Electrical Injury

Aka: Electrical Injury, Electrical Burn, High Voltage Electricity, Electricity Shock, High Voltage Injury, Low Voltage Injury, Electrocution

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II. Epidemiology

  1. Electrical injuries cause 1000 deaths in U.S. per year

III. Pathophysiology

  1. Electricity travels a path until it meets resistance
    1. Skin offers resistance to low current, but with enough current a burn hole through the skin is established
      1. Burn allows current to pass bypass intact skin via Electrolytes into nerves, Muscles, vascular structures
    2. Skin resistance is lowered by a factor of 100 when it is wet (i.e. wet skin is a much reduced barrier to Electrical Injury)
    3. Carbonized tissue resists continued current
  2. Electrical Injury results in Thermal Burn injury
  3. Most common injury sites
    1. Deep Skin Injury
    2. Neurologic injury
      1. Spinal Cord Injury (e.g. motor or sensory deficit)
      2. CNS injury (e.g. Altered Level of Consciousness)
    3. Eye Injury
      1. Cataracts
      2. Corneal burn
      3. Retinal Detachment
    4. Cardiovascular injury
      1. Cardiac Arrest
      2. Arrhythmia

IV. Types

  1. Alternating Current (AC): Low voltage home injury
    1. AC is 3 times more dangerous than DC at same voltage
    2. Typical AC current is at 60 Hz and may result in muscle Tetany
      1. Patient involuntarily grips source
      2. Prolongs duration of contact and increases injury
      3. Diaphragmatic paralysis (apnea) may occur even with low voltage (e.g. welding)
      4. Alternating current may cause Ventricular Fibrillation
  2. Direct Current (DC): High voltage Occupational Injury
    1. May throw patient from jolt of energy
    2. May result in blunt injury in addition to burns
    3. Low voltage DC current may cause brief Asystole followed by sinus rhythm (similar to Defibrillation)
  3. Voltage
    1. Amperage (current through tissue) is most related to tissue injury
      1. However, as amperage is typically unknown, voltage is used as a surrogate
    2. Low voltage Electrical Injury: <1000 Volts
      1. House power outlet: 110 to 240 volts
      2. Serious injury and morbidity increases significantly over 600 volts
    3. High voltage Electrical Injury: >1000 Volts
      1. Power Lines: 7200 volts
      2. High voltage power lines: 155,000 to 765,000 volts
      3. At high voltage, differences between AC and DC current becomes less important
    4. Lightning Injury: 30 million to 1 billion volts
  4. Arc Injury (High Voltage Injury)
    1. Occurs when patient is too close to a high voltage line and electricity diverts from line to body
    2. Patient becomes part of arc of current between 2 objects
    3. Most serious Electrical Injury
      1. Severe blunt Trauma may result
      2. Temperature may exceed 2500 C (4532 F)

V. Risk Factors: Lethal Electrical Injury

  1. Wet skin exposure
  2. Tetany
  3. Voltage >600-1000
  4. Electrical current that passes across the head
  5. Transthoracic electrical pathway (Arm-to-arm transmission, Arm to leg transmission, Chest direct contact)
    1. Does not increase risk of delayed Arrhythmia if alive at Emergency Department presentation
    2. Bailey (2007) Emerg Med J 24(5):348-52 [PubMed]

VI. History

  1. Type of electrical exposure (e.g. house power outlet, battery or power line)
    1. Attempt to estimate voltage (see above)
  2. Direct current or alternating current
  3. Duration of electrical current exposure (e.g. may occur with Tetany)
  4. Modifying factors (e.g. wet skin that increases electrical conductivity)
  5. High risk distribution of injuries (trans-thoracic contact points to electrical source)
    1. Arm-to-arm transmission
    2. Arm to leg transmission
    3. Chest direct contact
  6. Secondary Traumatic injuries (e.g. patient thrown)
  7. Arrhythmias noted on prehospital evaluation

