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Monitoring of the responsiveness to noxious stimuli during sevoflurane mono-anaesthesia by using RIII reflex
F von Dincklage1, H Velten, B Rehberg
1Department of Anesthesiology, Charité, Universitätsmedizin Berlin, Berlin, Germany. falk.von-dincklage@charite.de
Background:
We investigated the accuracy of the (normalized) RIII reflex threshold, the bispectral index (BIS), and the end-tidal sevoflurane concentration for predicting movement responses during mono-anaesthesia using sevoflurane.
Methods:
Fourteen male subjects were included. Each received a sevoflurane mono-anaesthesia for which the end-tidal concentration was increased in steps of 0.2 vol% every 10 min. Every 5 min, the reactions to noxious stimuli (10 s trapezius squeeze and 30 s 80 mA tetanic stimulus) were tested. The administration of sevoflurane was halted after no movement reactions occurred for three concentration steps. RIII reflex threshold and BIS were recorded continually in all subjects.
Results:
Thirteen subjects completed the study. The prediction probabilities for movement reactions to the noxious stimuli were 0.79 for the BIS, 0.91 for the RIII threshold, and 0.89 for the end-tidal sevoflurane concentration (PKDMACRO-Statistics: BIS vs RIII, P<0.05; BIS vs C(sevo), P<0.05; RIII vs C(sevo), P>0.05). All population prediction probability values differed significantly from 0.5 (P<0.01, PKDMACRO).
Conclusions:
All three instruments can be used for a prediction of movement responses to a noxious stimulus under sevoflurane mono-anaesthesia with an accuracy exceeding prediction by chance. The accuracy of the BIS to predict these responses appears to be lower compared with the RIII reflex threshold or the end-tidal sevoflurane concentration.
Insights
The RIII reflex threshold and end-tidal sevoflurane concentration accurately predict movement during anesthesia, outperforming the Bispectral Index (BIS). These findings aid in monitoring anesthetic depth and patient safety.
Area of Science:
- Anesthesiology
- Neuroscience
- Pharmacology
Background:
- Assessing anesthetic depth is crucial for patient safety.
- Sevoflurane is a common inhalation anesthetic.
- Monitoring movement responses to noxious stimuli helps determine anesthetic adequacy.
Purpose of the Study:
- To evaluate the accuracy of the RIII reflex threshold, Bispectral Index (BIS), and end-tidal sevoflurane concentration in predicting movement responses during sevoflurane mono-anesthesia.
- To compare the predictive performance of these three monitoring methods.
Main Methods:
- Fourteen male subjects received escalating doses of sevoflurane mono-anesthesia.
- Movement responses to noxious stimuli (trapezius squeeze, tetanic stimulation) were tested every 5 minutes.
- RIII reflex threshold and BIS were continuously recorded; sevoflurane administration ceased upon sustained lack of movement response.
Main Results:
- The prediction probabilities for movement were 0.79 for BIS, 0.91 for RIII threshold, and 0.89 for end-tidal sevoflurane concentration.
- The RIII reflex threshold and end-tidal sevoflurane concentration showed higher predictive accuracy than BIS (P<0.05).
- All tested parameters demonstrated predictive accuracy significantly better than chance (P<0.01).
Conclusions:
- The RIII reflex threshold, BIS, and end-tidal sevoflurane concentration can predict movement responses during sevoflurane mono-anesthesia.
- The RIII reflex threshold and end-tidal sevoflurane concentration are more accurate predictors of movement than BIS.
- These findings support the use of RIII reflex and sevoflurane concentration monitoring for assessing anesthetic depth.
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