10. Type of circuit
Either direct current (DC) or
alternating current (AC).
High-voltage DC contact tends to
cause a single muscle spasm, often
throwing the victim from the source
AC exposure to the same voltage
tends to be three times more
dangerous than DC.
11. Resistance
Resistance is the tendency of a
material to resist the flow of electric
current; it is specific for a given tissue,
depending on its moisture content,
temperature, and other physical
properties.
The higher the resistance, the greater
the potential for transformation of
electrical energy to thermal energy.
12. Nerves, muscle and blood vessels,
because of their high electrolyte and
water content, have a low resistance
and are good conductors.
Bone, tendon, and fat, which all
contain a large amount of inert matrix,
have a very high resistance and tend
to heat up and coagulate rather than
transmit current.
The other tissues of the body are
13. Current
Current, expressed in amperes, is a
measure of the amount of energy that
flows through an object
Amperage is dependent on the source
voltage and the resistance of the
conductor. (Remember I=V/R)
The voltage of the source is known but
the resistance varies
The physical effect vary with different
amperage.
14. "let go" current
• The maximum current at which a person
can grasp the current and then release it
before muscle tetany makes letting go
impossible.
15. Duration of contact
The longer the duration of contact with
high-voltage current, the greater the
electro thermal heating and degree of
tissue destruction.
With lightening injury The extremely
short duration and extraordinarily high
voltage and amperage of lightning
both result in a very short flow of
current internally, with little, if any, skin
breakdown and almost immediate
flashover of current around the body.
16. Voltage
Voltage is a measure of the difference
in electrical potential between two
points and is determined by the
electrical source. Electrical injuries are
conventionally divided into high or low
voltage using 500 or 1000 V as the
most common cutpoint.
The higher the voltage the more is
tissue distraction
17. Pathway
The pathway that a current takes
determines the tissues at risk, the type
of injury seen, and the degree of
conversion of electrical energy to heat.
Heart: Dysrhythmias and myocardial
damage
Brain: Seizures, and paralysis.
Eyes: Cataracts
18. Mechanisms of Injury
Direct effect of electrical current
Thermal burns (conversion I to E)
Mechanical Trauma
Post-trauma sequelae
19. Direct effects of current
In general, type & extent of injury depends on
current intensity (amps) (I = V/R)
Cardiac, neurologic and respiratory systems
most susceptible to direct effects
Skin is the resistor most effecting severity of
injury
◦ Wet skin has lower R (~1K ohm) vs. dry or
thick skin (>100K ohm), resulting in greater
current flow
20. Thermal (Burn) Injuries
Heat (E) = IVT
Type & extent of injury depends on current
intensity (I)
R varies significantly between tissues
◦ Tissues with high R (e.g., bone), generate
more heat, resulting in osteonecrosis and
deep tissue periosteal burns
◦ Skin also has high R, thus entry/exit wounds
◦ Decreasing R (e.g., wet skin) results in lower
thermal injury, but higher current
conductance
Coagulation of muscle, fat, vessels
21. Mechanical Trauma
Trauma can result from fall or muscle
contraction
Classic example is shock wave of lightning
causing blast injuries
Even at low V, tetanic muscle contraction
can result in bone fx
◦ Cord injury can result from severe muscle
contraction, w/o any external signs of
trauma
Can result in vascular compromise
◦ Acute hypotension should always prompt
search for thoracic or intra-abdominal
22. Post-trauma sequelae
Crush injury syndrome (rhabdomyolysis,
myoglobinuria)
Multi-organ ischemic injury 2o to vascular
coagulation or dissection
Hypovolemic shock 2o to massive 3rd
spacing
Iatrogenic injuries from acute resuscitation
◦ Abdominal compartment syndrome
◦ ARDS
23.
24.
25.
26. Lichtenberg Figures
Rare pathognomonic
“flower-like” branching
skin lesions in persons
struck by lightning
Caused by “flashover”
effect of non-penetrating
current
Rapidly fade, not
typically serious
27. Management I
Standard ABCDEs of any major trauma
Pulmonary
◦ Low threshold for intubation, as respiratory
failure common
Cardiac
◦ Serial monitoring if high V, abnormal ECG,
LOC, respiratory arrest, or PMH of CV
dysfunction
Neuro
◦ C-spine and log-roll precautions; CT head &
spine often warranted
◦ Thorough serial neurological exams, as
vessel coagulation can result in late
28. Management II
Musculoskeletal
◦ Thorough evaluation for fractures
◦ Serial evaluations of limbs for compartment
syndrome requiring emergent decompression
◦ Even in absence of compartment syndrome,
persistent aciduria or myoglobinuria may require
limb amputation
Skin
◦ Early debridement and later reconstruction
◦ Antibiotic prophylaxis (controversial)
Renal
◦ Fluid resuscitation key, as 3rd spacing common &
myoglobinuria 2o/2 rhabdomyolysis can cause ARF
29. Management III
GI
◦ Ulcer prophylaxis, as gastric ulcers
(Curling’s ulcers) can develop
◦ Ileus uncommon, but should prompt
evaluation for other injury
Serial evaluation of liver, pancreatic, & renal
function for traumatic/anoxic/ischemic injury
Judicious management of fluid and
electrolytes to avoid acidosis and
compartment syndromes
30. Admission:
In contact >600V
Symptoms (Chest Pain, Palpitation, LOC,
confusion, weakness, dyspnea, abdominal
pain)
Signs (weakness, burns with subcutaneous
damage, vascular compromise)
Ancillary changes (ECG, CK,
myoglobinuria)
Cardiac monitoring: If ECG abnormal
No Admission:
Household voltage injury 100-220V in adult
Negligible risk for delayed arrhythmias
Asymptomatic, normal ECG and normal
31. Prognosis
Highly variable, depending on severity of
both initial injury and subsequent
complications
High morbidity/mortality in patients with
multisystem organ failure
Advances in surgical interventions (early
excision, fasciotomy, skin grafts, etc…)
have improved
32.
33. References
DM Mozingo & BA Pruitt. 1998. Electric Injury. in Fundamentals
of Surgery, 1st ed, JE Niederhuber, pp 194-195.
DS Pinto & PF Clardy. 2007. Environmental electric injuries. Up-
to-Date, accessed 06/01/2007.
TN Pham & NS Gibran. 2007. Thermal & Electrical Injuries.
Surg Clin N Am 87:185-206.
AC Koumbourlis. 2002. Electrical Injuries. Crit Care Med
30:S424-S430.
C Spies & RG Trohman. 2006. Electrocution & Life-Threatening
Electrical Injuries. Ann Intern Med 145:531-537.
