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.
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
CK or myoglobin, if deep injuries are suspected based on muscle pain, for instance
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: