Article

Assessing the depth of hypnosis of xenon anaesthesia with the EEG

De Gruyter
Biomedical Engineering / Biomedizinische Technik
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Abstract

Xenon was approved as an inhaled anaesthetic in Germany in 2005 and in other countries of the European Union in 2007. Owing to its low blood/gas partition coefficient, xenons effects on the central nervous system show a fast onset and offset and, even after long xenon anaesthetics, the wake-up times are very short. The aim of this study was to examine which electroencephalogram (EEG) stages are reached during xenon application and whether these stages can be identified by an automatic EEG classification. Therefore, EEG recordings were performed during xenon anaesthetics (EEG monitor: Narcotrend®). A total of 300 EEG epochs were assessed visually with regard to the EEG stages. These epochs were also classified automatically by the EEG monitor Narcotrend® using multivariate algorithms. There was a high correlation between visual and automatic classification (Spearman's rank correlation coefficient r=0.957, prediction probability Pk=0.949). Furthermore, it was observed that very deep stages of hypnosis were reached which are characterised by EEG activity in the low frequency range (delta waves). The burst suppression pattern was not seen. In deep hypnosis, in contrast to the xenon EEG, the propofol EEG was characterised by a marked superimposed higher frequency activity. To ensure an optimised dosage for the single patient, anaesthetic machines for xenon should be combined with EEG monitoring. To date, only a few anaesthetic machines for xenon are available. Because of the high price of xenon, new and further developments of machines focus on optimizing xenon consumption.

