Haemodynamic and electroencephalograph responses to intubation during induction with propofol or propofol/fentanyl.

PURPOSE: To observe the changes in EEG bispectral index (BIS), 95% spectral edge frequency (95% SEF) and median frequency (MF) with haemodynamic changes to intubation during induction with propofol or propofol and 2 micrograms.kg-1 fentanyl i.v.

METHODS: Twenty four ASA I-II patients were randomized to receive either propofol infusion preceded by normal saline (group P, n = 12) or propofol preceded by 2 micrograms.kg-1 fentanyl (group PF, n = 12). Intubation was performed five minutes after maintenance of BIS within 45 +/- 5. EEG and haemodynamic variables were recorded at before induction, and before and after intubation.

RESULTS: Haemodynamic responses to intubation were greater in group P than in group PF (P < 0.05). Postintubation SBP, DBP and HR increased, compared with preinduction values, more in group P than in group PF. Postintubation BIS values increased from 45.5 +/- 3.5 and 44.2 +/- 4.1 to 51.1 +/- 4.1 and 50.9 +/- 5.3 in groups P and PF, respectively, compared with preintubation values. The BIS values were not different between treatment groups before and after intubation, and 95% SEF and MF values did not increase after intubation.

CONCLUSION: Fentanyl, 2 micrograms.kg-1 i.v., blunted the haemodynamic responses to intubation, but failed to attenuate the arousal of cerebral cortical activity. The different haemodynamic responses postintubation but similar BIS and 95% SEF changes in the two groups suggest that BIS or 95% SEF cannot predict the haemodynamic responses to intubation during anaesthesia induction with propofol and fentanyl.