366
J. Raeder
The research questions were fairly simple and straightforward:
(1) What characterises (in the test battery) the awake versus the general anaesthetic
state?
(2) What characterises general anaesthesia with propofol versus general anaesthesia
with sevoflurane?
For these questions the software development looked for ways to pick out relevant
raw signals and signals of biorhythms which were useful for answering the question,
and then make an optimal synthetises of the relevant methods in terms of optimal
sensitivity and specificity.
The goal was to find a algorithm with 100% sensitivity and specificity in terms of
putting each individual patient into the categories above: Awake or asleep? Propofol
or sevoflurane?
The measurements were taken from the EEG signal, and also from a number
of other oscillating neuronal networks in the body: the heart, the vasculature, the
skin, the ventilation. The concept evolved not just on studying how they change, but
also on how their interactions and oscillations change during general anaesthesia.
For this purpose, soon after the start of this millennium, Aneta Stefanovska and
colleagues were able to collect a major European Union research grant, and set up an
extensive group of physicists, mathematicians and anaesthesiologists from a number
of different European countries, in the BRACCIA Project.
The practical parts of the project were:
(1) To set up and develop a number of tools, including new monitoring devices, for
extensive mapping of neuronal functions and networks.
(2) To use this basket of tools in real patients during either inhalational (sevoflurane)
or intravenous (propofol) general anaesthesia, and compare with the awake state.
(3) To apply extensive and complicated tools of signal- and wave-analyses to
the collected data, in order to develop a targeted, essential algorithm for
characterizing general anaesthesia with 100% specificity and sensitivity.
23.4 The Braccia Results, so far
The BRACCIA project has produced new knowledge, published in major journals.
In the first publication the use of non-EEG measures was evaluated [8].
We recorded ECG, respiration, skin temperature, pulse and skin conductivity
before and during general anaesthesia in 27 subjects in good cardiovascular health,
randomly allocated to receive propofol or sevoflurane. Each subject served as their
own control for the awake to anaesthetized state, whereas in-group differences was
determined for propofol anaesthesia versus sevoflurane anaesthesia. All changes
described (below) was statistically significant at < 0.05 level (Fig. 23.1).
For the mean values; respiratory rate, skin conductivity and skin temperature
changed with sevoflurane, and skin temperature with propofol. Pulse transit time
increased by 17% with sevoflurane and 11% with propofol. Sevoflurane reduced the
J. Raeder
The research questions were fairly simple and straightforward:
(1) What characterises (in the test battery) the awake versus the general anaesthetic
state?
(2) What characterises general anaesthesia with propofol versus general anaesthesia
with sevoflurane?
For these questions the software development looked for ways to pick out relevant
raw signals and signals of biorhythms which were useful for answering the question,
and then make an optimal synthetises of the relevant methods in terms of optimal
sensitivity and specificity.
The goal was to find a algorithm with 100% sensitivity and specificity in terms of
putting each individual patient into the categories above: Awake or asleep? Propofol
or sevoflurane?
The measurements were taken from the EEG signal, and also from a number
of other oscillating neuronal networks in the body: the heart, the vasculature, the
skin, the ventilation. The concept evolved not just on studying how they change, but
also on how their interactions and oscillations change during general anaesthesia.
For this purpose, soon after the start of this millennium, Aneta Stefanovska and
colleagues were able to collect a major European Union research grant, and set up an
extensive group of physicists, mathematicians and anaesthesiologists from a number
of different European countries, in the BRACCIA Project.
The practical parts of the project were:
(1) To set up and develop a number of tools, including new monitoring devices, for
extensive mapping of neuronal functions and networks.
(2) To use this basket of tools in real patients during either inhalational (sevoflurane)
or intravenous (propofol) general anaesthesia, and compare with the awake state.
(3) To apply extensive and complicated tools of signal- and wave-analyses to
the collected data, in order to develop a targeted, essential algorithm for
characterizing general anaesthesia with 100% specificity and sensitivity.
23.4 The Braccia Results, so far
The BRACCIA project has produced new knowledge, published in major journals.
In the first publication the use of non-EEG measures was evaluated [8].
We recorded ECG, respiration, skin temperature, pulse and skin conductivity
before and during general anaesthesia in 27 subjects in good cardiovascular health,
randomly allocated to receive propofol or sevoflurane. Each subject served as their
own control for the awake to anaesthetized state, whereas in-group differences was
determined for propofol anaesthesia versus sevoflurane anaesthesia. All changes
described (below) was statistically significant at < 0.05 level (Fig. 23.1).
For the mean values; respiratory rate, skin conductivity and skin temperature
changed with sevoflurane, and skin temperature with propofol. Pulse transit time
increased by 17% with sevoflurane and 11% with propofol. Sevoflurane reduced the