Electrical Injuries in Emergency Medicine Clinical Presentation

Electrical injuries can present with a variety of problems, including cardiac or respiratory arrest, coma, blunt trauma, and severe burns of several types. It is important to establish the type of exposure (high or low voltage), duration of contact, and concurrent trauma.

Low-voltage AC injury without loss of consciousness and/or arrest

These injuries are exposures of less than 1000V and usually occur in the home or office setting. Typically, children with electrical injuries present after biting or chewing on an electrical cord and suffer oral burns. Adults working on home appliances or electrical circuits can also experience these electrical injuries. Low-voltage AC may result in significant injury if there is prolonged, tetanic muscle contraction.

Low-voltage AC injury with loss of consciousness and/or arrest

In respiratory arrest or ventricular fibrillation that is not witnessed, an electrical exposure may be difficult to diagnose. All unwitnessed arrests should include this possibility in the differential diagnosis. Query EMS personnel, family, and coworkers about this possibility. Inquire if a scream was heard before the patient’s collapse; this may be due to involuntary contraction of chest wall muscles from electrical current.

High-voltage AC injury without loss of consciousness and/or arrest

Usually high-voltage injuries do not cause loss of consciousness but instead cause devastating thermal burns. In occupational exposures, details of voltage can be obtained from the local power company.

High-voltage AC injury with loss of consciousness and/or arrest

This is an unusual presentation of high-voltage AC injuries, which do not often cause loss of consciousness. History may need to come from bystanders or EMS personnel.

Direct current (DC) injury

These injuries typically cause a single muscle contraction that throws the victim away from the source. They are rarely associated with loss of consciousness unless there is severe head trauma, and victims can often provide their own history.

Conducted electrical devices

Conducted electrical weapons (CEWs) such as tasers are weapons used by law enforcement that deliver high-voltage current that is neither true AC or DC but is most like a series of low-amplitude DC shocks. ^[16] They can deliver 50,000 V in a 5-second pulse, with an average current of 2.1 mA. ^[17] Though they have been temporally associated with deaths in the law enforcement setting, conducted electrical devices (CEDs) in healthy volunteers have been shown to be safe without evidence of delayed arrhythmia or cardiac damage as measured by troponin I. ^{[18, 17]}

One study of their use in 1201 law enforcement incidents showed mostly superficial puncture wounds from the device probes, and significant injuries only from trauma subsequent to shock, not from the device itself. Of 2 deaths in custody, neither was related to CEW exposure. ^[19]

Overall significant injuries from CEW exposure are rare, and usually occur due to trauma or in conjunction with intoxication. ^{[20, 21]} Of the more than 3 million CEW applications by law enforcement in the United States, only 12 published case reports suggest a link to cardiac arrest. ^[22] However, the issue of whether CEW usage can cause cardiac arrest is not without controversy, as some suggest a direct cardiac risk. ^[23]

Electrical injuries can cause multiorgan dysfunction and a variety of burns and traumatic injuries. A thorough physical examination is required to assess the full extent of injuries. Occupational injuries have a high likelihood of future litigation, and physical examination findings should be documented with photographs if possible, with the proper releases, and filed in the patient's medical record.

Overall, low-voltage exposure tends to cause less overall morbidity than high-voltage, but it is important to ensure by accurate history that a seemingly low-voltage burn was not in fact from a high-voltage source (like a microwave, computer, or TV monitor—any device that "steps-up" voltage via a transformer). Low-voltage burns can still cause cardiac arrhythmias, seizures, and long-term complications if contact is near the chest or head.

Cardiovascular

Patients may present in asystole or ventricular fibrillation (VF) in addition to other arrhythmias. Sudden death due to VF is more common with low-voltage AC, whereas asystole is more often associated with high-voltage AC or DC. Ventricular fibrillation can be caused at voltages as low as 50-120 mA, which is lower than the typical household current. One series showed cardiac arrhythmias following 41% of low-voltage injuries. ^[11]

Electricity can also cause conduction abnormalities and direct trauma to cardiac muscle fibers. Survivors of electrical shock can experience subsequent arrhythmias, usually sinus tachycardia and premature ventricular contractions (PVCs). One study identified three cases of delayed ventricular arrhythmias up to 12 hours after the incident. ^[24] Other studies have shown no risk of delayed arrhythmias in patients with initially normal ECGs, both in low-voltage household exposures and after CEW exposure. ^{[19, 20, 25, 26]} One case report describes coronary artery dissection after electrical injury. ^[27] Long-term cardiac complications from electrical injury are rare.

Respiratory

Chest wall muscle paralysis from tetanic contraction may cause respiratory arrest if the current pathway is over the thorax. Injury to the respiratory control center of the brain can also cause respiratory arrest. The lungs are a poor conductor of electricity and generally are not as susceptible to direct injury from current as tissues with lower resistance. Case reports have described pneumothorax after electrical injury. ^[28]

Skin

A variety of burns and thermal injuries from electricity affect the skin and soft tissues. These are often the most severe sequelae of electrical burns after cardiac arrhythmias and may initially appear minor despite significant deep tissue injury subsequently requiring fasciotomy or amputation. Burns are often most severe at the source and ground contact points; the source is usually the hands or the head while the ground is often in the feet. The strength and duration of contact with the source largely influence the severity and extent of tissue damage. All burns should be carefully documented and, if possible, photographed.

