Electrical injuries and lightning strikes: Evaluation and management

INTRODUCTION — Electrical injuries can present with a wide range of pathologies. The direct effect of electrical current, conversion of electrical to thermal energy, and blunt mechanical trauma can result in tissue destruction and organ dysfunction. Respiratory or cardiac complications can occur, as well as burns and tissue injury requiring multiple surgical interventions (including fasciotomy and skin grafting) and prolonged supportive and rehabilitative care.

Lightning is a powerful phenomenon of nature, with several unique properties differentiating it from other electrical injuries.

Electrical injuries, including those from lightning strikes, are reviewed here. The evaluation and management of burns, general aspects of trauma management, and injuries related to conductive energy devices (eg, TASERs) are discussed separately.

●(See "Emergency care of moderate and severe thermal burns in adults".)

●(See "Moderate and severe thermal burns in children: Emergency management".)

●(See "Initial management of trauma in adults".)

●(See "Evaluation and management of injuries from conductive energy devices (eg, TASERs)".)

EPIDEMIOLOGY — Electrical burns and lightning injuries result in more than 3000 admissions to specialized burn units each year in the United States, and they account for 3 to 4 percent of all burn-related injuries [1-3]. Up to 40 percent of serious electrical injuries are fatal, resulting in an estimated 1000 deaths per year [3,4].

There is a bimodal distribution of environmental electrical injuries with respect to age. The incidence of electrical injuries decreases through the teenage years and increases again as adults enter the workplace. Electrical injuries are the second leading cause of occupation-related deaths in the United States. Construction and electrical workers combined account for about two-thirds of all electrical injuries, and more than 90 percent of victims are male [1,4-6]. In children, accidental electrical injuries are twice more common in males compared with females.

The incidence of electrical injuries depends on the type of electricity exposure:

●Low voltage – Incidence is increased among children younger than six years, often because of contact with electric cords or outlets [7,8]. Household alternating current (AC) is a common cause of more serious injury because of its arrhythmogenic frequency that can cause prolonged exposure from hand tetany. (See 'Prolonged exposure from alternating current' below.)

●High voltage – Older children and adults generally suffer high-voltage injuries from occupational exposures and power lines while climbing trees or utility poles [8-10].

●Lightning – Lightning injuries, a small and unique subset of electrical injuries, are responsible for an average of 300 injuries and up to 100 deaths per year in the United States [11-14]. It is likely that lightning-related fatalities and hospitalizations are underestimated [15]. Lightning injuries occur most commonly in young males who are involved in work or recreational activities outdoors, predominately in the spring and summer months. Lightning may strike individuals or injure a group of people simultaneously. There are more than 6000 lightning strikes every minute around the globe, and more than 25 million lightning strikes in the United States annually [16,17].

PHYSICS AND MECHANISM OF ELECTRICAL INJURY

Terminology of electricity — Electricity is the flow of electrons between points of high concentration to points of lower concentration (or potential). For typical electrical injuries, the factor we most often know is voltage, and we therefore use this to classify injuries and the anticipated degree of tissue damage [18].

●Voltage (V) – The force that drives the electrons across the potential difference. Electrical injuries are generally classified as being low-voltage or high-voltage injuries and are compared in the table (table 1).

•Low voltage is generally less than 600 V and is found in household current (North American countries use 110 V; European and Asian countries use 220 V).

•High voltage refers to greater than 1000 V. For example, high-tension power lines carry greater than 100,000 V.

•Lightning strikes are a unique type of high-voltage exposure since there is a potential difference between the atmosphere and the ground in excess of 10 million volts with a duration of only milliseconds [9].

●Current (I) – The volume (or number) of electrons that flow between these points per second, measured in amperes (A).

•Direct current (DC) – The direction of flow of electrons remains constant. DC is found in batteries, railway tracks, automobile electrical systems, and lightning.

•Alternating current (AC) – The direction of flow of electrons changes on a cyclical basis, expressed in cycles per second or hertz (Hz). Standard household current is AC at 50 to 60 Hz.

●Electrocution – Fatality from electrical injury.

●Electric arc – A high-voltage electric current is conducted ("jumps") by ionizing gas in air to an area of lower voltage, generating heat in the process. This can occur when a person comes in close proximity to downed high-tension power lines.

●Electric flash – Thermal energy generated from an electric arc, which may reach more than 50,000°C (90,000°F).

General mechanisms of electrical injury — The amount of current flowing through the body, voltage, tissue resistance, type of current (AC or DC), current pathway, and duration of contact all influence the mechanism and extent of injury [18]. For example, contact with a 120 V circuit carrying a 1 milliampere (mA) current is imperceptible to most persons, 3 mA leads to mild tingling, and 10 to 12 mA leads to pain. One hundred mA directed across the heart can cause ventricular fibrillation (table 2) [19,20].

Injuries due to electricity and lightning can occur by multiple mechanisms:

●Direct effect of electrical current on body tissues – This can lead to ventricular dysrhythmia or respiratory arrest.

●Conversion of electrical energy to thermal energy – The tissue damage (ie, electrothermal burn) inflicted by most electrical currents can be primarily attributed to the thermal energy generated by the current when the body becomes part of a circuit. Tissues with higher resistance (eg, skin, bone, and fat) have a tendency to heat up and coagulate, whereas tissues with lower resistance (eg, nerves, blood vessels) tend to transmit current. Generally, current follows the path of least resistance, but resistance is affected by area of contact, pressure applied, and the presence of moisture. Skin's resistance changes dramatically when wet, which determines flow of current and amount of heat generated. (See 'Skin' below.)

●Creations of pores in cell membranes (ie, electroporation) – Electrical current can disrupt cell membranes directly, resulting in cell death without generating heat or causing coagulation [21,22].

