<unk>  is a method of assessing the effect of certain anaesthetic drugs on the brain's EEG. It was commercially developed by Datex-Ohmeda, which is now part of GE Healthcare.<unk>  is a quantitative EEG device which captures a single-lead frontal EEG via a 3-electrode sensor applied to the patient's forehead. The system calculates the "spectral<unk> " of the electroencephalogram (EEG) signals, which is a measure of the degree that the power spectrum is uniform. Increasing brain levels of anaesthetic drugs causes the predominant frequencies in the EEG to be lower than when awake, and this is reflected in a decrease in the spectral<unk> .<unk>  monitors generate two numbers that are derived from different frequency bands used. The State<unk>  (SE) is calculated from the 0.8 Hz to 32 Hz range, whereas the Response<unk>  (RE) uses frequencies up to 47 Hz. Electromyogram activity is more predominant in those higher frequencies, and so the Response<unk>  may respond more quickly when muscle activity is present. Published studies show that<unk>  values do relate to clinical levels of anaesthetic depth. Most of the commonly used anaesthetic drugs are detectable by<unk> , a notable exception being nitrous oxide, in common with BIS<unk> . Other vital signs such as pulse, heart rate, blood pressure, and movement are indirect indicators of consciousness, but are unreliable. When these are combined with expired gas analysis of inhalational anaesthetic agents, an experienced anaesthetist can be confident a patient is unconscious and not aware of their surroundings. However, the direct measurement of brain activity using a basic EEG is purported to measure effects of anaesthetics more comprehensively. Unlike the Bispectral Index monitor, the algorithm of the<unk>  monitor has been fully disclosed.
Entropy monitoring
Vectorcardiography
Impedance threshold device
Tilt table test
Cardiac electrophysiology
Evoked potential
HeartScore
Fractional flow reserve