Alprazolam, a member of the benzodiazepine class of sedative agents, at low doses typically produces characteristic changes in the resting electroencephalogram (EEG). This study, involving a cohort of healthy participants, aimed to show that not only could the BAR monitor detect such changes. Results from the trial are due soon.
Liley DTJ, Cadusch PJ, Gray M, Nathan P. Drug-induced modification of the system properties associated with spontaneous human electroencephalographic activity. Phys Rev E 2003;68:051906.
Nitrous Oxide + Sevoflurane
Nitrous oxide, while not potent enough to be a sole anaesthetic agent, is often co-administered with more powerful volatile agents such that the inspired concentrations of such agents can be reduced. However the effects of nitrous oxide are poorly detected by existing electroencephalography (EEG) based methods. This study demonstrated the BAR methodology to be more sensitive in detecting the effects of nitrous oxide than the leading existing EEG based method.
Liley DTJ, Leslie K, Sinclair NC, Feckie M. Dissociating the effects of nitrous oxide on brain electrical activity using fixed order time series modelling. Comput Biol Med 2008;38(10):1121-30
Remifentanil + noxious stimulus
This trial involves the application of the BAR methodology, and other EEG based methods, to detecting the effects of a painful intraoperative stimulus in the presence of varying levels of remifentanil, an important analgesic agent used routinely during surgery.
Shoushtarian M, Sahinovic MM, Absalom AR, Kalmar AF, Vereecke HEM, Liley DTJ, Struys, MMRF. Comparisons of Electroencephalographically Derived Measures of Hypnosis and Antinociception in Response to Standardized Stimuli During Target-Controlled Propofol-Remifentanil Anesthesia. Anesth Analg 2016;122(2):382-92
Xenon and/or Sevoflurane
The BAR Monitor is currently being used head-to-head with the market leading BIS monitor to monitor brain electrical activity during the randomized administration of either Xenon or Sevoflurane in patients undergoing ultrasonic lithotripsy. Results from this trial are due soon
Remifentanil + Propofol
Remifentanil, an ultra-short acting synthetic opioid, is an important intraoperative analgesic agent. Being able to reliably detect its physiological effect is an important step towards monitoring the analgesic state of a patient. This study involved the reanalysis of electroencephalographic (EEG) data recorded during propofol-remifentanil anaesthesia and showed that the BAR methodology, unlike existing EEG monitoring approaches, was capable of differentiating the effects of the anaesthetic agent propofol from the analgesic agent remifentanil.
Sleigh J. Disentangling Hypnos from His Poppies. Anesthesiology 2010:113(2):271-2 (Editorial)
Liley, DTJ, Sinclair NC, Lipping T, Heyse B, Vereecke HEM, Struys MMRF. Propofol and remifentanil differentially modulate frontal electroencephalographic activity. Anesthesiology 2010;113(2):292-304
The BAR Monitor was used on patients undergoing elective first-time coronary artery bypass graft surgery. Patients received propofol for anaesthesia induction and were randomised to receive a low or moderate dose of the analgesic fentanyl. In this trial, the BAR monitor demonstrated the potential to monitor the level of hypnosis following anaesthesia induction with propofol via the CCS index and to facilitate the titration of fentanyl as a component of balanced anaesthesia via the CI index.
Shoushtarian M, McGlade DP, Delacretaz L, Liley DTJ. Evaluation of the brain anaesthesia response monitor during anaesthesia for cardiac surgery: a double-blind, randomised controlled trial using two doses of fentanyl. J Clin Monit Comput 2016;30(6):834-44