TITRATION OF INHALATIONAL ANAESTHETICS WITH BISPECTRAL INDEX MONITOR DURING LAPAROSCOPIC SURGERY

Abstract

Over 150 years of anaesthetic history, anaesthetists couldn't find a reliable clinical method for accurate assessment of the depth of anaesthesia. The introduction of muscle relaxants in the 1940s increased the reported cases of awareness under general anaesthesia, and patients started to express their fears of being awake and unable to move during surgery. The problem was further drawn into attention when psychologists distinguished memory into two systems : • Explicit memory which represents direct conscious recollection of an experience (e.g. an event in human like). • Implicit memory which represents unconscious recall of the event without remembering being exposed to it. Consequently, the need has increased nowadays for a reliable monitor for the anaesthetic depth. The Bispectral index represents non-invasive, processed electroencephalogram parameter that directly measures the effect of hypnotic and sedative agents on the target organ the brain. The BIS is based on the electroencephalogram of the frontal brain, which reflects the level of hypnosis. The BIS system comprises a sensor attached to the patient's forehead and a monitor. The BIS index ranges from 0 (i.e. no brain activity) to 100 (i.e. the patient is fully awake), reflecting a patient's state of hypnosis and responsiveness.