Electrical burn

Electrical burn on hand

An electrical burn is a burn that results from electricity passing through the body causing rapid injury. Approximately 1,000 deaths per year due to electrical injures are reported in the United States, with a mortality rate of 3-5%.^[1] Electrical burns differ from thermal or chemical burns in that they cause much more subdermal damage.^[2] They can exclusively cause surface damage, but more often tissues deeper underneath the skin have been severely damaged. As a result, electrical burns are difficult to accurately diagnose, and many people underestimate the severity of their burn. In extreme cases, electricity can cause shock to the brain, strain to the heart, and injury to other organs.^[3]

For a burn to be classified as electrical, electricity must be the direct cause. For example, burning a finger on a hot electric steam iron would be thermal, not electrical. Electricity passing through resistance creates heat, so there is no current entering the body in this type of burn. Likewise, a fire that is ruled to be "electrical" in origin, does not necessarily mean that any injuries or deaths are due to electrical burns. Unless someone was injured at the exact moment that the fire began, it is unlikely that any electrical burns would occur.

Pathophysiology

Four electrical factors determine the severity of the damage caused by electrical burns: voltage, current, resistance, and frequency. The severity of the burn also depends on the pathway the current takes through the body.^[4] Generally, the pathway of the current will follow the course the least resistant tissues: firstly blood vessels, nerves, and muscle, then skin, tendon, fat, and bone.^[5] Most commonly, electric injuries primarily damage the outer limbs, but more critical portions of the body may be affected as well causing severe complications.^[6]

As the body comes into contact with an electrical source, it becomes part of the electrical circuit. As such, the current has a point of entry and an exit at two different points on the body. The point of entry tends to be depressed and leathery whereas the exit wound is typically more extensive and explosive.^[5] It is hard to accurately diagnose an electrical burn because only the entry and exit wounds are visible and the internal damage is not.^[7]

Causes and classification

Electrical burns can be caused by a variety of ways such as touching or grasping electrically live objects, short-circuiting, inserting fingers into electrical sockets, and falling into electrified water. Lightning strikes are also a cause of electrical burns, but this is a less common event.^[8] With the advances in technology, electrical injuries are becoming more common and are the fourth leading cause of work-related traumatic death.^[9] One third of all electrical traumas and most high-voltage injuries are job related, and more than 50% of these injures result from power line contact.^[9]

Electrical burns can be classified into six categories, and any combination of these categories may be present on an electrical burn victim:

• Low-voltage burn. A burn produced by contact with a power source of 500 volts or less is classified as a low-voltage burn. The current at this voltage is not enough to cause tissue damage along its path except at the contact site. This type of burn may be mild, superficial, or severe depending on the contact time.^[10]
• High voltage burn. This burn is very severe as the victim makes direct contact with the high voltage supply and the damage runs its course throughout the body. Exterior injuries are misleading as most of the damage occurs underneath the skin. In this case, subdermal tissues are severely damaged.^[5]
• Arc burn. This type of burn occurs when electrical energy passes from a high-resistance area to a low-resistance area.^[7] No contact is required with an arc burn as the electricity ionizes air particles to complete the circuit. The heat generated can be as high as 4,000 degrees Celsius - hot enough to vaporize metal and ignite a victim’s clothing.^[11] A form of explosion dissipates excess energy from the arc.^[10] In addition, a high-amperage arc can produce a pressure wave blast in excess of 1000 pounds per square inch of pressure. This can throw the victim and cause severe injuries.^[12]
• Flash burn. Flash burns are caused by electrical arcs that pass over the skin. The intense heat and light of an arc flash can cause severe burns in a fraction of a second.^[13] Although the burns on the skin are largely superficial and cover a large area, tissues beneath the skin are generally undamaged and unaffected. This typically occurs when the frequency of the AC current is significantly higher than the 50 or 60 Hz used in land-based electrical distribution systems (such as in aircraft).^[7]
• Flame burn. Flame burns are caused by contact to objects that were ignited by an electrical source when associated with flash and arc burns.^[7]
• Oral burns. This is caused by biting or sucking on electrical cords, and it most commonly happens to children.^[14] Electric current typically passes from one side of the child’s mouth to the other, possibly causing deformity.

Treatment

First aid

An electrically burned patient should not be touched or treated until the source of electricity has been removed.^[4] Electrical injuries often extend beyond burns and include cardiac arrhythmia, such as ventricular fibrillation. First aid treatments include assessment of consciousness of the victim, evaluation of pulse and circulation, and treatment of burns.^[15]

Hospitalization

Typically, an electrical burn patient has a lower affected body surface area than other burn patients, yet complication risks are much higher due to internal injury.^[16] Often, the damaged internal tissue demands hospitalization. If not treated, this damaged tissue can cause complications (such as gaseous gangrene from dead tissue or loss of blood flow to limbs) and the damaged body parts may need to be amputated.^[7] Repeated removal of the damaged tissue and extensive rehabilitation are common while limb amputation rates for victims who experience direct electrical contact can be as high as 75%.^[17] Burn treatment for severe wounds may require skin grafting, debridement, excision of dead tissue, and repair of damaged organs.^[18]

Rehabilitation

Electrical burning has an effect on most vital body functions and is accompanied by several other electrical related injuries:

• Damage to the veins and arteries which can cause ischaemic necrosis.
• Involuntary contraction of muscles due to electrical interference which can cause bone fractures and dislocations.
• Interference with the electrical conductivity of organs such as the heart and nerves. This can lead to seizures, lung injury due to severe central nervous system damage, and cardiac arrest.
• Forceful propulsion of the body, producing such injuries as spinal and limb fractures.^[5]

