PHYSICS OF INJURY

RESISTANCE

Resistance is the tendency of a material to resist the flow of current.  Although the exact pathophysiology of electrical in- flow of current and is specific for a given tissue, depending on the injury is not well understood, there is at least an appreciation on its moisture content, temperature, and other physical

Table 1. Factors Determining Electrical Injury
Type of circuit
Resistance of tissues
Amperage
Voltage
Current pathway
Duration
Environmental factors

properties The higher the resistance (R) of a tissue to the flow of current, the greater its potential to transform electrical energy (1) to thermal energy (P) at any given current, as described by Joule's law:

P = I^2 X R

Nerves, designed to carry electrical signals, and muscle and blood vessels, because of their high electrolyte and water content, are good conductors. Bone, tendon, and fat have a very high resistance and tend to heat up and coagulate rather than transmit current. The other tissues of the body are intermediate in resistance (Table 2). (14,15) Skin is the primary resistor to the flow of current into the body (Table 3) (10) Much of the energy may be dissipated at the skin surface, causing significant surface burns in a heavily calloused area, sometimes resulting in less deep internal damage than would be expected if the current were delivered undiminished to the deep tissues. Sweating can decrease the skin's resistance to 2500 to 3000 Q. Immersion in water can reduce this further to 1200 to 1500 Ohms and thus allow more energy to flow through the body, resulting in electrocution with cardiac arrest but no surface burns, such as in a bathtub injury

DURATION

In general, the longer the duration of contact with high voltage current, the greater the degree of tissue destruction. Although there is an extraordinarily high voltage and amperage with lightning, the extremely short duration and the peculiar physics of lightning result in a very short flow of current internally, with little, if any, skin breakdown and almost immediate flashover of current around the body, usually resulting in little, if any, burning of tissues.(8,16))

Current, expressed in amperes, is a measure of the amount of energy that flows through an object (Table 4). There is a very narrow range of safety with electric current between the threshold of perception of current (0.2 to 0 4 mA) and let-go current (6 to 9 mA), the level at which a person becomes unable to let go of the current source because of muscular tetany and becomes fixed to the electrical source, lengthening the duration of contact. Thoracic tetany can occur at levels just above the let-go current and result in respiratory arrest from the person's inability to move the muscles of respiration. Ventricular fibrillation is estimated to occur at an amperage of 50 to 120 mA). (17) As the tissue breaks down under the energy of the current flow, its resistance may change markedly, making it impossible to predict the amperage for any given electrical injury

VOLTAGE

Voltage is a measure of potential difference between two points. It is determined by the electrical source. Electrical injuries are conventionally divided into high or low voltage using 500 or 1000 V as the most common dividing lines. Although both high and low voltage can cause significant morbidity and mortality, high voltage has a greater potential for tissue destruction and can be responsible for severe injuries leading to major amputations and tissue loss.

PATHWAY

The pathway that a current takes determines the tissues at risk, the type of injury seen, and the degree of conversion of electrical energy to heat regardless of whether high, low, or lightning voltages are being considered. Current passing through the heart or thorax can cause cardiac arrhythmias and direct myocardial damage. Current passing through the brain can result in respiratory

arrest seizures, direct brain injury, and paralysis. Current passing close to the eyes can cause cataracts.

As current density increases, its tendency to flow through the less-resistant tissues is overcome, so that it eventually flows through the tissues indiscriminately, treating the body as a volume conductor, with potential destruction of all tissues in the current's path. Damage to the internal structures of the body may be irregular, with areas of normal-appearing tissue next to burned tissue and with damage to structures at sites distant from the apparent contact and ground points.

Probably the most important difference between light- and high-voltage electrical injuries is the duration of exposure to the current. The mathematics of the rapid rise and decay of lightning energy makes predicting lightning injury even more complicated than predicting man-made electrical injury. The study of such massive discharges of such short duration is not well advanced, particularly with regard to effects on the human body.

