TRAUMA TUESDAY
Today’s trauma pearl of the day is about electrical injury! Thanks to Mark Ramzy for the suggestion and for the clinical images from a patient he had yesterday.
⚡️Electrical Injury⚡️
Electrical injuries can range from mild to severe
- injuries and management will depend on the level of exposure
- lightning
- high voltage > 600V
- low voltage < 600V
- type of current (AC or DC)
To give you an idea of how much voltage you’re dealing with, typical household electricity provides 110V for general and 240V for high power appliances, industrial electrical lines can have more than 100,000V.
Voltage: the relationship between voltage (V), current (I) and resistance (R) as V = I x R
Current is the measure of the amount of energy flowing through the body
- Skeletal muscle tetany occurs at 16-20 mA - this is why someone is unable to let go when being electrocuted
- Ventricular Fibrillation occurs at 50-100mA
Resistance is the impedance to flow, depending on electrolyte and water content
Circuit:
- Alternating current (AC) - the most common in homes and offices
→ Much more dangerous than DC! The alternating current causes muscle tetany, so the patient can’t let go
→ High voltage AC: overhead power lines
→ Low voltage AC: household electric appliances
- Direct current (DC) - causes a single muscle contraction, throwing the person away from the source
→ The third rail of the subway
ED Approach to electric injury - things to know and do
- Carefully detailed history
→ what type of current? estimated voltage? loss of consciousness?
- Detailed physical exam, especially careful to look for burns
→ Lichtenberg figures is pathognomonic for lightning injury
- Autonomic dysfunction
→ Dilated pupils may persist for 24-48 hours
→ Keraunoparalysis - transient weakness, sensory changes, pallor, pulselessness affecting lower limbs > upper limbs
- Entry and exit points in electrical injury (not lightning)
- Beware of delayed bleeding from the labial artery in peri-oral burns (kiddos biting on electrical cords)
- TMs may rupture due to blast effect in lightning strikes
- Always get an EKG!
→ Sinus tach, PVCs are common
→ Dysrhythmias may include VT, VF, asystole
→ Long QT or TWI may also be seen
- If the injury was high voltage, patients should be on a cardiac monitor for 24 hours to watch closely for dysrhythmias
- Other workup as expected for trauma patients - head CT, other imaging as needed, labs, etc.
What if my patient got tased??
- Conducted electrical weapons (CEW aka tasers) are used by police, and those patients sometimes end up in the ED
- The current is high voltage, but neither AC nor DC, but more like a series of low amplitude DC shocks
- A 5 second pulse can delivery 50,000V (current 2.1 mA)
- Generally considered safe without cardiac damage or delayed arrhythmias
This patient was an electrician who got electrocuted while working. Note the area of burned skin where the hair is singed completely off!
