Awareness detection during caesarean section under general anaesthesia using EEG spectrum analysis.

Department of Anesthesiology, Bnai-Zion Medical Centre, Haifa, Israel.
Canadian Journal of Anaesthesia (Impact Factor: 2.5). 06/1995; 42(5 Pt 1):377-81. DOI: 10.1007/BF03015480
Source: PubMed

ABSTRACT This study examined the relationship between the EEG (spectral edge frequency 90-SEF90) and the occurrence of awareness defined for the purpose of this study as responsiveness to verbal commands. Fifty women undergoing general anaesthesia for elective Caesarean section were examined. Responsiveness to verbal commands was detected every minute in the period from the induction of anaesthesia to the delivery of the newborn using the Tunstall isolated forearm technique and correlated with the SEF90 value. The patients were assigned by a randomized code to receive either thiopentone (4 or ketamine (1 for induction of anaesthesia. Before the administration of succinylcholine a tourniquet was applied to the free arm, and inflated to 200 mmHg, to maintain motor function to one arm. The EEG recordings started five minutes before induction and were recorded throughout anaesthesia. The incidence of responsiveness to verbal commands was lower in the ketamine group (24%) where the average SEF90 was 12.0 +/- 3 Hz, than in the thiopentone group (52%), where the average SEF90 was 18.09 +/- 3 Hz (P = 0.01). The results suggest that SEF values of < or = 8.6 Hz were sufficient to avoid responsiveness to verbal commands.