Lightning current may flow internally for an incredibly short time and cause short-circuiting of the body's electrical systems, but it seldom causes any significant burns or tissue destruction (3,15,18)  Thus burns and myoglobinuric renal failure play a small part in the injury pattern from lightning, whereas cardiac and respiratory arrest, vascular spasm, neurologic damage and autonomic instability play a much greater role. (3,15 Lightning will tend to cause ventricular asystole rather than fibrillation. Although automaticity causes the heart to begin beating again, the respiratory arrest that often accompanies cardiac arrest may last long enough to cause secondary deterioration of the rhythm to ventricular fibrillation and asystole, which is more resistant to therapy than was the first arrest. (15,18) '9 The secondary arrest, just a theory in the past, has recently been elegantly shown to occur experimentally in sheep. (16,18) Other injuries caused by blunt trauma or ischemia from vascular spasm, such as myocardial infarction (20-27) spinal artery syndromes, may occasionally occur. (28-30)

MECHANISMS OF INJURY

The mechanisms of electrical injury are listed in Table 5. It is often difficult to determine which mechanism of injury has caused burns at the time of a patient's presentation to the emergency department. This may make it difficult to assess the injury and offer a prognosis based on history and physical examination alone. The most destructive indirect injury occurs when a person becomes part of an electrical arc, since the temperature of an electrical arc is approximately 2500 degrees Celsius. (14) The arc may cause clothing to ignite and cause secondary thermal burns. The electrical flash burn usually results in only superficial partial-thickness burns.

Blunt injury may occur in electrical injury as the person is thrown clear of the source by intense muscular con-

traction or it may result from a fall from a height. The violent muscle spasms associated with AC injuries can cause fractures and dislocations. (31.32)

Muscle damage may be spotty, with areas of viable and nonviable muscle found in the same muscle group. Periosteal muscle damage may occur even though overlying muscle appears to be normal

Vascular damage is greatest in the media, possibly because of the diffusion of heat away from the intima by the How of blood, but can lead to delayed hemorrhage when the vessel eventually breaks down. (14,33,34) Intimal damage may result in either immediate or delayed thrombosis and vascular occlusion as edema and clots form on the damaged internal surface of the vessel over a period of days. (34) This injury is usually most severe in the small muscle branches, where blood flow is slower. (35) This damage to small arteries in muscle, combined with mixed muscle viability that is not visible to gross inspection, creates the illusion of "progressive" tissue necrosis. Damage to neural tissue may occur from many mechanisms. Nerve tissue may show an immediate drop in conductivity as it undergoes coagulation necrosis similar to that observed in muscle tissue. In addition, it may suffer indirect damage as its vascular supply or myelin sheaths are injured. As with other vascular damage and edema formation, signs of neural damage may develop immediately or be delayed by hours to days.

The brain is frequently injured, because the skull is a common contact point. Histologic studies of the brain have revealed focal l petechiae in the brain stem, widespread chromatolysis and cerebral edema. (14)

Immediate death from generated electricity may be from asystole, ventricular fibrillation, or respiratory paralysis, depending on the voltage and pathway.

Lightning injury may occur by five mechanisms (Table 6). The mechanism of injury of a direct strike is self-evident . Recently, it has been postulated (20) and substantiated experimentally in sheep (16,18,36) (18) 36) that lightning strikes near the head may enter orifices such as the eyes, ears, and mouth to flow internally, as reported in the article by Andrews in this issue. This would help to explain the myriad eye and ear symptoms and signs that have been reported with lightning injury.

Injury from contact occurs when the person is touch- object that is part of the pathway of lightning current, such as a tree or tent pole. Side flash or splash occurs as lightning jumps from its pathway to a nearby person and adopts the person as its pathway. (3,28,33,37) 33 3'

Step voltage occurs as a result of lightning current spreading radically through the ground. A person who has one foot closer than the other to the strike point will have a potential difference between the feet so that a current may be induced through the legs and body. This is a frequent killer of large livestock such as cattle and horses because of the distance between their hind legs and forelegs. (3)

Blunt injury from lighting may occur as the person is thrown by the opisthotonic contraction caused by current passing through the body and from the explosive/implosive fore c caused as the lightning pathway is instantaneously superheated and then rapidly cooled after the passage of the lightning is over.  The heating is seldom long enough to cause severe burns but does cause rapid expansion of air followed by rapid implosion of the cooled air as it rushes back into the void. (3)

DIFFERENTIAL DIAGNOSIS

Electrical injuries are usually self-evident from history and physical surroundings, except in the case of bathtub accidents, where no burns occur, or of foul play. It is necessary to attempt to differentiate between mechanisms of burn injury because flash burns have a much better prognosis than arc or conductive burns. Injuries from blunt trauma and falls may also be present.

