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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 is an extreme and unique form of electrical injury. This chapter also discusses injuries caused by electronic control devices, such as the Taser®. 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 the chapter 216, "Thermal Burns."
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Approximately 6500 electrical injuries occur per year in the United States, accounting for 4% of total burns. Of these, the majority are work related (61%), mostly industrial injuries. The overall complication rate is 10.6%, with the fewest complications among children age 1 to 5 years (2%).1 The most common high-voltage injuries in the United States are also work related and include arc burns in electricians and high-voltage injuries in power line workers.2 The Electrical Safety Foundation International estimates that contact with electric current caused nearly 1800 workplace fatalities between 2003 and 2010.3 High-voltage power line injuries are particularly disabling because they often lead to deep-muscle necrosis and the need for fasciotomy and amputation.2
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BASICS OF CURRENT FLOW
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Electric current is the movement of electrical charges. Table 218-1 lists a few key terms related to electricity.
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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-V source in the other hand will experience a current flow through the body, the magnitude of which varies inversely with the resistance of the circuit. If 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.
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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 ...