●Secondary mechanical trauma – High-voltage DC tends to cause a single muscle spasm that throws the victim from the source, resulting in a shorter duration of exposure but a higher likelihood of associated trauma. Lighting strikes can cause blunt mechanical injury directly, throw the victim, or create a blast effect.

Prolonged exposure from alternating current — AC at frequencies between 15 and 150 Hz repetitively stimulates muscle contraction, causing skeletal muscle tetany. When the site of exposure is the palm, the victim may actually grasp the source because the flexors of the hand and arm are stronger than the extensors, prolonging the duration of contact and perpetuating tissue injury (ie, "can’t let-go current" or “let-go threshold”). It is for this reason that a 20 mA current may not be perceptible at 10 Hz, but the same current may cause respiratory paralysis or ventricular fibrillation at a higher frequency [9,23,24].

Mechanisms of injury specific to lightning — Lightning strikes result in unique phenomena and mechanisms of injury because they are DC exposures that last from 1/10 to 1/1000 of a second but often have voltages that exceed 10 million V [3,9,25]. Lightning is a naturally occurring electric arc.

Lightning current can be transmitted to the victim in the following ways:

●Direct strike

●Contact strike – The victim receives current from another object with which they are in contact that is struck by lightning, such as a tree or pole. Lightning injuries can also occur indoors if the electric current produced by lightning travels through plumbing, electrical appliances, or corded telephones [26].

●Side-flash or splash – The victim is in close proximity to another object that is struck by lightning and is injured when the current jumps through air and hits them. This is a type of electric arc burn.

●Ground strike – The lightning bolt hits the ground and is carried to the victim. Stride voltage describes the enhanced current flow when the victim's contact points (eg, feet) are separated, creating a potential difference. Stride voltage can result in multiple victims from a single lightning strike and likely the reason multiple livestock in a field may die after a strike.

The following phenomena are unique to lightning strikes compared with other electrical injuries:

●Flashover effect – This refers to a massive current transmitted rapidly over the skin, often aided by the decreased resistance of rain or sweat-moistened skin. The central nervous system can effectively be short-circuited and reset by this massive flow, causing temporary shutdown in cardiac and respiratory centers and a state of "suspended animation" at the cellular level. Lightning strikes tend not to cause deep burns because the current travels on the skin surface without penetrating to deeper tissues and is discharged to the ground.

●Keraunoparalysis – This refers to the flashover effects on the peripheral nervous and vascular systems causing a transient paralysis associated with peripheral vascular spasm and sensory disturbances. The extremities can be blue, mottled, and pulseless, with a predilection for the lower extremities. These findings often resolve within hours to days but can be permanent [27,28].

●Autonomic dysfunction – This refers to reversible autonomic dysfunction resulting in fixed and dilated or asymmetric pupils, which does not correlate with degree of brain injury, if present [9].

●Secondary trauma from shock wave – Peak temperature within a bolt of lightning rises within milliseconds to 30,000 Kelvin (five times hotter than the sun), generating a shock wave of up to 20 atmospheres induced by the rapid heating of the surrounding air [9,25,29]. This shock wave then can be transmitted through air to the body and result in blast effect and secondary mechanical trauma.

INJURY AND CLINICAL FEATURES BY ORGAN SYSTEM

Cardiac

●Dysrhythmias – Acute electrical cardiac injury can result in immediate sudden cardiac arrest due to asystole (classically associated with lightning and high voltage) or ventricular fibrillation (direct current [DC] and alternating current [AC]) [30]. The overall estimate of dysrhythmia following electrical injury is approximately 15 percent. Most of these are benign, such as sinus tachycardia, atrial fibrillation, and premature ventricular complexes, and occur within the first few hours after exposure [31-35]. Ventricular fibrillation is the most common fatal dysrhythmia, occurring in up to 60 percent of patients in whom the current pathway travels from one hand to the other [11,33].

•Timing of dysrhythmia – Most ventricular dysrhythmias occur early, but some have occurred as late as 12 hours after the exposure [36]. Two-thirds of lightning-associated deaths occur within one hour of injury and are generally due to a fatal dysrhythmia or respiratory failure [37,38]. This immediate cardiopulmonary arrest from lightning likely accounts for its high mortality rate compared with other types of electrical injuries.

•Lightning – After lightning exposure, the original dysrhythmia is more likely to be asystole (with concomitant respiratory arrest) rather than ventricular fibrillation. Frequently, spontaneous cardiac activity restarts before respiratory activity can restart, and the subsequent hypoxemia leads to an otherwise sustainable cardiac rhythm deteriorating into ventricular fibrillation [39].

•Low-voltage AC – Even though fatalities are uncommon, low-voltage household AC is particularly dysrhythmogenic and can cause ventricular dysrhythmias [9,40,41]. Also, many low-voltage electrocution victims do not have visible burns. For example, this may occur if an appliance falls into a bathtub. In a postmortem study of 220 fatal electrical injuries, 43 percent of low-voltage victims had no visible electrical burns [24].

●Conduction disturbances – Electrical injury can cause first- and second-degree atrioventricular (AV) blocks and bundle branch blocks [32,42]. It is postulated that the anterior location of the right coronary artery leaves the sinus and AV nodal arteries vulnerable to electrical injury. Conduction disturbances can be associated with myocyte changes around the sinus and AV nodes, not necessarily related to myocardial ischemia or arterial injury. Conduction disturbances generally resolve without specific treatment but also may persist. (See "Basic approach to delayed intraventricular conduction".)

