Figure 39-13 Evoked electromyographic printout from a Relaxograph. Initially, single-twitch stimulation was given at 0.1 Hz, and vecuronium (70 µg/kg) was given intravenously for tracheal intubation. After approximately 5 minutes, the mode of stimulation was changed to TOF stimulation every 60 seconds. At a twitch height (first twitch in TOF response) of approximately 30% of control (marker 1), 1 mg of vecuronium was given intravenously. At marker 2, 1 mg of neostigmine was given intravenously, preceded by 2 mg of glycopyrrolate. The printout also illustrates the common problem of failure of the electromyographic response to return to control level. (Courtesy of Datex-Ohmeda, Helsinki, Finland.)