These injuries must be treated in addition to the burns themselves. In very rare instances, a high voltage electric shock can cause cataracts in the lens of the eyes, and detachment of the retina. This may be delayed for some days or weeks after the initial injury.^[19]

Prevention

Basic electrical safety

The following are some basic safety rules for preventing electric injury (cannot cover every possible scenario):^[20]

• Avoid using electrical appliances while showering or bathing.
• Avoid using electrical equipment and appliances when wet, with an exception for quality appliances intended for the bathroom when not simultaneously showering, bathing, or being in a path of water going to plumbing.
• Use child safety plugs in all outlets, and keep children away from electrical cords.
• All power mains outlets should have a wall cover to avoid accidentally touching the electrified sides between the wall and outlet. This is especially important for children, as their small fingers can easily reach into this gap along the sides.
• If the prongs of an electrical cord are too wide or narrow, never adjust them with your fingertips while simultaneously plugging the cord into the power mains.
• Follow manufacturer safety instructions for electrical appliances. This includes not using and immediately unplugging any appliance with a damaged electrical cord. If this cannot be done safely (i.e. damage is too close to the plug), turn off the circuit breaker first.
• Never touch metallic areas of an AC electrical appliance while simultaneously touching faucets, water pipes, another metallic AC appliance, or being even partly immersed in water (including wet feet). This avoids grounding the body through metal or water, with the risk that the appliance is electrically "hot" on its outside cover or chassis.
• Have a qualified electrician install Ground Fault Circuit Interrupter (GFCI) outlets or circuit breakers in all areas with plumbing, bare concrete flooring, exposed to the elements, or outdoors. (Many newer homes already have these devices pre-installed.) Do not defeat the safety feature by running an extension cord from non-GFCI areas such as bedrooms and hallways. Oral burns (above) cannot be prevented by GFCI.
• Swimming pools are a particular concern due the use of electric lights and pumps where persons are immersed in water. All electrical devices that are an integral part of the pool should be connected to a "feed-through" type GFCI. These have the typical "test" and "reset" buttons, but no plug-in outlets.
• Never use an ordinary vacuum cleaner in wet or damp areas. Only a "wet vac" is suitable for this purpose. Do not overfill its collection container.
• Although 12-volt batteries used in vehicles are at a safe voltage, a short circuit can still cause electrical burns and an explosion. Always double check polarity before doing a jump start, and never attempt on a frozen battery.
• Replace high-risk appliances of decades past with new ones (hand-held corded electric drills, blow dryers, etc.)
• Always inquire about the voltage when traveling abroad for those residing in the Americas, Japan, and Taiwan (countries with 110-125 volts). This includes inter-American travel, as a few countries commonly use 220-240 volts. A matching electrical socket (power mains) does not necessarily mean the voltage is the same as one's home country. The doubling of voltage results in a very dangerous four-fold increase in power and heat. Make certain any dual-voltage small appliances have been adjusted correctly for 220-240 volts.
• Never go near or under a downed power line, even if there's no direct contact with the wire. (If crossing is absolutely unavoidable, lie as flat as possible while crawling underneath where the wire is at its highest point.)
• See also Lightning safety

Residential electrical wiring

While installing, modifying, and repairing residential wiring is not for the inexperienced, some basic safety rules are:

• Never work without wearing shoes. Wearing rubber (or similar) gloves is highly recommended. If not wearing gloves, do not touch more than one bare wire at a time, in addition to not touching any bare metal with the other hand or exposed skin elsewhere on the body.
• Turn off the circuit breaker before doing any type of electrical wiring work, and be absolutely certain the disabled breaker is the correct one. If in doubt (e.g. wiring was already dead), turn off the master circuit breaker (no matter how inconvenient). Never assume malfunctioning wiring is on the same circuit as nearby wiring.
• If any tingling in the skin is felt where it is touching a bare wire, assume the wire is live, and immediately let go of wire and stop all work. Take precautions to avoid a short circuit, isolate wire, and turn off the master circuit breaker. (This is caused by a very small amount of current through the body to ground with sufficient resistance to avoid—for the moment—a devastating shock or burn.)
• Never use a light switch as a convenient substitute for turning off the circuit breaker. The circuit may be wired as permanently "hot," and the switch merely disconnects the neutral wire. Electrocution from hot to ground is still possible.
• If checking voltage using a multi-function electrical tester, make certain both the dial and test leads are in the correct position for "volts." A tester previous set to measure amperage ("amps") will short and explode, possibly causing an electrical burn. (Unlike voltage, amperage is measured in series with the appliance or electrical device.)
• Always use the correct thickness ("gauge") of wiring and proper ground connections.
• Wiring running through a hole in sheet metal must be protected by a rubber grommet (e.g. overhead fluorescent lighting).
• If using wire nut connectors, closely follow directions, and always use the correct size (by color and the presence or absence of hex-like wings tips) for the gauge and quantity of the joined wires. These should be placed in normally inaccessible locations only. Make certain there is no protruding bare wire (except ground wiring) and all connections are firm.
• Treat neutral wiring with the same respect as "hot" wiring. Although neutral provides the path to ground, it has not reached ground yet, and can contain dangerous voltages. This is especially true where neutral wiring terminates at a switch set to "off," as touching both the switch and ground will complete the circuit.
• Never cut a live electrical cord or wiring, as it will short across the metal cutting tool, causing an explosion. Electrocution is also possible.
• When installing a Ground Fault Circuit Interrupter (GFCI) outlet, replace the first outlet on the circuit with GFCI to protect all the other outlets (if any) on same circuit. GFCI can protect downstream, but not upstream. Follow the manufacturer's safety and installation instructions.

In addition, electricians, power-line repair, and other industry workers should always follow proper safety procedures. What is safe at 120-240 volts in the home can be very dangerous at higher voltages.

References