The differential diagnosis for lightning injuries is more complex, often because the incident is unobserved (Table 7). It includes the differential for unconsciousness, paralysis, or disorientation from a number of causes. (3) Evidence- of a thunderstorm or a witness to the lightning strike may not be available. The presence of typical burn patterns, when present, may be helpful.

CLINICAL FINDINGS AND MANAGEMENT

RESUSCITATION AND TRIAGE AT THE SCENE

Once the accident scene is controlled, a quick initial assessment of the patient is indicated with attention to the airway, breathing, and circulation. High-flow oxygen and intubation should be provided if necessary. Cardiac monitoring is essential and, if the patient is in cardiac arrest, standard advanced life support protocols should be instituted.

Electrical injury patients often require a combination of cardiac and trauma care, since they often have blunt injuries and burns as well as cardiac damage. At least one large-bore intravenous line of normal saline or Ringer s lactate solution should be started, with fluid resuscitation dependent on the degree of apparent injury. Injury to the cervical spine should be presumed, and protective measures provided until it can be excluded on the basis of history, physical examination, or radiologic study. Use of a backboard, as with other trauma patients, is helpful for both stabilization and transport. Any fractures should be splinted and burns dressed with clean, dry dressings. An electrical injury should be treated like a crush injury rather than a thermal burn because of the large amount of tissue

damage under normal skin. No formula for optimal intravenous fluids based upon percentage of burned body surface area can be counted on. A bolus of 10 to 20 ml/kg of isotonic fluid can reasonably be given to  a hypotensive patient

I The major cause of death in lightning injuries is car-arrest  est.'!' In the absence of cardiopulmonary arrest, patients are highly unlikely to die of any other cause."' Lightning acts like a cosmic DC countershock, sending the heart into asystole. (3,16) Although automaticity may lead to the heart s restarting, the respiratory arrest often lasts longer than the cardiac pause and may lead to a secondary cardiac arrest with ventricular fibrillation from hypoxia. (3,19.33) If the patient is properly ventilated during the time between the two arrests, the second arrest may theoretically be avoided. Hypothermia should also be ruled out when patients have been soaked with rainwater.

EMERGENCY DEPARTMENT ASSESSMENT AND RESUSCITATION

The patient after an electrical injury is often unable to give a good history, either because of the severity of injury and accompanying shock and hypoxia or because of unconsciousness or confusion that often accompanies less severe in juries. History from bystanders and emergency medical personnel regarding the type of electrical source, duration of contact, environmental factors at the scene, and resuscitative measures provided can be helpful. Information on prior medical problems, medication history, tetanus immunization status, and allergies should be sought. Likewise, the patient after a lightning strike, as in other environmental emergencies, may be unable to provide a history, and bystanders stories of the incident may be confused. Although it is interesting to try to unravel the history, this is often difficult to do and may take unnecessary time during the acute resuscitation phase. With both types of injuries, the patient may grossly appear to be alert, oriented and able to repeat his history and give complaints, but this does not preclude serious functional brain injury similar to that found with blunt head injury patients. All patients receiving a high-voltage injury should be transported to a hospital and receive an electrocardiogram (EGG), cardiac isoenzyme level study, urinalysis for myoglobin, complete blood count (CBC), and other tests and radiographic studies as appropriate for their injuries. Resuscitative efforts should be continued in the emergency department with adequate fluid administration and insertion of a Foley catheter for the more severely injured electrical patient. If rhabdomyolysis is present, appropriate treatment should be carried out, with a rate sufficient to maintain a urine output of at least 1.0 to 1.5 ml/kg/hr when heme pigment is present in the urine and 0.5 to 1.0 ml/kg/hr when it is not. Because burns from lightning and low-voltage sources seldom involve deep tissues, myoglobinuria and the need for fluid loading, mannitol or furosemide diuresis or fasciotomy for compartment syndromes are rare. (3,19,28.38) '9   If cardiac arrest or suspected intracranial injuries occur in lightning patients, fluid restriction may actually be desirable to avoid pulmonary edema and increased intracranial pressure. (3,19,39,40) Patients with lightning and low-voltage injuries may present with little objective evidence of injury or, alternately, cardiopulmonary arrest. After initial resuscitation of these patients, other conditions may be identified. These are rarely life-threatening Such patients too may have significant residual morbidity from pain syndromes or neurologic and cognitive damage that is similar to that experienced with blunt head injury. (41-49) (see Primeau and Engelstatter in this issue of Seminars) .