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    Anesthesiology 11/2012; 117(5):1140-1. · 6.17 Impact Factor
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    ABSTRACT: Intraoperative monitoring of electroencephalograms (EEGs) is becoming more commonplace as the technology advances,7 and 39 making it easier and less costly to apply.48 Although the cardiovascular status and systemic perfusion are routinely monitored during anesthesia, the brain, which is the target organ of general anesthesia, is generally not monitored. Instead, it is generally assumed that without prior known pathology, adequate cerebral perfusion can be assumed by maintaining adequate mean arterial pressure.72 Cerebral blood flow is not only dependent on adequate cerebral perfusion pressure, which is decreased by elevations in intracranial pressure, but also by changes in cerebral vascular resistance and cerebral vascular pathology.74 Monitoring for cerebral perfusion, however, is not the only application for intraoperative EEG monitoring. EEG can also be used to monitor the depth of sedation and the degree of burst suppression produced by barbiturate infusion, as well as monitoring for the occurrence of seizures while the patients are under the influence of muscle relaxants.20 Each of these applications are discussed in this article, but for intraoperative EEG to be most effectively applied, a number of fundamental principles must first be addressed.
    Anesthesiology Clinics of North America 09/1997; 15(3):551-571.
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    ABSTRACT: Fragestellung. Vergleich der mütterlichen Kreislaufparameter, der mütterlichen und kindlichen endokrinen Stressreaktion, der kindlichen Vitalparameter und weiterer klinischer Effekte wie Aufwachverhalten, Übelkeit und Erbrechen sowie Analgetikabedarf bei zwei Verfahren der Allgemeinanästhesie sowie der Spinalanästhesie zur geplanten oder dringlichen Sectio caesarea. Methodik. Die Patientinnen mit Allgemeinanästhesie wurden prospektiv-randomisiert der Esketamin- (n=21; Einleitung mit 0,5 mg/kg KG Esketamin und 1,5 mg/kg KG Methohexital;Beatmung bis zur Abnabelung mit FiO2 1,0) oder Sevofluran-Gruppe zugeordnet (n=21; Einleitung mit 1,5–2,0 mg/kg KG Methohexital,Beatmung bis zur Uterotomie mit N2O/O2 [FiO2 0,5] sowie Sevofluran etwa 1,0 Vol.-% endtidal).Nach Abnabelung wurden in beiden Gruppen 2,5 μg/kg KG Fentanyl und Sevofluran (etwa 1,0 Vol.-% endtidal) unter Beatmung mit N2O-O2 (FiO2 0,33) zugeführt. Als weitere, nichtrandomisierte Kontrolle wurde eine Spinalanästhesie (SPA)-Gruppe (n=22; 2,6–3,0 ml isobares 0,5 %iges Bupivacain) untersucht. Die mütterlichen Kreislauf- und endokrinen Stressparameter wurden an 5 Messzeitpunkten, die kindlichen Parameter einmalig nach der Entbindung bestimmt.Das Signifikanzniveau betrug α≤0,05. Ergebnisse. Bei vergleichbaren biometrischen Daten der Mütter lag der systolische arterielle Druck in der Esketamin-Gruppe höher (p=0,008),während die Herzfrequenz in der SPA-Gruppe niedriger war (p<0,001). Noradrenalin sank in allen Kollektiven ab (p<0,001); das Gruppenniveau war in der SPA-Gruppe geringer (p=0,04).Auch das Adrenalin-Gruppenniveau lag in der SPA-Gruppe niedriger (p<0,001). ADH blieb in allen Kollektiven im Normalbereich oder geringfügig darüber;ACTH stieg in allen Kollektiven zunächst an und fiel danach ab (p<0,001).Kortisol stieg in allen Gruppen an (p<0,001); das Gruppenniveau in der SPA-Gruppe war geringer (p<0,001).Das Aufwachverhalten blieb in den Kollektiven mit Allgemeinanästhesie vergleichbar; intraoperative Wachheit oder negative Traumreaktionen traten nicht auf.Die postoperative Inzidenz hypoxischer Ereignisse (psaO2 <90%) war in allen 3 Kollektiven vergleichbar. In der SPA-Gruppe erfolgte die erste Analgetikaanforderung später als in den anderen Kollektiven (p=0,001); die Gesamtdosis an Piritramid war geringer (p=0,02); Übelkeit und Erbrechen traten häufiger auf (p=0,03). Die Akzeptanz des Verfahrens betrug jeweils 100%.Die kindlichen Kollektive (69 Kinder, 5 Zwillingsgeburten) waren hinsichtlich Apgar- und pH-Werten sowie Noradrenalin-, Adrenalin- und Kortisol-Konzentrationen vergleichbar.Die Esketamin-Werte im Plasma der Kinder lagen unter den mütterlichen Konzentrationen (251 vs.493 ng/ml). Schlussfolgerungen. Im Vergleich mit Methohexital, Sevofluran und N2O erlaubt die initiale totale intravenöse Anästhesie zur Sectio mit Esketamin und Methohexital eine spezifische Antinozizeption ohne negative mütterliche und fetale Begleiteffekte und ohne Beachtung einer Invasionskinetik bei der Einleitung bzw. einer Eliminationskinetik zwischen Uterotomie und Abnabelung.Der Verzicht auf N2O ermöglicht die optimale Oxygenierung der fetomaternalen Einheit. Bei suffizienter Stressabschirmung ist die Kreislaufsituation stabil; intraoperative Wachheit oder negative Traumreaktionen traten nicht auf.Vorteile der Spinalanästhesie liegen im geringeren postoperativen Analgetikabedarf,während die Inzidenz von Übelkeit und Erbrechen bei diesem Verfahren erhöht war. Objectives. The study was undertaken to compare different anaesthetic techniques for scheduled or urgent caesarean section with respect to maternal circulatory parameters, maternal and fetal endocrine stress response, fetal vitality parameters and further clinical parameters such as recovery and analgesic demand. Methods. After ethical approval,patients scheduled for general anaesthesia were randomly allocated to the esketamine group (n=21; induction with 0.5 mg/kg BW esketamine and 1.5 mg/kg BW methohexitone, ventilation until cord cuting with FiO2 1.0) and the sevoflurane-group (n=21; induction with 1.5–2.0 mg/kg BW methohexitone, ventilation until uterotomia with N2O/O2 [FiO2 0,5] and endtidal sevoflurane concentrations about 1.0 vol%).After fetal development, all patients received 2.5 μg/kg BW fentanyl and sevoflurane (about 1.0 vol% endtidal) during ventilation with N2O/O2 (FiO2 0.33). As a further control, a group with spinal anaesthesia (n=22; 2.6–3.0 ml isobaric bupivacaine 0.5 %) was investigated. Maternal circulatory and endocrine plasmatic stress parameters were investigated at five time points and fetal parameters once after development.α≤0.05 was considered significant. Results. Biometric data were comparable in all groups.Systolic arterial pressure was higher in the esketamine group (p=0.008), whereas the heart rate was lower during spinal anaesthesia (p<0.001).Plasma noradrenaline decreased in all collectives (p<0.001) and mean group levels of noradrenaline (p=0.04) and adrenaline (p<0.001) were lower during spinal anaesthesia. In all groups, antidiuretic hormone (ADH) remained within the normal range or was slightly increased.Adrenocorticotropic hormone (ACTH) initially increased in all groups and decreased in later time course (p<0.001).Cortisol increased in all groups (p<0.001) but group levels were lower during spinal anaesthesia (p<0.001). In the groups with general anaesthesia, no significant differences in recovery times were obvious, and neither recall nor dream reactions were observed.Postoperative hypoxic incidents (psaO2 <90%) were comparable between the groups.After spinal anaesthesia, first analgesic demand was later than in the controls (p=0.001), and the total amount of piritramide was lower (p=0.02).Nausea and vomiting were more frequent during spinal anaesthesia (p=0.03). All patients were content with their regimen.Apgar scores, pH-values and adrenaline, noradrenaline and cortisol in plasma were comparable in all groups of children (69 children, 5 gemini). The fetal concentration of esketamine (251 ng/ml) was lower than the corresponding maternal values (493 ng/ml). Conclusions When compared with methohexitone, sevoflurane and N2O for caesarean section, initial total intravenous anaesthesia with esketamine and methohexitone mediated specific antinociception without negative maternal or fetal effects and not taking invasion kinetics or elimination between uterotomia and cord cutting into consideration. Avoidance of N2O allows optimal oxygenation of the fetomaternal unit.Stress protection and hemodynamic responses were well balanced, and intraoperative recall or negative dream reactions were lacking. Superior postoperative pain protection was advantageous after spinal anaesthesia, but in contrast, nausea and vomiting were more frequent in this group.
    Der Anaesthesist 12/2002; 52(1):23-32. · 0.74 Impact Factor

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