●Myocardial damage – Damage to the myocardium, although uncommon, can occur from electrothermal injury, electroporation (ie, formation of cell membrane pores due to electrical current), myocardial contusion resulting from blast effect, or secondary blunt trauma. Cardiac contusion is the most common pathologic cardiac finding, while myocardial infarction is rare [43]. Lightning may cause focal wall motion abnormalities or a Takotsubo-shaped cardiomyopathy [44,45]. Other rare cardiac manifestations include coronary artery spasm or thrombosis and myocardial rupture due to coagulation necrosis [29,46-50]. The evaluation and management of cardiac contusion and the clinical manifestations of myocardial infarction and rupture are described separately. (See "Acute myocardial infarction: Mechanical complications" and "Initial evaluation and management of blunt cardiac injury" and "Diagnosis of acute myocardial infarction".)

Neurologic — Damage to both the central and peripheral nervous systems, which more commonly occurs with high-voltage injuries, includes the following [28,51,52]:

●Respiratory arrest – This can occur immediately following electrical injury, possibly from direct effect on central nervous system respiratory centers or respiratory muscle paralysis, and may persist after return of spontaneous circulation in the setting of a cardiorespiratory arrest.

●Peripheral nerve injury – Sensory and motor findings due to peripheral nerve damage are common. The deficits may be "patchy," with the sensory deficits not corresponding to the motor findings. Unless the patient attempts to ambulate, lower extremity weakness may go undiagnosed initially. The clinical manifestations of neurologic damage from high-voltage exposures may be delayed for days and sometimes even months after the injury.

●Other common sequelae – Loss of consciousness, neuropsychologic sequelae, and memory disturbances also occur.

●Effects specific to lightning strikes – These include keraunoparalysis and autonomic dysfunction and can also include hypoxic encephalopathy, intracerebral hemorrhage, cerebral infarction, and spinal fractures that may occur as a result of the strike itself or from secondary blunt trauma when the victim is thrown [53,54]. (See 'Mechanisms of injury specific to lightning' above.)

Skin — Superficial, partial-thickness, and full-thickness thermal burns can occur following electrical injury. Dry skin has a high resistance (approximately 100,000 ohms) and generates heat when exposed to a current, resulting in skin burns and potentially burns to adjacent tissue. However, dry skin is protective to internal organs because it prevents passage of current. The protective effects are lost with wet skin, which has a much lower resistance (less than 2500 ohms) and generates less heat but passes more current to internal organs for an equivalent voltage [9]. (See 'General mechanisms of electrical injury' above.)

Electrothermal burns, which are the classic injury pattern that develops when the body becomes part of a circuit and are associated with contact point wounds, generate large amounts of heat. Blistering and swelling can develop when the skin temperature is raised to 50°C (122°F) as occurs with exposure to approximately 20 to 35 mA per mm² of skin surface for 20 seconds [55]. More severe burns and charring can develop with 75 mA per mm² for the same period, which can raise the skin temperature to 90ºC (194ºF) [23].

Burns are most common at the site of electrical contact and at places in contact with the ground at the time of injury. These wounds generally do not help predict the path of the current, and the skin findings typically significantly underestimate the degree of internal thermal injury. After high-voltage exposure, seemingly minor surface burns may coexist with massive muscle coagulation and necrosis as well as internal organ injury (ie, “tip of the iceberg” analogy). Almost all fatalities following high-voltage injury have visible electrical burns [24].

Other types of burn patterns from electrical injury include:

●"Kissing burns" – These are a unique type of burn seen with electrical injuries that occur at flexor creases, where the flexor surfaces adjacent to a joint touch.

●Oral burns – These occur more often in young children from sucking or chewing on extension cords and are particularly dangerous because of the risk of delayed hemorrhage (picture 1) [56]. (See 'Pediatric' below.)

●Flame burns – These occur from clothing catching fire in the presence of an electrical source, which can rarely occur after a lightning strike. Metallic objects (eg, jewelry or steel-toed boots) that are in contact with skin can super-heat after a lightning strike. Coincidentally, wearing these items may also increase the chance of the victim being struck in the first place.

●Lichtenberg figures – A lightning strike flashover effect can occasionally cause the formation of rapidly fading, branching, cutaneous "feather" lesions, which are pathognomonic of lightning injury (picture 2) [57].

●Electric arc burns – These are high-voltage injuries associated with contact point skin burns that classically have a dry, whitish center and deep muscle and tissue injury.

●Electric flash burns – The electric flash passes over the skin, causing diffuse superficial or partial-thickness burns without deep injury.

Musculoskeletal and renal

●Bones and nearby tissue injury – After a high-voltage exposure (excluding lightning), the areas sustaining the greatest electrothermal injury are often the deep tissues surrounding long bones. Bone has the highest resistance of any body tissue and therefore generates the greatest amount of heat when exposed to an electrical current. Periosteal burns, destruction of bone matrix, and osteonecrosis can occur [9]. Deep tissue injuries are uncommon with lightning strike due to the incredibly short duration of the exposure.

●Compartment syndrome and rhabdomyolysis – Deep electrothermal injury can cause tissue necrosis and edema and result in a compartment syndrome. Massive tissue necrosis can then cause rhabdomyolysis and/or visceral injury. (See "Acute compartment syndrome of the extremities" and "Rhabdomyolysis: Clinical manifestations and diagnosis" and 'Monitor for extremity compartment syndrome' below.)

●Secondary trauma – Fractures can occur from falls, being thrown, or blast injuries; or under the stress of repetitive tetanic muscle contractions.

●Acute kidney injury – This can occur from hypovolemia or pigment-induced injury from rhabdomyolysis. Hypovolemia due to extravascular extravasation of fluid can lead to prerenal azotemia and acute tubular necrosis. These complications are discussed separately. (See "Crush-related acute kidney injury" and "Clinical features and diagnosis of heme pigment-induced acute kidney injury".)

