Awareness detection during Caesarean section under general anaesthesia using EEG spectrum analysis

Abstract

This study examined the relationship between the EEG (spectral edge frequency en utilisant sur l'avant-bras la technique de Tunstall du garot isolant. Les patientes ont dtd rdparties au hasard pour recevoir soit du thiopentone (4 rag" kg -I) soit de la kdtamine (1 mg" kg-t) pour l'induction. Avant l'administration intraveineuse de succinylcholine, un garot isolant a dtd appliqud sur l'avant-bras et gonfl~ d 200 mmHg pour conserver l'activitd motrice de l'avant-bras. L'EEG a dt~ enregistrd 5 rain avant l~nduction et pendant l'anesth~sie. L~ncidence des r~ponses des ordres verbaux a dtd inf~rieure dans le groupe k~tamine (24%) (SEF90 moyenne 12,0 -t-3 Hz) comparativement au groupe thiopentone (52%) (SEFgO moyenne 18,09 + 3). Ces rdsultats suggbrent qu'une valeur de SEF inf~rieure ,~ 8.6 Hz suffit pour pr~venir la rdponse aux ordres verbaux.Awareness is the unintentional regaining of consciousness during presumed general anaesthesia and it has been recognized increasingly since the routine use of neuromuscular relaxants, i It can be a terrifying experience, representing a human and a medico-legal problem. [2][3][4] Although the brain is the major target organ of anaesthetic drugs, ironically this organ system has been largely ignored in routine monitoring during anaesthesia and major surgery. The complexity of the equipment and the difficulty of reading an unprocessed EEG tracing has limited its use in the operating room. 5During the past decade, as a result of advances in computer-processed EEG analyzers, routine EEG monitoring in the operation room is becoming more common; the information obtained from the EEG being converted into a simplified form for the clinician.The most widely used technique to process the EEG is power-spectrum analysis, which uses a computer to perform a Fourier transformation. In an attempt to simplify the description of the EEG, a number of descriptive variables has been derived from the power-spectrum analysis and they have been suggested as indicators of anaesthetic depth. 6,7 One of the most commonly used is CAN J ANAESTH 1995 / 42:5 / pp 377-81

Electro-deposited Nanoporous Platinum Electrode for EEG Monitoring

“…As many EEG studies have noted, a recommended range of the skin-electrode impedance is below 10 or 20 kΩ. 32 33 34 When compared to the skin-electrode impedances of commercially available electrodes, such as Ag/AgCl electrode (in a range of a few tens of kΩ) 35 or gold cup electrodes (12 kΩ in this study) with conductive paste, that of the developed L2-ePt electrode (10 kΩ in this study) falls within in a practical range. The L2-ePt electrode with moistened pad is conceptually similar to the “wet” electrode because the skin and the electrode of both conventional electrodes and the L2-ePt electrode is mediated by moisture and gel, respectively.…”