Electrocution



Background

Cardiac monitoring is not needed in household electrical injury in patients with a normal ECG [BestBets].

Electrical Injury dependant upon

  1. Power source (lightning or electrical)
  2. Voltage (potential difference). High voltage >600V. Domestic supply = 240V
  3. Current (amount of energy flowing).
  4. Duration of contact
  5. Type of current (AC or DC)
  6. Contact : Damp or wet hands/contact significantly reduce resistance to current

Skeletal muscle tetany occurs particularly with AC current. DC current tends to throw contact away, AC (50Hz as in domestic supply) causes tetany

  • For adults, the "let go" current is 6-9 mA
  • VF occurs at 50-100 mA

Current usually passes through body causing burns at entry and exit points.


Clinical

Electrical injuries can cause:

  • Cardiac or respiratory arrest (may be seen with low voltage)
  • LOC
  • Blunt trauma (usually high voltage or DC current that throws patient from contact)
  • Burns (particularly with high voltage, without LOC or cardiorespiratory arrest)

Approach

Thorough (and collateral) history

Trauma primary & 2° surveys

If concern:

  • Trauma series x-rays
  • FBC, x-match (significant trauma)
  • U&E & Creat, CK
  • Urinalysis (myoglobin)
  • ABG if severe rhabdomyolysis
  • Troponin if pathway across chest
  • ECG (arrhythmia / ischaemia)

Electrical Burns

  • Photograph if possible

High-voltage electrothermal burns:

  • Contact point and ground point
  • May have very significant deep burn with skin sparing (painless, little bleeding)
  • Full thickness will have intact skin hairs (as opposed to flash or flame burns)

Arc burns (only high voltage)

  • High temperature at contact and ground sites
  • Dry centre, cratering , surrounding oedema/erythema

Flash burns

  • Due to intense heat from nearby arc
  • May "splash" over surface of body with superficial burn, no "electrocution"

Flame burns

  • Nearby clothing etc. igniting with resulting thermal burn
  • Vary local superficial to full thickness

Management points

  • Admit (CDU) those with chest pain/ arrhythmia / abnormal initial ECG, Hx arrest
  • Domestic electrocution with no cardiac complaints and normal ECG can be discharged [BestBets]

Content by Dr Íomhar O' Sullivan. Last review Dr IOS 21/06/21.