Eye and ear — The blast effect from lightning strikes causes ruptured tympanic membranes in 50 to 80 percent of patients [43,58,59]. A ruptured tympanic membrane can be an important clue to the mechanism of injury when a patient presents with altered mental status after being found outside with no other clear cause. Sensorineural hearing loss, tinnitus, vertigo, and injury to the facial nerve have also been described [58,60]. (See "Ear barotrauma".)

Cataracts, hyphema, vitreous hemorrhage, and optic nerve injury can also occur following lightning injury [9,28]. (See "Cataract in adults" and "Approach to the adult with acute persistent visual loss", section on 'Vitreous hemorrhage' and "Traumatic hyphema: Clinical features and diagnosis" and "Traumatic hyphema: Management".)

Vascular and related injuries

●Vascular and thrombotic injury – Vascular injury can result from compartment syndrome or electrical coagulation of small blood vessels although this is uncommon after a lightning strike. Delayed arterial thrombosis as well as aneurysm formation and rupture have been reported following electrical injury and are due to medial coagulation and necrosis [33,61-63].

●Gastrointestinal injury – Even though direct damage to internal organs is uncommon, when abdominal involvement does occur, it is typically from a vascular insult similar to mesenteric ischemia. Symptoms and signs include persistent ileus, abdominal pain, or abdominal tenderness and may be delayed, making the diagnosis sometimes difficult. Gastrointestinal injury can also be complicated by fistula formation, perforation, secondary polymicrobial infection, sepsis, and death [64,65].

PREHOSPITAL CONSIDERATIONS — In a mass-casualty electrocution event (such as may occur with a lightning strike), the general principles of prehospital triage should be reversed: first responders should attend initially to patients who appear dead followed by patients who have signs of life. Electrocution victims who do not suffer immediate cardiac or respiratory arrest will likely survive without intervention. On the other hand, cardiac dysrhythmia or respiratory arrest, which are usually reversible, may be the only issues in a victim who has no signs of life [11,28,66-68].

First responders should evaluate the safety of any disaster scene for electrical hazards (eg, downed high-tension power lines) and not proceed until the scene is safe, which may require the lines to be de-energized.

After a lightning strike, prehospital providers should be advised to leave the scene as soon as possible and continue resuscitation and stabilizing efforts en route to the hospital, as the environmental conditions that led to a lightning strike in that location may persist (ie, lightning can strike twice!).

INITIAL EVALUATION AND MANAGEMENT

Triage of multiple patients — Triage of patients in the emergency department is essentially the same as in the prehospital setting: patients without signs of life are treated first, as patients that exhibit cardiac and respiratory activity can be assumed to have some degree of stability. (See 'Prehospital considerations' above.)

Patient in cardiac or respiratory arrest — In a patient with cardiac arrest following severe electrical injury, we suggest prolonging cardiopulmonary resuscitation (CPR) regardless of the initial rhythm or pupillary examination. Good outcomes have been reported even among patients with asystole [11,69]. Do not stop resuscitation based on fixed, dilated, or asymmetric pupils in lightning victims since pupil function can be affected due to autonomic dysfunction instead of brain injury [9]. For example, a school-aged boy was struck by lightning while riding his bicycle, had initial pulselessness and apnea, survived prolonged CPR, and returned to school without cognitive impairment (his subsequent intelligence quotient [IQ] was higher than his pre-injury scores) [70]. Clinical judgment should be used to determine the appropriate duration of resuscitative efforts.

The treatment for particular dysrhythmias is unchanged from Advanced Cardiac Life Support (ACLS) principles [28]. (See "Advanced cardiac life support (ACLS) in adults" and "Pediatric advanced life support (PALS)".)

Patients may resume spontaneous cardiac activity but persist with absence of respiratory activity. Prompt restoration of gas exchange via ventilation management, which may include securing the airway, is critical to prevent secondary cardiac and neurologic injury from hypoxemia. (See "Basic airway management in adults" and "Overview of advanced airway management in adults for emergency medicine and critical care" and "Basic airway management in children".)

All patients

General trauma evaluation — The patient who suffers a serious electrical burn or lightning strike has sustained significant trauma, and the initial evaluation should involve general trauma principles (ie, primary survey, secondary survey) including the following (see "Initial management of trauma in adults" and "Trauma management: Approach to the unstable child"):

●Rapidly assess the airway, cardiopulmonary status, and pulses.

●Evaluate for coexisting smoke inhalation or airway burns. (See "Inhalation injury from heat, smoke, or chemical irritants".)

●In patients with significant electrical injuries or an altered mental status, immobilize the cervical spine as appropriate, given the risk of secondary trauma. (See "Cervical spinal column injuries in adults: Evaluation and initial management".)

●In a patient with hypotension, search for thoracic or intra-abdominal bleeding secondary to blunt trauma. (See "Initial evaluation and management of blunt abdominal trauma in adults" and "Initial evaluation and management of blunt thoracic trauma in adults".)

●Obtain brain imaging in a patient with altered mental status, coma, or neurologic deficit. (See "Management of acute moderate and severe traumatic brain injury", section on 'Neuroimaging'.)

●Obtain radiographic studies of any region that may have been injured. It is often reasonable to obtain imaging studies of the cervical spine to assess for fracture.

Focused physical examination — Careful clinical assessment of the organ systems most often affected, recognizing that surface findings may underestimate the extent of tissue damage or necrosis, should be used to guide management. Some injuries may not be apparent initially and become evident later in the patient's course. Once the initial trauma evaluation is complete, focus the physical examination on the following:

●Perform a thorough neurologic examination including pupillary reactivity, strength and motor function, and sensation. (See 'Neurologic' above.)

●Inspect the entire body for burns, looking for discoloration, blisters, charred skin, and other lesions. Pay attention to skin creases and areas around joints. In a young child, closely examine the mouth. Do not try to infer presence or degree of internal injuries based on skin burns. (See 'Skin' above.)