HEAD AND NECK

The head is a common point of contact for high volt-injuries and the patient may exhibit burns as well as neurologic damage. Cataracts develop in approximately 6 percent of cases of high-voltage injuries and should be suspected whenever electrical injury has occurred in the vicinity of the head. (50) Although cataracts may be present initially or develop shortly after the accident. they more typically begin to appear months after the injury. Visual acuity and fun- examination should be performed at presentation or as soon as practical for documentation. Referral to an ophthalmologist familiar with electrical cataract formation may be necessary after the patient s discharge from the hospital. (51,52)

Cataracts may also occur with lightning injuries but are probably less common. (3,19,54) Clinical findings in lightning pa tie patients may include skull fractures. (3,28,29,54)   Typanic membrane rupture is frequently found h1 lightning patients and may be secondary to the shock waves direct burn or basilar skull fracture. (3,19,55) Although most recover without serious sequelae '9 disruption of the ossicles and mastoid (19,55) may occur as well as cerebrospinal fluid otorrhea hematympanic and permanent deafness. (56-60) Other injuries to the eyes may include corneal lesions, uveitis, iridocyclitis, vitreous hemorrhage, optic atrophy, retinal detach, and chorioretinitis. Cervical spine injury may be caused by a fall or being thrown in either type of injury.

CARDIAC  INJURY

Cardiac arrest either from asystole or ventricular fibrillation is a common presenting condition in electrical accidents. Other observed presenting arrhythmias include sinus tachycardial transient ST elevation reversible QT prolongation premature ventricular contractions atrial fibrillation and bundle branch block. (33,65-68) Acute myocardial infarction has been reported but seems to be relatively rare. (67, 69-71 Recent research has shown that damage to skeletal muscles may produce an inordinate rise in the vtrsyinr creatine kinase (CK) MB fraction leading to a spurious diagnosis of myocardial infarction in some settings.(7)

In lightning injuries cardiac damage or arrest caused by either the electric shock or induced vascular spasm may occur. (2?) Lightning patients who do not have cardiopulmonary arrest at the time of the strike generally do well with supportive therapy. (3,19) Those who have cardiopulmonary arrest may have a poor prognosis particularly if there is hypoxic brain damage. (3,19,39)

Numerous arrhythmias have been reported with light-injuries in the absence of cardiac arrest. (3,14) Nonspecific ST-T wave-segment changes and prolonged QT interval may occur and serum levels of cardiac enzymes are some- elevated.  (3,38,73-75) '; Hypertension is often present initially with lightning injury but usually resolves in an hour or two so that treatment is not usually necessary. (3)

Although ECG changes and arrhythmias are common with electrical injuries large series of patients have under-

Table 8. Indications for Electrocardiographic Monitoring

Cardiac arrest
Documented loss of consciousness
Arrhythmia observed in prehospital or emergency department setting
History of cardiac disease
Presence of significant risk factors for cardiac disease
Concomitant injury severe enough to warrant admission
Suspicion of conductive injury
Hypoxia
Chest pain

gone anesthesia and surgical procedures in the first 48 hours of care without cardiac complications. If the patient has none of the indications listed in Table 8 cardiac monitoring probably is not necessary or can be safely discontinued after 12 hours of normal rhythms. (39) Invasive monitoring such as for central venous pressure or intracranial pressure and use of Swan-Ganz catheters should be guided by the patient s status. (40,76)

CUTANEOUS INJURY

Other than cardiac arrest the most devastating immediate injuries that can accompany an electrical injury are burns. The most common sites of contact for the current include the hands and the skull. The most common areas of ground are the heels. There may be multiple contact and ground points.

Because high-voltage current often flows internally and can create massive muscle damage one should not attempt to predict the amount of underlying tissue damage from the amount of cutaneous involvement or use the rule of nines for calculating fluid resuscitation. (15, 33) Cutaneous burns should be covered with antibiotic dressings such as mafenide acetate (Sulfamylon) or sulfadiazine silver (Silvadene). (77) (78) Mafenide is preferable for localized full-thickness burns because of its better penetration. Sulfadiazine silver may be preferable for patients with extensive burns: when Mafenide is used on more than 15 to 20% of the body electrolyte abnormalities may occur because it inhibits carbonic anhydrase. Electrical burns are especially prone to tetanus infection and patients should receive tetanus toxoid and tetanus immune globulin on the basis of their immunization history. Clostridial myositis is common but prophylactic administration of high-dose penicillin to prevent clostridial myonecrosis is controversial and should be discussed with the managing surgeon or burn unit. In general systemic antibiotics are usually not used unless there is infection proved by culture or biopsy.

