Train of four' is characteristically used in concern with

B i.e., Nondepolarizing neuromuscular blockers Post titanic stimulation, and fade on titanic stimulation & train of fourQ is a characteristic feature present in non depolarizing block or phase II block. Succinyl choline is typically a depolarizing neuromuscular blocker that classically presents with features of depolarizing or phase I block. However, when administered at high doses (>500 mg) or over a long period, it causes dual or biphasic block i.e. phase I followed by phase II (or non depolarizing) block. This transition occurs from desensitization of receptors to acetylcholine. During transition from phase I to phase II dose is 4-5 mg/kg and train of four ratio is 0.4-0.7.