●Inspect and palpate bones and spine for signs of fracture. Palpate all compartments and perform passive range of motion of all joints. (See 'Musculoskeletal and renal' above.)

●Inspect the tympanic membranes for rupture. (See 'Eye and ear' above.)

●Perform a thorough eye exam, including testing visual acuity, inspecting the conjunctiva, and performing a slit lamp evaluation (if patient is not restricted to supine position) of the anterior chamber and lens and a fundoscopic examination as appropriate. If the patient has symptoms attributable to the vitreous (eg, floaters), perform bedside ocular ultrasound if available. (See 'Eye and ear' above and "Slit lamp examination".)

Continuous cardiac monitoring — Because of the high incidence of dysrhythmia and autonomic dysfunction, place the patient on continuous cardiac monitoring (ie, telemetry) unless they meet all of the following criteria: low-voltage exposure, asymptomatic, no reported loss of consciousness, and normal physical examination (without cutaneous burns or contact point wounds). The duration of cardiac monitoring is discussed below. (See 'Evaluation and management by type of electricity' below.)

Ancillary testing — Clear guidelines do not exist regarding which studies to obtain following electrical injury, and to a large degree, this must be determined clinically on a case-by-case basis. All patients, even if asymptomatic, should have an electrocardiogram (ECG) performed. A patient with any persistent symptoms or presence of cutaneous burns (including contact point wounds) should also have a urinalysis obtained to evaluate for myoglobinuria.

For patients with a high-voltage or lightning exposure, large body surface burns, or concern for deep tissue injury; or those for whom observation or admission to the hospital is anticipated, we generally also obtain the following studies:

●Basic serum electrolytes (including calcium)

●Creatine phosphokinase (CK)

●Serum troponin

●Complete blood count

●Kidney function tests (creatinine and blood urea nitrogen)

Wound management — In general, wounds are treated in a similar manner to flame or other thermal burns. Patients with low-voltage exposure and survivors of lightning strikes typically sustain only superficial burns, while those with high-voltage exposure commonly sustain deep burns. Patients with prolonged low-voltage alternating current (AC) exposure (eg, when unable to release their grasp) may sustain full-thickness skin and local subcutaneous tissue, tendon, and muscle burns [71]. Patients with extensive burns (either high-voltage or AC) should be managed in a burn unit since they often need fasciotomy, escharotomy, extensive skin reconstruction, or limb amputation. (See "Treatment of minor thermal burns" and "Emergency care of moderate and severe thermal burns in adults" and "Moderate and severe thermal burns in children: Emergency management".)

Topical antibiotic prophylaxis is indicated for non-superficial burns. The value of prophylaxis with intravenous (IV) antibiotics is controversial. Some physicians give penicillin to cover clostridial species since myonecrosis has been reported [33]. (See "Topical agents and dressings for local burn wound care".)

Administer tetanus prophylaxis as needed. (See "Tetanus-diphtheria toxoid vaccination in adults", section on 'Immunization for patients with injuries'.)

EVALUATION AND MANAGEMENT BY TYPE OF ELECTRICITY

Patients with high-voltage (except lightning) injury — High-voltage injury is more likely to cause deep tissue (picture 3) and internal organ injury compared with low-voltage injury or lightning strike (table 1). Examples of high-voltage current sources are discussed above. (See 'Terminology of electricity' above.)

Assess for deep tissue injury — On initial examination, it may be difficult to determine if deep tissue or organ injury occurred or the extent of injury [72]. The degree of external skin injury cannot be used to determine the extent of internal damage since the current flows through variable paths depending on tissue resistance encountered, surface area, and volume of tissue exposed. Patients with any full-thickness skin burn, those complaining of persistent deep ache or pain, and those who have pain with passive range of motion of joints should be presumed to have deep muscle or bone injury. (See 'Musculoskeletal and renal' above.)

Creatine phosphokinase (CK) elevation greater than 400 U/L (6.7 microkat/L) is a sign of deep tissue injury and is associated with an increased risk of needing skin grafting or amputation [73]. Patients with extremely high CK concentrations (>5000 U/L; 83.3 microkat/L) on the first day after injury are most likely to require extremity amputations and have the highest mortality [74].

Fluid resuscitation — In a patient with soft tissue injuries from electrical exposure, especially if there are signs of muscle necrosis, we recommend aggressive intravenous (IV) fluid replacement. The optimal fluid and rate of repletion are unclear, but the approach should be comparable to that used for the prevention of acute kidney injury from heme pigments (ie, myoglobinuria) and major crush injuries. Pay close attention to volume status and serum electrolytes since large fluid shifts can occur following electrical injury. Fluid choice and monitoring include the following and are discussed in detail separately (see "Prevention and treatment of heme pigment-induced acute kidney injury (including rhabdomyolysis)", section on 'Prevention' and "Crush-related acute kidney injury", section on 'After extrication'):

●Fluid type and rate – In an adult, begin initial fluid resuscitation with isotonic saline at a rate of 1 L/hour. Given the risk of hyperkalemia, avoid IV fluids containing potassium. Parkland and similar formulas used for fluid resuscitation following thermal burns should not be used in victims of electrical injuries since surface burns may grossly underestimate the extent of injury.

●Monitor physiologic parameters – Physiologic measures, including heart rate, blood pressure, and urine output, are useful in guiding resuscitation. Urine output in adults should be maintained at over 100 mL per hour (for young children, a goal of approximately 1.5 to 2 mL/kg per hour is reasonable) to minimize intratubular cast formation. Central venous pressure monitoring may be beneficial in patients with more severe injuries.

