Chapter 212

Electrical injuries are divided into high-voltage injuries (≥1000 V), low-voltage injuries (<1000 V), and electric arc flash burns, which by definition do not result in passage of current through the tissues. Lightning injury, the other form of electrical injury, is discussed in Chapter 213, Lightning Injuries. Burns from electrical accidents can result from heating due to electric current flow through tissues, explosions, and burning of flammable liquids, clothes, and other objects. Burns are discussed in Chapter 210, Thermal Burns. This chapter also discusses injuries caused by electronic control devices, such as the Taser®.

The actual incidence of electrical injuries is unknown. The most common high-voltage injuries in the U.S. are work related and include arc burns in electricians and high-voltage injuries in linemen.1 Other groups at risk are construction workers, laborers, painters, tree trimmers, roofers, crane operators, and firefighters. High-voltage power line injuries account for 7% of burn center admissions and are particularly disabling because they often lead to deep muscle necrosis and the need for fasciotomy and amputation.1

Electric current is the movement of electrical charges. Table 212-1 lists a few key terms related to electricity.

Table 212-1 Electrical Terms and Units of Measure

Current flow is measured in amperes. Current flow is driven by an electrical potential difference, which is measured in volts. Intervening material between two or more contact points resists electric current flow; this resistance is measured in ohms. Ohm’s law describes the relationship between current (I), voltage (V), and resistance (R) and states that the current through a conductor between two points is directly proportional to the potential difference or voltage drop across the two points and inversely proportional to the resistance between them. For example, a person who grasps a grounded pipe in one hand and a metal cable connected to a 120-volt source in the other hand will experience a current of 120 mA through the body. The total resistance from the power source, through the person, and to ground is estimated to be 1000 Ω. The current would be I = (120 V)/(1000 Ω) = 0.120 A = 120 mA.

Conductors are materials that allow electric current to flow easily. Insulators are materials that do not allow electric current flow. Most biologic materials conduct electricity to some extent. Tissues with high fluid and electrolyte content conduct electricity better than tissues with less fluid and electrolyte content. Bone is the biologic tissue with the greatest resistance to electric current. Dry skin has high resistance, but sweaty or wet skin has much less resistance.

Many of the physiologic effects of electric shock are related to the amount, duration, and type of current ...

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