Background Excessive workload may impact the anaesthetists' ability to adequately process information during clinical practice in the operation room and may result in inaccurate situational awareness and performance. This exploratory study investigated heart rate (HR), linear and non-linear heart rate variability (HRV) metrics and subjective ratings scales for the assessment of workload associated with the anaesthesia stages induction, maintenance and emergence. Methods HR and HRV metrics were calculated based on five min segments from each of the three anaesthesia stages. The area under the receiver operating characteristics curve (AUC) of the investigated metrics was calculated to assess their ability to discriminate between the stages of anaesthesia. Additionally, a multiparametric approach based on logistic regression models was performed to further evaluate whether linear or non-linear heart rate metrics are suitable for the assessment of workload. Results Mean HR and several linear and non-linear HRV metrics including subjective workload ratings differed significantly between stages of anaesthesia. Permutation Entropy (PeEn, AUC=0.828) and mean HR (AUC=0.826) discriminated best between the anaesthesia stages induction and maintenance. In the multiparametric approach using logistic regression models, the model based on non-linear heart rate metrics provided a higher AUC compared with the models based on linear metrics. Conclusions In this exploratory study based on short ECG segment analysis, PeEn and HR seem to be promising to separate workload levels between different stages of anaesthesia. The multiparametric analysis of the regression models favours non-linear heart rate metrics over linear metrics.

Studying sleep behavior in animal models demands clear separation of vigilance states. Pure manual scoring is time-consuming and commercial scoring software is costly. We present a LabVIEW-based, semi-automated scoring routine using recorded EEG and EMG signals. This scoring routine is •designed to reliably assign the vigilance/sleep states wakefulness (WAKE), non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) to defined EEG/EMG episodes.•straightforward to use even for beginners in the field of sleep research.•freely available upon request. Chronic recordings from mice were used to design and evaluate the scoring routine consisting of an artifact-removal, a scoring- and a rescoring routine. The scoring routine processes EMG and different EEG frequency bands. Amplitude-based thresholds for EEG and EMG parameters trigger a decision tree assigning each EEG episode to a defined vigilance/sleep state automatically. Using the rescoring routine individual episodes or particular state transitions can be re-evaluated manually. High agreements between auto-scored and manual sleep scoring could be shown for experienced scorers and for beginners quickly and reliably. With small modifications to the software, it can be easily adapted for sleep analysis in other animal models.

Schulz, C.; Krautheim, V.; Hackemann, A.; Kreuzer, M.; Kochs, E. F.; Wagner, K. J. Author Information

Kellermann, K.; Müller, M.; Blobner, M.; Kochs, E. F.; Jungwirth, B. Author Information

BACKGROUNDMAC (minimum alveolar concentration of an inhaled anaesthetic) and CP₅₀i (minimum plasma concentration of i.v. anaesthetics) are well-established measures to compare potencies of anaesthetics. The underlying clinical endpoint immobility reflects mainly effects of anaesthetics on the spinal cord, which limits the use of this measure for comparison of effects on the main target organ of general anaesthesia--the brain. The present study determines the median concentration of sevoflurane, isoflurane, and propofol that induce the onset of electroencephalogram (EEG) suppression ('silent second'): MACBS and CP₅₀BS.METHODSFifty-five unpremedicated patients (ASA physical status of I or II) undergoing elective surgery were randomly assigned to receive general anaesthesia with sevoflurane, isoflurane, or propofol. A two-channel EEG was continuously recorded to identify 'silent second'. Independent cross-over pairs were analysed using the 'Dixon's up-and-down' method, and MACBS/CP₅₀BS values were calculated by logistic regression.RESULTSCP₅₀BS was 4.9 µg ml(-1) for propofol. MACBS was 2.9 vol% for sevoflurane and 1.5 vol% for isoflurane. CP₅₀BS of propofol was less than one-third of CP₅₀i, whereas MACBS of sevoflurane was >1.4-fold of MAC; MACBS of isoflurane was 1.3-fold of MAC.CONCLUSIONSImmobility and cerebral effects reflect different entities of anaesthetic action. The median concentration of anaesthetic drug (volatile or i.v. agent) required to induce 'silent second' might be a more useful metric than the median concentration required to prevent movement in response to a surgical stimulus in order to compare relative potencies of anaesthetic agents on the brain. Advantage of the 'silent second' is an easy identification of this endpoint, while such a deep level is not required for clinical anaesthesia.

