Electrical injuries continue to be clinically and surgically challenging for surgeons and critical care physicians worldwide. Gross underestimation of the initial injury has repeatedly proven to increase morbidity and detrimental to the overall outcome.

To briefly review, electricity is the flow of electrons through a conductor via the force of voltage. Voltage is categorized into low (<1,000 volts) and high (≥1,000 volts). Alternating current (AC) and direct current (DC) are the two forms of electrical energy. Alternating current produces cyclic back and forth movement of electrons and is the common current in most households. Direct current is the flow of energy in one direction.

Severity of electrical injury is a function of three factors: (1) current source or voltage, (2) duration of contact, and (3) pathway of current flow. The clinical interplay of these factors can best be understood by Ohm’s law (I = V/R), which states that current (I) is directly proportional to voltage (V) and inversely proportional to the resistance (R) of the conductor. Therefore, current will follow the path of least resistance. Histologically, tissues with high fluid and electrolyte contents (i.e., nerves, vessels, muscle, and mucosal membranes) have lower resistance. Therefore, the pathway of electrical current has a higher affinity for these tissues and will preferentially damage these sites. Tissues such as fat, bone, tendon, and dry skin have lower fluid and electrolyte content and therefore have higher resistance. These tissues do generate an intense amount of thermal injury, however, due to their poor ability to conduct electrical current. Because of this, the initial assessment of the severity of an electrical injury typically underestimates the extent of soft tissue injury.

It is important to note that electrical burns with alternating current, especially low-voltage current, have the propensity to produce muscle tetany due to its cyclic flow of energy. This, in turn, prolongs the duration of contact, which increases the potential of injury developing, especially from current flow through tissues with high resistance. This impeded flow of current can generate a tremendous amount of thermal injury that is often hidden in the form of coagulated necrosis of underlying subcutaneous fat, bone, and tendon.

High-voltage exposure typically produces a single violent muscle contraction leading to a shorter duration of contact due to ejection away from the primary source of current. This ejection increases the risk of fractures, dislocations, loss of consciousness, and closed-head injuries. High-voltage contact also generates severe skin burns due to arcing and flashing of the electrical current. As always, the path of current flow determines organ system involvement and overall injury severity. A flow of current parallel to the body’s vertical axis increases the potential of multisystem injury. A horizontal flow of current is associated with less organ system involvement (e.g., the transfer from hand to hand).