Electrical and Lightning Injuries

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Chapter 65 Electrical and Lightning Injuries

Amanda Pratt, MD

1 What characteristics of electrical energy predispose to severe injury?

image In general, the higher the voltage and current, the worse the injury.

image Alternating current (AC) causes intense muscle contractions, thus prolonging the exposure.

image Direct current (DC) can cause significant trauma by throwing the victim from the source.

image AC is three times more dangerous than DC of the same voltage.

2 Which body tissues offer the highest resistance?

From greatest to least resistance: bone > fat > tendon > skin > muscle > nerve. The most important resistor of current flow is skin, because it is typically the site of first contact. Dry skin over palms and soles can have a resistance of 100,000 ohms. When skin is wet, the resistance drops to 2500 ohms; when skin is immersed in water, resistance can be as low as 1500 ohms. Lowered resistance allows more current to penetrate deeper tissue.

Jain S, Bandi V: Electrical and lightning injuries. Crit Care Clin 5:319–331, 1999.

3 How does the pathway of the current through the body affect the degree of injury?

The path that a current takes determines the number of organs affected and thus the severity of injury. A vertical path parallel to the body involves almost all vital organs and is thus the most dangerous. A horizontal path from hand to hand spares the brain but can still be fatal because it can involve the heart, spinal cord, or respiratory muscles. A horizontal path through the lower body may cause severe local damage but is not typically fatal.

Koumbourlis AC: Electrical injuries. Crit Care Med 30:S424–S430, 2002.

4 Do electrical injuries cause significant external signs that provide a clue to the severity of injury?

No. Injury potential ranges from a superficial wound to multisystem failure. Deep injury may not be immediately apparent, particularly if the resistance of the skin has been lowered by moisture. Low-resistance structures sustain significant injury and necrosis that may not be apparent on initial physical examination.

Martinez JA, Nguyen T: Electrical injuries. South Med J 93:1165–1168, 2000.

5 What are the cardiac manifestations of electrical injuries?

image Sinus tachycardia, premature ventricular contractions, reversible QT prolongation, and other arrhythmias have been reported.

image Low-voltage AC may cause ventricular fibrillation.

image High-voltage AC or DC is likely to cause ventricular asystole.

6 How may electrical injuries affect the respiratory system?

image Primary central nervous system dysfunction at the respiratory center of the brain can induce apnea.

image Paralysis or tetany of the respiratory muscles and diaphragm may occur.

7 How are the kidneys affected in electrical injuries?

Myoglobinuria with subsequent renal failure is possible; direct renal injury is rare.

8 Describe the neurologic effects of electrical injuries

Acute findings may include altered mental status, loss of consciousness, seizures, and paralysis.

Delayed findings (days to years) may include depression, memory loss, motor neuropathy, and transverse myelitis.

9 What are the dermatologic manifestations of electrical injuries?

image Entrance and exit burns may be seen and should be evaluated to determine the path of current.

image Burns across joints at the flexor creases on both flexor surfaces may be seen, known as “kissing burns.”

image Mouth commissure burns are a unique problem in children; other issues are associated with their management (see Question 14).

10 How do I manage patients with significant electrical exposure?

1 Most patients with significant electrical exposure (i.e., high-voltage, DC, or AC injury with respiratory, hemodynamic, or neurologic sequelae) should undergo rapid trauma assessment and resuscitation.

2 Provide the ABCs of trauma care (airway, breathing, and circulation).

3 In patients with DC exposure, immobilize the cervical spine until further clinical and radiographic evaluations are done.

4 Aggressive fluid resuscitation should be initiated to treat presumed myonecrosis and prevent renal failure.

5 Assess for compartment syndrome due to myonecrosis.

6 Provide local burn care and tetanus prophylaxis.

7 Obtain laboratory data: complete blood count, seven-panel chemistry study, creatine phosphokinase, urinalysis, urine for myoglobin, electrocardiography (12 lead), and appropriate radiography. If severe injury or suspected abdominal trauma, add liver function tests, amylase, prothrombin time, partial thromboplastin time, and type and crossmatch.

KEY POINTS: INITIAL MANAGEMENT OF VICTIMS OF SIGNIFICANT ELECTRICAL INJURY

1 Treat the victim as a trauma patient.

2 Initiate the ABCs.

3 Provide cervical spine immobilization.

4 Aggressive fluid resuscitation.

11 How should fluid resuscitation be approached in victims of electrical injury?

Fluid resuscitation should not be based on the rule of nines as in thermal burns because there is typically more extensive internal injury than manifested by the skin findings. Patients with rhabdomyolysis should be given fluids to maintain urine output of 1–1.5 mL/kg/hr. If there is no evidence of blood in the urine, the goal is 0.5–1 mL/kg/hr.

12 For the typical child with short-sustained exposure to household current, how do I approach evaluation and management?

Most pediatric electrical exposures are minor. A tailored evaluation with specific attention to cardiac and neurologic issues, as well as local wound care, is warranted. For household, low-voltage exposures (120–240 volt), any patient with loss of consciousness, history of tetany, wet skin, or current path across heart (hand-to-hand contact) should be monitored for 4 hours for delayed cardiac rhythm disturbances before a disposition is made. If injury is regarded as minor, risk factors are absent, and the general physical examination is normal, brief observation, local wound care, and discharge with appropriate follow-up are sufficient.