●Monitor serum electrolytes and kidney function – Serum electrolyte concentrations, particularly potassium, should be measured approximately every two to four hours early during management depending upon the prior value, renal function, and clinical status. If myoglobinuria develops, continue IV fluids until pigment has cleared from the urine [3,9]. In a patient who develops acute kidney injury with oliguria or anuria, avoid massive fluid overload from excessive administration.

Monitor for extremity compartment syndrome — Patients should be monitored for the development of acute compartment syndrome of the extremities and rhabdomyolysis. Perform frequent examinations for tense, painful muscle compartments, pain with passive stretch of muscles, paresthesias, pallor, or diminished sensation, especially in a patient who complains of persistent deep ache, burning pain, or pain out of proportion to the external signs of injury. Monitor serial serum CK since it increases as compartment syndrome develops and appears to correlate with need for surgery [73,74]. Recognition and management of acute compartment syndrome and the prevention and treatment of heme pigment-induced kidney injury are reviewed separately. (See "Acute compartment syndrome of the extremities" and "Prevention and treatment of heme pigment-induced acute kidney injury (including rhabdomyolysis)".)

Amputation of the injured extremity may be necessary, particularly when there is a large volume of tissue loss. Fasciotomy within six hours following injury to prevent ongoing muscle necrosis by decompressing compartments may prevent amputation (picture 3) [74]. However, the optimal timing of fasciotomy and necrotic tissue debridement is controversial and should be determined by the burn surgeon. Radionuclide imaging with technetium-99 has been used to identify nonviable muscle following severe electrical injury and help determine when amputation is needed; however, it is not clear if these imaging results decrease the number of procedures or improve mortality [75-77]. Persistent myoglobinuria is another warning sign that amputation may be needed. (See "Severe lower extremity injury in the adult patient", section on 'Extremity electrical injury'.)

Cardiac evaluation, monitoring, and management — We provide 12 to 24 hours of cardiac monitoring for patients when high-voltage exposure is suspected, even if they have no apparent injury. Some ventricular dysrhythmias have occurred up to 12 hours after the exposure, although they are unlikely to occur if the initial electrocardiogram (ECG) is completely normal [31]. Additional indications for prolonged monitoring include the current passing through the thorax (eg, wounds on both hands), history of cardiac disease, active chest pain, reported loss of consciousness, documented dysrhythmia in the field or the emergency department, or any abnormality on the initial ECG [28,36].

Myocardial damage is possible but often difficult to diagnose. ECG changes are poor measures of myocardial injury following electrical trauma, and the presence of CK-MB elevation is of unclear significance [46-50]. Some experts believe that troponin concentration and echocardiography can detect myocardial injury after electric exposure [78]. However, others have found that troponin is not useful for predicting left ventricular dysfunction [79]. The optimal approach to assess myocardial damage following electrical injury remains unclear, but we typically check serial troponin concentrations.

Tachyarrhythmias and atrioventricular (AV) blocks are treated according to standard approaches. (See "Overview of the acute management of tachyarrhythmias" and "Basic approach to delayed intraventricular conduction".)

Gastrointestinal prophylaxis and monitoring — Provide prophylactic therapy (eg, proton pump inhibitor) to prevent stress ulcer formation, particularly in patients with severe burns and those who cannot or are not permitted to take food by mouth. Patients have a greater chance of developing gastric ulcers following electrical burns (Curling ulcers) than with other burns [3,9,80]. (See "Stress ulcers in the intensive care unit: Diagnosis, management, and prevention".)

Persistent ileus, abdominal pain, or tenderness should prompt abdominal imaging and surgical consultation due to concern for abdominal organ injury or mesenteric ischemia [9]. (See 'Vascular and related injuries' above.)

The combination of aggressive fluid repletion and restrictive surface burns can lead to the development of increased intra-abdominal pressure and the abdominal compartment syndrome. Symptoms and signs include dyspnea, abdominal bloating, abdominal pain, or a tensely distended abdomen; and the initial screening test is bladder (ie, intravesical) pressure measurement. (See "Abdominal compartment syndrome in adults".)

Patients with lightning strike — Approximately 30 percent of those struck by lightning die, and up to 74 percent of survivors may have permanent disabilities [3,12,81]. However, in many victims who survive the acute phase, the prognosis is good and depends mainly on the extent of secondary injury [82]. Patients with cranial burns or leg burns are at higher risk for death than others struck by lightning, possibly because more current has passed through the body [66]. The following are issues unique to the evaluation and management of victims of lightning strikes.

●Interpreting ECG ST segment changes – Lightning strike victims commonly manifest ECG changes such as ST elevation, nonspecific ST and T wave changes, and QT interval prolongation [28,29,82]. However, ST segment changes should be interpreted in the context of the patient's clinical status (eg, signs of cardiomyopathy or cardiogenic shock) and suspicion for direct lightning strike, which increases the risk of cardiovascular collapse. The initial ECG can mimic ST-elevation myocardial infarction but then resolve without sequelae or troponin elevation (waveform 1). ST segment changes and troponin/CK-MB elevation, which frequently occur, are poor measures of myocardial injury and not typically prognostic [28].

●Deep tissue burns are unlikely – Superficial burns are common in victims of lightning injury, but deep burns or tissue injury are unusual [28]. One series of patients following lightning strike injury noted an 89 percent incidence of burns, but only 5 percent were deep [66].

A patient with blue, mottled, and pulseless extremities should generally not be treated with fasciotomy (which may be needed with similar findings from high-voltage injury), as these findings are more likely to be from keraunoparalysis and thus resolve spontaneously within hours to days. (See 'Mechanisms of injury specific to lightning' above.)

Aggressive IV fluid replacement is not needed as opposed to patients with thermal burns or those with electrical injures and deep tissue involvement [9].

