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Chapter 22: Monitoring Methods, Instrumentation, and Alarms

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A surgical procedure requires the strict avoidance of any sudden patient movement. Anesthetic includes large doses of a nondepolarizing neuromuscular blocking drug. Which method of electrical nerve stimulation is the best to monitor this degree of neuromuscular blockade?

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(A) double burst stimulation

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(B) train-of-four stimulation

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(C) single-twitch stimulation

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(D) tetanic stimulation

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(E) post-tetanic count stimulation

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The answer is E. Post-tetanic count (PTC) can be used to assess neuromuscular blockade when large doses of nondepolarizing neuromuscular blocking drugs have been used and there is no reaction to single-twitch or train-of-four stimulation (TOF). PTC applies tetanic stimulation (50-Hz for 5 seconds) then 3 seconds later single-twitch stimulation at 1 Hz.

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Double burst stimulation is two short bursts of 50-Hz stimulation 750 msec apart. It correlates to TOF stimulation.

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TOF stimulation applies four supramaxial stimuli every 0.5 second (2 Hz). Each stimulus in the train causes “fade.” Dividing the fourth response by the first response allows for calculation of TOF ratio.

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Single-twitch stimulation applies a single supramaximal stimulus over a set frequency. This is sometimes used during induction.

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Tetanic stimulation is a rapid delivery of stimuli (50-Hz for 5 seconds) that causes a sustained muscle contraction.

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Ref: Miller RD. Miller's Anesthesia, 8th ed. Philadelphia, PA: Elsevier; 2015.

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The evoked response of peripheral nerve stimulation can be recorded by a variety of methods. Which method records compound action potentials produced by stimulation of a peripheral nerve?

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(A) mechanomyography (MMG)

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(B) electromyography (EMG)

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(C) acceleromyography (AMG)

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(D) piezoelectric neuromuscular monitor (PzEMG)

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(E) phonomyography (PMG)

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The answer is B. Electromyography (EMG) records compound action potentials produced by stimulation of a peripheral nerve.

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Mechanomyography (MMG) records the force of muscle contraction with a force-displacement transducer. It typically requires careful positioning of the studied muscle.

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Acceleromyography (AMG) measures the acceleration of the thumb after ulnar nerve stimulation.

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Piezoelectric neuromuscular monitors (PzEMG) record the voltage generated in a piezoelectric film attached to the thumb after ulnar nerve stimulation.

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Phonomyography (PMG) records low-frequency sounds generated by skeletal muscles during contraction.

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Ref: Miller RD. Miller's Anesthesia, 8th ed. Philadelphia, PA: Elsevier; 2015.

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Adequate neuromuscular recovery, ...

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