Electrical injury, commonly known as electrical shock, refers to damage to body tissues, dysfunction of organs, or sudden death caused by a certain amount of electrical current passing through the human body. Electrical injuries are classified into three types: low-voltage electrical injuries (≤380V), high-voltage electrical injuries (>1,000V), and ultra-high-voltage electrical injuries or lightning injuries (voltage exceeding 100 million volts). The incidence of electrical injury increases during summer when the weather is hot and humid, and heavy rainfall leads to excessive sweating. Lightning injuries, in particular, are more common among outdoor workers like farmers, construction workers, and athletes. After floods, lightning injuries rank as the leading weather-related cause of harm, ahead of events such as sandstorms, cold waves, high winds, and frost.
Etiology
Accidental electrical injuries often occur during workplace or daily activities when safety regulations regarding electrical operations are violated. They may also occur during storms, earthquakes, or fires that result in broken wires. Most electrical injuries are seen in adolescent males or individuals engaged in electrical work.
Pathogenesis
The severity of electrical injury to the human body depends on factors such as the voltage of the electrical source, the type of current (direct current [DC] or alternating current [AC]), the intensity and frequency of the current, the electrical resistance of the skin at the point of contact, the duration of exposure, the pathway of the current through the body, and the environmental and weather conditions at the time of contact.
The electrical resistance generated during the injury is based on the path the current takes through the body. The electrical resistance of human tissues varies in the following order from least to greatest: nerve tissue, blood, mucous membranes, muscle, dry skin, tendons, fat, and bone. AC under 500V is more hazardous than DC. AC can cause depolarization of muscle cell membranes, leading to sustained, spasmodic muscle contractions, which can cause the victim's hand to grasp the power source tightly, preventing detachment. For this reason, AC poses a greater risk to the human body than DC. The frequency of AC also affects the degree of injury; low-frequency AC (15–150Hz) is more harmful than high-frequency AC. Household AC at a low frequency of 50–60Hz is particularly more likely to lead to ventricular fibrillation. Ventricular fibrillation can occur with an electrical current intensity of 60–120mA.
Electrical injuries involve two main mechanisms: direct cellular damage caused by the electrical current and tissue or organ damage caused by heat generated from electrical resistance. Examples include burns of the skin and subcutaneous tissues, localized edema in deep tissues such as muscles, fat, and tendons that compress and occlude blood vessels leading to ischemia and necrosis, and rapid "carbonization" of tissues upon contact with ultra-high voltage electricity. If the current passes through the central nervous system, it can immediately cause respiratory and cardiac arrest, resulting in death. Most high-voltage electrical injuries result in thermal damage, which is pathologically characterized by coagulative necrosis. Postmortem findings in fatalities caused by high-voltage electrical injuries often include congestion, edema, hemorrhage, and necrosis in the central nervous system and other systemic tissues and organs.
Clinical Manifestations
Systemic Manifestations
Individuals who experience low-voltage electrical injuries may present symptoms such as fear, palpitations, dizziness, headache, painful muscle contractions, and pallor. High-voltage electrical injuries, particularly those caused by lightning strikes, can result in loss of consciousness, sudden cardiac arrest, and respiratory arrest. Survivors may exhibit disorientation and epileptic seizures. Some patients may experience myocardial damage or injury to the cardiac conduction system, reflected on an electrocardiogram as nonspecific ST-segment depression, atrial fibrillation, or changes indicative of myocardial infarction. Extensive surface burns or excessive fluid loss at injury sites can lead to hypovolemic shock. Acute kidney failure may occur due to direct kidney damage, muscle necrosis causing myoglobulinuria and myohemoglobinuria, and hemoglobinuria resulting from hemolysis. Dehydration or inadequate blood volume may further hasten or worsen the progression of the condition.