A peculiar type of burn associated with electrical injury is the kissing burn which occurs at the flexor creases as the electric current arcs causing arc burns on both flexor surfaces. (16) Extensive underlying tissue damage is often present here where the current became concentrated in its passage. Severe burns to the skull and occasionally to the aura have been reported. (79-82)

A special type of burn from low-voltage injuries is the mouth burns that occur secondary to sucking on household electrical extension cords and are the most common electrical injury seen in children under 4 years of age. (5) These burns usually represent local arc burns may involve the oricularis oris muscle and are especially worrisome when the commissure is involved because of the need for splint and the likelihood of cosmetic deformity. (83-85) A significant risk of delayed bleeding from the labial artery exists when the eschar separates. (84, 85) s 8's Damage to developing dentition has been reported and referral to an oral surgeon familiar with electrical injuries is recommended. (83, 86)

With lightning injuries the skin may show no signs of injury initially. Deep burns occur in less than 5% of the reported injuries.' As mentioned previously burns are usually superficial if present at all. They may consist of four typeset l, l ~

I. Linear bums tend to occur in areas where sweat or water accumulates (for example, under the arms or down the chest) (19)

2. Punctate burns appear like multiple small cigarette burns often with a heavier central concentration in a rosette like pattern They seldom require grafting. (88)

3. Feathering burns are not true burns and actually show no damage to the skin itself. (87) They seem to be a complex caused by electron showers induced by the lightning and make a fern pattern on the skin.(87,89,90) They require no therapy. Regular thermal burns occur if the clothing is ignited (88) or may be caused by metal that the person is wearing or carrying (87) that heats up with the  flashover 4. Combinations of all of these may occur. (3)

EXTREMITY INJURY

In high-voltage injuries muscle necrosis can extend to sites distant from the observed skin injury and compartment syndromes can occur secondary to vascular ischemia and muscle edema. With electrical injuries the thought in regard to damaged extremities is to favor early and aggressive surgical management including early decompressive escharotomy fasciotomy carpal tunnel release or even amputation of an obviously nonviable extremity. (2,5,91,94)  Although it is preferable to stabilize the patient prior to transfer to the operating room this is not always possible.

Extremities that have teen burned should be splinted in functional position to minimize edema and contracture formation. The hand should be splinted in 35° to 45° extension at the wrist 80° to 90° flexion at the metacarpophalaneals and almost full extension of the proximal interphalaneal and distal interphalangeal joints to minimize the space available for edema formation. (93) During the first several days of hospitalization frequent monitoring of the neurovascular status of all extremities is essential.

Fractures of most of the long bones and spine (95) because of trauma associated with electrical injury have been reported. Both posterior and anterior shoulder dislocations caused by tetanic spasm of the rotator cuff muscles have been reported but do not seem to be as common as most texts stress.''-" Numerous types of fractures and dislocations have been reported with lightning injury.'

VASCULAR INJURY

Vascular damage from the electrical energy may be evident early or late (34,35) Because the arteries are a high-flow system heat may be dissipated fairly well and result in little apparent initial damage but thrombosis with subsequent thrombosis or rupture  The veins on the other hand, arc a low-flow system allowing the heat energy to cause more rapid  Pulses and  capillary refill should be assessed and documented in all extremities, and neurovascular checks should be repeated x  frequently

This progressive vascular compromise can cause a burn that initially was  assessed as a partial-thickness burn develop into a full-thickness burn as the vascular  supply to the area becomes compromised. Progressive loss of muscle because of vascular ischemia downstream from damaged vessels may lead to the need for repeated deep debridements.