●Monitoring of electrolytes and kidney function – A patient with hyponatremia with signs of extracellular volume depletion (eg, hypotension, decreased skin turgor, increased hematocrit) may be developing cerebral salt wasting, which has been reported as a complication of lightning-related injuries [83]. Diagnosis and treatment, which may require hypertonic saline, is discussed elsewhere. (See "Cerebral salt wasting".)

Acute kidney injury is less likely to occur with lightning strikes compared with other electrical sources unless it is a result of blast injury or secondary blunt trauma.

●Duration of continuous cardiac monitoring – A patient with persistent ECG changes, dysrhythmia, cardiac arrest, elevated troponin, other evidence of cardiac dysfunction (ie, new cardiomyopathy), or suspicion of direct lightning strike should be admitted for 24 hours of cardiac monitoring and further evaluation. Patients not meeting these criteria can be monitored in the emergency department for four to six hours and discharged if they do not develop a dysrhythmia [28].

Patients with low-voltage injury — Examples of low-voltage current sources are discussed above. (See 'Terminology of electricity' above.)

●Deep skin and local soft tissue burn – Although uncommon, a patient with prolonged alternating current (AC) exposure, which typically occurs in the upper extremities when the victim is unable to release their grasp, may sustain full-thickness skin and local subcutaneous tissue, tendon, and muscle burns [71]. In these patients, the degree of external injury does not always correlate with the extent of local soft tissue injury. They should be transferred to a burn center for evaluation since they will likely need debridement, skin reconstruction surgeries, and rarely digit amputation.

●Mild symptoms – Patients with mild persistent symptoms or minor cutaneous burns should have an ECG and urinalysis obtained, and we observe on a continuous cardiac monitor generally for six hours.

If the initial ECG is normal, myoglobinuria is absent, and there were no dysrhythmias during the observation, the patient can be discharged with appropriate follow-up based upon their injuries. (See 'Follow-up Care' below.)

If there is an dysrhythmia or myoglobinuria, admit (or place in an observation unit) for at least 12 to 24 hours of continuous cardiac monitoring and serial CK measurement. IV fluids may be needed if the patient develops rhabdomyolysis, which is discussed in detail elsewhere. (See "Rhabdomyolysis: Clinical manifestations and diagnosis" and "Prevention and treatment of heme pigment-induced acute kidney injury (including rhabdomyolysis)".)

●Asymptomatic – Patients who have no symptoms or for whom all symptoms have resolved, did not sustain loss of consciousness, have a normal physical examination (without cutaneous burns or contact point wounds), and have a normal initial screening ECG do not require further ancillary diagnostic tests or cardiac monitoring and can be reassured and discharged [9,84-88].

DISPOSITION — In a patient who requires prolonged (>6 hours) cardiac monitoring (see above discussion on high-voltage and lightning exposure) and has no serious injuries identified, an inpatient or observation unit with telemetry is adequate. However, intensive care setting admission may be required if there are signs of instability (eg, recurrent dysrhythmia or hypotension), significant trauma, large area of burns, or concern for deep tissue injury. Transfer patients with significant burns or deep tissue injury to a burn center when stable. Patients with a reassuring emergency department evaluation and no risk factors for serious cardiac sequelae may be discharged after four to six hours of monitoring.

SPECIAL POPULATIONS — Some additional considerations in pregnant and pediatric victims of electrical injury are discussed below.

Pregnant — Obtain obstetric consultation and a fetal heart rate in a pregnant patient who sustains anything more than mild electrical exposure. Accidental, mostly low-voltage electrical exposure during pregnancy did not appear to pose a major fetal risk in an observational study with 31 patients [89]. However, placental abruption may be associated with even minor abdominal trauma, including electrical injuries.

Effects on the fetus are unpredictable with a lightning strike. Given the risk of significant abdominal trauma in the pregnant patient, it is reasonable to obtain continuous fetal heart rate monitoring and ultrasound evaluation of the fetus if potentially viable (ie, at least 23 to 24 weeks gestation). Case reports describe pregnancy loss following significant electrical injuries or lightning strike [90].

Pediatric — Evaluation and management of children after electrical or lightning injury are similar to adults, with the exception of oral burns (picture 1), which are a common injury in young children after chewing an electrical or extension cord. A child with an oral commissure burn can develop significant bleeding from the labial artery when the eschar separates, which can occur days to two weeks after the initial burn was sustained [91]. Cosmetic defects are also common with these injuries [92].

When significant oral injuries are present, admit for intravenous (IV) hydration, pain control, and plastic surgery evaluation. A child with a minor burn confined to the oral commissure may be discharged if follow-up with an otolaryngologist or plastic surgeon can be ensured within two to three days and the parents are warned about the potential for serious, delayed bleeding.

Parents should also be counseled to implement preventive measures in the home, such as electrical outlet plugs and keeping electrical cords out of the reach of children.

FOLLOW-UP CARE — Patients who sustain high-voltage or lightning injury should be encouraged to arrange the following follow-up care:

●Primary care doctor or otolaryngologist for otologic examination and audiometric testing, which may reveal injuries that are amenable to delayed repair [3,9,66].

●Ophthalmologist for evaluation of delayed cataract formation, which generally develops days, weeks, or even months after injury [67,80]. All victims of lightning strikes, even if they are initially asymptomatic, should be referred to an ophthalmologist for an outpatient comprehensive eye examination and to establish long-term monitoring.

●Cardiologist for a patient who has developed electrocardiogram (ECG) changes or atrioventricular (AV) or bundle branch blocks.

Any child discharged with an oral commissure burn (picture 1) needs to follow up with an otolaryngologist or plastic surgeon within two to three days, as discussed above. (See 'Pediatric' above.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Care of the patient with burn injury" and "Society guideline links: Management of environmental emergencies".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Electrical burns (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Mechanism of injury – The amount and type of current flowing through the body, voltage, tissue resistance, current pathway, and duration of contact all influence the mechanism and extent of injury (table 1). (See 'Physics and mechanism of electrical injury' above.)

