Electrical Injury Flashcards
Factors that determine extent of injury in electrocution:
It is the experienced CURRENT (amps) that determines injury.
1- Voltage
- HIGH = >1000v
2- Current type (AC/DC)
- AC worse
3- Path
- Eg. In and out a limb, vs across thorax or vertically down whole body
- Smaller surface area = more dense, damaging current Eg. Finger vs trunk
4- Tissue resistance
- Wet
- Tissue type: nerve < membranes < thick skin <bone
5- Duration
- Tetany can increase
Risk of taser:
50,000V in brief pulses over 5secs
Electrical risk negligent
- Look/Tx secondary injury
- Check barb site
- Consider ECG/ BSL
Which organ systems are most susceptible to electrical injury?
Nervous
Cardiovascular
*Amniotic fluids conducts ++- fetal risk
How risky is household power?
AUS household:
- 250V (voltage)
- 50 Hz (frequency)
- AC
POTENTIAL FOR SERIOUS HARM
- In vulnerable range of 40 - 150 Hz
- Capable of causing VF
- Worse if wet
ELECTRICAL TERMINOLOGY:
Voltage
Current
Frequency
AC/DC
Resistance
Voltage (volts)
- Driving force of current
Current (amps)
- Volume of electricity flowing
- Thing that is significant to injury
Frequency (Hz)
- Number of pulses per second
Alternating current vs direct current
- Household is AC
- Batteries/ lightening are DC
Resistance (Ohms)
- Hinderance to current
- Can offset high voltage
- Current travels path of lease resistance
What electrical parameters carry risk of serious injury:
Experienced CURRENT:
10mA = tetany
20mA = resp paralysis
100mA = VF , often fatal
1amp = cardiac standstill, multiorgan injury, unsurvivable burns
DCR is about 30amps
VOLTAGE >600v
(‘High’= >1000)
FREQUENCY >40Hz
*Human tissue sensitive to 40-150Hz
AC vs DC
Potential electrocution injuries:
External injuries are NOT a good guide of internal damage
NERVOUS
Highly susceptible
ALOC, seizure etc.
Motor deficit
Delayed up to 2 years: ALS,
Ascending paralysis, transverse myelitis etc.
*Kauranoparalysis (lightening)
CVS
Nonspecific ST/T
VF
Standstill
Delayed arrythmia doesn’t often occur
Myocardial necrosis
Thrombosis, vessel rupture/haemorrhage
GI
Ulcers
Ileus
Bowel perf
Solid organ injury incl liver/ pancreas necrosis
DERM
Entry/exit wounds
Thermal burns
Flash, arc, ignition
MSK
Rhabdo
Compartment syndrome
OTHER
Traumatic injury
Retinal detachment, retinal artery occlusion, vitreous haemorrhage, cataracts, optic neuropathy
Tympanic rupture, Deafness, vestibular dysfunction
Discharge criteria following electrocution:
Low voltage (<1000v)
No LOC
No dysrhythmia
No organ damage incl. rhabdo
Not a transthoracic current (admit 24/24 telem + enzymes)
Refer all electrical burns to a burn unit
APPROACH TO ELECTROCUTION:
ACLS + Trauma + burns
IMMEDIATE
CSpine precautions
ECG, telemetry, attach pads
First aid to burns
ASSESS
Fully expose
Complete, multi system assessment. Assess for:
- Burns
- Compartment syndrome
- Secondary traumatic injuries (remember tympanum, eyes)
INVESTIGATE
CT Cspine
+- Trauma series
Bloods incl gas, coags, trop, CK, LFT, lipase, CMP
Urine myoglobin
SUPPORTIVE
NGT, esomeprazole
IDC, fluid balance
Tx SPECIFIC CX eg. Rhabdo
Why does lightening strike have good prognosis?
70-90% survive
Including 50% who arrest
Up to 2 billion volts, 300,000 amps
BUT:
Brief (millisecs)
Much is’flashover’/external
Often not direct hit: Ground strike, splash arcs,
What are the 2 pathognomic lightening injuries?
Keraunoparalysis
Temporary (1-6 hours) ‘stunning’ of the nervous system
Flaccid paralysis, sensation loss
Cool, mottled limbs (vasospasm)
Lichtenberg flowers
+cataracts
Ohms Law:
Current (amps) = voltage (volts) / resistance (ohms)
What is the concern when children bite electrical cords?
Burn to lip
When eschar falls off, risk of bleeding+++
