Intravenous lidocaine infusion reduces bispectral index-guided requirements of propofol only during surgical stimulation.
BACKGROUND
I.V. lidocaine reduces volatile anaesthetics requirements during surgery. We hypothesized that lidocaine would also reduce propofol requirements during i.v. anaesthesia.


METHODS
A randomized controlled study of 40 patients tested the effect of i.v. lidocaine (1.5 mg kg(-1) then 2 mg kg(-1) h(-1)) on propofol requirements. Anaesthesia was maintained with remifentanil and propofol target-controlled infusions (TCI) to keep the bispectral index (BIS) around 50. Effect-site concentrations of propofol and remifentanil and BIS values were recorded before and after skin incision. Data were analysed using anova and mixed effects analysis with NONMEM. Two dose-response studies were then performed with and without surgical stimulation. Propofol TCI titrated to obtain a BIS around 50 was kept constant. Then patients were randomized into four groups: A, saline; B, 0.75 mg kg(-1) bolus then infusion 1 mg kg(-1) h(-1); C, 1.5 mg kg(-1) bolus and infusion 2 mg kg(-1) h(-1); and D, 3 mg kg(-1) bolus and infusion 4 mg kg(-1) h(-1). Lidocaine administration coincided with skin incision. BIS values and haemodynamic variables were recorded. Data were analysed using linear regression and two-way anova.


RESULTS
Lidocaine decreased propofol requirements (P<0.05) only during surgery. In the absence of surgical stimulation, lidocaine did not affect BIS nor haemodynamic variables, whereas it reduced BIS increase (P=0.036) and haemodynamic response (P=0.006) secondary to surgery.


CONCLUSIONS
The sparing effect of lidocaine on anaesthetic requirements seems to be mediated by an anti-nociceptive action.
Hans
G A
GA
Department of Anaesthesia and Intensive Care Medicine, CHU de Liège, University of Liège, Domaine du Sart-Tilman, B-4000 Liège, Belgium.
Lauwick
S M
SM
Kaba
A
A
Bonhomme
V
V
Struys
M M R F
MM
Hans
P C
PC
Lamy
M L
ML
Joris
J L
JL
D000759:Adjuvants, Anesthesia / Q000008:administration & dosage / Q000494:pharmacology; D000328:Adult; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004347:Drug Interactions; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D008012:Lidocaine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D015742:Propofol / Q000008:administration & dosage / Q000494:pharmacology*; D013965:Thyroidectomy; D055815:Young Adult
D000759:Adjuvants, Anesthesia; D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D008012:Lidocaine; D015742:Propofol