Injuries produced by receiving an electric shock are relatively common and almost always accidental. More importantly, they are largely preventable. Two age groups are most commonly affected: small children under six years of age, who might touch or suck on a cable, or stick their fingers in a socket, and adults who work with unsecured electrical currents at work, as in the construction sector.
Electric shocks can cause injuries in several ways. The first to consider is the direct effect of the shock, which can cause entry and exit wounds of varying severity depending on the charge and contact time. Secondly, electricity can be converted into heat generating burns – mainly on the skin but even in the internal organs. Between 3 and 4% of admissions to burns units are due to this type of injury. Burns can also happen when clothing catches fire via electrical sparks. Lastly, muscle contractions can cause injury including bone fractures, as we occasionally see when someone is struck by lightning.
The main factor determining the severity of an injury is the power of the electrical charge, i.e. the amount of current that flows through the body. For this reason, we qualify injuries as high voltage when the body has received more than a thousand volts, and low voltage below a thousand volts. High voltage power lines exceed 100,000 volts and lightning has a charge of more than 10 million volts.
When caring for someone who has received an electric shock, we have to assess the voltage they have received, the area that is affected and the total size of their body. The effects of an electric shock on a two-year-old child are not the same as on a hefty adult, even if the voltage is the same.
Burns can range from first degree (the mildest) to third degree (the most serious). Depending on the surface area and depth of the burn, tissue necrosis or cell death may occur, and substances will be released into the bloodstream capable of blocking the kidneys and causing renal failure, requiring dialysis until recovery. Sometimes the peripheral nerves can also be injured, so if a person touches a high-voltage cable, he or she can become paralyzed and suffer a permanent, lifelong decrease in skin sensitivity.
The most serious injury that can occur is electrocution or cardiorespiratory arrest when an electrical current flows through our body. Electrocution below 500 volts normally causes malignant arrhythmias that lead to cardiorespiratory arrest. In the case of lightning, the heart may stop suddenly (flatlining, or asystole). In either case, cardiopulmonary resuscitation must be prolonged because the cardiac tissue is not injured, but the arrhythmia or asystole is caused by the electric shock. These patients survive more frequently than those who suffer other types of cardiac arrest.
Finally, bone fractures can happen either as a consequence of intense muscular contractions or because the power of the discharge can throw you backwards and cause serious blunt trauma when you land.
All possible injuries must be closely monitored as exposure to electrical currents may cause a small entry wound and slight skin burns, but may also have caused significant internal injuries that initially pass unnoticed. Low-voltage currents, such as household electricity supply, do not usually cause serious injury.
In any case, prevention is simple and easy to ensure, especially at home and in the workplace, so we must remain vigilant to avoid injuries caused by electric shock.
Begoña Zalba Etayo is the head of the Multi-Role Unit at the ICU in the Hospital Clínico Universitario Lozano Blesa in Zaragoza.