Electrical burn 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 (â‰¥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 burn 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 burn 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 electrical burn 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).
Lightning is a form of extremely high-voltage direct current, and its strikes are fortunately rare occurrences. Lightning can strike directly or indirectly via ground or inanimate object transfer.
It also has the ability to flow along the body’s surface without directly entering the body. This flashing phenomenon produces a pathognomonic fern-like pattern over the body that resolves in about 24 hours.
Electrical burn should be viewed and assessed from a multisystem perspective. Initial evaluation should proceed as in any major trauma, with primary and secondary surveys.
Special attention should be given to high-voltage injury complications (e.g., extremity or digit amputation, muscle necrosis, compartment syndrome, and sepsis). Although multiple organ systems may be involved, it is damage to the major systems that may require intensive care unit evaluation and treatment.
The cardiovascular system may be affected via cellular necrosis or, more commonly, dysrhythmias. Myocardial injury could involve direct necrosis of myocytes, pacing nodes, and/or coronary vessels. Fatal dysrhythmias include ventricular fibrillation and asystole resulting from cell membrane instability, whereas a myriad of less dangerous dysrhythmias can be precipitated.
Large blood vessels are susceptible to rupture or aneurysmal formation. Smaller vessels are more vulnerable to coagulation necrosis, which may lead to a compartment syndrome in the peripheral circulation. The cardiovascular system should be monitored via continuous electrocardiogram (ECG) if any dysrhythmias are detected on an initial 12-lead ECG.
Cardiac enzymes should be checked and followed as clinically indicated. Physical examination and measurement of compartment pressures as needed will detect potential peripheral vascular complications.
Cutaneous electrical burn varies depending on voltage, contact duration, and resistance of the involved skin. Normal adult skin has a high resistance and therefore will generate underlying coagulation necrosis if prolong contact ensues.
However, young children who naturally have higher water content in their skin and adults exposed to water suffer more superficial cutaneous injury due to the lowered resistance in their skin. These cutaneous burns should be approached as any electrical burn would be.
Careful resuscitation should be given to those electrical burn that may involve subcutaneous fat, tendon, or bone necrosis. Do not under-resuscitate. However, the initial assessment of the extent and severity of an electrical burn is quite difficult and usually underestimates the amount of soft tissue involved.
Thus, multiple excisions to establish a healthy wound bed for grafting are the rule rather than the exception when excising an electrical burn.
Perioral burns from an electrical cord are the most common cutaneous electrical burn in children. These should primarily be monitored for labial artery bleeding. Special attention to potential feeding difficulties is of paramount importance in infants and warrants hospital admission until a regular feeding pattern is re-established.
Respiratory arrest is related to direct injury of the brain stem respiratory center or diaphragmatic muscle tetany impeding respiratory effort. Typically, respiratory arrest from electrical burn manifests at the scene. This is monitored for and treated symptomatically via mechanical ventilation.
Renal dysfunction can occur directly or indirectly via exposure to hypoxemia, myoglobin, and/or creatinine phosphokinase. Serial urine myoglobin and creatinine phosphokinase should be measured as clinically indicated. Adequate resuscitation and hydration should be provided.
Renal failure should be treated as indicated. Volume resuscitation should be based on a urinary output of 30 cc per hour in an adult without myoglobinuria. A minimal urine output of 100 mL/h is the goal in a patient with myoglobinuria.
Central and peripheral nervous system injuries should be evaluated and recognized during the initial trauma assessment. Ophthalmologic examination should be performed on all patients suffering high-voltage injuries to assess for premorbid cataracts because cataract development is a delayed complication of high-voltage injuries.