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Chapter 13. Electrical Nerve Stimulators and Localization of Peripheral Nerves
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All of the following answers are correct except one. Choose the answer that is not correct. Motor response to nerve stimulation of the femoral nerve is absent:
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A. Under general anesthesia with sevoflurane, rocuronium, and a continuous infusion of remifentanil
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B. Under spinal anesthesia
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C. In a patient who already received two injections of local anesthetics
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D. When the saphenous nerve is the target
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B is correct. Reliability of peripheral nerve stimulation is not affected by the presence of spinal or epidural anesthesia; therefore, motor response to stimulation of the femoral nerve will be present in this case.
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Which setting (electrical repetition rate) of the peripheral nerve stimulator should be used to detect muscular twitches, when the current is set at 0.5- to 1-mA intensity and 0.1 ms duration?
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A is correct. 2 Hz is ideal to detect motor responses. See Figure 13–1.
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Regarding action potential, which of the following statements is correct?
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A. Pain fibers have a short chronaxy.
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B. It takes a shorter time to depolarize the membrane of pain fibers compared to motor fibers.
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C. Motor fibers have a long chronaxy.
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D. Motor fibers have a short chronaxy (only the area of the nodes of Ranvier count).
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D is correct. Pain fibers have ...