Anaesthesia - can the patient feel the knife?

October 10, 2005

Anaesthetic agents are potentially dangerous drugs, and major patient

complications can occur. If the patient is overdosed, death or major

body organ damage can occur. Conversely, if the patient is under-

dosed, patient awareness can occur. There is a narrow drug

concentration " window " for both drug safety and anaesthetic efficacy,

and the development of ways in which to monitor drug delivery

concentration has been a major driver in anaesthetic agent safety

research.

The Oxford invention has met this anaesthesia challenge by using

modified statistical techniques to classify the physiological state

of a human or animal subject. The classification monitors changes in

the physiological state that occur over time either spontaneously or

from external stimuli. Analysis of data obtained from anaesthetic

trials has demonstrated the efficacy of the method for monitoring the

depth of anaesthesia.

As well as using encephalograms the invention may be used

advantageously with other forms of physiological data:

electromyography to indicate muscle activity; analysis of images from

magnetic resonance, computed tomography, X-ray and ultrasound;

electrocardiography for blood pressure and blood oxygenation. The

method also has many other applications including the monitoring of:

consciousness, sleep, neuropathology, cerebral intoxication,

cognitive state and muscle tremor.

ISIS INNOVATION LTD

Ewert House,

Ewert Place,

Summertown,

Oxford OX2 7SG,

UK

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