[The circulatory responses to tracheal intubation using the timing principle]

The circulatory responses to tracheal intubation using timing principle were investigated in 40 adult patients who underwent elective surgery. They were randomly assigned to one of two groups; 1) timing principle group, and 2) SCC group. In timing principle group, vecuronium 0.15 mg.kg-1 was administered. At the onset of clinical muscle weakness, thiopental 5 mg.kg-1 was given promptly. Sixty seconds after thiopental, patients were intubated. In SCC group, thiopental 5 mg.kg-1 was administered, and when patients lost consciousness, SCC 1 mg.kg-1 was given. After fasciculation, patients were intubated. The increases in systemic blood pressure, heart rate and rate pressure product were significantly lower in patients in timing principle group than in those in SCC group. Intubating conditions were almost excellent in both groups, and there were no complications in this study. In timing principle group, intubation was done 60 seconds after thiopental administration, and its timing coincided with the peak cerebral concentration of thiopental. We considered this coincidence was one of the reasons of fewer responses in patients in timing group than in those in SCC group.