section name header

Information

Editors

JanneAlakare

Electrical Accidents

Essentials

  • The patient must no longer be in contact with the electrical circuit before he/she can be safely helped. The electricity company should confirm that a high-voltage current has been switched off, as necessary. A high-voltage electrical arc may reach several metres.
  • Initial treatment aims at safeguarding vital functions with ABCDE principles (securing breathing and circulation; resuscitation, if needed).
  • Find out the power source and voltage, the flow of electrical current, whether there was loss of consciousness, and any other symptoms.
    • The possibility of associated injuries must be taken into account (neck injury in an unconscious patient, other fractures, damage to the muscles or internal organs).
    • Severe electrical injuries are usually associated with high-voltage current and require intensive care in most cases.
    • Low-voltage injuries involve immediate danger at the time of exposure to electricity, but injuries are rare.
  • After exposure to low voltage (< 1 000 V), there is no need for laboratory tests or follow-up in a hospital if the ECG is normal, there are no skin burns or other injuries, and the patient is asymptomatic.
  • Patient guidance by phone
    • If there is a high-voltage injury or the patient was struck by lightning, or if they have skin burns or significant symptoms, instructions should be given to call the emergency services call centre on 112 for assessment and arrangement of initial treatment.
    • There is no need to seek treatment if an adult's dry skin was momentarily in contact with a household electricity network or other low-voltage current, there was no loss of consciousness, and there are no clear symptoms or skin injuries following the event.

Epidemiology

  • In the USA (population 340 million), about 1 000 people die each year because of electrical accidents http://www.ncbi.nlm.nih.gov/books/NBK448087/. In Finland (population 5.5 million, 0-3 people every year die of an electrical injury.
  • Deaths from being struck by lightning are very rare in many countries.

Danger level of electrical current

  • Electrical injuries are classified by voltage.
    • High-voltage injuries are caused by a voltage of at least 1 000 volts (V).
    • In low-voltage injuries, the voltage is below 1 000 V.
  • High-voltage injuries may occur without contact with the circuit, through an electrical arc.
  • According to Ohm's law, the strength of the electrical current in tissues depends on the voltage and the resistance of the body.
    • Electrical current I (in amperes, A) = voltage U (in volts, V) / resistance R (in ohms, Ω)
    • The resistance of the human body depends essentially on whether the skin is moist.
      • Dry skin, up to 100 000 Ω
      • Moist skin, 1 000-2 500 Ω
      • Deep tissues, 500 Ω
    • In low-voltage injuries, dry skin protects the person quite well at first, but if exposure continues and the skin is damaged, its resistance decreases.
  • Typical effects of 50 hertz alternating current at various levels of electrical current
    • 1 mA: barely perceptible
    • 16 mA: maximum alternating current a human can grasp and let go
    • 20 mA: muscle spasms in the extremities
    • 20-50 mA: spasm of respiratory muscles
    • 50-100 mA: ventricular fibrillation possible
    • 2 A: cardiac arrest likely
  • The effects of electrical current are due to
    • heat injury caused by electrical energy being converted to heat due to resistance in tissues
    • depolarization caused by the current
    • direct damage to cell membranes (electroporation).
  • When moving from one limb to another, the current flows through the route with the lowest resistance, primarily through blood vessels, predisposing the patient to risks of cardiac origin.

Injuries

  • Burn injuries to the skin (heat injury caused by electrical current)
  • Direct damage to tissues in blood vessels, muscles, internal organs (including the heart) and the CNS
    • Usually due to high-voltage injuries
    • Since the electrical current flows from the already-damaged skin area to deep tissues, the extent of the injury cannot be concluded from the extent of the skin burn.
  • Ventricular fibrillation and other arrhythmias caused by depolarization
  • Loss of consciousness caused by depolarization in the CNS
  • Damage to the myocardium or conduction pathways caused by the electrical current
  • Muscle injury associated with prolonged muscle spasm
  • Secondary injuries and acute cases
    • Falling from standing or from a height due to loss of consciousness or a muscle spasm
    • Secondary cardiac events resulting from a catecholamine storm

Treatment

Initial management

  • Make sure that the patient is not in contact with the electrical circuit or that the power supply has been switched off.
  • Resuscitation according to protocol if the patient does not show signs of life (unresponsive, apnoeic, pulseless) Treatment of Cardiac Arrest in Primary Health Care
  • Assessment and treatment based on systematic assessment of vital functions (ABCDE)
  • Examination of the skin to assess skin injuries (burns) caused by the electrical current
  • ECG
  • Observation of any associated injuries
  • Investigation of the exact description of the event to assess the type and duration of the electrical shock
    • Examination and treatment of patients with high-voltage injuries: treatment as per patients with high-energy injuries; refer for treatment at a burn centre, or to another unit responsible for such severe injuries.

Low-voltage injuries in health care units

  • Find out about the description of the event, survey of symptoms
  • Examination of the patient according to general principles, assessment of vital functions
  • Examination of the skin to assess burns caused by electrical current, observing any associated injuries
  • ECG
  • Referral to an emergency unit, as necessary, treatment according to the findings
  • Laboratory tests or follow-up in hospital are not indicated in adults if all of the following criteria are met:
    • normal ECG
    • no injuries or skin burns
    • no significant symptoms.
  • After low-risk low-voltage injuries, some patients with no clinical findings have mild symptoms, such as mild numbness. Risk assessment of such symptoms requires interpretation by a clinician.
    • Nature of the symptoms in relation to what is known about the event
    • Being startled is associated with sympathicotonia, which may cause secondary symptoms of cardiac origin.

Instruction by phone

  • In any of the following cases, provide instructions to contact initial treatment (112) to arrange assessment and treatment:
    • high-voltage injury or struck by lightning
    • significant symptoms
    • skin burns
    • loss of consciousness
    • child patient.
  • There is no need for emergency assessment, if all of the following criteria are met:
    • low-voltage injury of short duration on dry skin
    • no loss of consciousness
    • patient asymptomatic after the event
    • no skin burns.