Effects Of Intramuscular Administration Of Lidocaine In Hynotic Effect And On Induction And Maintenance Doses Of Propofol

Background. In a prospective, randomized, double-blind study we tested whether local anaesthetic administered i.m. potentiates the hypnotic effect of propofol. Methods. Sixty patients (two groups, n=30) undergoing lower abdominal surgery with total i.v. propofol anaesthesia were investigated. Patients in Group Lidocaine (Group L) received i.m. 100 mg and patients in Group Control (Group C) received i.m. saline 5 ml before the operation. Hypnosis was measured with responses to verbal commands. Results. In Group L, the time required for failure to open the eyes in response to verbal command, and the time and dose for achieving hypnosis were significantly shorter than Group C. The induction, and the maintenance doses of propofol were significantly less in Group L compared with the control group. Induction doses were 1.52 and 2.05 mg kg respectively; p<.0001. Maintenance doses were 7.28 and 9.93 mg kg respectively in the first hour; p<.0001. Conclusion. I.M. administered local anaesthetics are associated with a decrease in both the induction and maintenance doses of propofol during total i.v. anaesthesia and a reduction in haemodynamic responses.