Anesthesiology
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Comparative Study
Performance characteristics of five new anesthesia ventilators and four intensive care ventilators in pressure-support mode: a comparative bench study.
During the past few years, many manufacturers have introduced new modes of ventilation in anesthesia ventilators, especially partial-pressure modalities. The current bench test study was designed to compare triggering and pressurization of five new anesthesia ventilators with four intensive care unit ventilators. ⋯ Regarding trigger sensitivity and the system's ability to meet inspiratory flow during pressure-supported breaths, the most recent anesthesia ventilators have comparable performances of recent-generation intensive care unit ventilators.
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Randomized Controlled Trial
Positron emission tomography study of regional cerebral metabolism during general anesthesia with xenon in humans.
The precise mechanism by which the gaseous anesthetic xenon exerts its effects in the human brain remains unknown. Xenon has only negligible effects on inhibitory gamma-aminobutyric acid receptors, one of the putative molecular targets for most general anesthetics. Instead, xenon has been suggested to induce anesthesia by inhibiting excitatory glutamatergic signaling. Therefore, the authors hypothesized that xenon, similar to ketamine and nitrous oxide, increases global and regional cerebral metabolism in humans. ⋯ Xenon induces metabolic depression in the human brain, suggesting that the inhibition of the glutamatergic system is likely to be of minor significance for the anesthetic action of xenon in vivo.
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Comparative Study Clinical Trial
No sex differences in memory formation during general anesthesia.
Women respond differently to anesthesia than men, initially recovering more rapidly, but having more postoperative morbidity. Studies on surgical patients report evidence of memory formation during anesthesia. However, sex differences in memory formation have not been explored. Therefore, the authors investigated sex differences in the implicit and explicit memory formation during general anesthesia. ⋯ Patients showed greater memory performance for words presented during general anesthesia than for words not presented. However, sex differences in memory formation were not observed. A relation between hypnotic state and memory during sevoflurane anesthesia was also established, suggesting that memory formation is possible even at hypnotic depths considered to be adequate anesthesia.
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Dexmedetomidine, a selective alpha2-adrenoceptor agonist, has counteracting effects on the cardiovascular system. It mediates sympatholysis by activating alpha2 adrenoceptors in the central and peripheral nervous system, and vasoconstriction and vasorelaxation by activating postsynaptic alpha2 adrenoceptors in blood vessels. The goal of this study was to determine the effects of therapeutic and high concentrations of dexmedetomidine on myocardial perfusion and cardiac function in healthy subjects. ⋯ In healthy subjects, plasma concentrations of dexmedetomidine that significantly exceed the recommended therapeutic level do not seriously attenuate myocardial perfusion below the level that is observed with usual therapeutic concentrations and do not induce evident myocardial ischemia.