9 Electrical Injury

Question 1

High vs low voltage

Answer 1

High: ≥1000 V
Low <1000 V

Question 2

Ohm’s law

Answer 2

Current = voltage/resistance

Question 3

Biologic tissue with the greatest resistance to electric current

Answer 3

Bone

Question 4

Biologic tissue with the low resistance to electric current

Answer 4

Nerves and vascular structures

Question 5

Remarks on AC

Answer 5

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

Question 6

Remarks on home outlets

Answer 6

US: 120 V
Europe and Australia: 240 V
Philippines: 220 V

Question 7

Mechanism of injuries in electrical-induced injuries

Answer 7

1. Direct tissue damage from the electrical injury
2. Tissue damage from thermal energy
3. Mechanical injury from trauma induced by a fall or muscle contractions

Question 8

Remarks on low-voltage injuries

Answer 8

1. 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.
2. Low-voltage injuries who are asymptomatic and with normal physical examination do nOT require laboratory testing and imaging.

Question 9

Remarks on high-voltage injuries

Answer 9

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.

Question 10

Commonly seen with orthopedic injury with electrical injuries

Answer 10

Posterior shoulder dislocations

Question 11

Stay at least ______ from downed power lines

Answer 11

10 meters, but even this distance is not without risk

Question 12

remarks on vehicle in contact with a power line

Answer 12

1. 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.
2. 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.
3. 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.

Question 13

Other management of electrical injuries

Answer 13

Maintain spinal immobilization

Question 14

Fluid resuscitation in electrical injuries

Answer 14

4 ml/kg/% tBSA

Question 15

If myoglobinuria is present, maintain a urinary output of

Answer 15

1-2 mL/kg/hour

Question 16

All patients having contact with _______ voltage should be admitted for obsevation, **even if there is no apparent injury

Answer 16

≥600 V AC

Question 17

Lighting fatalities are most common in

Answer 17

fishermen

Question 18

Remarks on lightning prognosis

Answer 18

70-90% survive
but as many as 75% of these survivors have permanent sequelae

Question 19

Types of lightning strikes

Answer 19

1. Direct strike
2. Side flash
3. Contact strike
4. Ground current
5. Upward streamer

Question 20

Cardiac and respiratory arrests in lightning injuries

Answer 20

1. Both cardiac and respiratory arrest may be present without evidence of external injury
2. Although cardiac automaticity may spontaneously return, concomitant respiratory arrest may persist and lead to a secondary hypoxic cardiac arrest.
3. The duration of apnea, rather than the duration of cardiac arrest, appears to be the critical prognostic factor

Question 21

Remarks on lightning casualties

Answer 21

1. 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
2. Such victims may have little physical damage, and they have a reasonable chance of successful resuscitation.
3. 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

Question 22

The most lethal neurologic injuries from lightning-strike victims

Answer 22

1. Heat-induced coagulation of the cerebral cortex
2. Epidural or subdural hematoma
3. ICH

Question 23

Pathognomonic for lightning strikes

Answer 23

Lichtenberg figures

Question 24

Remarks on other lightning-related injuries

Answer 24

1.Skeletal muscle injury and rhabdomyolysis is rare in lightning strike
2. Cataracts are the most common ocular sequelae (usually bilateral)