Electrocution injuries occur when a person comes into contact with an electrical source. Although rare, many electrocution injuries are categorized as critical because of the strong likelihood of internal damage between entry and exit wounds. Electrocution injuries have the potential to be deadly, and as EMS providers it is imperative that we know how to recognize and treat them. Electrocution injuries are classified in three ways: source (electrical or lighting), voltage (high or low), and current (alternating or direct). Each different classification results in a different injury pattern.
When dealing with electrical injuries, it is important to understand the basics of electricity and how it travels through the body. Electricity is the flow of electrons through a conductive material across a potential gradient from high to low concentration. The voltage is essentially the pushing force of a current, which is determined by the source of electricity. The extent of injury depends on the voltage, current strength, the resistance of the body tissue, the intensity of the current, the type of current, and the duration of the electrocution.
Current is essentially the movement of electrons through something. The more electrons that are moving through something, the larger the current is. You can think of it like a river; the more water, the stronger the current. Current can be classified as direct current (DC) or alternating current (AC). Direct current means the electrons travel through the circuit in one direction at a steady rate. This is commonly used in batteries. Alternating current means the flow of electrons continuously changes direction. This is used in household circuits. Low voltage AC current causes muscle contractions (tetany) when touched, which can cause the person's hand to freeze to the electrical source prolonging the exposure. Alternating current is three times more dangerous than direct current at the same voltage. Exposure to direct current typically causes a single muscle contraction, which usually throws the person away from the source.
As mentioned earlier voltage is the driving force of the current and is defined as a difference in charge between two points. The fact that voltage is a difference between two points is key. For example, when a bird lands on a high voltage wire, nothing happens because the bird is not connected to anything. But if a person touches the same line while touching the ground (which has a lower voltage than the wire), the current will flow through the person since current travels from high voltage to a lower voltage. Voltage is classified as high or low-voltage in regards to injuries. The standard US household circuit delivers about 120 volts. Whereas a transmission line can feed up to 345,000 volts.
Resistance is a measure of the difficulty of a currents ability to pass through something. Muscles, blood vessels, and nerves have low resistance because they contain water and electrolytes, giving them low resistance and making them good conductors of electricity. On the contrary, bones, tendons, fat and dry, dirty, calloused skin add resistance to electrical current making them slow conductors. These parts of the body are more susceptible to thermal burns since they are heated as current travels through them as opposed to just transmitting the current.
Ohm’s law shows us the relationship between Voltage (V), Current (I), and Resistance (R):
V = I x R
A variety of injuries may occur from coming into contact with electrical sources. Direct contact with a source will allow the current to pass directly through the tissue, causing electrothermal burns to the tissue as well as the skin. Holding a tool or grabbing a wire by the hand are common ways in which people encounter these injuries. It is common to see an entrance and exit wound, which are referred to as the contact and ground points.
Electrical arcs are another way in which people experience electrocution injuries. Electrical arcs are when current travels from one object to another of different electrical potential, without directly touching it. For example, if someone gets close to a high voltage power line, the difference in voltage between the person and the powerline can be enough that the current will arc through the air, burning the person in what is known as an arc burn. The temperature of an electrical arc can reach 3000-5000 degrees Celsius.
The two most common causes of death by electrocution are from asphyxiation and cardiac arrest. Asphyxia can occur if a person comes in contact with an alternating current resulting in prolonged exposure and contractions of the respiratory muscles. It can also be caused by current traveling through the brain, destroying the impulses for the patient to take breaths. Cardiac arrest can result if a current travels through the heart muscle, disrupting the natural electrical current of the heart and sending the heart into ventricular fibrillation.
The first priority in treating a patient who has suffered an electrocution injury is to ensure the scene is safe. Do not try to remove a patient from an electrical source or try to cut any wires. If there is a downed power line, do not enter the scene until the power company has turned off the power. Once the hazard has been dealt with, you may enter the scene to treat the patient. If the patient is in cardiac arrest, perform CPR as normal. Attach the monitor and open the airway using the jaw thrust maneuver. Regardless of whether the patient is in cardiac arrest or not, you will want to attach a cardiac monitor to check for any dysrhythmias. Administer oxygen to the patient and treat for shock if needed. Expose the patients’ body and try to determine the path the current took through the body, looking for entrance and exit wounds. Keep in mind that trauma could be involved if the patient fell after obtaining an electrical shock. If in your scope of practice, administer fluids to treat for shock, and manage pain using IV pain medication. Make your transport decision early and contact air support or medical control if needed. Reassess the patient every 5 minutes if critical, checking vitals and distal pulses.