Anesthesiology
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Ketamine produces potent analgesia combined with psychedelic effects. It has been suggested that these two effects are associated and possibly that analgesia is generated by ketamine-induced dissociation. The authors performed a post hoc analysis of previously published data to quantify the pharmacodynamic properties of ketamine-induced antinociception and psychedelic symptoms. The hypothesis was that ketamine pharmacodynamics (i.e., concentration-effect relationship as well as effect onset and offset times) are not different for these two endpoints. ⋯ The authors conclude that their data support an association or connectivity between ketamine analgesia and dissociation. Given the intricacies of the study related to the pain model, measurement of dissociation, and complex modeling of the combination of ketamine and norketamine, it is the opinion of the authors that further studies are needed to detect functional connectivity between brain areas that produce the different ketamine effects.
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Effect of Nitrous Oxide and of Narcotic Premedication on the Alveolar Concentration Required for Anesthesia. By , Eger EI II. Anesthesiology 1964; 25:302-6. ⋯ A rare side effect of a volatile anesthetic is that in some patients, malignant hyperthermia may occur with or without succinylcholine use. This phenomenon was detected in a patient in whom halothane MAC was being measured. The availability of the Severinghaus blood gas device allowed for the first ever measurement of the metabolic and respiratory acidemia that accompanies malignant hyperthermia.
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Vigorous spontaneous effort can potentially worsen lung injury. This study hypothesized that the prone position would diminish a maldistribution of lung stress and inflation after diaphragmatic contraction and reduce spontaneous effort, resulting in less lung injury. ⋯ Prone position, independent of positive end-expiratory pressure levels, diminishes a maldistribution of lung stress and inflation imposed by spontaneous effort and mitigates spontaneous effort, resulting in less effort-dependent lung injury.
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The neural circuitry underlying sevoflurane-induced modulation of consciousness is poorly understood. This study hypothesized that the paraventricular thalamus bed nucleus of the stria terminalis pathway plays an important role in regulating states of consciousness during sevoflurane anesthesia. ⋯ In mice, axonal projections from the paraventricular thalamic neurons to the bed nucleus of the stria terminalis contribute to regulating states of consciousness during sevoflurane anesthesia.