Anesthesiology
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Comparative Study Clinical Trial
Postural stability following ambulatory regional analgesia for labor.
The safety of mobilization following low-dose regional analgesia in parturients remains controversial. Previous studies have demonstrated preserved balance function despite clinically elicited sensory deficits. The aim of this study was to use the Balance Master 6.1, a device capable of real-time analysis of ambulation, to score the performance of basic maneuvers following initiation of low-dose combined spinal-epidural analgesia in laboring women compared with pregnant and nonpregnant controls. ⋯ Being pregnant at term significantly affects balance function, although initial low-dose spinal-epidural analgesia does not impair function further. Subsequent supplemental epidural analgesia may have a detrimental effect on balance, but properly designed studies are awaited to confirm this. This study supports the practice of allowing laboring women with initial low-dose spinal-epidural analgesia to ambulate, but indicates that further studies need to be conducted on the effects of subsequent epidural supplementation.
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Reactive oxygen species (ROS) contribute to myocardial protection during ischemic preconditioning, but the role of the ROS in protection against ischemic injury produced by volatile anesthetics has only recently been explored. We tested the hypothesis that ROS mediate isoflurane-induced preconditioning in vivo. ⋯ The results indicate that ROS produced following administration of isoflurane contribute to protection against myocardial infarction in vivo.
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Animal experiments in recent years have shown that attenuation of motor responses by general anesthetics is mediated at least partly by spinal mechanisms. Less is known about the relative potency of anesthetic drugs in suppressing cortical and spinal electrophysiological responses in vivo in humans, particularly those, but not only those, connected with motor responses. Therefore, we studied the effects of sevoflurane and propofol in humans using multimodal electrophysiological assessment. ⋯ The large effect of both anesthetics on all spinal motor responses, compared with the small effect on electroencephalography and middle-latency auditory evoked responses, assuming that they represent cortical modulation, may suggest that the suppression of motor responses to transcranial magnetic stimulation is largely due to submesencephalic effects.
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In a previous study, the authors found that nitrous oxide (N2O) exposure induces c-Fos (an immunohistochemical marker of neuronal activation) in spinal cord gamma-aminobutyric acid-mediated (GABAergic) neurons in Fischer rats. In this study, the authors sought evidence for the involvement of alpha1 adrenoceptors in the antinociceptive effect of N2O and in activation of GABAergic neurons in the spinal cord. ⋯ These findings support the hypothesis that N2O activates GABAergic interneurons through alpha1 adrenoceptors to produce its antinociceptive effect.
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Acoustic reflectometry allows the construction of a one-dimensional image of a cavity, such as the airway or the esophagus. The reflectometric area-distance profile consists of a constant cross-sectional area segment (length of endotracheal tube), followed either by a rapid increase in the area beyond the carina (tracheal intubation) or by an immediate decrease in the area (esophageal intubation). ⋯ Acoustic reflectometry is a rapid, noninvasive method by which to determine whether breathing tube placement is correct (tracheal) or incorrect (esophageal). Reflectometry determination of tube placement may be useful in airway emergencies, particularly in cases where visualization of the glottic area is not possible and capnography may fail, as in patients with cardiac arrest.