Lightning and electrical injury case file

Lightning and electrical injury case file

Eugene C. Toy, MD, Barry C. Simon, MD, Terrence H. Liu, MD, MHP, Katrin Y. Takenaka, MD, Adam J. Rosh, MD, MS

Case 46

You are in the emergency center when two patients are brought in by paramedics. By report, the two men in their twenties were victims of lightning injury while playing golf. Eyewitnesses at the scene report that the victims were standing several feet apart, when one of the men was struck directly by lightning that resulted in both men falling to the ground immediately and becoming unconscious. One of the victims was found pulseless at the scene and cardiopulmonary resuscitation (CPR) was initiated by a bystander. The second man was noted to be unconscious for several minutes after the incident and has remained confused. On examination, one victim has extensive soft-tissue burn over his back, and he is intubated and ventilated without spontaneous respirations. No palpable pulse is identified and fine ventricular fibrillation appears on the electrocardiogram (ECG) monitor. The second victim is awake with a pulse rate of 80 beats per minute, blood pressure of 130/80 mm Hg, respirations of 18 breaths per minute, Glasgow coma scale (GCS) score of 13, with no identifiable external sign of injury.

⯈ What are the complications of lightning injury?

⯈ How are the complications identified?

ANSWER TO CASE 46:

Lightning and Electrical Injury

Summary: Two adult victims present to the emergency center following lightning injuries. One patient with cardiac arrest appears to have been a victim of direct lightning strike, while the second victim appears to have minimal external signs of injury.

• Lightning-related complications: Cardiac injury, usually in the form of arrhythmia, neurological damage, burns, spinal cord injury, and respiratory arrest.
• Identification of complications: Thorough and careful physical examination and electrocardiography will identify arrhythmia and cutaneous burns. Computed tomography (CT) scan of the head is indicated in all patients with severe lighting injury and those with abnormal neurological examination. Spinal protection and immobilization are necessary until injury is ruled out, and aggressive, persistent resuscitation according to advanced life support protocol is indicated, including airway control and ventilation support until spontaneous respiration is restored.

ANALYSIS

Objectives

1. Learn to recognize and treat the immediate and late complications associated with electrical injury and lightning injury.
2. Learn to recognize the spectrum of injury associated with lightning and electrocution.
3. Understand the relationship between Ohm law and injuries produced by electric current.

Considerations

One patient suffered a direct lightning strike and is in cardiac arrest. Because of its massive direct current countershock, lightning strike can induce depolarization of the entire myocardium leading to cardiac standstill. Immediate cardiac arrest is the most common cause of death after a lightning strike. However, respiratory arrest may also occur, either due to paralysis of the respiratory center in the medulla, or as a result of tetany of the respiratory muscles from electric current passing through the thorax. Many patients will regain cardiopulmonary function if timely and appropriate resuscitation efforts are able to sustain oxygenation and circulation while the organ systems recover.

Given the first patient’s young age and lack of comorbid factors, there is a greater likelihood for response to resuscitation efforts than in victims with cardiac arrest from other traumatic causes. The heart’s inherent automaticity renders it possible for spontaneous recovery if immediate defibrillation and tissue oxygenation is maintained.

The second patient, although hemodynamically stable, has suffered a high-risk electrical injury with loss of consciousness. Head and/or spinal injury could be present as a consequence of being “thrown” by the lightning strike. He requires evaluation with CT scan of the head, ECG, spinal immobilization, and evaluation and initial observation in the ICU for close monitoring of the cardiopulmonary status.

Approach To:

Lighting and Electrical Injury

CLINICAL APPROACH

Although lightning strike is a rare phenomenon, this injury is associated with a 25% fatality rate, and more than 70% of those who survive have permanent injuries. Lightning strike is responsible for approximately 100 deaths annually in the United States. Electrical injury, excluding lightning, is responsible for more than 500 deaths annually, with approximately 20% of its victims being younger than age 18 years. The effects of electrical injury are related to the intensity and magnitude of the electric current. According to Ohm law, the current flow (amperage) is directly related to the voltage and inversely related to the resistance in the current’s pathway, represented by the following formula: current (amperage) = voltage/ resistance. Because of their low resistance, nerves, blood vessels, mucous membranes, and muscle are the preferred pathways for electric current passage and are most susceptible to electrical and lightning injury. Bones, fat, tendon, and skin have relatively high resistance, and therefore sustain less damage during electric and lightning injuries. The probable path of the electrical current should be assessed; for example, burns on both hands indicate a path likely through the heart, which has a poor prognosis.

Electrical current exists in two forms: alternating current (AC) and direct current (DC). AC involves electrons flowing back and forth in cycles, whereas in DC, the electron flow occurs in only one direction. Alternating current (AC) is more dangerous because it may cause tetanic muscle contractions and the “locking on” phenomenon, preventing the victim from releasing the electrical source and prolonging the exposure to the current. Lightning strike is a form of DC electrical injury with extremely high voltage and amperage, but short duration of exposure. During lightning injury, the electrons flow in only one direction, thereby typically inducing a single intense muscle contraction that “throws” its victim and causes simultaneous fractures and spinal injury. There are four types of lightning injury (Table 46–1).

