Does a single dose of intravenous nicardipine or nimodipine affect the bispectral index following rapid sequence intubation?

Abstract

Background

Theoretically, L-type calcium channel blockers could modulate anesthetic effects. Nicardipine does not affect the bispectral index (BIS), but nimodipine, which can penetrate the blood-brain barrier, has not been studied. The aim of this study was to evaluate whether a single dose of intravenous nicardipine or nimodipine could affect BIS following rapid sequence intubation.

Methods

This study was done in a double-blind, randomized fashion. Anesthesia was induced with fentanyl 2 µg/kg, thiopental sodium 5 mg/kg, and 100% oxygen. After loss of consciousness, patients received rocuronium 1.0 mg/kg and either a bolus of 20 µg/kg nicardipine, nimodipine, or a comparable volume of normal saline (n = 20). Intubation was performed 1 min after study drug administration. BIS, mean blood pressure (MBP), and heart rate (HR) were measured before anesthetic induction, after loss of consciousness, before intubation, during intubation, and 1, 2 and 5 min after intubation.

Results

BIS dropped rapidly after induction but increased to 60 before intubation in all groups irrespective of study drug. In nimodipine, the increase in BIS during intubation was not significant compared to pre-intubation, in contrast to the other two groups, but there was no difference in BIS during intubation. HR significantly increased, but MBP just rose to pre-induction values after intubation in nicardipine and nimodipine groups. BIS, MBP, and HR following intubation increased in control group.

Conclusions

A single dose of intravenous nicardipine or nimodipine could attenuate blood pressure increases but not affect BIS increases in rapid sequence intubation.