Effect of Remifentanil on Electroencephalographic BAR Index During Propofol Anaesthesia

Effect of Remifentanil on Electroencephalographic BAR Index During Propofol Anaesthesia

Current cortical EEG based depth of anaesthesia monitors do not accurately reflect the effect of opioid drugs. We have developed a new theoretically-based method of analysing the EEG. Our hypothesis is that this new method will more accurately predict depth of anaesthesia than the Bispectral Index (BIS) monitor in patients having elective surgery.

Patients aged 18-60 years presenting for elective surgery under general anaesthesia will be recruited. They will be randomised to receive remifentanil effect-site target 0, 2 or 4 ng/ml. Then anaesthesia will be induced with propofol. Loss of the eyelash reflex, response to command and response to electrical stimulation will be measured. The raw EEG will be recorded and analysed off-line using our new method and also for BIS values. Anaesthesia will then proceed according to the needs of the patient and the surgery.

Inclusion Criteria:

• Male and female patients, aged 18-60 years, of ASA physical status 1-3, presenting for elective surgery under general anaesthesia

Exclusion Criteria:

• Inadequate English comprehension due to a language barrier, cognitive deficit or intellectual disability
• Epilepsy or other EEG abnormality
• Prescription or illicit drugs known to affect the EEG