Systemic lidocaine decreases the Bispectral Index in the presence of midazolam, but not its absence.
OBJECTIVE
To evaluate the effects of intravenous (IV) lidocaine on the Bispectral Index (BIS) in the presence or absence of midazolam.


METHODS
Prospective, randomized, double-blinded, placebo-controlled clinical study.


METHODS
Operating room of a university hospital.


METHODS
96 ASA physical status 1, 2, and 3 patients undergoing general anesthesia.


METHODS
Patients were assigned to one of 6 treatment groups to receive IV midazolam (0.03 mg/kg) or placebo, followed 5 minutes later by one of three IV preinduction doses of lidocaine: 0.5, 1.0, or 1.5 mg/kg.


METHODS
BIS values were recorded before administration of lidocaine and at 30-second intervals afterwards for three minutes. The primary endpoint was the average BIS level recorded.


RESULTS
Baseline BIS values were lower in the midazolam group (94 ± 4 vs. 90 ± 7, P < 0.001). There was no significant decrease in BIS values in the placebo group for any of the three lidocaine doses. However, in the midazolam groups, significant decreases in BIS levels versus baseline values were measured.


CONCLUSIONS
IV lidocaine decreases BIS in the presence of midazolam, suggesting that the effect of lidocaine on BIS is not direct, but rather results from modulation by midazolam.
Department of Anesthesia, University of Virginia, Charlottesville, VA 22908-0710, USA.
Antje
A
Gottschalk
Allannah M
AM
McKay
Zahra M
ZM
Malik
Michael
M
Forbes
Marcel E
ME
Durieux
Danja S
DS
Groves
D000328:Adult; D000368:Aged; D000768:Anesthesia, General / Q000379:methods; D018686:Anesthetics, Intravenous / Q000627:therapeutic use*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology*; D056805:Consciousness Monitors; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007275:Injections, Intravenous; D008012:Lidocaine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008874:Midazolam / Q000627:therapeutic use*; D008875:Middle Aged; D011446:Prospective Studies
D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D008012:Lidocaine; D008874:Midazolam