Hintergrund: Die moderne Intensivmedizin ist sowohl dem kurativen Einsatz lebenserhaltender Maßnahmen, als auch der Beherrschung palliativer Behandlungskonzepte verpflichtet. In diesem Spannungsfeld der Balance zwischen Lebensverlängerung und Lebensqualität ist daher eine hohe Qualifikation und Behandlungsqualität gefordert. Ziel dieser Untersuchung war die Erhebung von Daten zur Selbsteinschätzung und zum palliativmedizinischen Kenntnisstand der auf Intensivstationen tätigen Ärzte.

Background. New cardiopulmonary resuscitation (CPR) guidelines have been published in 2010 emphasizing the importance of minimizing interruptions during chest compression. The aim of our study was to compare the simulator-based CPR training performance of physicians not specialized in anaesthesia and intensive care nurses before and after implementation of new resuscitation guidelines.Methods. In autumn 2010, a total of 74 scenarios during six 1.5 day simulation-based CPR trainings were performed. Four of them were conducted after the implementation of the 2010 guidelines. During each simulated scenario a programmed script standardized the conditions of the simulator and its reactions on the trainees' actions. CPR relevant parameters were extracted on the basis of the simulator's log files and no-flow-time fraction and median cardiac output of the simulator were calculated. Results before and after the guideline implementation were compared using the Wilcoxon Two Sample Test.Results. Thirty-four out of 74 scenarios were included into the analysis. During training according to the 2010 guidelines, the no-flow-time fraction was lower (median: 21.8% [IQR: 16.1-27.1%] vs. 29.1 % [IQR: 25.0-30.9 %]; P=0.04). The median cardiac output increased from 1.60 L/min(-1) [IQR: 1.50-1.65 L/min(-1)] to 1.90 L/min(-1) [IQR: 1.80-2.10 L/min(-1)]; P<0.001) when the CPR training was conducted according to the 2010 resuscitation guidelines.Conclusion. Non-anesthesiological physicians and intensive care nurses training demonstrated an improved CPR performance in a high-fidelity human patient simulator with respect to the median cardiac output and duration of no-flow-time when 2010 CPR guidelines were applied.

Heuser, F.; Schulz, C. M.; Schneider, E.; Kochs, E. F.; Wagner, K. J.; Lehnen, N. Author Information

Untergehrer, G.; Jordan, D.; Bretschneider, M.; Grimberg, S.; Kochs, E. F.; Schneider, G. Author Information

The involvement of the neuropeptides oxytocin (OXT) and vasopressin (AVP) in human socio-emotional behaviours is attracting increasing attention. There is ample evidence for elevated plasma levels upon a wide variety of social and emotional stimuli and scenarios, ranging from romantic love via marital distress up to psychopathology, with cause versus consequence being largely unclear. The present study examined whether plasma levels of both OXT and AVP are reflective of central neuropeptide levels, as assumed to impact upon socio-emotional behaviours. Concomitant plasma and cerebrospinal fluid (CSF) samples were taken from 41 non-neurological and nonpsychiatric patients under basal conditions. Although OXT and AVP levels in the CSF exceeded those in plasma, there was no correlation between both compartments, clearly suggesting that plasma OXT and AVP do not predict central neuropeptide concentrations. Thus, the validity of plasma OXT and AVP as potential biomarkers of human behaviour needs further clarification.

Kellermann, K.; Kadera, V.; Stigler, M.; Blobner, M.; Kochs, E. F.; Jungwirth, B. Author Information

Consciousness is related to the brains ability to process information. This is inline with EEG studies observing decreased signal “complexity” under anaesthesia induced unconsciousness. In the present investigation, 64channel electroencephalogram (EEG) of 15 volunteers was analyzed during consciousness, propofol induced sedation and unconsciousness. Univariate EEG parameters (spectral power, Higuchi fractal dimension, permutation entropy) and cortico-cortical information exchange in EEG based on symbolic transfer entropy (STE) were analysed to indicate effects of anaesthetics on the systemic information processing of the brain. The STE revealed affected interaction between frontal and parietal brain regions during unconsciousness.

Jordan, D.; Omerovic, A.; Kreuzer, M.; Berger, S.; Schneider, G.; Kochs, E. F. European Multicenter EEGAEP Anaesthesia Monitoring Study Group Author Information