. However, there are two possibilities.

    • High Voltage Without Loss of Consciousness and/or Arrest:

      This is the characteristic situation with an electrical injury from high voltage. Unless there is a very high resistance pathway in the circuit, voltages of more than 780 usually do not cause cardiac/respiratory arrest. Thus, the history obtained from the patient should tell you how the injury occurred. Details of the voltages can be obtained from the power company.

    • High Voltage with Arrest and/or Loss of Consciousness:

      This is the more unusual presentation from high voltage circuit injuries presenting to the ED. If the circuit traverses the head, there will be loss of consciousness and amnesia for the events immediately prior to the injury. Thus, history taking should be directed to rescue personnel, co-workers, family or friends who have knowledge of the circumstances. Details of the voltages can be obtained from the power company.

  • Direct Current:

    Direct current electrical injuries are generally seen in electrical train circuits. These often involve risk taking behavior by young males. Arrest and coma are rarely, if ever, seen. The history can be obtained from the patient.

Physical:

The physical examinations should include a careful documentation of injuries. There is a bit of difference depending upon the voltage.

  • High Voltage (and, Occasionally, Low Voltage With Flash Burns): These cases are characterized by burns. Some attention to the characteristics and nature of the burns will assist in treatment.
    • Flash or Thermal Burns:

      These are seen in some low voltage and occasionally in high voltage injuries. These burns appear to be indistinguishable from ordinary thermal burns and often do not have an internal electrical component. Using the same techniques as with any burn case, diagram the body areas and estimate severity.

    • Arc Burns:

      Arc burns characteristically have a dry parchment center and a rim of congestion about them. The central parchment area may be less than 1 mm or may be as large as several centimeters. Recognition of these injuries is important in assessing the extent of internal damage.

    • Contact Burns:

      Contact electrical burns generally have a pattern from the contacted item and are more limited in size than flash burns, although their appearance otherwise is nearly identical to a flash burn. One means of distinguishing is that in skin with hair, a contact burn of apparent full thickness will have unburned hair, whereas a flash burn will always have the hair singed and generally gone.

    • Documenting the Types of Burns:

      Arc and contact burns are associated with internal electrical injury; flash burns are not. Entrance and exit burns in alternating electrical injuries are not possible, as alternating current has no such wounds. However, there are arcing and contact burns. These are markers to where the circuit traversed the body.

  • Low Voltage:

    In low voltage injuries, there may be flash burns from various sources that will behave exactly as ordinary thermal burns and should be documented as such. However, there are electrical burns that should be documented.

    • Arcing Burns:

      These are not seen in low voltage. Thermal burns from arcs, where the arc was from an energized conductor to a grounded conductor are seen. These are the flash type.

    • Direct Contact Burns:

      These will be seen only if the circuit through the person was prolonged for more than a few seconds. In low voltage there is insufficient heat to produce skin burns quickly. Thus, the areas where there was electrical contact will often not be distinguishable on physical examination or will only show focal erythema.

  • Lightning:

    There is wide variability of findings in a lightning strike victim. Burns are generally not significant, but should be documented. They will generally be of the flash type. Singeing of the hair, without burning is characteristic. There are a few things to look for which are out of the routine:

    • Scrotal and Penile Burns:

      In males, there is occasional burning on the undersurface of the scrotum. This injury needs to be identified for early treatment. The postictal state that the usual lightning patient presents with often makes early identification of these lesions from complaints of pain unlikely.

    • Ear Lesions:

      The presence of perforation of the eardrum is an occasional feature of a lightning struck patient. Hemorrhage behind the intact drum is probably more common. The examinations of the lightning struck patient should include an otoscopic exam.

Causes:

Electrical injuries are caused when a person becomes part of an electrical circuit or is affected by the thermal effects of a nearby electrical arc. The most common classifications of these injuries are lightning, and high and low voltage alternating current (AC) and direct current (DC).

  • Lightning:

    Lightning injuries occur when the patient is part of or is near the lightning bolt. Generally, the patient will have been the tallest object around or near a tall object, such as a tree. There is always a thunderstorm in the vicinity but oddly, the overhead sky can be clear.

  • High Voltage AC:

    High voltage injuries most commonly occur when a conductive object touches an overhead high voltage power line. In America, most electric power is distributed and transmitted by bare aluminum or copper conductors, which are insulated by air. If the multiple feet of air are breached by a conductor, such as an aluminum pole, antennae, sailboat mast or crane and a person is on the ground at the time the conductor becomes energized, that person will be injured. Rarely, patients will get into electrical switching equipment and directly touch energized components.

  • Low Voltage AC:

    Generally, there are 2 types: the child who bites into the cord producing severe lip, face and tongue injuries and the child or adult who becomes grounded while touching an appliance or other object that is energized.

    The latter type is declining in frequency in North America due to the use of ground fault circuit interrupters (GFCIs) in any circuits which supply kitchens, bathrooms or the outside, as these are places where persons may become easily grounded. GFCIs stop current flow if there is a leakage current (ground fault) or more than 0.005 amps (0.6 watts at 120 volts).

  • DC:

    Direct current injuries are generally encountered when young males inadvertently contact the energized rail of an electrical train system while grounded. This sets up a circuit which produces myonecrosis and electrical burns.