(A) In the unblocked muscle, the mechanical response to a 50 Hz tetanic stimulation is characterized by a sustained contraction with no fade or post-tetanic potentiation.
(B) Application of tetanus during deep block resulted in a faint contraction for 5 seconds, and post-tetanic potentiation that results in eight progressively weaker contractions (PTC = 8). Note that when measuring the PTC one always uses 1 Hz stimulation.
(C) Single twitch is repeated every 12 seconds, followed by a 5 second tetanus, then decay to an amplitude lower than the pre-tetanic single twitch amplitude. The pre-tetanic stimulus twitch amplitude is 16% of the control value and the first post-tetanic twitch amplitude increased to 76% of the control value.
(D) With further spontaneous recovery of neuromuscular blockade, the tetanic and post-tetanic twitch amplitudes increase.
From: Naguib M, Brull SJ, Johnson KB. Conceptual and technical insights into the basis of neuromuscular monitoring. Anaesthesia 2017; 72 Suppl 1:16.
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