 

NERVOUS SYSTEM

Acutely, computed tomography (CT) or magnetic resonance imaging (MRI) is indicated to rule out intracranial hemorrhage or other injury in any patient with neurologic deterioration or clouded mental status. (19,76,96,96a,b,c)  With high-voltage injuries, loss of consciousness may occur but is usually transient unless there has been a significant head injury as well, although prolonged coma with recovery has been reported. Patients may exhibit confusion, Pat affect, and difficulty with short-term memory and concentration (see Primeau and Engelstatter in this issue of Seminars). A seizure may occur after electrical injury as either an isolated event or part of a new-onset seizure disorder. (4) Hypoxia and injury should be ruled out as causes of the seizure. Neurologic symptoms may improve, but long-term disability is common.

Spinal cord injury may result from fractures of the cervical, thoracic, or lumbar spine (95, 97-99) Neurologic damage in patients without evidence of spine injury seems to follow two patterns, immediate and delayed. (97,98,100) Patients with immediate damage develop symptoms of weakness and paresthesias within hours of the insult, although extremity weakness frequently goes undiagnosed until ambulation is attempted. (41,97) Lower extremity findings are more common than upper extremity findings. These patients have a good prognosis for partial or complete recovery. Delayed neurologic damage may present from days to years after the insult. (The question of causal connection is addressed elsewhere in this issue of Seminars.) The findings usually fall into three clinical pictures: ascending paralysis, amyotrophic lateral sclerosis, or transverse myelitis. (99) Although recovery has been reported, the prognosis is usually poor. (97)

With lightning, up to two thirds of the seriously injured patients have keraunoparalysis on initial presentation, with lower and sometimes upper extremities that are blue, mottled, cold, and pulseless because of vascular spasm and sympathetic nervous system instability. (19,101) Generally, this clears within a few hours, although some patients may be left with permanent paresis or paresthesias. (3,19,25,33) Paraplegia (2) intracranial hemorrhages (57,77,97) creatinine kinase (CK) MB isoenzyme elevations, 3. 38, 73-75) 75 seizures, 89 and electroencephalographic (EEG) changes have been reported.' The vast majority of lightning patients will behave as though they have had electroconvulsive therapy, being confused and having anterograde amnesia for several days after the incident. Loss of consciousness for varying periods is common. (19,103)

Peripheral nerve damage is common, and recovery is usually poor for all types of electrical injuries. (45,104)

Table 9. Primary Complications and Causes of Death in Electrical Injuries in Temporal Order of Occurrence

Cardiopulmonary arrest
Overwhelming injuries
Cardiac arrhythmias
Hypoxia and electrolytes
Intracranial injuries
Myoglobinuric renal failure
Abdominal injuries
Sepsis
Tetanus
Iatrogenic
Suicide

 A syndrome of  delayed muscle atrophy caused by electrical injury of the nerves has been described even in the absence of cutaneous burns. (32)

VISCERAL INJURY

Injury to the lungs may occur because of associated blunt trauma but is rare from electrical current perhaps because air is a poor conductor. injury to solid visceral organs is rare but damage to the pancreas and liver has been reported. (105) Injuries to hollow viscera including the small intestine , (106,107)  large intestine , (14,105)  bladder (81,106)  and gallbladder. (105) have also been reported. With lightning pulmonary contusion and hemorrhage have been reported . (29,108,109)  Blunt abdominal injuries have been reported but are rare/ (3) None of the other intraabdominal catastrophes associated with electrical injury has been reported with lightning injury.

LOW VOLTAGE INJURIES

Evaluation of low-voltage injuries should include a good history because injury that initially appears to be from a low-voltage source may turn out to have been caused by a discharge from a capacitor (as in the repair of televisions and convection or microwave ovens) or other high-energy source. Although burns from  low-voltage sources are usually less severe than those from high-voltage sources , (5,6,110,111)      patients may still complain of paresthesias for an extended period experience cardiac arrhythmias or develop cataracts if the shock occurs close to the face or head. Low voltage mouth injuries in children were discussed in the section of this article on cutaneous injuries.

COMPLICATIONS

The complications of high-voltage electrical burns are listed in Table 9. Cardiac arrest generally occurs only with the initial presentation or as a final event after a long and complicated hospital course.

Many of the complications are like those of thermal burns and crush injuries; they include infection clostridial myositis and myoglobinuria The incidence of acute myoglobinuric renal failure seems to have decreased since the institution of adequate fluid therapy. Fasciotomies or carpal tunnel release may be necessary for treatment of compartment syndromes. (91-94) Tissue loss and major amputations are common with severe high-voltage injuries and result in the need for extensive rehabilitation.

