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Electrical Injuries

Author: Ronald K Wright, MD, JD, Associate Professor (Retired), Department of Pathology, University of Miami School of Medicine; Private Practice, Forensic Pathology
Contributor Information and Disclosures

Updated: Jul 25, 2007

Introduction

Background

Electrical injuries though infrequent are eventually encountered by most emergency medicine practitioners. Electrical injuries encompass various diagnostic and treatment modalities. Generally, they may be classified as lightning, low voltage, and high voltage. Further, each classification may be subclassified depending on whether the injured person required cardiopulmonary resuscitation (CPR).

Pathophysiology

Electrons flowing abnormally through the body produce injury and/or death by depolarizing muscles and nerves, initiating abnormal electrical rhythms in the heart and brain, or producing internal and external electrical burns both by heating and by poration (producing holes in cell membranes) of the cellular membranes.

Current passing through the brain, in both low-voltage and high-voltage circuits, produces unconsciousness instantly and directly because of the depolarization of the brain's neurons.

Alternating current (AC) may produce ventricular fibrillation if the path of the current involves a passage through the chest. This may occur when the current flows arm to arm, arm to leg, or head to arm or leg. 

Circuits through a person that last for protracted periods (minutes) produce ischemic brain damage if they interfere with respiratory movement. All circuits may produce myonecrosis, myoglobinemia, and myoglobinuria and their attendant complications.

Circuits may produce electrical burns with relatively massive amounts of tissue destruction by heating the tissues (physical property of friction from the passages of electrons [joule heating]) and/or by the destruction of cell membranes by poration.

In addition, thermal burns that result from electrical flashes generally are considered electrical injuries, although such injuries generally do not involve a circuit through a person.

Frequency

United States

More than 500 lightning deaths and generated electrical deaths per year are estimated to occur. Between 3 and 5% of burn unit admissions are associated with electrical burns.

Mortality/Morbidity

Morbidity and mortality depend upon a broad range of factors unique to each exposure.

• Lightning: Overall, the survival rate following a lightning strike may be as low as 5%; however, morbidity may be as high as 70%. If cardiac and/or respiratory arrest has occurred, prolonged CPR may result in recovery. Unfortunately, prolonged arrest comes with an increasing probability of permanent brain injury, persistent vegetative states, and brain death.
• Low-voltage electrical injury without cardiac and/or respiratory arrest: This situation is encountered frequently in children who bite extension cords. The burns of the mouth are often severe and require extensive plastic revision. However, systemic problems are infrequent.
• Low-voltage electrical injury with cardiac and/or respiratory arrest: These patients often are not transported to the ED since they are pronounced dead at the scene. If they are transported to the ED and if CPR has been prompt and effective, they may completely recover, usually with no apparent injury. Unfortunately, as with lightning, protracted periods without brain perfusion result in permanent brain damage.
• High-voltage injury: Generally, patients who have been in high-voltage circuits do not arrest but have extensive injuries from burns and are at risk of acute and chronic problems from myoglobinuria. Electrical burns from high-voltage circuits generally are much worse than they appear in the ED.

Race

No racial variation is apparent in electrical injury susceptibility. Historically, tradespersons in the United States have been predominately white; thus, the number of injuries has shown a white predominance in the United States.

Sex

According to Dalziel, females are more perceptive of low-intensity electrical current.¹ However, females are markedly underrepresented in injury and death, probably because of lack of exposure.

Age

Electrical injuries are most frequent in young adult men aged 20-40 years. This probably reflects exposure opportunities more than differences in susceptibility.

Clinical

History

Because of multiple causes in electrical injury cases, the history can be obvious or subtle. In any case involving cardiorespiratory arrest, some consideration of the possibility of electrocution should be entertained.

