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300 mamp to amp12/9/2023 ![]() 4 Even if the current amplitude is large, it may not occur during the vulnerable period of the cardiac cycle. In contrast, with direct current, there is a feeling of shock only when the circuit is made or broken unless the voltage is relatively high. The heart is most sensitive to such stimulation during the “vulnerable period” of the cardiac cycle that occurs during much of the T wave. If the amplitude of the current is sufficient, ventricular fibrillation will occur. ![]() Cardiac muscle cells will receive 60 stimulations per second. This will give a tetanic muscle contraction, resulting in the loss of voluntary control of muscle movements. This rate is slower than 60 times per second. If there is enough current, skeletal muscle cells will be stimulated as rapidly as they can respond. With alternating current, if the current level is high enough, there will be a feeling of electric shock as long as contact is made. Therefore, with alternating current, there is a continuous changing of the voltage, with 60 cycles of voltage change occurring per second. The skin is somewhat similar in that it passes more current when the voltage is changing. Membranes of excitable tissues (eg, nerve and muscle cells) will pass current into cells most effectively when an applied voltage is changing. Understanding how electric current reaches and travels through the body can help one understand how and why specific accidents occur and what medical and surgical problems may be expected. Topics related to high-voltage burns include ground faults, ground potential gradient, step and touch potentials, arcs, and lightning. After the review of basic principles, a number of clinically relevant examples of accident mechanisms and their medical effects are discussed in part B. There are discussions of skin resistance (impedance), internal body resistance, current path through the body, the let-go phenomenon, skin breakdown, electrical stimulation of skeletal muscles and nerves, cardiac dysrhythmias and arrest, and electric shock drowning. ![]() There are discussions of how electric current is conducted through the body via air, water, earth, and man-made conductive materials. This multidisciplinary topic is explained in part A by first reviewing electrical and pathophysiological principles, and later in part B by considering specific types of accidents. This article explains ways in which electric current is conducted to and through the human body and how this influences the nature of injuries. Understanding how electric current reaches and travels through the body can help the clinician understand how and why specific accidents occur and what medical and surgical problems may be expected. Conclusions: There are a variety of types of electrical contact, each with important characteristics. Results: The practicing physician will have a better understanding of electrical mechanisms of injury and their expected clinical effects. ![]() After the review of basic principles, a number of clinically relevant examples of accident mechanisms and their medical effects are discussed. There are also discussions of skin resistance (impedance), internal body resistance, current path through the body, the let-go phenomenon, skin breakdown, electrical stimulation of skeletal muscles and nerves, cardiac dysrhythmias and arrest, and electric shock drowning. Methods: This multidisciplinary topic is explained by first reviewing electrical and pathophysiological principles. Objective: The objective of this article is to explain ways in which electric current is conducted to and through the human body and how this influences the nature of injuries.
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