Injuries caused by electricity are relatively common and almost always accidental. And more importantly, they are preventable. They can be avoided. We are talking about two age groups that are common in these types of accidents. On the one hand, there are small children, under the age of six, who can playfully touch or suck on a cable or stick their fingers in a socket. And, on the other hand, adults who suffer an electrical shock related to their professional activity, and this usually happens in the construction sector.
Electric shocks can cause injuries by various mechanisms, but the most relevant are three. The first of them is a direct effect of that discharge that can cause an entry and exit wound, of different magnitude depending on the power and contact time. Second, that electrical energy is converted into thermal energy, generating burns, especially on the skin and even on internal organs. Between 3-4% of admissions to Burn Units are due to this type of injury. Added to this are also the burns caused by flames in case the clothes catch fire. And, finally, a muscle contraction of a greater or lesser degree can occur, even with bone fractures that, as I explained a few weeks ago, could cause a lightning strike.
The main determinant of injury is the power of the discharge, the amount of current that will flow through the body. For that reason, we rate injuries as high-voltage, when the body has received more than a thousand volts, and low-voltage, below a thousand volts. We can remember that high voltage power lines exceed 100,000 volts or that lightning has more than ten million volts. And the closest thing to day to day, in European homes the electric current is 220 volts.
When we care for a patient who has received an electric shock, we have to take into account the voltage that has been received, the resistance of the tissues, the area that is affected and the total volume of his body. The effects of a shock in a two-year-old child are not the same as in an adult, even though the voltage was the same.
As I said at the beginning, in terms of injuries, the most common are burns that can range from first degree, which are the lightest, to third degree, the most serious. Depending on the extent and depth of the burn, tissue necrosis or cell death can occur, with the release into the bloodstream of substances capable of blocking the kidney and causing kidney failure that requires dialysis until recovery. Sometimes the peripheral nerves can also be injured, so that if a person touches a high-tension cable they can have paralysis and anesthesia, which is a permanent decrease in the sensitivity of the hands, for life.
The most serious injury that can occur in an electric shock is what we know as electrocution or cardiorespiratory arrest due to the passage of current through our body. Electrocutions with discharges below 500 volts normally cause malignant arrhythmias that lead to cardiorespiratory arrest. And in the case of lightning, cardiac arrest is caused by asystole, the heart stops suddenly. In any of the cases, cardiopulmonary resuscitation must be prolonged in time because the cardiac tissue does not have any injury but the arrhythmia or asystole have been caused by the electric shock. These patients survive more often than those with other types of structural cardiac arrest.
Finally, bone fractures can be caused. Either as a consequence of the intense muscular contracture or because, as happens with lightning, the power of the discharge can displace you in space and cause serious trauma.
All potential injuries need to be closely monitored because current exposures can cause a small entry wound and minor skin burns, but also have caused significant internal organ injuries that go unnoticed initially. Special mention should be made of low-voltage currents, such as those in homes, which do not usually cause serious injuries.
In any case, prevention is simple and easy to apply, especially at home and in the workplace, so we must focus on the appropriate measures to avoid these injuries.
Begoña Zalba Etayo She is head of the Multipurpose Unit of the ICU of the Lozano Blesa University Clinical Hospital in Zaragoza.
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