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Background: The pharmacokinetic properties of the new benzodiazepine remimazolam have been studied only in adults. We investigated the pharmacokinetics of remimazolam after i.v. infusion in anaesthetised paediatric patients., Methods: Twenty-four children (2-6 yr, ASA physical status 1-2, BMI 15-18 kg m -2 ) undergoing general anaesthesia with sevoflurane were enrolled. During surgery, remimazolam was administered as an i.v. infusion over 1 h at 5 mg kg -1 h -1 for 5 min, followed by 1.5 mg kg -1 h -1 for 55 min. Plasma concentrations of remimazolam and its metabolite CNS7054 were determined from arterial blood samples using ultra-high performance liquid chromatography-mass spectrometry. Pharmacokinetic modelling was performed by population analysis., Results: Pharmacokinetics were best described by a three-compartment model for remimazolam and a two-compartment model for CNS7054 linked by a transit compartment. Remimazolam showed a high clearance of 15.9 (12.9, 18.2) ml kg -1 min -1 (median, Q 25 , Q 75 ), a small central volume of distribution of 0.11 (0.08, 0.14) L kg -1 and a short terminal half-life of 67 (49, 85) min. The context-sensitive half-time after an infusion of 4 h was 17 (12, 21) min. The metabolite CNS7054 showed a low clearance of 0.89 (0.33, 1.40) ml kg -1 min -1 , a small central volume of distribution of 0.011 (0.005, 0.016) L kg -1 , and a long terminal half-life of 321 (230, 770) min., Conclusions: Remimazolam in children was characterised by a high clearance and short context-sensitive half-time. When normalised to weight, pharmacokinetic properties were similar to those reported for adults., Clinical Trial Registration: ChiCTR2200057629., (Copyright © 2023 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

Preparations for anesthesiological management of patients build on preoperative patient self-reports concerning risk factors and comorbidities. In this setting, electronic documentation could facilitate innovative computerized functions, although patient-facing digital questionnaires require appropriate tools that patients can access effectively. To explore the feasibility of an electronic application for preoperative data acquisition directly from patients, a digital, tablet-based prototypical application has been developed within a user-centered design process in order to replace a previously used paper-based anamnesis sheet for perioperative risk evaluation. The implemented prototype has been extensively tested and iteratively improved to progressively provide an easy-to-use data entry function. To assess the suitability of this tool for everyday data acquisition by patients and physicians and to identify usability problems, the stepwise development process was accompanied by a heuristic evaluation as well as a think-aloud evaluation, while another 56 participating patients completed a feedback sheet according to ISO 9241/10. The latter method detected additional usability problems that occurred during the use of the application, which contributed to iterative improvements of the prototype. Throughout the development process, 81 issues were identified and largely resolved. After these revisions of the prototype, the number of problems found per tester decreased from 4.75 to 0.96, while the overall rating increased to 6.14 out of 7 points (SD = 1.2). These improvements demonstrate the value and efficiency of such a user-centered design process and illustrate that a user-friendly patient-facing digital data entry can replace preoperative paper questionnaires for anesthesiological management.

Spontaneous or evoked electrical brain activity is increasingly used to monitor general anesthesia. Previous studies investigated the variables from spontaneous electroencephalogram (EEG), acoustic (AEP), or somatosensory evoked potentials (SSEP). But, by monitoring them separately, the available information from simultaneous gathering could be missed. We investigated whether the combination of simultaneous information from EEG, AEP, and SSEP shows a more discriminant power to differentiate between anesthesia states than from information derived from each measurement alone. Therefore, we assessed changes of 30 EEG, 21 SSEP, and 29 AEP variables recorded from 59 patients during four clinical states of general anesthesia: "awake," "light anesthesia," "surgical anesthesia," and "deep surgical anesthesia." The single and combined discriminant powers of EEG, AEP, and SSEP variables as predictors of these states were investigated by discriminant analysis. EEG variables showed a higher discriminant power than AEP or SSEP variables: 85%, 46%, and 32% correctly classified cases, respectively. The frequency of correctly classified cases increased to 90% and 91% with information from EEG + AEP and EEG + AEP + SSEP, respectively. Thus, future anesthesia monitoring should consider combined information simultaneously distributed on different electrophysiological measurements, rather than single variables or their combination from EEG or AEP or SSEP.

Objective: Bispectral analysis of the electroencephalogram (EEG) has been used to monitor depth of anesthesia. In the majority of publications this has been done using the so called Bispectral (BIS) Index. The exact relation of this index to bispectral quantities like the bispectrum and its normalized version the bicoherence has not yet been published. In case the EEG is a linear random process the bicoherence is trivial. It is a mere constant independent of the EEG frequency. If the signal is a linear Gaussian random process this constant is zero. In this case both the bispectrum and bicoherence are zero. The aim of this study was to determine the proportion of EEG epochs with non-trivial bicoherence during anesthesia with isoflurane/nitrous oxide., Methods: We reanalyzed 26.4 hr of EEG signal recorded in 8 patients during anesthesia for general abdominal surgery which were stored in digitized form on CD-Rom. The test developed by Hinich for Gaussianity and linearity was applied to these data. The test was validated with various kinds of surrogate data; especially the phase randomized (pr) EEG, synthetic Gaussian random data and the z-component of the Lorenz attractor and its pr version., Results: The proportion of epochs for which a non-trivial bicoherence was detected by the test was as follows: Lorenz data 95%, pr Lorenz data 5%, synthetic Gaussian data 13.8%, pr EEG 5.4%, original EEG 6.2%., Conclusion: As expected the test procedure correctly identified for the Lorenz data for 95% of all epochs a non-trivial bicoherence. For the original EEG data we could not find a significant greater percentage of epochs with non-trivial bicoherence than for the pr data and the synthetic Gaussian data. We conclude that the EEG during anesthesia with isoflurane/alfentanil appears to be largely a linear random process.