Background
Cardiac monitoring is not needed in household electrical injury in patients with a normal ECG [BestBets].
Electrical Injury dependant upon
- Power source (lightning or electrical)
- Voltage (potential difference). High voltage >600V. Domestic supply = 240V
- Current (amount of energy flowing)
- Duration of contact
- Type of current (AC or DC)
- 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)
- VBG 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]