Using the isolated forearm technique (IFT), we wished to determine if patients known to be unresponsive to commands during general anaesthesia with nitrous oxide, halothane and neuromuscular blocking agents had any evidence of explicit or implicit recall. Two groups of women, studied in a single-blind sequential block design, heard different tapes, either a command and information tape (n = 34) or radio static (n = 34), throughout surgery.
The possibility of awareness during general anesthesia causes apprehension for the patient and the Certified Registered Nurse Anesthetist (CRNA). The goals of general anesthesia are to prevent the sensation of pain and produce a state of sedation, hypnosis, and unconsciousness so the patient will not remember the surgical procedure. An inadequate level of anesthesia can result in patient awareness during surgery.
Despite advances in anesthetic technique and technology, intraoperative awareness continues to occur with alarming regularity. The psychological effects on patients and the medicolegal consequences to providers have created the need for a reliable monitor of the hypnotic component of anesthesia. A new technology known as bispectral analysis (BIS) has the potential to put an end to the devastating occurrence of intraoperative awareness, as well as improve the overall effectiveness of anesthetic delivery and the surgical experience.
We studied the movement response to skin incision in 68 adult (males/females) ASA I-II patients receiving propofol +/- fentanyl intravenous anaesthesia using the bispectral index and 95% spectral edge frequency monitoring with an A-1050 EEG monitor.
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.
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.
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.
The bispectral index (BIS) and the auditory evoked potential (AEP) index as calculated by the new A-line monitor were measured during hypnosis with propofol, which included an episode of wakefulness. Both indices followed a similar pattern during sedation, with values decreasing with sedation and increasing when awake. Baseline AEP values varied between 60 and 98, and BIS values were between 96 and 98. The AEP-index value was at all times 10-20 points lower than the BIS-index. The transition to loss of response occurred at a mean AEP value of 46 and BIS value of 58.
INTRODUCTION: Electroencephalographic monitoring is one of the techniques used to measure hypnosis during anesthesia. Efforts to find a means to apply this monitoring function are justified by cases of intraoperative awakening and are in the interest of guaranteeing patient welfare and controlling anesthesia. OBJECTIVES: To determine the changes in two electroencephalographic parameters, the bispectral index (BIS) and the spectral edge frequency 90 (SEF90), during the different phases of anesthesia. Patients and method.
OBJECTIVE: To determine the influence that bispectral index (BIS) monitoring of hypnosis might have on need for analgesia during surgery under total intravenous anesthesia provided by bolus administration of fentanyl. PATIENTS AND METHOD: Prospective, randomized and partially double-blind study of 40 patients undergoing major gynecological surgery under total intravenous anesthesia with propofol and fentanyl. In the BIS group (n = 20) propofol administration was adjusted to maintain BIS between 40 and 60.