Electrical injuries

Disclaimer

These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline. 

Read the full PCH Emergency Department disclaimer.

Aim

To guide staff with the assessment and management of electrical injuries.

Background

  • Electrocution occurs when current passes through a person and disrupts normal electrical function of cells
  • Most electrical injuries occur in the home, usually associated with electrical cords (60-70%) and wall outlets (10-15%)
  • If a healthy child is exposed to common household electric current, is asymptomatic and no evidence of arrhythmia/ cardiac arrest, they can be discharged safely

The extent of the damage done is determined by: 

Amount of electrical current flow:

  • High voltage (>1000V) vs low (<1000V) 

Type of current (AC v DC):

  • AC (most common in Australian homes), is more dangerous, causes tetanic muscle contraction and ‘lock-on’ effect
  • DC is less dangerous, patient tends to be thrown away from source.

Current path:

  • Trans-thoracic (hand to hand), has a high mortality (>60%) due to increased spinal cord and myocardial damage
  • Vertical (hand to foot), mortality >20% due to cardiac arrhythmias
  • Straddle (foot to foot) low mortality <5%.

Which tissues did it flow through?

  • Moist tissue (mouth) or wet skin increases conduction and therefore results in a more severe injury
  • Thin skin increases susceptibility to severe injuries.

Duration:

  • Prolonged contact increases severity of injury.

Three main electrical injury patterns:

  • Direct trauma from electric current (direct tissue damage, e.g. cardiac ischaemia/arrhythmia, compartment syndromes, rhabdomyolysis, peripheral nerve injury)
  • Trauma from conversion of electrical energy to thermal energy (burns)
  • Mechanical effects of electric current (violent muscle contraction which may lead to fractures/dislocations, falls resulting in possible trauma).

Lightning injuries:

  • Results in an instantaneous massive unidirectional current (DC) and thus a different pattern of injury to electrical injury
  • Rarely causes burns/soft tissue destruction as it is too quick and no 'lock on'
  • Likely to cause asystolic cardiac arrest (depolarises entire myocardium) or respiratory arrest (thoracic muscle spasm/central respiratory depression)
  • Relatively high (up to 50% chance of survival) if CPR commenced early and continued  
  • Asystole may spontaneously recover therefore management of apnoea and respiratory arrest is imperative
  • Cardiac: 
    • VF likely secondary to hypoxia not lightning shock induced
  • Neurologic:
    • Immediate transient (LOC, confusion, anterograde amnesia, weakness, paraesthesia)
    • Immediate persistent (hypoxic encephalopathy, intracranial haemorrhage)
    • Delayed (motor neuron disease, movement disorders)
  • Traumatic:
    • Fall resulting in spinal cord injury, epidural or subdural haematoma
  • Autonomic instability:
    • Keraunoparalysis (transient paralysis and appearance of acute arterial insufficiency of limb).

Assessment

History

  • Electrical source, voltage, duration of contact, environmental factors at scene, resuscitative measures already provided
  • Previous medical history (especially cardiac)
  • Tetanus immunisation status.

Examination

General

Consider whether critically unwell or not, if so take ABCDE approach, in particular:

  • Airway: burns or soft tissue swelling to mouth, face, anterior neck (children may have oral burns from chewing electric cord)
  • Cervical spine: consider need for immobilisation if thrown from source
  • Circulation: VF commonest arrhythmia in arrested patients. Asystole common in high voltage and lightning strikes. Other arrhythmias are also possible.

Specific

Skin

  • Size, location of burns
  • Entry and exit wounds: may be deceptively small, with extensive underlying soft tissue damage
  • Wound location give information about the pathway of the current through the body, if far apart increase tissues exposed for internal injuries to have occurred
  • Low voltage: small, well-demarcated contact burns at entry and exit sites
  • High voltage: serious burns, painless, yellow-grey charred craters with central necrosis, or skin sparing with damage to underlying soft tissue and bone
  • Kissing burn: occurs at flexor crease when current arcs across both flexor surfaces, associated with extensive underlying tissue damage.

Neurological exam

  • Most common CNS symptom is loss of consciousness
  • Other CNS symptoms may include acute peripheral neuropathy, transient paralysis/paraesthesia
  • Incidence of spinal cord damage is 2-27% following high voltage injury when the current travels arm to arm or arm to leg
  • May resemble lower motor neuron disease, amyotrophic lateral sclerosis or transverse myelitis.

Eyes

  • Visual acuity and fundoscopy due to risk of direct trauma and cataract.

Ears

  • Hearing and examination of tympanic membrane as risk of tympanic membrane rupture.

Limbs

  • Check range of movement and for bony tenderness
  • Neurovascular observations to extremities to assess for vascular damage/delayed onset compartment syndrome.

Initial ECG for all:

  • Looking for arrhythmia or cardiac ischaemia
  • Incidence of arrhythmias is 4-17%
  • Low volt AC is more likely to cause cardiac consequences
  • Delayed arrhythmias are rare, only in those with arrhythmia on presentation (hence screening ECG on arrival).

Further investigation is only required for significant electrical injuries such as:

Urinalysis

  • For myoglobinuria to exclude rhabdomyolysis.

Bloods

  • In those at risk for conductive electrical injury (patients with entry/exit wounds or cardiac arrhythmia and patients with high voltage injury), CK, FBC, UEC, LFTs & Lipase (if intra-abdominal injury is suspected)
  • Patients may have a high potassium, low calcium, high phosphate or metabolic acidosis.

Radiology

  • Consider as clinically indicated.

Management

Initial management

  • Resuscitate as required according to advanced paediatric life support, specifically consider whether airway involvement will cause airway issues
  • Cardiac monitoring if evidence of ischaemia or arrhythmia on ECG, loss of consciousness or high voltage injury
  • Remove jewellery/constricting objects early to reduce risk of oedema
  • Cool burns
  • If patient appears well following a low voltage injury, they are likely well.

Further management

  • Supportive care:
    • Consider IV fluid to maintain urine output of 1-1.5ml/kg/hour (Burns Parkland formula not applicable for fluid calculation)
    • Discuss with Paediatric Burns team early.

Medications

  • Ensure tetanus immunisation is up to date.

Admission criteria

  • History of loss of consciousness, documented dysrhythmia or evidence of cardiac ischaemia - admit for cardiac monitoring
  • Evidence of significant burns - admit under Paediatric Burns team
  • Evidence of significant trauma - admit under Paediatric Surgical, Orthopaedic, or Burns Team dependent on injury
  • Evidence of rhabdomyolosis - admit under Paediatric Burns team or other team depending on other injuries.

Discharge criteria

  • Normal ECG
  • No history of loss of consciousness
  • No burn/trauma injury requiring admission.

 

Bibliography

  1. Czuczman AD, & Zane RD, Electrical injuries: a review for the emergency clinician. Emergency Medicine Practice. Evidence Based Medicine. 2009, Vol 11 (no. 10)
  2. Arnoldo B, Klein M & Gibran NS, Practice Guidelines for the Management of Electrical Injuries. Journal of Burn Care and Research. 2006, (Jul/Aug) pp. 439-447

Endorsed by:  Director, Emergency Department   Date:  Mar 2018


 Review date:   Feb 2021


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