A novel multivariate STeady-state index during general ANesthesia (STAN)

Purpose: electroencephalographic (EEG) information is used to monitor the level of cortical depression of a patient undergoing surgical intervention under general anesthesia. The dynamic state transitions into and out of anesthetic-induced loss and return of responsiveness (LOR, ROR) present a possibility to evaluate the dynamics of the EEG induced by different substances. We evaluated changes in the EEG power spectrum during anesthesia emergence for three different anesthetic regimens. We also assessed the possible impact of these changes on processed EEG parameters such as the permutation entropy (PeEn) and the cerebral state index (CSI). Methods: we analyzed the EEG from 45 patients, equally assigned to three groups. All patients were induced with propofol and the groups differed by the maintenance anesthetic regimen, i.e., sevoflurane, isoflurane, or propofol. We evaluated the EEG and parameter dynamics during LOR and ROR. For the emergence period, we focused on possible differences in the EEG dynamics in the different groups. Results: depending on the substance, the EEG emergence patterns showed significant differences that led to a substance-specific early activation of higher frequencies as indicated by the “wake” CSI values that occurred minutes before ROR in the inhalational anesthetic groups. Conclusion: our results highlight substance-specific differences in the emergence from anesthesia that can influence the EEG-based monitoring that probably have to be considered in order to improve neuromonitoring during general anesthesia.

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Comparison of bispectral index and patient state index during sevoflurane anesthesia in children: a prospective observational study

10.21203/rs.3.rs-53378/v1 ◽

2020 ◽

Author(s):

Sang-Hwan Ji ◽

Young-Eun Jang ◽

Eun-Hee Kim ◽

Ji-Hyun Lee ◽

Jin-Tae Kim ◽

...

Keyword(s):

Steady State ◽

Bispectral Index ◽

Prospective Observational Study ◽

Pediatric Population ◽

Sevoflurane Anesthesia ◽

Confidential Interval ◽

Prediction Probability ◽

Patient State ◽

State Index ◽

Patient State Index

Abstract Background: Cortical electroencephalography (EEG)-based devices are used to monitor the depth of anesthesia. In this study, we compared the values of bispectral index (BIS) and patient state index (PSI) during sevoflurane anesthesia in children. The ability/accuracy of BIS and PSI to predict the steady and recovery state of anesthesia was evaluated based on prediction probability (Pk) values and the secondary outcomes were agreement and correlation of two monitors. Methods: Fifty children (3-12 years old) were enrolled and the patients received sevoflurane anesthesia with remifentanil. Before the induction of anesthesia, BIS and PSI sensors were simultaneously placed on the forehead, and data were collected until the end of anesthesia. Steady state was defined as the period following intubation until the cessation of sevoflurane, while recovery state was defined as the period following the cessation of sevoflurane until awake. The prediction probability (Pk), agreement or correlation of BIS and PSI in different anesthesia state were calculated. Results: Anesthesia reduced mean BIS and PSI values. Pk of BIS (95% confidential interval (CI) [0.78-0.91])) and PSI (95% CI [0.82-0.91]) for anesthesia were 0.85 and 0.87, respectively. Agreement was 0.79 for recovery state and 0.73 for steady state. Conclusions: Pk values were comparable for BIS and PSI. Agreement between BIS and PSI measurements in the same state was relatively good. Therefore, these monitors are appropriate for monitoring for different state of anesthesia in pediatric population. Trial Registry Number: Clinical Trials.gov NCT03792334.

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Non-steady state, continuous measurement of O/sub 2/ uptake and Co/sub 2/ production during general anesthesia in man using the capnomac ultimxrm and a mini bypass mixing chamber

Proceedings of the 15th Annual International Conference of the IEEE Engineering in Medicine and Biology Societ ◽

10.1109/iembs.1993.978739 ◽

2005 ◽

Author(s):

V. Kapur ◽

S. Gregoretti ◽

G. Ritchie ◽

D.D. Doblar

Keyword(s):

Steady State ◽

General Anesthesia ◽

Continuous Measurement ◽

Mixing Chamber

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Influence of Auditory Stimulation Rates on Evoked Potentials during General Anesthesia

Anesthesiology ◽

10.1097/aln.0b013e31819dad6f ◽

2009 ◽

Vol 110 (5) ◽

pp. 1026-1035 ◽

Cited By ~ 17

Author(s):

Richard R. McNeer ◽

Jorge Bohórquez ◽

Özcan Özdamar

Keyword(s):

Steady State ◽

General Anesthesia ◽

Stimulus Presentation ◽

Quantitative Relation ◽

Middle Latency Response ◽

Auditory Middle Latency Response ◽

Latency Response ◽

Middle Latency ◽

Composite Nature ◽

40 Hz

Background The auditory middle-latency response (transient) and the 40-Hz auditory steady state response (ASSR) are modulated by anesthetics. However, the quantitative relation between these evoked responses is difficult to obtain because of technical limitations of the recording methods used to obtain transients at high stimulation rates. This study uses continuous-loop averaging deconvolution to fill this technical gap and to study the relation between the transient and ASSR waveform during general anesthesia. Methods The authors recorded 5- and 40-Hz transients and 40-Hz ASSRs in 13 subjects during general anesthesia. The 5- and 40-Hz transients were used to predict the 40-Hz ASSR by linearly superimposing the transient waveforms. The predicted and recorded ASSRs were analyzed and compared using phasor and Hotelling T(2) analyses. Results Grand-averaged recordings revealed differences in the early middle-latency peaks between 5- and 40-Hz transients, e.g., the peak P(x) was present only in 5-Hz transient. Only the predicted 40-Hz ASSR derived from the 40-Hz transient matched the actual ASSR. Phasor analysis showed that the early peaks contribute significantly to the steady state waveform, and this explains why 5-Hz transient does not predict the 40-Hz ASSR. Oscillations in both the 5- and 40-Hz transients were observed during anesthesia. Discussion The 40-Hz ASSR represents a composite waveform and arises when transient waveforms elicited with a 40-Hz stimulation rate are overlapped and superimposed. During general anesthesia, the morphology of the transient is dependent on the rate of stimulus presentation. The composite nature of the ASSR may explain nonmonotonic anesthetic dose-response relations observed by others.

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