A nasogastric tube should be placed in the seriously injured patient because of the risk of adynamic ileus and stress ulceration. Ulcer prophylaxis with H(2) blockers or sucralfate (Carafate) may be beneficial. Peritoneal ravage or abdominal CT scan may be indicated to rule out intrabdominal injuries if the ileus seems to be prolonged or if the history and physical examination indicate it.

A head CT or MRI scan is also indicated to rule out intracranial injuries and hemorrhage if the patient s level of consciousness does not markedly improve during the emergent course.

Ophthalmologic documentation is important in those patients having injury upward from the shoulders since they can develop cataracts.

Neurologic complications such as loss of consciousness difficulty with memory and concentration (47-49) peripheral nerve damage (46,104) and delayed spinal cord syndromes may occur. (41,95, 97-100) Damage to the brain may result in a permanent seizure disorder. (54)

Stress ulcers are the most common gastrointestinal complication after burn ileus Abdominal injuries from ischemia vascular damage burns or associated blunt trauma may be missed initially, 14,81,105-111)  The most common causes of hospital mortality are pneumonia sepsis, and multiple organ failure because of the complexity of the injury.

Long-term psychiatric sequelae include body image changes marital problems inability to continue working in the same profession and suicide. Treatment for lightning patients can usually be based primarily on routine common-sense treatment of their presenting injuries with attention and follow-up for the long term problems of pain and cognitive dysfunction. In the past patients with lightning injuries have often been treated like those with high-voltage injuries. However these injuries are distinctly different. High-voltage injuries tend to cause deep internal injuries myoglobinurea renal failure shock and massive loss of tissue and function. Lightning injuries tend to cause few external or internal burns and rarely cause myoglobinuria. There is usually little tissue loss although there may certainly be permanent functional impairment. As a result treatment of lightning patients rarely requires massive fluid resuscitation fasciotomies for compartment syndromes mannitol and furosemide diuretics alkalinization of the urine amputations or large repeated debridements. In fact most lightning patients particularly those with head injuries should probably have their fluids restricted to decrease the likelihood of cerebral edema.

LABORATORY, ELECTROCARDIOGRAPHIC, AND RADIOLOGIC EVALUATION

The laboratory evaluation of the patient sustaining an electrical injury depends on the extent of injury. All patients with evidence of conductive injury or significant surface burns should have the following laboratory tests: CBC electrolyte level serum myoglobin blood urea nitrogen creatinine level and urinalysis with special attention to myoglobinuria. Patients with severe electrical injury or suspected intra-abdominal injury should also have obtained amylase aspartate and alanine transaminases alkaline phosphatase and clotting indexes. (68) Sending blood for type and cross-match should be considered, particularly if major debridement embridements may be necessary. Arterial blood gas determinations arc indicated if the patient needs ventilatory interior or alkali therapy.

All patients should be evaluated for myoglobinuria a common complication of electrical injury. A patient with an ortho-toluidine dipstick examinationa of the urine that is positive for blood, but with no red blood cells seen on microscopic analysis, should be presumed to have myoglobinuria and be treated accordingly. creatine kinase CK levels should be determined and isoenzyme analysis performed Peak CK levels have been shown to predict the amount of muscle injury, risk of amputation, and ultimate hospital stay; however, the clinical value of a single level in the acute setting has not been established." Cardiac enzyme levels should be interpreted with care in diagnosing myocardial infarction in the setting of electrical injury. The peak CK level is not indicative of myocardial damage in electrical injury because of the large amount of muscle injury. Although CK-MB fractions, ECG changes, thallium studies, angiography, and echocardiography have correlated poorly in most reports of acute myocardial infarction, (66,67,69) cases of infarction with all of these present have been reported. it' Recent human studies have indicated that skeletal muscle cells damaged by electrical current can contain as much as 20% to 25% CK-MB fraction, as opposed to the usual 2% to 3%, suggesting injured skeletal muscle as the source of the elevated CK-MB fraction and not true myocardial injury." All patients sustaining an electrical injury should receive cardiac monitoring in the emergency department and an ECG regardless of whether the source was high or low voltage. Indications for admission for ECG monitoring are listed in Table 8.'969