13 What are the admission criteria for cardiac monitoring in children who sustain electrical injuries?

An electrocardiogram should be obtained if there is a history of tetany or decreased skin resistance by water or burns, or if it is an unwitnessed event. Patients should be admitted to the hospital for 24 hours of cardiac monitoring if there is an abnormal electrocardiogram, past cardiac history, loss of consciousness, or voltage greater than 240 volts.

Bailey B, Gaudreault P, Thivierge RL: Experience with guidelines for cardiac monitoring after electrical injury in children. Am J Emerg Med 18:671–675, 2000.

14 What are the special concerns in children with mouth commissure burns sustained from biting an electric cord?

Such burns occur most frequently from 6–36 months of age. The burn is caused by direct contact with the electrical source as well as an arc burn in contact with the wet mouth surface. Patients are often stable on initial presentation, but as the eschar begins to loosen (after approximately 7–14 days), labial artery bleeding may occur. Local care, along with use of an acrylic oral splint, is the mainstay of treatment. Discharge instructions should include an understanding of the risk of rebleeding during the following 1–2 weeks. For the best cosmetic results, surgical reconstruction should be delayed until the burn has fully healed (at least 6–9 months).

15 List the common pitfalls in evaluation and treatment of electrical injuries

image Rescuer injuries at the scene due to inappropriately secured, active electrical lines

image Failure to immobilize the cervical spine and perform the ABCs of trauma assessment

image Failure to consider occult blunt trauma injuries in children with DC exposure

image Underestimating fluid requirements for the severity of the burn, specifically depth of thermal injury

16 What are the four mechanisms of a lightning strike?

Direct strike (to either the victim or an object held by the victim) has the highest mortality rate.

Side flash, the most common form, involves a lightning strike that jumps from a primary strike area through the surrounding air to the nearby victim.

Ground strike impacts the ground near the victim. The current enters the victim usually from one foot and exits the other.

Blast phenomenon can occur when rapid cooling of air superheated from lightning causes an explosion with enough force to create blunt trauma, including concussive symptoms.

17 What is the voltage potential in a lightning strike?

A typical lightning strike usually exceeds 1 million volts, but its duration is short (on the order of 1/1000 to 1/10,000 of a second). Because of the extreme voltage potential, the mortality rate is approximately 30% and the morbidity rate approximately 70% for all lightning injuries.

Whitcomb D, Martinez JA, Daberkow D: Lightning injuries. South Med J 95:1331–1334, 2002.

18 How successful is cardiopulmonary resuscitation in victims of a lightning strike?

If resuscitation is initiated promptly, the survival rate is significantly higher than in other causes of cardiopulmonary arrest. Because of the high voltage and DC, asystole is the usual initial rhythm, whereas ventricular fibrillation results from AC. Aggressive and persistent efforts should be provided.

19 Discuss the rules of triage for lightning victims

Lightning injuries frequently involve more than one victim because people tend to seek shelter in groups. The rules of triage are reversed for lightning injuries, and attention should first be given to those not breathing. Victims with signs of life at the scene are highly likely to survive and should not be treated first. Victims with cardiac or respiratory arrest should receive the greatest efforts because they have a high likelihood of survival with aggressive cardiopulmonary resuscitation.

Stewart CE: When lightning strikes. Emerg Med Serv 29:57–67, 2000.

20 Explain feathering burns

Feathering burns are microburns due to the electron shower that results in the lightning exposure. They are seen within several hours of injury and resolve within 24 hours. These are called Lichtenberg figures and are pathognomonic for lightning injuries.

21 How are hearing and vision affected by a lightning strike?

Perforated tympanic membranes and sensorineural hearing loss have been reported in up to 50% of victims. Fixed, dilated pupils can result from autonomic effects of the lightning strike and are not a reason to terminate resuscitative efforts. Retinal detachment and optic nerve injury also have been reported.

KEY POINTS: APPROACH TO VICTIMS OF A LIGHTNING STRIKE

1 Reverse the rules of triage. Treat those who are not breathing.

2 Pursue aggressive cardiopulmonary resuscitation.

3 Remember that a blown pupil is not an ominous sign and continue resuscitation.

22 Define keraunoparalysis

Keraunoparalysis is the vasospastic paralysis of limbs unique to lightning strikes. It may last several hours before resolution. Keraunos is Greek for “thunderbolt” and is used as a prefix to describe lightning-related phenomena.

23 What are the risks of sustaining a lightning injury indoors?

The dangers of lightning injury to persons who are indoors are not well known. The two potential risks are telephone and plumbing lines. A current surge on a telephone line, due to a direct lightning strike or, more commonly, to current traveling along the ground, may result in a large voltage difference between telephone apparatus and user. Deaths are rare. Acoustic trauma is the most common form of injury. Current also may travel in grounded pipes to bathtubs and showers. Such injuries have high morbidity and mortality rates because the ground current is highly conductive by the water in the bathtub or shower.

24 What is the “30–30 Rule”?

This is an easy way to remember how to avoid lightning injury. If the time between seeing lightning and hearing thunder is less than 30 seconds, an individual should be seeking shelter. Outdoor activities should not resume until 30 minutes after the last sound of thunder or sighting of lightning. Another easy reminder that can be taught to children is, “If you can see it, flee it; if you can hear it, clear it.”

Zimmermann C, Cooper MA, Holle RL: Lightning safety guidelines. Ann Emerg Med 39:660–664, 2002.

National Lightning Safety Institute: www.lightningsafety.com

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