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Train-of-four stimulus

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A method for measuring or monitoring the degree and type of neuromuscular blockade by measuring the twitch or muscle response to a train of four consecutive stimuli applied to a peripheral motor nerve at 2 Hz each for 2 seconds at brief intervals (e.g. 10 seconds), then taking the ratio of the fourth response to the first response.


This method is a reliable test for monitoring neuromuscular blockade, as well as a basis for delivering a dose of a neuromuscular blocking agent when inducing a temporary paralysis. The most common sites for this test are the ulnar nerves of the arm and the superficial peroneal nerve of the foot.

Abbreviation: TOF stimulus