However, there are several concerns regarding the studies that have been conducted using the BIS monitor. There have been no parameters guiding administration of anesthesia in the control groups. BIS data have not been collected for patients in control groups, which prevents retrospective analysis and assessment of the true sensitivity, specificity, positive and negative predictive values of the BIS recordings. Most of the studies have been funded by the manufacturer of the device, which introduces a potential conflict of interest and investigator bias. In view of the current pressure to adopt BIS monitoring or an equivalent into the standard of anesthesia care, it is essential to conduct a study to address some of the concerns. The hypothesis of this proposed study is that an anesthetic algorithm can be designed for high-risk surgical patients such that the incidence of awareness will be equivalent to or lower than that in a group where anesthesia depth is guided by the BIS monitor.