Electrocution at a Construction Site: A Case Report

     EMS was called for a 35-year-old male who had been on an aluminum ladder at a construction site using a 115 volt, 60 Hz alternating current electric drill. At 9:26 a.m., he leaned against the wall and his chest came in contact with the (apparently defective) drill cord. The patient received an electrical shock that threw him off the ladder. He landed on his back on a concrete floor 10 feet below. Coworkers described a bright flash and then a loud crash. They called 9-1-1 at 9:28 a.m. Bystander CPR was not performed.

     The paramedics arrived at 9:31 and found the patient lying on electrical cords. After ensuring safety by shutting down the job-site's power, they evaluated the patient, who was in cardiopulmonary arrest with a rhythm of ventricular fibrillation. While maintaining spinal immobilization, consecutive defibrillation at 200, 300 and 360 J was administered at 9:32, resulting in a lethal rhythm felt to be asystole or fine ventricular fibrillation. An endotracheal tube was placed via the orotracheal route, chest compressions began, and IV access was established by 9:36 a.m. Radio contact was made with the receiving facility, and IV epinephrine (1 mg) and lidocaine (120 mg) were given. At 9:41, when repeat defibrillation at 360 J was ineffective, an additional dose of epinephrine (1 mg) was administered. Finally, the patient responded to a defibrillating shock of 360 J with a perfusing rhythm. At 9:43, the patient had a blood pressure of 180/P with a heart rate of 130, believed initially to be ventricular tachycardia.

     The patient was immobilized on a board with a cervical collar in place and transported at 9:57 a.m. On secondary examination en route, medics noted occipital scalp bleeding, burns to the chest and burns to the medial ankles. They also suctioned frothy pink sputum from the endotracheal tube (see Figure 1). On closer inspection, the patient's cardiac rhythm was thought to be sinus tachycardia. His condition remained unchanged, and the ambulance arrived (Code 3) at the emergency department at 10:04 a.m.

ED TREATMENT
     The mobile intensive care nurse (MICN), in communication with the medics, activated the trauma team prior to the patient's arrival. The team verified endotracheal tube placement. Breath sounds were rhonchorous, and the respiratory therapist suctioned additional pink, frothy sputum from the endotracheal tube. Concurrently, a second antecubital IV catheter was placed and blood samples were obtained for analysis. Pulses were easily palpated in all extremities, and there appeared to be good peripheral perfusion. Blood pressure was 154/94 with a pulse rate of 156. The patient was non-responsive to noxious stimuli and was assigned a Glasgow Coma score of 3T (intubated). Pupils were sluggishly reactive from 3 to 2 mm bilaterally.

     Secondary survey revealed a superficial scalp abrasion with hematoma. A 5 x 3 cm erythematous patch, believed to be the electrical entrance wound, was noted over the sternum (Figure 2). Bilateral ulcerated lesions (6 x 3 cm) surrounded by erythema and ecchymosis were present on the medial malleoli. These were assumed to be exit wounds (Figure 3).

     Chest radiography demonstrated pulmonary edema. A CAT scan of the head indicated mild diffuse cerebral edema, in addition to soft tissue swelling of the scalp. Cerebral edema may have resulted from anoxia, trauma or both. Electrocardiogram was markedly abnormal, with striking ST segment elevations across the precordial leads suggesting acute myocardial infarction (Figure 4 on page 192). On echocardiogram, a wall motion abnormality was found in the apex, notably the area of the myocardium directly beneath the sternal entrance wound. Numerous abnormalities were found in the blood and urinalysis that pointed toward rhabdomyolysis, as well as probable brain and cardiac injury.

HOSPITAL CARE
     The patient was admitted to the surgical intensive care unit. He eventually awoke and was able to move his extremities. Rhabdomyolysis was treated with aggressive hydration and alkalinization, and the patient's renal function remained normal. The several serum abnormalities noted during the emergency department stay slowly normalized. Wound debridement promoted healing of the leg wounds. The pulmonary edema resolved and the patient was extubated. Although he was following commands and ambulatory by the time he got to rehabilitation, he did have persistent cognitive and speech problems. Intensive physical, occupational, speech and neuropsychiatric therapies were completed. He progressed well and, by the time of discharge on the 28th day of hospitalization, his only obvious problem was with short-term memory. Additional outpatient rehabilitation for this problem was recommended.

THE CASE IN CONTEXT
Electrical Injuries
     Unfortunately, this scenario is all too common. Electrical appliances, most commonly drills, are involved in 9% of occupational electrocutions.¹ Metal ladders are involved in 10%.² It was not known whether a ground-fault circuit interrupter protection was present at this work site, although the prevalence of these devices seems to have reduced the frequency of injury in both domestic and industrial locations.³ Workers in the construction industry are at significant risk of electrocution. Forty-four percent of all on-the-job deaths from electrical injuries involve construction workers.⁴ Workplace electrocutions declined from 0.6 to 0.3 per 100,000 workers in the last decade,⁵ but they remain the fifth most common cause of occupation-related death. Despite multiple safety recommendations to prevent electrical injury in the home and at work, there are still some 52,000 hospitalizations a year.

