British journal of anaesthesia
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Comparative Study
Validation of the index of consciousness during sevoflurane and remifentanil anaesthesia: a comparison with the bispectral index and the cerebral state index.
The purpose of this study was to validate a new level of consciousness monitor derived from the EEG, called the index of consciousness (IoC), by comparing it with the bispectral index (BIS) and the cerebral state index (CSI) during general anaesthesia for cardiac surgery using sevoflurane, remifentanil, and atracurium. ⋯ The three indices performed equally well during the induction phase and were able to predict the level of consciousness of the patients satisfactorily. During maintenance, the IoC and the BIS showed good agreement with the clinical signs. The CSI was significantly influenced by the administration of atracurium; therefore, the agreement with the OAAS scale during the maintenance phase was significantly less for CSI than for IoC and BIS.
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Propofol is mainly metabolized in the liver, but extrahepatic clearance may also be important since systemic propofol clearance exceeds hepatic clearance. Recent reports suggest that the kidneys contribute to propofol elimination in humans and here we investigated renal elimination of propofol in a controlled animal study. ⋯ The kidneys are a minor site of propofol elimination in a swine model.
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Hyperventilation, with the resulting hypocapnia, reduces cerebral blood flow and causes slowing of the EEG activity. However, neuronal oscillating properties including the thalamocortical network during hyperventilation have not been elucidated. To assess these features provoked by hyperventilation, the present study examined quadratic phase coupling features by means of bicoherence analysis. ⋯ Hypocapnia enlarged bicoherence growth in the delta- frequency range, suggesting the contribution of subcortical oscillating mechanisms in regulating EEG during hyperventilation.
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In this study, we have investigated whether intrathecal (i.t.) lidocaine administration is accompanied with changes of cerebrospinal fluid (CSF) prostaglandin E(2) (PGE(2)) levels. ⋯ I.T. lidocaine (400 or 1000 microg) increases PGE(2) levels in the CSF for 90-120 min along with a transient period of mechanical hyperalgesia after sensory and motor block recovery.