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Electrocution
Pathophysiology
Clinical features
Microshock
High tension and lightning injuries
Investigations
Management
Late complications
Pregnancy
Further reading
Pathophysiology
Extent of injury depends on:
- amount of current that passes through the body
- duration of current
- tissues traversed by the current
- Although the extent of injury is most directly related to amount of
current (amperage) often only the voltage is known. In general, low voltage
causes less injury but voltages as low as 50V have caused fatalities
Clinical features
Tissue heat injury
- currents > 1 A generate sufficient heat to cause burns to skin and
internal tissues
- blood vessels and nervous tissue particularly susceptible
Cardiac effects
- AC of 30-200 mA may cause VF
- currents >5 A cause asystole
- other arrhythmias may occur
- myocardial damage. ST and T wave changes. Global LV dysfunction may occur
hours to days later, even with minimal ECG changes
- MI has been reported. Diagnosis difficult due to raised CK levels (including
CK-MB) from extensive muscle injury
Skeletal muscle
- tetanic contractions with currents >15-20 mA. Prevent voluntary release
of source of electrocution
- may cause #s of long bones and vertebrae
- compartment syndrome is a common manifestation of electrical injury to a
limb
Vascular injuries
- thrombosis and occlusion with resultant ischaemia and necrosis
- affected limbs may require amputation
Neurological injuries
- can be central or peripheral, and immediate or late in onset.
- spinal cord damage resulting in para- or quadriplegia can result from a
current traversing both arms
- acute symptoms tend to resolve in comparison to the more ominous delayed
onset symptomatology
- monoparesis may occur in affected limbs (median nerve is very susceptible),
then ulnar, radial and peroneal.
- electrocution to the head can result in LOC, paralysis of the respiratory
centre and late complications such as epilepsy, encephalopathy, and
Parkinsonism.
- autonomic dysfunction can also occur, causing acute vasospasm or a late
sympathetic dystrophy.
Others
- acute renal failure due to rhabdomyolysis
- ruptured ear drum (high-voltage)
- cataracts may develop later
- associated injuries. Result of victim being thrown or falling or clothing
catching fire
Microshock
- above refers to macroshock, when current flowing through the intact skin
and body passes through the heart.
- microshock occurs when there is a direct current path to the heart
muscle
- pathway may include: a PA catheter, transvenous pacemaker wires
- current required to produce pathological effects is in the order of 60mA.
- can result from direct contact with faulty electrical equipment, or stray
currents
High tension and lightning injuries
- tissue damage usually due to generation of heat
- loss of consciousness usual in initial phase
- many survive and survival has been reported despite initial poor prognostic
signs (eg fixed dilated pupils)
- immediate death is usually due to cardiac arrest (asystole>VF)
Image
Investigations
- ECG, echo
- CT, EEG, nerve conduction studies
- X-rays of spine and long bones
- Hb, electrolytes
- CK and urine myoglobin
- arteriograms may help in decisions to amputate limbs
Management
- treat burns (complete excision required) with fasciotomies ± amputation
- consider the possibility of traumatic injuries
- ± prophylactic treatment to prevent
rhabdomyolysis induced renal failure
- large volumes of IV fluid often required
- supportive
Late complications
- muscle fibrosis
- peripheral neuropathies
- loss of tissue from debridement
- joint stiffness
- reflex sympathetic dystrophy
- cataracts
- paraplegia
- quadriplegia
- subtle mental changes
- electrical pathway if often from hands to feet and therefore passes
through the uterus
- high prevalence of fetal death. Other fetal complications include
oligohydramnios and intrauterine growth retardation
- management includes cardiotocography, ultrasound and obstetric
consultation
Further reading
Critchley LA, Oh TE. Electrical safety and injuries. In Oh TE, Intensive Care
Manual 4th ed, Butterworth Heinemann, Oxford 1997
©Charles Gomersall and Ross Calcroft September 1999
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