Recovery of dynamic balance after additional small divided doses of midazolam given intravenously for sedation

We have previously reported that a dynamic balance test with perturbation stimuli and computerised dynamic posturography sensitively reflected the inhibitory effect on balance of intravenous midazolam sedation given intravenously as a single dose, and recovery time was within 80 min. The purpose of this study was to investigate the recovery of dynamic balance after additional doses of midazolam. Eighteen young adult male volunteers were sedated with midazolam given intravenously. The initial dose was given until the Wilson sedation score reached 3, and an additional dose was given until the same score was obtained 40 min later. They were tested with perturbation stimuli 40, 80, 100, and 120 min after the additional doses had been given. Their recovery time was recorded. The mean (S.D.) initial dose of midazolam was 0.07 (0.005) mg kg−1, and additional doses were 41 (7)% of the initial dose. The serial changes in bispectral index after initial and additional doses were similar. The recovery time for the dynamic balance test (within 80 min) was the same as that recorded in the previous single-dose study. The recovery time of the psychomotor function test was within 75 min. Additional doses of midazolam aiming for a Wilson sedation score of 3 at a dose about 40% of the initial dose and given 40 min after the initial dose are valid in terms of the maintenance of sedation and recovery of dynamic balance. Complete recovery time, including psychomotor function, was within 80 min of the additional dose of the drug.