Effects of two calculated plasma sufentanil concentrations on the hemodynamic and bispectral index responses to Mayfield head holder application

The effects of two calculated plasma sufentanil (SUF) concentrations on the hemodynamic and bispectral index (BIS) responses to Mayfield head holder ( MH) application were studied in 20 patients scheduled for intracranial surg ery. Premedication consisted of hydroxyzine, alprazolam, and atropine given orally 1 hour before surgery. Anesthesia was provided with propofol (PPF) and SUF using a target-controlled infusion device. Patients were randomly a ssigned to one of two groups according to calculated plasma concentrations: 3 mu g/mL(-1) of PPF and 0.5 ng/mL(-1) of SUF in group I (Gi) and 3 mu g/m L(-1) of PPF and I ng/mL(-1) of SUF in group II (Gn). The MH was fixed 33.0 +/- 6.6 minutes (mean +/- SD) after induction. Systolic (SAP), diastolic ( DAP), and mean arterial pressure (MAP) as well as heart rate (HR) and BIS w ere recorded 1 minute before pinning (baseline) as well as 1 minute (P1), 2 minutes (P2), and 3 minutes (P3) after pinning. Multivariate repeat-measur ed analyses of variance were applied to the baseline-subtracted measurement s of hemodynamic and BIS values. Groups were compared using the Student's t test, and P < .05 was considered to be statistically significant. Patients ' characteristics, baseline hemodynamic values, and BIS values were similar in both groups. A significant overall time effect was observed for all var iables, but no significant overall SUF effect was detected. Increases in SA P, MAP, DAP, and HR did not differ significantly between groups. The increa se in hemodynamic variables did not exceed 20% of baseline value in either group. In contrast, at P1, the increase in BIS over the baseline value was significantly higher in GI (15.0 +/- 7.9) than in GII (6.7 +/- 6.5). In con clusion MH application was associated with a significant, although not clin ically relevant, increase in hemodynamic variables whatever the calculated plasma SUF concentration (0.5 or 1.0 ng/mL(-1)). In contrast, the increase in BIS observed at pinning was significantly higher in patients with the lo west calculated plasma SUF concentrations. This suggests that the BIS respo nse to noxious stimulation is modulated by the analgesic regimen.