Radiographs of the cervical spine should be performed if spinal injury is likely. Radiographs of any other areas in which the patient complains of pain or has an apparent deformity should be performed. CT scan and MRI may be useful in evaluation of trauma and are essential for evaluation of possible intracranial injuries, particularly if the patient does not show progressive improvement in level of consciousness (56, 76, 96, 96c)

In lightning patients, studies should include CBC, urine for myoglobin (using the Quick visual check and dipstick methods), and an ECG. Cardiac isoenzymes are indicated in patients with chest pains, abnormal ECGs, or altered mental states. Other laboratory examinations may be indicated by the severity of the patient's injuries (for example, arterial blood gas measurement if he or she is on a ventilator). Radiographic studies, particularly cerebral scanning, may be indicated, again depending on the individual patient's presentation and progress during evaluation and treatment.(96)

DISPOSITION

All patients with significant electrical burns should be stabilized and transferred to a regional burn center with expertise in electrical injuries, if possible. (94) In addition to burn care and extensive occupational and physical rehabilitation, severely injured patients may need counseling for themselves and their family because of the extensive life changes consequent to the injury.

Purely thermal burns should be treated as such and disposition made accordingly with appropriate close follow-up.

Asymptomatic patients with low-voltage injuries   in the absence of significant cutaneous involvement changes or urinary heme pigment can probably be discharged  safely will, reflect in follow-up.

Indications for admission for 12 to 24 hour ECG monitoring are listed in Table 8. Any case in which corporal conduction is suspected should probably be admitted for monitoring. Patients should be informed of the potential for development of delayed cataracts, weakness, and paresthesias, and appropriate referrals made if these develop.

Electrical injury during pregnancy from low voltage sources hits been reported to result in stillbirth. (113) Obstetric consultation should probably obtained in all pregnant patients reporting electrical injury, regardless of any symptomatology a the time of presentation. Patients in the second and third trimesters should receive fetal monitoring and be followed as high-risk patients for the remainder of their pregnancy. (114) First trimester patients should be informed of the risk of spontaneous abortion and if no other inclinations for admission exist, may be discharged with instructions for threatened miscarriage and close obstetric follow up. Prognosis for fetal survival after lightning stroke varies. (3, 19) Consultation with other specialists may be indicated for otic and ophthalmic damage, although these are usually' not emergent considerations.

Treatment of pediatric patients with oral burns is more controversial. There is good evidence for cardiac injury, need for ECG monitoring, or occurrence of myoglobinuria in isolated oral burns. In general, these patients need surgical and dental consultation for planning of debridement, oral splinting, and, occasionally, reconstructive surgery. Since there is a 10% risk of delayed hemorrhage from the labial artery, some centers recommend admission until separation of the eschar occurs. Admission for observation and planning of definitive therapy is also recommended by some centers. Treatment of patients with lightning injuries usually calls for simple common sense and patience. Many of the signs, such as lower extremity paralysis and mottling and the neurologic signs of confusion and amnesia, resolve with time and need only observation, provided spinal cord and intracranial injuries have been ruled out. More severely injured lightning patients may need both trauma and cardiology consultations although lightning injuries tend to be more of a medical problem than a trauma problem in most cases.

SUMMARY

High-voltage electrical injuries may be devastating, with extensive burns, cardiac arrest, amputations, and long, complicated hospitalizations. Low-voltage injuries, after other pathologic and high-voltage sources are ruled out, tend to be rather benign acutely although they may have significant long-term morbidity, including chronic pain syndromes.

Lightning injuries affect 800 to 1000 persons per year.(9) In lightning injury, cardiac arrest is the main cause of death, burns tend to be superficial, and injuries often are what one would expect of short-circuiting or overloading the body's electrical systems (tinnitus, blindness, confusion, amnesia, cardiac arrhythmias, and vascular instability
 ). Although high-voltage injuries may require the services of trauma Puma surgeons, in general, therapy for low-voltage and lightning Jury is supportive and involves cardiac r resuscitation for the more seriously injured and supportive care for the less severely injured. long-term problems from sleep disturbances, anxiety attacks, pain syndromes, peripheral nerve damage, fear of storms (for lightning patients), and diffuse neurologic and neuropsychological damage may occur in electrical and lightning patients.(42) Other sequclae such as seizures or severe brain damage from hi hypoxia during cardiac arrest and spinal artery syndrome vascular spasm are indirect results of electrical and lightning injury.

 

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