     Scene safety cannot be over-emphasized. A 31-year-old fire chief in North Carolina was electrocuted when he attempted to extricate a victim from a wrecked car and made contact with a steel winch cable touching downed power lines. A paramedic and another firefighter were also seriously injured.⁶ In a similar event in Ohio, four people, including two firefighters and one EMT, were electrocuted while trying to rescue a victim from a pick-up truck that had struck a utility pole.⁷

     The present case illustrates some of the common and uncommon injuries seen following an electrical injury. Knowledge of the electrical source can sometimes be useful in predicting the nature and types of lesions encountered. The differences between lightning, high-voltage (>1,000 V) and low-voltage (<1,000 V) injuries are important (Table 1). The pathophysiologic effects of current on tissue are not completely understood, but seem to involve thermal (tissues with high resistance such as skin and bone), electrical (tissues with low resistance such as muscles, nerves and blood) and poorly understood electromagnetic effects. Concurrent traumatic injuries, especially falls, are more prevalent with the low voltage, alternating current (115 V, 60 Hz) seen here, since tetanic contractions may occur. The benign-appearing entrance wound and ominous-appearing exit wounds are also typical of alternating current. Direct-current skin exit lesions are rarely so striking. It is also worth considering whether arcing was responsible for the bright flash described by co-workers. Arcing may have occurred when the current traveled through the patient and the metal ladder to reach the ground, which generally produces more serious injuries.

Cardiopulmonary Effects
     Serious cardiac manifestations following electrical injury are rare and occurred in only 3% of patients in one retrospective review.⁸ The likelihood of an adverse cardiac event seems to increase in situations in which the current transverses the thorax or myocardium, as was noted in the present case. Our patient showed EKG abnormalities, cardiac enzyme elevations and focal wall motion defects on echocardiogram. Ventricular fibrillation (presumably induced by the tetanic effects of the current) and focal apical myocardial necrosis (presumably induced by the thermal effects of the current) demonstrate the myriad ways in which electricity can injure tissue. Similar effects on the diaphragm may have resulted in simultaneous cardiac and respiratory arrests.

     The frothy pink sputum coming from this patient's endotracheal tube represented pulmonary edema. Acute pulmonary edema has been reported following electrical injury.⁹ In this case, pulmonary edema most likely resulted from the myocardial infarction and wall motion abnormalities following electric shock.

Musculoskeletal Effects
     Electric shock can injure muscle in several ways, causing compartment syndrome and rhabdomyolysis. Compartment syndrome occurs when swelling of the muscle results in nerve injury and impaired blood supply. Remember that muscles are normally tightly contained in a wrapper called the fascia. The space inside the fascia containing bone, muscle, nerves, arteries and veins is called a compartment. When the muscles swell after an injury (such as a crush, fracture or electrocution), the fascia is so tight that the structures inside the compartment are injured. Decreased sensation and decreased pulses are late findings. An early clue to a compartment syndrome is pain out of proportion to the apparent injury, especially with passive motion of the muscle. Treatment is fasciotomy, or surgical opening of the fascial compartment around the affected muscle.

     Rhabdomyolysis is a complication to be anticipated following nearly any severe electrical injury. This occurs when injured muscle cells release muscle proteins (especially myoglobin) into the blood. This protein can injure the renal tubules. Careful attention to this problem is important, since resulting renal failure causes death in many of these patients. Mainstays of treatment include fluid rehydration and alkalinization of urine. The saline helps to wash these proteins out. Alkalinization with bicarbonate helps to prevent myoglobin from precipitating in the tubules.

Nervous System Effects
     Although cerebral edema has been reported following electrical injury,¹⁰ it is often not clear whether this is the result of electrical injury, trauma or anoxic encephalopathy following cardiopulmonary arrest. In the present case, the patient had a prolonged arrest (approximately 10 minutes) and may have also sustained a head injury. Spinal cord injury may also result from the electrical shock itself or from traumatic effects such as falls, fractures or dislocations.

PREHOSPITAL CONSIDERATIONS
     This case illustrates features common to many electrical injuries. Most important, it illustrates how timely resuscitation of these victims can result in excellent outcomes. Keep the following in mind when dealing with these patients:

1. Ensure scene safety with proper insulating gear and de-energizing the electrical source.
2. Patients with prolonged cardiac and respiratory arrests may have good outcomes.
3. Consider metabolic effects such as rhabdomyolysis.
4. Look for occult traumatic or spinal injuries.

References

1. Suruda A, Smith L. Work-related electrocutions involving portable power tools and appliances. J Occup Med 34(9):887–892, 1992.
2. Electrocutions in the construction industry involving portable metal ladders--United States, 1984-1988. Morb Mortal Wkly Rep 41(11):187–189, 1992.
3. Rai J, Jeschke MG, Barrow RE, Herndon DN. Electrical injuries: A 30-year review. J Trauma 46(5):933–962, 1999.

4. Cawley JC, Homce GT. Occupational electrical injuries in the United States, 1992-1998, and recommendations for safety research. J Safety Res 34: 241–248, 2003.
5. Achievements in Public Health, 1900-1999. Improvements in Workplace Safety—United States, 1900-1999. Morb Mortal Wkly Rep 48(22); 461–469, 1999.
6. Worker Deaths by Electrocution, A Summary of NIOSH Surveillance and Investigative Findings. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, May 1998
7. Emergency rescuers killed in tragic electrocution. Emergency Net News Emergency Services Report 1997: 1, No. 158.

8. . Arrowsmith J, Usgaocar RP, Dickson WA. Electrical injury and the frequency of cardiac complications. Burns 23(7-8):576–578, 1997.
9. Schein RM, Kett DH, De Marchena EJ, Sprung CL. Pulmonary edema associated with electrical injury. Chest 97(5):1248–1250, 1990.
10. Kleinschmidt-DeMasters BK. Neuropathology of lightning-strike injuries. Semin Neurol 15(4):323–328, 1995.

Stephen W. Corbett, MD, FACEP, is medical director at the Department of Emergency Medicine at Loma Linda University Medical Center in Loma Linda, CA.