F.A. Beger

Hannover Medical School, Hanover, Lower Saxony, Germany

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Publications (7)9.64 Total impact

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    ABSTRACT: The aim of this study was to compare the EEG parameter Narcotrend Index with the spectral and entropy-based EEG parameters median frequency, 95% spectral edge frequency, burst-compensated 95% spectral edge frequency, spectral entropy, amplitude entropy, and approximate entropy with regard to their ability to describe cerebral anaesthetic drug effects during induction of propofol-remifentanil anaesthesia. Three induction schemes were studied with 10 patients each receiving 2 mg propofol/kg/60s (group 1), 4 mg/kg/120s (group 2), and 4 mg/kg/240s (group 3). The EEG was recorded with the EEG monitor Narcotrend. To analyse the relation between drug effect and EEG parameters, Spearman rank correlation of the different EEG parameters with the calculated propofol effect-site concentration was computed. In all groups Narcotrend Index showed the highest correlation with the propofol effect-site concentration and the lowest variability of individual correlation values. Furthermore, only the Narcotrend Index showed a monophasic behaviour over the entire time period analysed. In the group of entropy parameters approximate entropy yielded the best results. Among the spectral parameters the burst-compensated 95% spectral edge frequency had the highest correlation with the propofol effect-site concentration. It was markedly higher than for the standard spectral edge frequency. The correlations of median frequency and amplitude entropy with propofol effect-site concentration were the lowest. CONCLUSIONS. Changes in the propofol effect-site concentration during induction of anaesthesia were best described by the multivariate Narcotrend Index compared to conventional spectral EEG parameters and different entropy measures.
    No preview · Article · Sep 2004 · Journal of Clinical Monitoring and Computing
  • A Schultz · U Grouven · FA Beger · B Schultz
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    ABSTRACT: A reliable assessment of the depth of hypnosis during sedation and general anaesthesia using the EEG is a subject of current interest. The Narcotrend Index implemented in the latest version 4.0 of the EEG monitor Narcotrend provides an automatic classification of the EEG on a scale ranging from 100 (awake) to 0 (very deep hypnosis, EEG suppression). The classification algorithms implemented in the EEG monitor Narcotrend are described. In a study the correlation of the propofol effect-site concentration with the Narcotrend Index and with the traditional spectral parameters total power, relative power in the standard frequency bands delta, theta, alpha, and beta, median frequency, 95% spectral edge frequency, burst-compensated spectral edge frequency, and spectral entropy was investigated. The Narcotrend Index had the highest average correlation with the propofol effect-site concentration and the smallest variability of the individual correlation values. Moreover, the Narcotrend Index was the only parameter which showed a monophasic trend over the whole investigated time period. The Narcotrend monitor can make a significant contribution to the improvement of the quality of anaesthesia by adjusting the dosage of hypnotics to individual patient needs.
    No preview · Article · Apr 2004 · Biomedizinische Technik
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    ABSTRACT: Age-related differences in the spectral composition of the EEG in induction and emergence times, and in drug consumption during propofol anaesthesia were investigated. The EEGs of 60 female patients between 22 and 85 years of age were monitored continuously during standardized induction of anaesthesia with 2 mg of propofol kg(-1)60 s(-1). The EEGs were visually assessed in 20-s epochs according to a scale from A (awake) to F (very deep hypnosis). Visual EEG classifications, spectral parameters, and induction times were compared between different age groups. Additionally, data of 546 patients included in a multicentre study with 4630 patients (EEG monitor Narcotrend, MT MonitorTechnik, Bad Bramstedt, Germany) were analyzed with regard to age-dependent changes of propofol consumption using target-controlled infusion (TCI). During induction, patients older than 70 years reached significantly deeper EEG stages than younger patients, needed a longer time to reach the deepest EEG stage, and needed more time until a light EEG stage was regained. In patients aged 70 years and older, the total power, mainly in deep EEG stages, was significantly smaller due to a distinctly smaller absolute power of the delta frequency band. No single spectral parameter was able to reliably distinguish all EEG stages. During the steady state of anaesthesia, older patients needed less propofol for the maintenance of a defined stage of hypnosis than younger patients. Older patients differ from younger ones regarding the hypnotic effect of propofol and the spectral patterns in the EEG. For an efficient automatic assessment of the EEG during anaesthesia a multivariable approach accounting for age-effects is indispensable.
    No preview · Article · Feb 2004 · Acta Anaesthesiologica Scandinavica
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    ABSTRACT: Cochlear implantation is a widely used means of treating deafness and severe hearing disorders. The surgical procedure includes inserting the cochlear implant electrode array into the cochlea and embedding the corresponding signal receiver in the mastoid bone behind the ear. Postoperative fitting of the externally worn speech processor is very important for successful use of the cochlear implant. For this purpose, electrically elicited stapedius reflex threshold values can be used. However, stapedius reflex threshold values measured intraoperatively are influenced by anaesthetics. The goal of this retrospective study was to find out whether electroencephalogram (EEG) control of anaesthesia produces more reliable reflex threshold values as a basis for the fitting of the speech processor. Three groups of children, after surgery for cochlear implantation, were analysed with regard to the magnitude of intraoperative electrically elicited stapedius reflex threshold values and their deviations from postoperatively determined maximum comfortable levels (group 1: methohexital/remifentanil with EEG monitoring, n = 10; group 2: isoflurane/fentanyl with EEG monitoring, n = 9; group 3: isoflurane/fentanyl without EEG monitoring, n = 11). Children with EEG monitoring had significantly lower electrically elicited stapedius reflex threshold values and also significantly lower differences between intraoperative stapedius reflex threshold values and postoperatively determined maximum comfortable levels. Electroencephalogram monitoring in cochlear implantation is of considerable value in controlling anaesthesia and improving speech processor fitting based on more reliable intraoperative neurophysiological data.
    No preview · Article · Dec 2003 · Pediatric Anesthesia
  • A. Schultz · B. Schultz · F.A. Beger

    No preview · Article · Jan 2003
  • B. Schultz · A. Schultz · F.A. Beger

    No preview · Article · Oct 2001 · Der Anaesthesist
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    ABSTRACT: In this article unexpected EEG findings are described which were observed during EEG monitoring under sevoflurane anesthesia. In seven non-epileptic adult patients sevoflurane was administered as inhalation anesthetic during routinely performed surgical operations. The EEG was recorded continuously as part of the standard monitoring process and served mainly as a dosage guide for anesthetics/narcotics. Occurrence of sharp transients in the EEG resembling distinctive waves which can be seen in epileptic disorders. In six of the seven patients under 8.0% sevoflurane, sharp transients were observed which appeared in very deep EEG stages, mostly with endtidal sevoflurane concentrations of 4.8-5.9%. The findings are in accordance with observations in non-epileptic children from our clinic. The clinical significance of the observed EEG pattern under sevoflurane anesthesia is still unclear. Taking into consideration that convulsive and nonconvulsive status epilepticus can be followed by signs of brain damage, it would appear to be important to further investigate the phenomenon.
    No preview · Article · May 2001 · International Journal of Clinical Pharmacy