NICE diagnostics guidance
Issued: November 2012
DG6

Depth of anaesthesia monitors – Bispectral Index (BIS), E-Entropy and Narcotrend-Compact M

This is an extract from the guidance. The complete guidance is available at www.nice.org.uk/dg6

1 Recommendations

1.1 The use of electroencephalography (EEG)-based depth of anaesthesia monitors is recommended as an option during any type of general anaesthesia in patients considered at higher risk of adverse outcomes. This includes patients at higher risk of unintended awareness and patients at higher risk of excessively deep anaesthesia. The Bispectral Index (BIS) depth of anaesthesia monitor is therefore recommended as an option in these patients.

1.2 The use of EEG-based depth of anaesthesia monitors is also recommended as an option in all patients receiving total intravenous anaesthesia. The BIS monitor is therefore recommended as an option in these patients.

1.3 Although there is greater uncertainty of clinical benefit for the E-Entropy and Narcotrend-Compact M depth of anaesthesia monitors than for the BIS monitor, the Committee concluded that the E-Entropy and Narcotrend-Compact M monitors are broadly equivalent to BIS. These monitors are therefore recommended as options during any type of general anaesthesia in patients considered at higher risk of adverse outcomes. This includes patients at higher risk of unintended awareness and patients at higher risk of excessively deep anaesthesia. The E-Entropy and Narcotrend-Compact M monitors are also recommended as options in patients receiving total intravenous anaesthesia.

1.4 Anaesthetists using EEG-based depth of anaesthesia monitors should have appropriate training and experience with these monitors and understand the potential limitations of their use in clinical practice.

Patients who are considered at higher risk of unintended awareness during general anaesthesia include patients with high opiate or high alcohol use, patients with airway problems, and patients with previous experience of accidental awareness during surgery. The risk of unintended awareness is also raised by the use of concomitant muscle relaxants. Older patients, patients with comorbidities and those undergoing certain types of surgery are also considered at higher risk of unintended awareness. This is because they are at greater risk of haemodynamic instability during surgery. In these patients, lower levels of anaesthetic are often used to prevent adverse effects on the cardiovascular system and these levels can be inadequate.

Patients who are considered at higher risk of excessively deep levels of anaesthesia include older patients, patients with liver disease, patients with a high body mass index (BMI), and patients with poor cardiovascular function.

Patients receiving total intravenous anaesthesia are not considered at higher risk of adverse outcomes from general anaesthesia than patients receiving inhaled anaesthesia. The use of EEG-based depth of anaesthesia monitors has been recommended in patients receiving total intravenous anaesthesia because it is cost effective and because it is not possible to measure end-tidal anaesthetic concentration in this group.