• Lightning: Patients who come to the ED generally are observed to have been struck by lightning with the characteristic flash and boom. Usually, patients are rendered unconscious or they arrest, and history must be obtained from bystanders.
• Low-voltage alternating current: Low voltage is 600 or fewer volts, the type of voltage encountered in domestic and industrial wiring. Injuries from low-voltage AC can be subcategorized into those with and those without cardiac and/or 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 appliance cords. The circuit generally is restricted to the mouth. The adult can almost always 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 may be the result of an electric circuit. Query rescue workers, coworkers, family, and friends about this possibility. Inquire if a scream was heard before the collapse. If so, it probably was caused by the involuntary contraction of the chest muscles; consider the cause of the arrest electrical until excluded.
• High-voltage alternating current: These cases involve voltages of more than 600 volts. Generally, the injuries are so characteristic that history taking is less important than in low-voltage injuries. However, 2 possibilities exist.
• • High voltage without loss of consciousness and/or arrest
    • This is the characteristic situation with an electrical injury from high voltage. Unless the circuit has a high-resistance pathway, voltages of more than 600 volts usually do not cause cardiac and/or respiratory arrest.
    • Thus, the history obtained from the patient should indicate 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 of patients with high-voltage circuit injuries observed in the ED.
    • If the circuit traverses the head, the person loses consciousness and develops amnesia concerning the events immediately preceding the injury. Thus, direct history taking to rescue personnel, coworkers, family, or friends who have knowledge of the circumstances.
    • Details of the voltages can be obtained from the power company.
• Direct current: Direct current (DC) electrical injuries generally are observed in electrical train circuits. These often involve risk-taking behavior by young males. Arrest and coma are rarely, if ever, observed. The history can be obtained from the patient.

Physical

Include a careful documentation of injuries in the physical examination. Depending on the voltage, some differences exist when examining the patient. Because litigation may well be involved at a later date, photographs of the injuries should be taken, with proper releases, and filed in the patient's medical records.

• High voltage (and occasionally, low voltage with flash burns): Burns characterize these cases. Some attention to the characteristics and nature of the burns assist in treatment.
• • Flash or thermal burns
  • • These are observed in some low-voltage (usually 480 V) 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 of a circuit with the patient in the circuit
  • • Arc burns characteristically have a dry parchment center and a rim of congestion about them. The central parchment area may be smaller than 1 mm or may be as large as several centimeters.
    • Recognition of these injuries is important in assessing the extent of internal damage, as the pathway of the circuit may be estimated.
  • Contact burns
  • • Contact electrical burns generally have a pattern from the contacted item (branding) and are generally more limited in size than flash burns, although their appearance in the ED is nearly identical to flash burns.
    • One means of distinguishing between the 2 burns involves hair-bearing skin; in such skin, a contact burn of apparent full thickness has unburned hair, whereas a flash burn always singes the hair. The hair is generally gone following transport to the ED.
  • Documenting 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 because AC does not produce such wounds. In general, burns are usually on the skin where the person touched an energized circuit and where he or she was grounded. These are markers of where the circuit traversed the body.
• Low voltage: Low-voltage injuries may involve flash burns from various sources. These behave exactly as ordinary thermal burns and should be documented as such.
• • Arcing burns
  • • Arcing burns are not observed in low-voltage injuries.
    • Thermal burns from arcs, in which the arc traveled from an energized conductor to a grounded conductor, are observed. These are the flash type.
  • Direct contact burns
  • • Direct contact burns are observed only if the circuit through the person was prolonged for more than a few seconds.
    • Low voltage contains insufficient heat to produce skin burns quickly. Thus, the areas where electrical contact occurred often are not distinguishable on physical examination or only exhibit focal erythema.
• Lightning: Findings in a lightning strike victim are widely variable. Burns generally are not significant but should be documented. They generally are of the flash type. Singeing of the hair without burning is characteristic. Look for the following items, which are not routine:
• • Scrotal and penile burns
  • • In males, occasional burning occurs on the undersurface of the scrotum. This injury needs to be identified for early treatment.
    • The postictal state with which the usual lightning strike patient presents 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 in a patient struck by lightning. Hemorrhage behind the intact drum is probably more common.
    • An otoscopic examination should be included when examining a patient struck by lightning.

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, high-voltage and low-voltage AC, and DC.

• Lightning
• • Lightning injuries occur when the patient is part of or near the lightning bolt.
  • Generally, the patient was the tallest object around or near a tall object, such as a tree. While a thunderstorm is always in the vicinity, the overhead sky can be clear.
• High-voltage alternating current
• • High-voltage injuries most commonly occur when a conductive object touches an overhead high-voltage power line.
  • In the United States, 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 (eg, aluminum pole, antennae, sailboat mast, crane) and a person is on the ground at the time the conductor becomes energized and is touching the conductor, that person is injured.
  • Rarely, patients get into electrical switching equipment and directly touch energized components.
• Low-voltage alternating current
• • Generally, 2 types of low-voltage AC injuries are possible: 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 because of the use of ground fault circuit interrupters (GFCIs or GFIs) in circuits that supply kitchens, bathrooms, or the outside, since these are places where persons easily may become grounded. GFCIs stop current flow in the event of a leakage current (ground fault) if the ground fault is greater than 0.005 amps (0.6 W at 120 V).
• Direct current
• • DC injuries generally are 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.

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