High-voltage electrothermal burns

Typically, these show a contact point where the person touched the circuit and a ground point. These may produce significant damage to underlying tissue while largely sparing the surface of the skin. These burns may appear as painless, depressed areas with central necrosis and minimal bleeding. The presence of surface burns does not accurately predict the extent of possible internal injuries, as skin with high resistance will transmit energy to deeper tissues with lower resistance. A high-voltage burn is shown below.

Arc burns

When an arc of current passes from an object of high to low resistance, it creates a high temperature pathway that causes skin lesions at the site of contact with the source and at the ground contact point (not always the feet). These areas typically have a dry parchment center and a rim of congestion around them. There will be clues to the internal pathway taken by the arc based on the location of these surface wounds. Arcs can also cause electrothermal, flash, and flame burns, so multiple burns of varying appearance may be observed. Arcs do not occur in low-voltage injuries. An arc burn is shown below.

Flash burns

Flash burns are caused by heat from a nearby electrical arc that can reach upwards of 5000^o C. These can pass over the surface of the body or through, depending on the path of the arc causing the flash. They may "splash" over the surface of the body, resulting in diffuse but relatively superficial partial-thickness burns. There is no internal electrical component. A flash burn is shown below.

Flame burns

Flame burns are caused by ignition of clothing or nearby objects. These cause thermal burns similar to other flame burns.

Low-voltage burns

These behave like ordinary thermal burns and range from local erythema to full-thickness burns. These require several seconds of contact to cause skin burns, sometimes reaching current levels high enough to cause VF before causing any significant skin damage. ^[4] Direct contact burns may occur only if the circuit through the person was prolonged for more than a few seconds. Low-voltage burns are shown below.

Contact burns

Contact burns usually have a pattern from the contacted item (branding) and may appear similar to flash burns. A contact burn is shown below.

Pediatric oral burns

These are most commonly encountered in children younger than 6 years who bite or suck on a household electrical cord. A local arc of current crosses from one side of the mouth to the other. The orbicularis oris muscle may be involved, and cosmetic deformity of the lips may occur if the burn crosses the commissure. Significant edema may be noted and within 2-3 days eschar formation. Life-threatening bleeding can occur at 2-3 weeks post injury if the labial artery is exposed when the eschar falls off. Initial presentations may underestimate the extent of the ultimate injury; patients require aggressive airway management. ^[15] These patients should be referred for early follow-up to a burn specialist, plastic surgeon, and an oral surgeon.

Neurologic

Most acute CNS or spinal deficits resulting from electrical injuries are due to secondary blunt trauma or burns. Often, the patient has transient confusion, amnesia, and impaired recall of events if not frank loss of consciousness. Direct effects of electrical current are most severe if the respiratory control center of the brainstem is affected resulting in respiratory arrest. Current may also cause seizure or direct spinal cord injury if there is hand-to-hand flow. Spinal cord injury can also result from direct current effects or blunt trauma. Unless a patient is completely lucid with full recollection of the events, initial C-spine immobilization is indicated.

Currents cause acute muscle tetany at relatively low currents and frequencies, like those found in most households. Muscle tetany causes victims to grasp the source, prolonging contact time, and can also paralyze respiratory muscles resulting in asphyxiation.

Long-term neurologic complications include seizures, peripheral nerve damage, delayed spinal cord syndromes, subacute infarcts, ^[29] and psychiatric problems from depression to aggressive behavior.

Musculoskeletal

Acute injuries include fractures from blunt trauma and compartment syndrome from burns. The chest and extremities should be examined for circumferential burns. Palpate the extremity and perform distal neurologic, vascular, and motor examination to determine if there is suspicion of a compartment syndrome. If this is the case, compartment pressure can be measured and early fasciotomy may help prevent subsequent amputation. ^[10] If available, early surgical consultation should be obtained for a patient with concerns for compartment syndrome. Massive muscle damage can cause severe rhabdomyolysis and subsequent renal failure.

ENT/head

The head is a common point of entry for high-voltage injuries. Patients may have perforated tympanic membranes, facial burns, and cervical spine injury. Approximately 6% of victims develop cataracts, usually months after the initial injury, with increasing frequency the closer contact is to the head. ^{[9, 30]}

Low-voltage

If no significant burns are present and if consciousness returns before arriving to or in the ED, full recovery is expected. Rare persistent arrhythmias have been reported.

Persistence of unconsciousness carries a worse prognosis, and full recovery is not expected after 24 hours of unconsciousness.

With proper treatment, the disfigurement of low-voltage mouth injuries can be minimized. Scarring is almost always present.

High-voltage

Survival with massive burns is now the rule rather than the exception. However, rates of amputation and significant morbidity from traumatic injuries and burns remain high.