Different remifentanil doses in rapid sequence anesthesia induction: BIS monitoring and intubation conditions

The aim of this prospective, randomized, double blind trial was to investigate the effects of two different doses of remifentanil on bispectral index (BIS) values and intubation conditions in a simulated model of rapid sequence anesthesia induction (RSAI).

54 ASA I-II adult patients undergoing elective surgery were randomly allocated to two groups. After preoxygenation for 3 minutes, induction and tracheal intubation was performed in a 300 head-up position. Group I (n=26) and Group II (n=28) received a 1 µg/kg or 0.5 µg/kg bolus of remifentanil, respectively, over 30 seconds. Propofol was the induction agent. 1 mg/kg of rocuronium was used in all patients. Patients were intubated 60 s after administration of the muscle relaxant. Hemodynamic data and BIS scores were obtained before induction (baseline), after induction, at intubation and at 1, 3, 5 and 10 minutes following intubation. Intubation conditions were scored with a standard scoring system.

The hemodynamic variables at all the measurement intervals and the area under the hemodynamic variable-time curves were similar among the groups. There was no difference among the groups for BIS measurements. Moreover, the mean area under the BIS-time curve for Group I (300±45cm2) was comparable to Group II (315±49cm2) (p=0.432). The mean total intubation condition score (maximum 14 points) in Group I (12.6±1.67) was higher than Group II (10.3±4.79) (p=0.030).

1 µg/kg of remifentanil compared to 0.5 µg/kg of remifentanil provides similar hemodynamic profiles and BIS scores, but 1 µg/kg of remifentanil was associated with superior endotracheal intubation conditions. According to this study design and medications used, a relation between BIS scores and intubation conditions couldn't be demonstrated.