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... [13][14][15] Xenon significantly reduces EEG background voltage activity in healthy adults, [16] and reports using EEG parameters to assess depth of anaesthesia in adult patients inhaling Xe have been published. [17][18][19][20] However, the anaesthetic potency of Xe, or MAC-Xe (the minimal alveolar concentration of Xe preventing purposeful movement in 50% of subjects in response to a standardised painful stimulus), appears to be highly variable and age-dependent. [21] For instance, in eight healthy, newborn pigs, individual MAC-Xe ranged from 60 -120%. ...
... [11,15,31,32] Xenon has a rapid onset and offset of action regardless of duration of administration, as it does not accumulate within the body. [18] As with most inhalational anaesthetics, Xe reduces EEG background voltage level in healthy adults [16], and monitoring has been developed using bispectral analysis of EEG traces to monitor depth of anaesthesia. [17][18][19][20] In the clinical setting of neonatal encephalopathy, Azzopardi et al. have shown that Xe reduces seizure activity, with seizures reoccurring when Xe was stopped. ...
... [18] As with most inhalational anaesthetics, Xe reduces EEG background voltage level in healthy adults [16], and monitoring has been developed using bispectral analysis of EEG traces to monitor depth of anaesthesia. [17][18][19][20] In the clinical setting of neonatal encephalopathy, Azzopardi et al. have shown that Xe reduces seizure activity, with seizures reoccurring when Xe was stopped. [24] In our clinical feasibility study, using Xe as an add-on treatment during therapeutic hypothermia in asphyxiated newborns, we found that Xe depressed aEEG background voltage activity in some newborns. ...
Article
Background: Changes in electroencephalography (EEG) voltage range are used to monitor the depth of anaesthesia, as well as predict outcome after hypoxia-ischaemia in neonates. Xenon is being investigated as a potential neuroprotectant after hypoxic-ischaemic brain injury, but the effect of Xenon on EEG parameters in children or neonates is not known. This study aimed to examine the effect of 50% inhaled Xenon on background amplitude-integrated EEG (aEEG) activity in sedated healthy newborn pigs. Methods: Five healthy newborn pigs, receiving intravenous fentanyl sedation, were ventilated for 24 h with 50%Xenon, 30%O2 and 20%N2 at normothermia. The upper and lower voltage-range of the aEEG was continuously monitored together with cardiovascular parameters throughout a 1 h baseline period with fentanyl sedation only, followed by 24 h of Xenon administration. Results: The median (IQR) upper and lower aEEG voltage during 1 h baseline was 48.0 μV (46.0-50.0) and 25.0 μV (23.0-26.0), respectively. The median (IQR) aEEG upper and lower voltage ranges were significantly depressed to 21.5 μV (20.0-26.5) and 12.0 μV (12.0-16.5) from 10 min after the onset of 50% Xenon administration (p=0.002). After the initial Xenon induced depression in background aEEG voltage, no further aEEG changes were seen over the following 24h of ventilation with 50% xenon under fentanyl sedation. Mean arterial blood pressure and heart rate remained stable. Conclusion: Mean arterial blood pressure and heart rate were not significantly influenced by 24h Xenon ventilation. 50% Xenon rapidly depresses background aEEG voltage to a steady ~50% lower level in sedated healthy newborn pigs. Therefore, care must be taken when interpreting the background voltage in neonates also receiving Xenon.
... В аналогичном исследовании с ксеноном авторы выяви ли еще более высокую корреляцию между визуальной и автоматической оценкой (r = 0,957), но при этом от метили прямую связь активности ЭЭГ в диапазоне низ ких частот (дельта волны [δволны]) с очень глубокими стадиями наркоза, в отличие от анестезии пропофолом. По мнению авторов, мониторинг ЭЭГ должен быть обя зательным элементом наркозных аппаратов для анесте зии ксеноном [12]. Цель исследования -оценить возможность при менения шкалы Kugler на основании данных ЭЭГ как алгоритма объективной оценки глубины угнетения со знания ксеноном в комбинации с наркотическими аналь гетиками или без них, в сочетании с регионарной блока дой во время операции эндопротезирования коленного сустава у пациентов пожилого и старческого возраста. ...
... Однако ограничением данной работы является применение ремифентанила для обе зболивания в процессе анестезии. Возможно, повыше ние уровня корреляции произошло за счет более ров ного профиля обезболивания при постоянной инфузии НС[12], в отличие от «традиционной» болюсной схемы введения НС «по требованию» в на шей работе (груп па 1). В результате проведенного нами исследования по сле расшифровки и анализа ЭЭГ получен более высокий ...
Article
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INTRODUCTION. Anesthesia with xenon is characterized by stable hemodynamic parameters, cardio- and neuroprotection preferable in elderly. Assessment of the depth of hypnosis remains challenging. The Kugler classification based on electroencephalogram has been suggested for such assessment. OBJECTIVES. To assess the feasibility of Kugler scale for objective assessment of the depth of hypnosis induced by xenon alone or in combination with narcotics and regional anesthesia during knee arthroplasty in elderly. MATERIALS AND METHODS. The study included 57 patients divided into 2 groups. In group 1, general anesthesia with xenon was performed, fentanyl and femoral nerve block were used for pain control. In group 2, xenon anesthesia was performed in combination with femoral and sciatic nerve block. The depth of hypnosis was monitored using EEG and matched with the Kugler scale. Also, the bispectral index (BIS) was recorded. RESULTS. At xenon concentration of 40 %, the depth of hypnosis reached D2 stage in group 1 and D1 in group 2 patients, while at 55 % and above it was D2 in both groups. Fentanyl increased the δ-rhythm by 19.08 %, which corresponded to reduction in the effective xenon concentration by 20 %. A correlation between δ-rhythm decrease and BIS was seen in groups 1 (r = –0.78; R2 = 60 %) and 2 (r = –0.61; R2 = 37 %). The differences could be related to the use of fentanyl in group 1. The intergroup difference between the reduction of BIS was not significant. CONCLUSIONS. In elderly patients undergoing knee arthroplasty under combined anesthesia, stage D2 according to Kugler scale (proportion of δ-rhythm more than 50 %) is achieved at xenon concentration of 55 % without narcotics and at concentration of 40 % with fentanyl. The diminished correlation between δ-rhythm and BIS in group 2 and no difference in decrease of BIS suggests that BIS is less accurate for determining the depth of hypnosis during xenon monoanesthesia.
... After an infusion of balanced Ringer's acetate solution, routine monitoring devices were set up. A Narcotrend® monitor (MT MonitorTechnik GmbH und Co. KG, 24576 Bad Bramstedt, Maienbass 27, Germany) validated for xenon anaesthesia by the author was used to monitor the anaesthetic depth by single-lead EEG [2]. Anaesthesia was induced and controlled by the target controlled infusion technique (TCI) using the Base Primea® unit (Fresenius Kabi GmbH, Bad Homburg, Germany ). ...
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The aim was to evaluate the performance of anesthesia depth monitors, Bispectral Index (BIS) and Entropy, during single-agent xenon anesthesia in 17 healthy subjects. After mask induction with xenon and intubation, anesthesia was continued with xenon only. BIS, State Entropy and Response Entropy, and electroencephalogram were monitored throughout induction, steady-state anesthesia, and emergence. The performance of BIS, State Entropy, and Response Entropy were evaluated with prediction probability, sensitivity, and specificity analyses. The power spectrum of the raw electroencephalogram signal was calculated. The mean (SD) xenon concentration during anesthesia was 66.4% (2.4%). BIS, State Entropy, and Response Entropy demonstrated low prediction probability values at loss of response (0.455, 0.656, and 0.619) but 1 min after that the values were high (0.804, 0.941, and 0.929). Thereafter, equally good performance was demonstrated for all indices. At emergence, the prediction probability values to distinguish between steady-state anesthesia and return of response for BIS, State Entropy, and Response Entropy were 0.988, 0.892, and 0.992. No statistical differences between the performances of the monitors were observed. Quantitative electroencephalogram analyses showed generalized increase in total power (P < 0.001), delta (P < 0.001) and theta activity (P < 0.001), and increased alpha activity (P = 0.003) in the frontal brain regions. Electroencephalogram-derived depth of sedation indices BIS and Entropy showed a delay to detect loss of response during induction of xenon anesthesia. Both monitors performed well in distinguishing between conscious and unconscious states during steady-state anesthesia. Xenon-induced changes in electroencephalogram closely resemble those induced by propofol.
Article
The noble gases have always been an enigma. Discovered late in the history of chemistry and in seemingly small quantities in our atmosphere, they are some of the most unreactive elements known. However, despite being extremely inert, the noble gases (helium, neon, argon, krypton, xenon and radon) have found diverse and ever expanding applications in medicine. Of all of them, the gases that have found the greatest number of uses in the field of anaesthesia and related specialties are helium and xenon. This review focuses on the history of the discovery of both gases, their unique physicochemical properties and describes their uses in clinical practice with particular emphasis on those applicable to anaesthesia.
  • Houfek EE