9 Electrical Injury Flashcards
High vs low voltage
High: ≥1000 V
Low <1000 V
Ohm’s law
Current = voltage/resistance
Biologic tissue with the greatest resistance to electric current
Bone
Biologic tissue with the low resistance to electric current
Nerves and vascular structures
Remarks on AC
Alternatint current (AC)
AC can be more dangerous than similar levels of direct current (DC) because the alternating current fluctuations can result in ventricular fibrillation
AC can produce muscular tetany, during which the victim cannot let go of the electrical source.
- may lead to hundred times worse heat-related injury to deep tissues
Remarks on home outlets
US: 120 V
Europe and Australia: 240 V
Philippines: 220 V
Mechanism of injuries in electrical-induced injuries
- Direct tissue damage from the electrical injury
- Tissue damage from thermal energy
- Mechanical injury from trauma induced by a fall or muscle contractions
Remarks on low-voltage injuries
- Asymptomatic patients with normal ECGs on arrival to the hospital do NOT develop later dysrhythmias after low-voltage (<1000 V) injuries, hence admission is not needed.
- Low-voltage injuries who are asymptomatic and with normal physical examination do nOT require laboratory testing and imaging.
Remarks on high-voltage injuries
Because of concomitant vascular and muscular destruction, patients at high-voltage shocks are at significant risk for compartment syndrome, even if the contact (or arcing) lasted <1 second.
Commonly seen with orthopedic injury with electrical injuries
Posterior shoulder dislocations
Stay at least ______ from downed power lines
10 meters, but even this distance is not without risk
remarks on vehicle in contact with a power line
- A rescuer standing on the ground touching any part of a vehicle that is in contact with a power line is likely to be killed or seriously injured.
- Electric shock is not prevented in this situation by the rescuer’s wearing rubber gloves and boots, unless these are designed for the voltage present and have bee recently tested for insulation integrity.
- Persons inside a vehicle in contact with a power line are likely to be killed as they step out of the vehicle and may also receive a shock if they touch objects at different potentials inside the vehicle.
Other management of electrical injuries
Maintain spinal immobilization
Fluid resuscitation in electrical injuries
4 ml/kg/% tBSA
If myoglobinuria is present, maintain a urinary output of
1-2 mL/kg/hour
All patients having contact with _______ voltage should be admitted for obsevation, **even if there is no apparent injury
≥600 V AC
Lighting fatalities are most common in
fishermen
Remarks on lightning prognosis
70-90% survive
but as many as 75% of these survivors have permanent sequelae
Types of lightning strikes
- Direct strike
- Side flash
- Contact strike
- Ground current
- Upward streamer
Cardiac and respiratory arrests in lightning injuries
- Both cardiac and respiratory arrest may be present without evidence of external injury
- Although cardiac automaticity may spontaneously return, concomitant respiratory arrest may persist and lead to a secondary hypoxic cardiac arrest.
- The duration of apnea, rather than the duration of cardiac arrest, appears to be the critical prognostic factor
Remarks on lightning casualties
- In contrast to patients with cardiac arrest caused by mechanical trauma, persons with lightning injury who appera to be dead (in respiratory arrest, with or without cardiac arrest) should be treated first
- Such victims may have little physical damage, and they have a reasonable chance of successful resuscitation.
- Lightning victims in cardiac arrest have a better prognosis than that of CAD, and so aggressive resuscitation efforts are indicated, and prolonged CPR is sometimes successful
The most lethal neurologic injuries from lightning-strike victims
- Heat-induced coagulation of the cerebral cortex
- Epidural or subdural hematoma
- ICH
Pathognomonic for lightning strikes
Lichtenberg figures
Remarks on other lightning-related injuries
1.Skeletal muscle injury and rhabdomyolysis is rare in lightning strike
2. Cataracts are the most common ocular sequelae (usually bilateral)
