BACKGROUND: Bispectral (BIS) index has been used as an indicator of hypnotic state. Fentanyl is well known for its cardiovascular stability during endotracheal intubation. The purpose of this study is to evaluate fentanyl\'s sedation effect and its contribution to cardiovascular stability during endotracheal intubation under the BIS monitoring.
METHODS: Twenty ASA class 1 or 2, patients were randomly allocated to Group I or II with or without fentanyl 1.5 microgram/kg IV during induction, respectively. The BIS, blood pressures and heart rates were measured at before and 2 minutes after fentanyl IV injection, preintubation, 1, 2, 3 and 5 minutes after tracheal intubation. The enflurane concentrations were continuously maintained at 2 Vol%.
RESULTS: The BIS at each stage of process were decreased more in Group I than Group II. The systolic and diastolic blood pressures were increased in Group I less than Group II at 1, 2 and 3 minutes after intubation. The heart rates were increased in Group I less than Group II at 1 minutes after intubation.
CONCLUSIONS: A small dose of fentanyl reduced BIS and blunted the intubation induced-sympathetic stimulation, and so its sedation effect partly contributed to maintain cardiovascular stability during endotracheal intubation. For the analgesic effect and central vagolytic effect of fentanyl during intubation, we need further studies.