Pathophysiology

Electrical injury can cause direct necrosis of the myocardium, ischemic injury as a result of vasoconstriction caused by excess catecholamine release, or disturbances in the cardiac rhythm. Even low currents can produce arrhythmias, including asystole and ventricular tachycardia. Late dysrhythmias are uncommon in previously healthy patients, but can be produced by patchy myocardial necrosis and injury to the

sinoatrial (SA) node. Lightning is able to induce cardiac standstill by depolarizing the entire myocardium. Because of the inherent automaticity of the heart, normal sinus rhythm often spontaneously returns.

Clinical Considerations

Cardiovascular Effects All victims of lightning strike and high-voltage electric injury should have immediate ECG monitoring and cardiopulmonary support to maintain tissue perfusion as needed. A cool, extremity with diminished sensation and pulse is usually caused by vasoconstriction and nerve ischemia, which may resolve spontaneously with time. Because extremity compartment syndrome may develop, reexamination with compartment pressure measurements is indicated in selective patients. Aggressive treatment by fasciotomy is indicated when elevated compartment pressures are identified. Victims of electrical injury with no loss of consciousness or physical findings who are asymptomatic and have normal ECG can be safely discharged home.

Neurological Effects Nerve damage is common after electrical injury, but no one condition is pathognomonic. Approximately 75% of patients struck by lightning will have transient loss of consciousness and brief extremity weakness or paresthesia. Lightning victims often have keraunoparalysis, a temporary paralysis with loss of sensation that typically involves lower limbs. Strength and sensation return to normal within a few hours. Other physical findings common in electrical injury are confusion, amnesia, headache, visual disturbance, and seizure. Direct spinal cord injury has been reported after hand-to-hand flow with damage to C4-C8.

The most serious effect, especially common after lightning strike, is injury to the respiratory control center in the medulla, resulting in respiratory arrest. In addition, lightning and electrical injury victims often have fixed and dilated pupils as a result of autonomic responses, and this should not be interpreted as a sign of non survival until cerebral function is fully assessed.

As in any apneic trauma victim, the airway, oxygenation, and ventilation should be restored immediately. CT scan of the head is indicated in patients with neurological findings or loss of consciousness to evaluate for possible intracranial pathology. Spinal immobilization should be continued until neurological examination is normal or injury is ruled out radiographically. Most victims of electrical and lightning injury without cardiac arrest will survive, but should be counseled that persistent sequelae, including memory deficit, sleep disturbances, dizziness, fatigue, headaches, and attention deficits may occur.

Skin Burns are common after high-voltage electrical injury, but are less often seen after lightning strike because of instantaneous exposure time. Victims of electrical injury have “flush burns” caused by heat generated by the electrical current, or “flame burns,” usually as a consequence of ignition of clothing. Because of its instantaneous exposure time, burns are less common after lightning injury. Lightning strike can cause partial-thickness linear burns in areas of high sweat concentration and low resistance, which result in a transient fern-like skin pattern called the Lichtenberg figure that is pathognomonic of lightning. In children, the most common mode of electrical injury is from chewing or biting electrical cords, which manifests as perioral edema and eschar formation.

Thorough physical examination will reveal any cutaneous manifestations of electrical injury. Early intravenous access should be established for fluid management as soon as possible in any burned patient. Fluids should be titrated to adequate urine output. Severe injuries will require admission to a specialized burn unit. Children may have excessive bleeding from the labial artery as a consequence of perioral burn.

Special Considerations

Other injuries associated with electrical and lightning injuries include fractures from severe muscle contraction or blunt trauma after exposure. Upper limb and spinal fractures are common. The kidneys are particularly vulnerable to anoxic damage that accompanies electrical injury, where rhabdomyolysis is common. However, rhabdomyolysis is rare after lightning injury. Rupture of the tympanic membrane occurs in up to 50% of lightning victims. Cataracts often present as a late sequelae of lightning strike. Curling ulcers are common in burn victims, and preventative treatment for these stress ulcers should be initiated at admission.

When lightning injuries are not witnessed, some victims may simply be found down, and in those situations, thorough evaluations need to be initiated to look for other causes (cerebral vascular accident, toxic ingestions, spinal cord injuries, closed head injuries, myocardial infractions, and primary seizure disorders) responsible for the unexplainable neurologic and cardiovascular deficits.

COMPREHENSION QUESTIONS

46.1 A 40-year-old man who is employed as an electrician is brought to the ED after he accidentally grabbed a high-voltage wire, and this caused him to fall from a 8-ft ladder onto his back on the pavement below. He was ambulatory at the scene but because of persistent pain in his left hand and arm, he presents to the ED for treatment. He is conscious and conversant but complains of intense pain in a 3-cm burn wound on his left hand and also pain throughout his left forearm. On examination, the patient has GCS of 15 and is stable from the cardiopulmonary view. He has dry eschar over the hand wound, the sensation and motor activities are diminished in his left hand, and he has fi rmness and tenderness throughout the left forearm. Which of the following next step is most appropriate?

