Asleep or awake? That is the question… A review of techniques available for monitoring the depth of anaesthesia
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Department of Anaesthesiology and Intensive Care, School of Medicine, Collegium Medicum, University of Warmia and Mazury in Olsztyn, Poland
Department of Nursing, School of Public Health, Collegium Medicum, University of Warmia and Mazury in Olsztyn, Poland
Lidia Glinka   

Department of Anaesthesiology and Intensive Care, School of Medicine, Collegium Medicum, University of Warmia and Mazury, Warszawska 30, 10-082 Olsztyn, Poland. Phone:+4889 524 53 08.
Submission date: 2019-08-19
Final revision date: 2020-01-22
Acceptance date: 2020-03-14
Online publication date: 2020-04-14
The problem of intraoperative awareness concerns about 0.1%–0.2% of patients .The perfect method to evaluate the depth of sleep should be objective, so that the response is quick and precise – to increase or decrease the depth of anaesthesia. More scales originated in order to detect cases of intraoperative awareness. Also, new equipment was built so that anaesthesiologists could properly monitor the depth of anaesthesia.

The aim is to describe methods and devices monitoring the depth of anaesthesia.

Material and methods:
This work was based on the available literature and the experience of the authors.

Results and discussion:
Recently a few devices were constructed, all of which can be divided into passive and active systems. Passive systems assess the collected data, while active ones first stimulate and then receive and process data. Passive systems use computer analysis of electroencephalographic signal, and some of them additionally evaluate alterations of frontal electromyogram. According to some, monitors currently available on the market show around 80% effectiveness in preventing intraoperative awareness. Other researchers showed that evidence of their effect on intraoperative awareness is limited.

It seems that when it comes to the effect of anaesthetic agents on such a precise organ as the brain, there is still much to discover. As long as we do not fully know what awareness is and what mechanisms influence the state of staying awake and of anaesthetic sleep, and on which levels it happens, we will not be able to prevent intraoperative awareness effectively.

None declared.
None declared.
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