Objective: To compare double burst stimulus (DBS) and the train-of-four stimuli (TOF) for monitoring neuromuscular blockade during anesthesia in terms of muscle relaxation requirements, dose of anticholinesterase agents and the possibility of postanesthetic residual relaxation.
Patients and methods: Patients were randomly assigned to two groups according to type of monitoring (DBS group, n = 29; and TOF group, n = 28), and were given an adjusted infusion of vecuronium to obtain response to stimulation with both methods of monitoring. When the block was considered to be sufficiently reversed in the operating theater, the patients were transferred to the postanesthesia recovery unit (PARU), where the coefficient between the fourth and first responses to TOF (T4/T1r) was obtained by electromyography and the patients were given the dose of neostigmine needed to obtain a T4/T1r > 70%
Results: Vecuronium was infused at a faster rate during anesthesia in the DBS group than in the TOF group (1.0 +/- 0.19 microgram.kg-1.min-1 and 0.8 +/- 0.24 microgram. kg-1.min-1, respectively, p = 0.005). T4/T1r was less than 70% upon arrival at the PARU in 10 DBS patients and in 2 TOF patients (p = 0.02). No differences were found in neostigmine doses given.
Conclusions: The use of DBS increased the vecuronium dose required during anesthesia and risk in those patients who arrived at the PARU with residual muscle block (T4/T1r < 70%).