Transition time: a new parameter coinciding with fair intubating conditions.

With rocuronium optimal intubating conditions are earlier achieved than the adductor pollicis muscle onset time. Using the transition time we defined a better parameter for clinical relaxation. The onset of relaxation was determined in 20 patients. After a stable response was achieved with a 0.1 Hz single twitch stimulation 0.60 mg/kg rocuronium was injected. The three different stades during the onset of relaxation were determined. These are the lag time, transition time (transition between second and third phase) and onset time. Whether the transiton time corresponds with optimal intubating conditions was evaluated in 40 other patients. The median transition time was 67.4 (P25:52.5, P75:76.3) seconds with a corresponding relaxation of 76.2 (P25:81.4, P75:70.7)%. The intubating conditions were significantly better at a relaxation level corresponding with the transition time. We conclude that the transition time approximates the intubating time and corresponds with fair intubating conditions. This parameter can be preferred to define the moment with optimal intubating conditions.