Anesthesiology
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Volatile anesthetics show an ischemic preconditioning-like cardioprotective effect, whereas intravenous anesthetics have cardioprotective effects for ischemic-reperfusion injury. Although recent evidence suggests that mitochondrial adenosine triphosphate-regulated potassium (mitoK(ATP)) channels are important in cardiac preconditioning, the effect of anesthetics on mitoK(ATP) is unexplored. Therefore, the authors tested the hypothesis that anesthetics act on the mitoK(ATP) channel and mitochondrial flavoprotein oxidation. ⋯ Inhalational anesthetics induce flavoprotein oxidation through opening of the mitoK(ATP) channel. This may be an important mechanism contributing to anesthetic-induced preconditioning. Cardioprotective effects of intravenous anesthetics may not be dependent on flavoprotein oxidation, but the administration of propofol or pentobarbital may potentially inhibit the cardioprotective effect of inhalational anesthetics.
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Ocular perfusion pressure is commonly defined as mean arterial pressure minus intraocular pressure (IOP). Changes in mean arterial pressure or IOP can affect ocular perfusion pressure. IOP has not been studied in this context in the prone anesthetized patient. ⋯ Prone positioning increases IOP during anesthesia. Ocular perfusion pressure could therefore decrease, despite maintenance of normotension.
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Clinical Trial
The transfer half-life of morphine-6-glucuronide from plasma to effect site assessed by pupil size measurement in healthy volunteers.
Clinical and experimental data suggested a long delay between the plasma concentration versus time course of morphine-6-glucuronide and the time course of its central opioid effects. This study was aimed at the quantification of the transfer half-life (t(1/2,ke0)) of this delay. ⋯ The reported numerical value of the t(1/2,ke0) of M6G in humans obtained after direct administration of M6G is a step toward a complete modeling approach to the prediction of the clinical effects of morphine. The study raises questions about the high interindividual variability of the transfer half-life between plasma and effect site (ke0) values and the apparent low potency of M6G.
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Comparative Study
Isoflurane and sevoflurane anesthesia in pigs with a preexistent gas exchange defect.
Decreased arterial partial pressure of oxygen (PaO2) during volatile anesthesia is well-known. Halothane has been examined with the multiple inert gas elimination technique and has been shown to alter the distribution of pulmonary blood flow and thus PaO2. The effects of isoflurane and sevoflurane on pulmonary gas exchange remain unknown. The authors hypothesized that sevoflurane with a relatively high minimum alveolar concentration (MAC) would result in significantly more gas exchange disturbances in comparison with isoflurane or control. ⋯ In pigs with an already existent gas exchange defect, sevoflurane anesthesia but not isoflurane anesthesia causes significantly more gas exchange disturbances than propofol anesthesia does.
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The general anesthetic ketamine is known to be an N-methyl-D-aspartate receptor blocker. Although ketamine also blocks voltage-gated sodium channels in a local anesthetic-like fashion, little information exists on the molecular pharmacology of this interaction. We measured the effects of ketamine on sodium channels. ⋯ Ketamine interacts with sodium channels in a local anesthetic-like fashion, including sharing a binding site with commonly used clinical local anesthetics.