USE OF ATRACURIUM OR VECURONIUM TO PROLONG THE ACTION OF TUBOCURARINE

Forty patients received tubocurarine in a dose greater thanED₉₀. When neuromuscular function had recovered to amplitudeof the first contraction of the train-of-four equals 10% ofcontrol, a small increment of atracurium or vecuronium was administered,repeating the same increment at each subsequent recovery to10%. The intensity and duration of the neuromuscular block followingthe first increment was always greater than that of subsequentincrements. The duration and intensity of the block was progressivelyreduced with subsequent increments until the responses to furtherincrements were unchanged. These final means at steady statewere: group 1 (atracurium 1.1 mg) 6.4 (0.3) min; group 2 (atracurium2.0 mg) 8.2 (0.9) min; group 3 (vecuronium 0.25 mg) 5.8 (0.4)min; group 4 (vecuronium 0.5 mg) 13.2 (0.4) min.