We assessed the effect of propofol on the auditory steady-state response (ASSR), bispectral (BIS) index, and level of consciousness in two experiments. In Experiment 1, propofol was infused in 11 subjects to obtain effect-site concentrations of 1, 2, 3, and 4 microg/mL. The ASSR and BIS index were recorded during baseline and at each concentration. The ASSR was evoked by monaural stimuli. Propofol caused a concentration-dependent decrease of the ASSR and BIS index values (r(2) = 0.76 and 0.93, respectively; P<0.0001).
OBJECTIVE: Assessment of the usefulness of Bispectral Index of the EEG (BIS) for the management of hypertension during laparoscopic surgery. STUDY DESIGN: Preliminary, non-randomized study. PATIENTS: 15 patients undergoing laparoscopic surgery. METHODS: Anaesthesia by TCI of propofol and boluses of fentanyl in order to maintain fentanyl effect site concentration above 2 ng.mL-1 according to Scott kinetics model. Mean arterial pressure (MAP), heart rate (HR) and BIS were recorded.
BACKGROUND: Hypovolemia decreases the dose requirement for anesthetics, but no data are available for propofol. As it is impossible to study this in patients, a rat model was used in which the influence of hypovolemia on the pharmacokinetics and pharmacodynamics of propofol was investigated. METHODS: Animals were randomly allocated to either a control (n = 9) or a hypovolemia (n = 9) group, and propofol was infused (150 mg x kg(-1) x h(-1)) until isoelectric periods of 5 s or longer were observed in the electroencephalogram.
OBJECTIVE: Consensus has not been achieved on the presence of unconscious memory of messages in general anesthesia for methodological reasons. Our objective was to apply a model of anesthesia that allows for clinical control of the level of hypnosis in order to evaluate the presence and characteristics of implicit memory in deep sedation with propofol. PATIENTS AND METHODS: We randomly assigned 48 consecutive patients undergoing lower limb surgery to two groups.
Recently it was reported that the pharmacokinetics of propofol are modified by changes in cardiac output. The objective of this study was to evaluate the effects of cardiac output and other factors on the hypnotic dose of propofol. One-hundred surgical patients were administered indocyanine green immediately before the induction of anesthesia to measure their cardiac outputs and blood volumes. Propofol (250 microg. kg(-1). min(-1)) was infused IV for 8 min, and the hypnotic dose of propofol and the time to hypnosis were recorded.
The present investigation dealt with the effect of simultaneous administration of flumazenil on the hypnotic activity of propofol using a behavioral model of ddY mice. The mixed solution of propofol and flumazenil was administered intravenously into the mice tail vein and the achievement of hypnosis was defined as the loss of the righting reflex. Flumazenil 0.2 mg.kg-1 significantly decreased the required dose of propofol for hypnosis (8.43 +/- 0.46 mg.kg-1) compared to the control group (10.55 +/- 0.55 mg.kg-1).
Memory for intraoperative events may arise from inadequate anesthesia when the hypnotic state is not continuously monitored. Electroencephalogram bispectral index (BIS) enables monitoring of the hypnotic state and titration of anesthesia to an adequate level (BIS 40 to 60). At this level, preserved memory function has been observed in trauma patients. We investigated memory formation in elective surgical outpatients during target-controlled propofol anesthesia supplemented with alfentanil.
This study investigated the effect of co-administration of nitrous oxide on the cardiovascular changes during induction of anesthesia with propofol infusion at a low rate. Sixty patients undergoing general anesthesia were randomly allocated into two groups, and received the inhalation of 100% oxygen (group 1) or 60% nitrous oxide and oxygen (group 2) via face mask for 3 minutes before administration of propofol at 15 mg.kg-1.hr-1.
Canadian Journal of Anaesthesia = Journal Canadien D'anesthésie
PURPOSE: This study investigates the interactions between midazolam premedication and propofol infusion induction of anesthesia for multiple anesthetic endpoints including: loss of verbal contact (LVC; hypnotic), dropping an infusion flex (DF; motor), loss of reaction to painful stimulation (LRP; antinociceptive) and attainment of electroencephalographic burst suppression (BUR; EEG). METHODS: In a double blind, controlled, randomized and prospective study, 24 ASA I-II patients received either midazolam 0.05 mg x kg(-1) (PM; n = 13) or saline placebo (PO; n = 11) i.v. as premedication.
STUDY OBJECTIVE: To evaluate the effect of a small dose of midazolam (10 microg kg(-1)) on induction and emergence during short-term propofol anesthesia and to investigate the effects of subsequent administration of flumazenil. DESIGN: Double-blinded, prospective, randomized study. SETTING: Operating room of a medical college hospital. PATIENTS: 30 male ASA physical status I and II patients (ages 51 to 75) scheduled for minor surgery under spinal anesthesia.