Anesthesiology
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Neurosurgical procedures that require a frontal approach could be an impediment for a successful Bispectral Index (BIS) frontal sensor placement. The aim of this study was to explore the utility of using the new BIS-Vista monitor (Aspect Medical Systems, Newton, MA) for occipital sensor placement in the patients undergoing brain neurosurgical procedures during propofol-remifentanil anesthesia. ⋯ We demonstrated that not only the regional limits of agreement are too wide to allow data of the two montages to be used interchangeably but also the variation is a function of anesthetic depth. However, keeping in mind a relatively consistent BIS-Vista -10 bias before induction and +10 bias during anesthesia maintenance with limits of agreement of approximately +/-11 BIS units, approximately double the clinically acceptable less than 10 BIS units level of agreement, BIS-Vista off-label occipital montage might be helpful in following a trend of propofol-remifentanil anesthesia in individual cases where frontal access is particularly difficult.
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Previous studies using linear regression analysis have shown that age, weight, gender, and the site of operation affect intravenous patient-controlled analgesia (IVPCA) narcotic use. However, there are inconsistent observations in the literature. The authors postulate that patient variables could have different effects at various doses of narcotics. To test this hypothesis, the authors analyzed the effect of patient variables on increasing doses of IVPCA narcotic with quantile regression. ⋯ The authors' findings highlight the heterogeneous postoperative pain requirements among patients and the consequent complex process of efficiently managing postoperative pain.
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Adenosine triphosphate-sensitive potassium (KATP) channels in brain are involved in neuroprotective mechanisms. Pharmacologic activation of these channels is seen as beneficial, but clinical exploitation by using classic K channel openers is hampered by their inability to cross the blood-brain barrier. This is different with the inhalational anesthetic xenon, which recently has been suggested to activate KATP channels; it partitions freely into the brain. ⋯ Xenon represents a novel KATP channel opener that increases KATP currents independently of the sulfonylurea receptor-1 subunit by reducing ATP inhibition of the channel. Through this action and by its ability to readily partition across the blood-brain barrier, xenon has considerable potential in clinical settings of neuronal injury, including stroke.
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Endothelial nitric oxide synthase activity is regulated by (6R-)5,6,7,8-tetrahydrobiopterin (BH4) and heat shock protein 90. The authors tested the hypothesis that hyperglycemia abolishes anesthetic preconditioning (APC) through BH4- and heat shock protein 90-dependent pathways. ⋯ The results indicate that tetrahydrobiopterin and heat shock protein 90-regulated endothelial nitric oxide synthase activity play a central role in cardioprotection that is favorably modulated by volatile anesthetics and dysregulated by hyperglycemia. Enhancing the production of BH4 may represent a potential therapeutic strategy.
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Recent experimental observations suggest that, in addition to induce neuroapoptosis, anesthetics can also interfere with synaptogenesis during brain development. The aim of this study was to pursue this issue by evaluating the exposure time-dependent effects of volatile anesthetics on neuronal cytoarchitecture in 16-day-old rats, a developmental stage characterized by intense synaptogenesis in the cerebral cortex. ⋯ These new results suggest that volatile anesthetics, with different potencies and without inducing cell death, could rapidly interfere with physiologic patterns of synaptogenesis and thus might impair appropriate circuit assembly in the developing cerebral cortex.