Lightning is an extremely high-voltage exposure that lasts milliseconds, resulting in unique phenomena such as flashover effect, keraunoparalysis, and shock waves. Lightning victims may resume spontaneous cardiac activity before respiratory activity, causing a secondary hypoxemic injury. (See 'Mechanisms of injury specific to lightning' above.)

●Clinical features and injuries – Clinical manifestations range from mild superficial skin burns to severe multiorgan dysfunction and death. Secondary trauma can occur from falls, being thrown, or shock wave from a lightning strike.

•Ventricular dysrhythmias are potentially lethal and typically occur early, but some have occurred up to 12 hours after the exposure. (See 'Cardiac' above.)

•Some injuries may not be apparent initially, and skin findings typically underestimate the degree of internal thermal injury. (See 'Skin' above.)

•Nervous system injury can cause loss of consciousness, temporary respiratory arrest, patchy peripheral nerve damage, keraunoparalysis, and autonomic dysfunction. (See 'Neurologic' above.)

•High-voltage thermal injury can cause massive soft tissue, muscle, and bone damage leading to rhabdomyolysis, acute compartment syndrome, or pigment-induced acute kidney injury. (See 'Musculoskeletal and renal' above.)

•Lightning strikes commonly rupture tympanic membranes but can also cause cataracts, hyphema, or vitreous hemorrhage. (See 'Eye and ear' above.)

●Cardiopulmonary resuscitation (CPR) – In a patient with cardiac arrest following severe electrical injury, even if asystole is present or the pupils are fixed, dilated, or asymmetric, we suggest prolonging resuscitative efforts (Grade 2C). Good outcomes have been reported regardless of the initial rhythm, and lightning victims can have abnormal pupil examination due to autonomic dysfunction instead of brain injury. (See 'Patient in cardiac or respiratory arrest' above.)

●Trauma evaluation and wound management – A trauma evaluation and appropriate resuscitation should be performed for any patient with a severe electrical exposure. Wounds from electrical injuries are managed similar to those from thermal burns. (See 'General trauma evaluation' above and 'Wound management' above.)

●Cardiac monitoring – Start continuous cardiac monitoring (ie, telemetry) unless the patient meets all of the following criteria: low-voltage exposure, asymptomatic, no reported loss of consciousness, and normal physical examination (without cutaneous burns or contact point wounds). (See 'Continuous cardiac monitoring' above.)

●Ancillary testing – All patients, even if asymptomatic, should have an electrocardiogram (ECG). Any symptomatic patient should also have a urinalysis. Patients with high-voltage or lightning exposure, large body surface burns, or concern for deep tissue injury, or for whom observation or admission to the hospital is anticipated, should have serum electrolytes, creatinine and blood urea nitrogen, calcium, creatine phosphokinase (CK), troponin, and basic blood counts. (See 'Ancillary testing' above.)

●High-voltage injury – Deep tissue (picture 3) and internal organ injury is more likely to occur compared with low-voltage injury or lightning strike. The initial degree of external injury cannot be used to determine the extent of internal damage. CK >400 U/L (6.7 microkat/L) is a sign of deep tissue injury. Patients with significant burns or deep tissue injury should be transferred to a burn center when stable. (See 'Patients with high-voltage (except lightning) injury' above.)

In a patient with soft tissue injuries from electrical exposure, especially if there are signs of muscle necrosis, we provide aggressive intravenous (IV) fluid replacement (eg, isotonic saline at 1 L/hour). We monitor for development of acute compartment syndrome and rhabdomyolysis. The evidence is presented elsewhere. (See "Prevention and treatment of heme pigment-induced acute kidney injury (including rhabdomyolysis)", section on 'Prevention' and "Crush-related acute kidney injury", section on 'After extrication'.)

●Lightning strike – Lightning strike victims who survive the acute phase have a good prognosis that depends mainly on the extent of secondary injury. ECG changes are common but typically not prognostic. Superficial burns are common in victims of lightning injury, but deep burns or tissue injury are unusual. (See 'Patients with lightning strike' above.)

A patient with persistent ECG changes, dysrhythmia, cardiac arrest, elevated troponin, other evidence of cardiac dysfunction (ie, new cardiomyopathy), or suspicion of direct lightning strike should be admitted for 24 hours of cardiac monitoring and further evaluation. A patient not meeting these criteria can be monitored in the emergency department for four to six hours and discharged if they do not develop a dysrhythmia.

●Low-voltage injury – A patient with a low-voltage exposure and minor cutaneous burns should be observed for six hours on a continuous cardiac monitor and discharged if the initial ECG is normal, myoglobinuria is absent, and there are no dysrhythmias noted. A patient who has no symptoms or for whom all symptoms have resolved, did not sustain loss of consciousness, has no cutaneous burns or contact point wounds, and has a normal initial screening ECG does not require further ancillary diagnostic tests or cardiac monitoring and can be reassured and discharged. Although uncommon, a patient with prolonged (from inability to release grasp) low-voltage, alternating current exposure may sustain full-thickness skin and local subcutaneous tissue, tendon, and muscle burns and is best managed in a burn center. (See 'Patients with low-voltage injury' above.)

●Children with oral burns – We admit a child with a significant oral injury for IV hydration, pain control, and plastic surgery evaluation. An oral commissure burn (picture 1) can develop significant delayed bleeding and cosmetic defects. A child with a minor burn confined to the oral commissure may be discharged if urgent follow-up with an otolaryngologist or plastic surgeon can be ensured. (See 'Pediatric' above.)