Electrical injuries: Difference between revisions
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###May result in little tissue damage, but [[cardiac dysrrhythmias]] are still of great concern | ###May result in little tissue damage, but [[cardiac dysrrhythmias]] are still of great concern | ||
:The primary determinant of injury is the amount of current flowing through the body which depends on | |||
# Voltage | |||
# Resistance | |||
*:# Amperage | |||
# Type of current | |||
# Current pathway | |||
# Duration of contact all influence the extent of injury. | |||
==Clinical Features== | ==Clinical Features== | ||
===Immediate Effects=== | ===Immediate Effects=== |
Revision as of 23:06, 6 February 2015
Background
- Tissue damage occurs via electrical energy, heat, and mechanical injury from trauma
- Skin, bone, tendon all have very high resistance
- Muscle, nerves, vasculature have lower resistance, more often damaged
- Types:
- Low-Voltage
- High-Voltage (>1000V), seen in industrial settings or transmission line injuries
- Associated with electrical burns
- Electric Arc
- Associated with high voltage sources
- May radiate enough heat to burn persons 10ft or more away from the arc
- Blast force may result in trauma
- Burn from biting an electric cord assoc w/ delayed labial bleeding (5d later) in ~10% of peds
- Direct (lightening) vs. alternating (household) current
- Alternating has combination of the following mechanisms
- Current arcs onto body, envelops surface of body, then arcs to lower electromotive potential (ground)
- Current flows through body tissues
- Direct current most often demonstrates flow-over phenomenon
- Lightening can reach 1-5 million volts, but current flows over the body and exits to the ground
- May result in little tissue damage, but cardiac dysrrhythmias are still of great concern
- Alternating has combination of the following mechanisms
- The primary determinant of injury is the amount of current flowing through the body which depends on
- Voltage
- Resistance
- Amperage
- Type of current
- Current pathway
- Duration of contact all influence the extent of injury.
Clinical Features
Immediate Effects
Cardiac Dysrhythmias
- Fatalities due to asystole or V-fib usually occur prior to arrival
- Most common dysrrhythmia at presentation is A-fib (V-fib is more common, but pts are dead PTA)
- Asymptomatic pts w/ normal ECGs do not develop later dysrhythmias after <1000V injuries
Cardiovascular Injury
- Contraction band necrosis[1]
- Medial necrosis of large vessels
- Aneurysm formation
- Coagulation necrosis of small vessels
- Can lead to compartment syndrome
CNS Injury
- Occurs in 50% of pts w/ high-voltage injuries
- Brain injury ranges from transient LOC to CVA to respiratory arrest
- High voltage injuries involving head are frequently associated with coma and persistent vegetative state
Orthopedic Injury
- Forceful muscle contractions can cause fracture and joint dislocations (especially shoulder)
- May occur with voltages as low as 120V
- Compartment Syndrome
- Usually a/w high-voltage injuries
- May occur even with 120V shocks if contact is sustained for longer than few seconds
- Pt experiences ongoing muscle pain with movement
- Need for fasciotomy predicted by:
- Myoglobinuria
- Burns >20% BSA
- Full-thickness burn >12% BSA
- Rhabdomyolysis
- Associated with:
- Contact with >1000V
- Prehospital cardiac arrest
- Crush injury
- Compartment syndrome
- Full-thickness skin burns
- Associated with:
Ocular Injury
- Cataract formation has been described weeks to years after electrical injury
- Document presence or absence of cataracts following all electrical injuries
Auditory Injury
- May be damaged by current or hemorrhage
- Check hearing in all pts
Cutaneous Burns
- Often seen at electrical contact areas
- Seriously injured pts often have burns on either arm or skull + feet
- Most pts w/ burns from electrical injury require admission and care by burn specialist
GI Injury
- Suspect in pts with:
- Electrical burns of abdominal wall
- History of a fall, nearby explosion, or other mechanical trauma
Workup
- EKG, telemetry
- BMP, CBC
- Lactate
- Serial troponins, CK-MB
- LFTs
- CK
- UA, urine myoglobin
Treatment
- Usual trauma evaluation and resuscitation applies
- Use Parkland formula as starting point for fluid resuscitation
- Fluids in first 24 hrs = TBSA burned(%) x Wt(kg) x 4ml; Give 1/2 in first 8 hours, then give other 1/2 over next 16 hrs
- Treat rhabdo and compartment syndrome in usual manner
Disposition
- Discharge
- Asymptomatic pts w/ normal ECG on presentation after a <600V injury
- Admit
- All pts with high-voltage injuries (even if asymptomatic)
- Pts w/ low-voltage injury if symptomatic (e.g. chest pain, burns, abnl ECG, abnl CK)