Chapter 23
General Anaesthesia and Oscillations
in Human Physiology: The BRACCIA
Project
Johan Raeder
Abstract General anaesthesia may be induced by a number of different types of
drugs, and no clear-cut, single mechanism of action is recognized. Traditional monitoring of general anaesthesia is based on surrogate measures of adequate degree of
unconsciousness during painful stimuli; such as heart rate , blood-pressure, respiration, muscle activity and, in recent years, EEG. The dose need of anaesthetic drugs
must be adjusted to the individual patient and the surgical invasiveness. The idea
of the BRACCIA project was to monitor concomitantly the most relevant physiological changes, to distinguish objectively between awake and general anaesthesia,
and between propofol versus sevoflurane anaesthesia in a setup of 27 patients. ECG,
respiration, skin temperature, pulse and skin conductivity were recorded. Both raw
data, oscillations and interactions between parameters were tested, new hardware and
software were developed. A total of 28 different physiological outputs were tested.
With a best selection of 11 attributes, 9 from the EEG, 1 from ECG and 1 from respiratory rate we were able with 97% precision to distinguish the state of being awake
from the state of general anaesthesia. For the distinction between general anaesthesia
caused by either sevoflurane or propofol the precision was 87%.
Until the advent of anaesthesia during the nineteenth century, extensive surgery was
almost impossible to do with success; due to intense pain, vigorous movements and
muscle spasm, as well as life-threatening cardiovascular responses. The basic requirements for surgery, in this context, is a non-moving patients with relaxed muscles and
minor patient discomfort. This may be achieved with local anaesthesia infiltration for
minor procedures or regional anaesthetic nerve-blocks, including spinal or epidural
anaesthesia, for some more extensive procedures. However, the use of general anaesthesia is a dominating technique for most of the 4–500 million surgical procedures
which are performed world-wide every year. Even though general anaesthesia is very
J. Raeder (B)
Department of Anaesthesia, University of Oslo and Senior Consultant, Oslo University Hospital,
Oslo, Norway
e-mail: johan.rader@medisin.uio.no
© Springer Nature Switzerland AG 2021
A. Stefanovska and P. V. E. McClintock (eds.), Physics of Biological
Oscillators, Understanding Complex Systems,
https://doi.org/10.1007/978-3-030-59805-1_23
361
General Anaesthesia and Oscillations
in Human Physiology: The BRACCIA
Project
Johan Raeder
Abstract General anaesthesia may be induced by a number of different types of
drugs, and no clear-cut, single mechanism of action is recognized. Traditional monitoring of general anaesthesia is based on surrogate measures of adequate degree of
unconsciousness during painful stimuli; such as heart rate , blood-pressure, respiration, muscle activity and, in recent years, EEG. The dose need of anaesthetic drugs
must be adjusted to the individual patient and the surgical invasiveness. The idea
of the BRACCIA project was to monitor concomitantly the most relevant physiological changes, to distinguish objectively between awake and general anaesthesia,
and between propofol versus sevoflurane anaesthesia in a setup of 27 patients. ECG,
respiration, skin temperature, pulse and skin conductivity were recorded. Both raw
data, oscillations and interactions between parameters were tested, new hardware and
software were developed. A total of 28 different physiological outputs were tested.
With a best selection of 11 attributes, 9 from the EEG, 1 from ECG and 1 from respiratory rate we were able with 97% precision to distinguish the state of being awake
from the state of general anaesthesia. For the distinction between general anaesthesia
caused by either sevoflurane or propofol the precision was 87%.
Until the advent of anaesthesia during the nineteenth century, extensive surgery was
almost impossible to do with success; due to intense pain, vigorous movements and
muscle spasm, as well as life-threatening cardiovascular responses. The basic requirements for surgery, in this context, is a non-moving patients with relaxed muscles and
minor patient discomfort. This may be achieved with local anaesthesia infiltration for
minor procedures or regional anaesthetic nerve-blocks, including spinal or epidural
anaesthesia, for some more extensive procedures. However, the use of general anaesthesia is a dominating technique for most of the 4–500 million surgical procedures
which are performed world-wide every year. Even though general anaesthesia is very
J. Raeder (B)
Department of Anaesthesia, University of Oslo and Senior Consultant, Oslo University Hospital,
Oslo, Norway
e-mail: johan.rader@medisin.uio.no
© Springer Nature Switzerland AG 2021
A. Stefanovska and P. V. E. McClintock (eds.), Physics of Biological
Oscillators, Understanding Complex Systems,
https://doi.org/10.1007/978-3-030-59805-1_23
361