Electrical Injury

Electrical injury is tissue damage from the passage of electric current through the body. Severity depends on voltage, current, tissue resistance, current path, contact duration and the type of current. Low voltage means under 1000 volts (domestic supply), high voltage means over 1000 volts (power lines, industrial). Alternating current at 50 to 60 Hz causes sustained muscle tetany that can prevent release from the source. Direct current causes a single violent contraction that often throws the victim.

Tissue resistance is lowest in nerves, blood vessels and muscle, intermediate in skin (very low when wet), and highest in bone and fat. Heat (Joule heating) injures deep tissue far beyond the skin wounds. Mechanisms include direct tissue damage, thermal injury, arc burns (temperatures up to 20,000 degrees Celsius) and blunt trauma from falls or muscle contraction (posterior shoulder dislocation, vertebral fractures). Toddlers sustain oral commissure burns from biting cables.

Complications

• Cardiac arrest: ventricular fibrillation with low-voltage alternating current, asystole with high voltage or direct current
• Arrhythmia and, rarely, myocardial injury
• Rhabdomyolysis, compartment syndrome and acute kidney injury
• Deep burns and amputation
• Delayed neurological deficits (transverse myelitis, peripheral neuropathy), cataracts months to years later, and neuropsychiatric sequelae
• Bowel injury, tympanic perforation, and fetal loss in pregnancy

• Entry and exit wounds, often on hands, feet or head, which are painless, leathery or charred, and understate deep injury
• Swollen, tense limb, severe pain and weak pulses (compartment syndrome)
• Transient loss of consciousness, confusion, amnesia, tetany, paresthesia and weakness
• Chest pain, palpitations and arrhythmia
• Dark urine, and abdominal pain or distension
• Oral commissure burns in children, with risk of delayed labial artery bleeding at 5 to 21 days
• Red flags: high-voltage exposure, loss of consciousness, abnormal ECG, hand-to-hand current path, dark urine, pregnancy, and signs of compartment syndrome

1. 12-lead ECG in all patients, with continuous monitoring when indicated.
2. Blood tests: creatine kinase (peaks at about 24 hours), myoglobin, creatinine, urea, potassium, calcium, blood gases, full blood count and troponin (nonspecific).
3. Urinalysis for heme-positive urine without red cells (myoglobinuria).
4. Imaging: radiographs and CT for falls or suspected fractures, cervical spine imaging, abdominal ultrasound or CT for visceral injury, and echocardiography for cardiac symptoms.
5. Compartment pressure measurement when swelling is tense (a pressure over 30 mmHg, or a perfusion pressure under 30 mmHg, indicates compartment syndrome).
6. Fetal assessment in pregnancy, and ophthalmologic and audiological examination as indicated.

Differentials: thermal burn without electrical contact, seizure, syncope of other cause, primary arrhythmia and trauma.

1. Scene safety: turn off the power source before approaching. Do not touch the victim until contact is broken.
2. Resuscitation: airway, breathing and circulation with cervical spine protection. In cardiac arrest, start CPR and defibrillation at once and continue for longer than usual, since many victims are young and healthy.
3. Fluids for tissue injury and myoglobinuria: lactated Ringer solution 1 L IV bolus, then 200 to 500 mL/h to keep urine output at 1 to 2 mL/kg/h (100 to 150 mL/h in adults) until urine clears. Burn resuscitation formulas underestimate needs. Add sodium bicarbonate 1 mmol/kg IV for persistent dark urine to keep urine pH over 6.5.
4. Cardiac monitoring: discharge is acceptable after a low-voltage, brief exposure in an asymptomatic patient with a normal ECG, no loss of consciousness and no burns. Monitor for 24 hours after high-voltage injury, loss of consciousness, abnormal ECG or chest pain.
5. Hyperkalemia: calcium chloride 1 g IV, and insulin 10 units IV with 50 mL of 50% dextrose.
6. Burn and wound care: clean, remove dead tissue and dress. Mafenide acetate 11% cream once or twice daily or silver sulfadiazine 1% cream twice daily for deep burns. Tetanus toxoid 0.5 mL IM if not immunized.
7. Surgery: early fasciotomy and escharotomy for compartment syndrome or circumferential burns, serial debridement and amputation of non-viable tissue. Reconstruction of oral commissure burns after healing, with splinting.
8. Analgesia: morphine 0.05 to 0.1 mg/kg IV titrated, with paracetamol 1 g orally or IV every 6 hours.
9. Kidney injury: renal replacement therapy for hyperkalemia, acidosis or overload.
10. Children with oral burns: warn the family about labial artery bleeding, to be controlled by pinching the lip and attending at once.
11. Pregnancy: continuous fetal monitoring for at least 24 hours and obstetric review.

Follow-up: ophthalmology at 3 to 6 months for cataracts, neurological review for delayed deficits, and psychological support. Prevention: safe wiring, protective covers, insulated tools and lock-out procedures at work.