A. Obtain x-rays to rule out fractures.

B. Measure forearm compartment pressures.

C. Administer systemic antibiotics to prevent skin infection.

D. Obtain electromyograms (EMGs) to rule out peripheral nerve injury.

E. Obtain a CT scan to evaluate the muscle and nerves.

46.2 A 49-year-old man was fixing the electrical wiring in his house as a remodeling project and neglected to shut off the electricity at the electrical box. He suffered a substantial electrical injury primarily on the right hand, and was taken by paramedics to the ED. Which of the following is most likely to be true regarding electrical injury?

A. Cataract formation usually only occurs when there is a contact point on the head.

B. Renal failure is usually a result of direct electrical injury to the kidney.

C. With high-voltage injuries, dysrhythmia usually develops 24 to 48 hours after injury.

D. Electrical burns commonly produce a fern-like skin burn pattern.

E. Even with minor cutaneous involvement, major internal injury can occur.

46.3 A 13-year-old adolescent boy and his friend were curious about the inner workings of high-voltage transformers. After scaling the fence around one such complex near their school, one of the boys touched the transformer, believing that because he was wearing rubber-soled tennis shoes, he would be immune to electrical shock. He suffered a significant jolt of electricity at 10,000 V. Which of the following organ systems is most susceptible to high-voltage injuries?

A. Bones, tendons, and muscles

B. Skin, brain, and fat

C. Fat, heart, and skeletal muscle

D. Blood, nerves, and mucous membranes

E. Hair

46.4 A 45-year-old accountant was getting into his car on the top of his high-rise office building during a thunderstorm. Suddenly, a lightning strike occurred, throwing him to the ground. Which of the following is most accurate regarding complications to his injuries?

A. Tetanic contractions are commonly caused by AC current.

B. The instantaneous duration of exposure lessens cutaneous burn risk compared to other high-voltage electrical injuries.

C. Rhabdomyolysis is a common delayed sequelae.

D. Respiratory arrest is caused by paralysis of thoracic muscles.

E. Lightning strike carries 80% mortality.

ANSWERS

46.1 B. This patient’s history of high-voltage injury and current complain of intense forearm pain, diminished motor and sensory function in the hand, and tenseness in the forearms are highly suspicious for compartment syndrome secondary to myonecrosis in the forearm. Direct compartment measurement is the most rapid and reliable approach to diagnosis. Even though fracture can occur from the fall, bony injury would not account for motor and sensory changes in the hand. Treatment of burn wounds with systemic antibiotics is not indicated. CT scan is not sensitive for identification of compartment syndrome.

46.2 E. Even with minor cutaneous involvement, major internal injury can occur. The renal failure following electrical shocks generally occurs as a result of myoglobinuria. Although dysrhythmia is common after electrical injury, it almost always develops immediately after exposure. Cataract formation may occur even when there is no contact point on the head. Lichtenberg fi gure is the transient fern-like pattern that occurs on the skin of lightning strike victim because the electricity is splashed onto skin based on the vascular and nerve distribution patterns of the skin.

46.3 D. In high-voltage injuries, the electricity tends to follow the path of least resistance. Blood, nerves, and mucous membranes are frequently injured after electrical exposure because of their low resistance. Fat, bones, and tendon have high resistance.

46.4 B. Because of instantaneous exposure, burns are relatively rare in lightning injury. Lightning is DC current, and respiratory arrest is usually a result of injury to the respiratory control center in the medulla. Rhabdomyolysis is common after high-voltage electrical injury, but rare after lightning strike. Contrary to popular beliefs, the mortality associated with lightning injuries are low with most recent series reporting rates of 5% to 10%.

CLINICAL PEARLS

⯈ Victims of lightning strike should be treated with aggressive ventilatory and circulatory support until cerebral function can be assessed, because many patients will recover function with time.

⯈ Typical signs of brain death, fixed/dilated pupils and apnea, do not necessarily indicate brain death in electrical victims. Moreover, typical triage criteria for mass casualty situations do not apply to electrical injury.

⯈ Even with small outward sign of injury, major internal damage is common.

⯈ Children may have excessive bleeding from chewing on electrical cords.

References

Fish RM, Geddes LA. Conduction of electrical current to and through the human body: a review. Journal of Plastic Surgery; 2009. www.eplasty.com 

Katz RD, Deune EG. Electrical and lightning injuries. In: Cameron JL, Cameron AM, eds. Current Surgical Therapy, 10th ed. Philadelphia, PA: Elsevier Saunders; 2011:1047-1057. 

O’Keefe Gatewood M, Zane RD. Lightning injuries. Emerg Med Clin N Am. 2004;22:369-403. 

Ritenour AE, Morton MJ, McManus JG, et al. Lightning injury: a review. Burn. 2008;34:585-594. 

Zimmermann C, Cooper MA, Holle RL. Lightning safety guidelines. Ann Emerg Med. 2001;39: 660-664.

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