Local Manifestations
The site of electrical contact is associated with the highest release of electrical energy, resulting in the most severe damage to the local skin and tissues. Burns around the contact site tend to be less severe. If clothing ignites, extensive burns unrelated to the contact site may occur. Hidden injuries can develop in tissues and organs along the current's pathway. High-voltage electrical injuries often cause severe entry wounds, where burns can lead to tissue charring or necrosis, leaving holes and revealing clear anatomical structures. Compartment syndrome frequently occurs in the forearm due to increased pressure in submuscular fascial tissues caused by muscle damage, edema, and necrosis. Signs of nerve and vascular compression may include weakened pulses, loss of sensation, and diminished pain perception. Strong tonic contraction of large muscle groups following electrocution may lead to compression fractures of the spine or dislocation of the shoulder joint.
Complications and Sequelae
Complications and sequelae typically manifest within 24 to 48 hours following an electric shock, including myocardial injury, severe arrhythmias, and cardiac dysfunction; aspiration pneumonia and pulmonary edema; gastrointestinal hemorrhage or perforation, paralytic ileus; disseminated intravascular coagulation (DIC) or hemolysis; myoglobinuria or hemoglobinuria with subsequent acute renal failure; fractures, shoulder dislocation, or avascular necrosis; unilateral or bilateral tympanic membrane rupture and hearing loss in approximately half of the cases; and secondary bacterial infections at burn sites.
Neurological manifestations such as ascending or transverse myelitis, polyneuritis, or paralysis may develop days to months after the electric shock. Ocular complications include corneal burns, retinal detachment, unilateral or bilateral cataracts, and visual impairment. In pregnant women, spontaneous abortion, stillbirth, or intrauterine growth retardation frequently occur following electrical injury.
Treatment
Power Disconnection
Following the discovery of a patient who has experienced an electrical injury, the power source is disconnected. Insulating materials are used to separate the patient from the electrical source.
Cardiopulmonary and Cerebral Resuscitation
For patients experiencing cardiac arrest and respiratory cessation, cardiopulmonary resuscitation (CPR) is performed immediately to preserve life. Continuous electrocardiographic monitoring for 48 hours is implemented for all patients with electrical injuries to detect delayed arrhythmias following the incident. Antiarrhythmic medications are selected to manage identified arrhythmias.
Acute Kidney Failure
Intravenous infusion of sodium lactate Ringer’s solution is administered to rapidly restore circulatory volume and maintain urine output at 50–75 ml/h. In cases of myoglobulinuria, urine output is maintained at 100–150 ml/h. Intravenous bicarbonate infusion (50 mmol/L) is administered to alkalinize the urine, ensuring the blood pH remains above 7.45 to prevent acute kidney failure. For patients with severe myoglobulinuria where urine output does not increase after restoring effective blood volume, 12.5 g of mannitol is added to 1 L of sodium lactate Ringer’s solution. Mannitol is discontinued once myoglobin disappears from the urine. For patients with thermal burns and insufficient blood volume, mannitol infusion is avoided until effective circulatory volume is restored. Hemodialysis is performed in cases of severe acute kidney failure depending on the patient’s condition.
Surgical Management
Extensive tissue burns, limb necrosis, and fractures are addressed with appropriate interventions. Necrotic tissues require debridement, and tetanus antitoxin (3,000 U) is administered as prevention. Secondary infections are treated with antibiotics. For patients with compartment syndrome, fasciotomy is performed when compartment pressure exceeds 30–40 mmHg to relieve pressure. In cases of deep tissue injury in limbs without clear assessment, diagnostic tools such as arterial angiography, radioactive xenon-133 washout, or technetium-99m pyrophosphate muscle scans may be utilized to guide treatment.
Prevention
Dissemination of general knowledge regarding safe electricity use is emphasized, with periodic inspection and maintenance of electrical appliances and wiring.
During thunderstorms, windows and doors are kept closed, and remaining indoors is recommended. Usage of televisions, audio equipment, and other electrical devices without lightning protection should be avoided.
Workers engaged in outdoor activities should avoid standing in elevated areas, walking in open fields, or taking shelter under trees during thunderstorms. Contact with antennas, water pipes, or metal structures should also be avoided.
When lightning is encountered in open fields, lying down is appropriate, while holding an umbrella or approaching trees or masts is avoided.