Comparison of the train-of-four fade profiles produced by vecuronium and atracurium.

In this double-blind study, we have allocated randomly 40 ASA I-III patients to one of four groups. After a standard anaesthetic induction, patients received vecuronium 0.08 mg kg-1 or 0.10 mg kg-1, or atracurium 0.4 mg kg-1 or 0.5 mg kg-1. Using an electromyogram (Datex Relaxograph) the train-of-four (TOF) response was measured during onset of and recovery from neuromuscular block. A greater degree of fade of TOF was observed with atracurium during onset of neuromuscular block than with equivalent doses of vecuronium. During recovery of neuromuscular transmission, vecuronium was associated with more fade than atracurium. The differences in the TOF profiles of these two drugs may be important when judging the adequacy of antagonism of neuromuscular block using the TOF response.