An electric shock injury occurs when the body becomes part of an active electrical circuit, allowing current to flow through tissues. The severity is determined not just by the voltage, but more significantly by the amount of current that passes through the body and the specific path it takes. While external burns are often the most visible sign of injury, the most profound and life-threatening damage frequently occurs deep inside the body’s internal systems due to the disruption of the body’s own delicate electrical processes.
How Electrical Current Damages the Body
Electrical current injures the body through two primary mechanisms: thermal and non-thermal effects. Thermal injury, or burning, occurs when tissues with high resistance, like the skin and bone, convert electrical energy into heat. This results in significant internal and external burns, which can be severe enough to cause tissue death and require amputation.
The non-thermal effects are often far more insidious, involving the disruption of the body’s internal electrical signaling. Tissues like nerves, blood vessels, and internal organs are highly conductive because they are wet and rich in electrolytes, offering low resistance. This allows the current to pass easily through these structures, interfering with the normal electrical impulses that regulate cellular function.
The Heart: Primary Target of Fatal Shock
The heart is recognized as the organ most vulnerable to immediate, life-threatening damage from electric shock. Its ability to pump blood relies on a complex, perfectly timed sequence of electrical signals generated by specialized pacemaker cells. This precise sequence controls the rhythmic contraction and relaxation of the cardiac muscle.
When an external electrical current passes through the chest cavity, it can override or completely disrupt this natural rhythm. The current can throw the heart into ventricular fibrillation (V-fib), where the ventricles merely quiver chaotically instead of executing a coordinated pump. This loss of effective pumping action means blood circulation stops immediately, making V-fib the most common cause of rapid death from electrocution.
The pathway the current takes is a major determinant of cardiac risk. Shocks traveling from one hand to the other, or from a hand to a foot, are dangerous because these pathways ensure the current crosses the thorax, directly exposing the heart to the electrical energy. Even a small amount of alternating current, sometimes as low as 100 milliamperes, can induce V-fib if the timing aligns with the heart’s vulnerable repolarization phase.
Neurological and Deep Tissue Effects
Beyond the heart, the nervous system is highly susceptible to electrical injury because nerve tissue is an excellent conductor. Damage can range from temporary stunning, resulting in loss of consciousness or temporary paralysis, to severe and long-lasting central nervous system injuries. Current passing through the brainstem can immediately disrupt the control centers for breathing, leading to respiratory arrest.
The current also causes violent, involuntary muscle contractions, which can be strong enough to fracture bones or dislocate joints. This deep muscle trauma results in rhabdomyolysis, where damaged muscle fibers rapidly break down. The contents of these destroyed cells, including the protein myoglobin, are released into the bloodstream.
The kidneys must filter this surge of myoglobin, which is highly toxic to the delicate filtration structures. This often leads to acute kidney injury (AKI) or complete renal failure, representing a significant delayed risk of electric shock injury. The extensive muscle damage combined with potential kidney failure can create a complex medical emergency.
Factors Determining Injury Severity
The severity of an electric shock injury depends on several variables that modulate the energy delivered to the body. The most important factor is the amount of current, measured in amperes, which dictates the magnitude of biological disruption. A longer duration of contact also increases the overall dose of electrical energy, leading to more extensive tissue damage.
The resistance of the body plays a role, particularly the resistance offered by the skin. Dry skin can offer resistance as high as 100,000 ohms, limiting current flow. However, wet skin, such as from sweat or water immersion, drastically reduces this resistance to as low as 1,000 ohms, allowing a far greater amount of current to enter the body.
Finally, the current pathway remains a major predictor of outcome because it determines which specific organs are exposed. A path that includes the heart or the brain carries the highest risk of immediate fatality and severe neurological impairment. This combination of current magnitude, duration, and pathway dictates the extent of damage.