Correlation of Sedline-generated variables and clinical signs with anaesthetic depth in experimental pigs receiving propofol

Abstract

Most of currently available electroencephalographic (EEG)-based tools to assess depth of anaesthesia have not been studied or have been judged unreliable in pigs. Our primary aim was to investigate the dose-effect relationship between increasing propofol dose and variables generated by the EEG-based depth of anaesthesia monitor Sedline in pigs. A secondary aim was to compare the anaesthetic doses with clinical outcomes commonly used to assess depth of anaesthesia in this species. Sixteen juvenile pigs were included. Propofol infusion was administered at 10 mg kg-1 h-1, increased by 10 mg kg-1 h-1 every 15 minutes, and stopped when an EEG Suppression ratio >80% was reached. Patient state index, suppression ratio, left and right spectral edge frequency 95%, and outcomes from commonly used clinical methods to assess depth of anaesthesia in pigs were recorded. The best pharmacodynamic model was assessed for Patient state index, suppression ratio, left and right spectral edge frequency 95% in response to propofol administration. The decrease of Patient state index best fitted to an inhibitory double-sigmoid model (including a plateau phase). The increase of suppression ratio fitted a typical sigmoid Emax model. No relevant relationship could be identified between spectral edge frequency 95% values and propofol administration. A large variability in clinical outcomes was observed among pigs, such that they did not provide a reliable evaluation of propofol dose. The relationship between propofol dose and Patient state index/suppression ratio described in the present study can be used for prediction in future investigations. The evaluation of depth of anaesthesia based on common clinical outcomes was not reliable.

Spatial and temporal frequency band changes during infarct induction, infarct progression, and spreading depolarizations in the gyrencephalic brain

“…The anesthetic drugs have specific anatomic regions of action and the frontoparietal cortex is one of their targets, the same place the electrodes were set. It was expected that the anesthetic agents such as midazolam, propofol, and isoflurane induce an unconscious state by modulating the brain activity of swine when attenuating the fast frequencies and increasing the slower ones ( Akeson et al, 1993 ; Mäkiranta et al, 2002 ; Bojak et al, 2015 ; Mirra et al, 2022 ). Furthermore, isoflurane is capable to suppress SD development.…”

Spatio-temporal electroencephalographic power distribution in experimental pigs receiving propofol

“…Given that this technique is not applicable in animals, other endpoints need to be used to identify a deep hypnotic state. In the present study, clinical parameters were excluded due to the great variability previously observed [ 17 ]. The occurrence of EEG suppression was rather targeted, and data collected after its supposed onset were excluded.…”

The effect of methylphenidate on anaesthesia recovery: An experimental study in pigs

“…Indeed, SedLine® EEG-related variables showed no relevant differences among groups. Being the SedLine® validated for humans, we cannot exclude that differences were not found due to possible miscalculations [ 18 ]. However, no differences were present in EEG power, supporting the hypothesis that MP is not effective in stimulating cerebral activity and shortening recovery time at the end of propofol anaesthesia in this species, at least at the doses used.…”