VII. Exam

  1. See Trauma Primary Survey
  2. See Trauma Secondary Survey
  3. Estimate the percentage of total body surface area burn
    1. Precaution: Deep tissue damage may be extensive despite minimal surface skin changes
  4. Evaluate and monitor extremities with Electrical Injury for Compartment Syndrome
    1. Diminished pulse
    2. Increased pain on passive extremity movement
    3. Pallor
    4. Increased Compartment Pressures
  5. Consider pathway of current
    1. Electrical current that passes across the head or chest is high risk for serious morbidity and mortality

VIII. Labs

  1. First-line labs
    1. Complete Blood Count (CBC)
    2. Basic metabolic panel (Chem8)
    3. Creatine Kinase (CK)
    4. Urinalysis
  2. Labs with lower efficacy in Electrical Burns
    1. Cardiac Enzymes (Troponin)
      1. Poor correlation with cardiac damage and LV dysfunction in Electrical Burns
      2. CK-MB is falsely increased in Electrical Burns

IX. Diagnostics

  1. Electrocardiogram higher risk new findings
    1. ST Elevation
    2. QTc Prolongation
    3. New onset Arrhythmia (e.g. Atrial Fibrillation)

X. Management: General

  1. Resuscitation and Stabilization should follow ACLS and Trauma protocols
    1. See ABC Management
    2. See Trauma Evaluation
    3. Manage Arrhythmias via ACLS protocol
  2. Electrical (Thousands of volts) and lightning (Millions of volts) injuries are treated differently
    1. See Lightning Injury
  3. Specific Electrical Burn management
    1. See Burn Management
    2. Parkland formula for fluid Resuscitation typically underestimates requirements in Electrical Burns
      1. GIve 4 ml/kg per %BSA LR per day (with half in first 8 hours) for all ages until urine clears
    3. Rhabdomyolysis management if elevated Creatine Phosphokinase (CPK)
      1. Maintain Urine Output 200-300 ml/hour in adults
      2. Maintain >1 to 1.5 ml/kg/hour in children
    4. Evaluate for Compartment Syndrome
      1. Deep Muscle layers adjacent to bone are most susceptible (as bone has higher resistance to electricity)
      2. High risk for amputation, especially upper extremities (28 to 45% risk)
      3. Early exploration and decompression in all suspected cases
  4. Mouth burns in young children who may have chewed on live wire
    1. May present with injury at lateral commissure at mouth
    2. Close interval follow-up with oral maxillofacial surgery or plastic surgery
    3. Complications
      1. Functional and disfiguring complications
      2. Delayed labial artery bleeding at 5-14 days after Burn Injury
  5. Other measures
    1. Update Tetanus Vaccine

XI. Management: Disposition

  1. Burn center transfer indications
    1. High voltage Extremity Injury (esp. if concerns of Compartment Syndrome)
  2. Indications for admission with continuous cardiac monitoring (same criteria in children and adults)
    1. High Voltage Injury (>1000 Volts)
      1. Admit all High Voltage Injury patients (and monitor with telemetry) for at least 12 to 24 hours
    2. Low Voltage Injury Observation Indications (may also observe on telemetry for 6 hours, and one ekg at discharge)
      1. Loss of consciousness
      2. Abnormal EKG (at any time in their evaluation following Electrical Injury)
      3. Extensive Soft Tissue Injury or intractable pain
  3. Indications for outpatient management (all criteria)
    1. Low-voltage exposure (<1000 Volts) for short duration AND
    2. Normal exam AND
    3. Normal laboratory examination (No Myoglobinuria, normal CK, normal Renal Function) AND
    4. Electrocardiogram (EKG) normal

XII. Complications

  1. Rhabdomyolysis
  2. Cardiac Injury including Arrhythmia (e.g. Ventricular Fibrillation, Asystole, Atrial Fibrillation)
  3. Compartment Syndrome (and risk of Extremity Amputation)
  4. Secondary injury (from being thrown from DC electrical source)
  5. Neurologic Injury (altered level of consciousness, Seizure Disorders)

XIII. References

  1. (2018) ATLS, ACS, Chicago, p. 174
  2. Swaminathan and Patel in Herbert (2019) EM:Rap 19(11):1-3
  3. Walrath, Wood, Della-Giustina (2019) Crit Dec Emerg Med 33(6): 3-11
  4. Martinez (2000) South Med J 93:1165-8 [PubMed]

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