Fig. 4.
A double burst stimulus (DBS) consists of two brief, 50-Hz tetanic bursts delivered 0.75 s apart. Each burst consists of three stimuli (DBS3,3) that result in two sustained muscle contractions. The DBS ratio (D2/D1) approximates the train-of-four (TOF) ratio. When quantitative monitoring is not available, the advantage of DBS over TOF is that subjectively determined fade is more easily perceived than the fade induced by TOF stimulation. However, once the TOF ratio exceeds 0.60, fade to DBS generally cannot be detected subjectively.