Anesthesiology
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We investigated the role of tandem pore potassium ion channel (K2P) TRESK in neurobehavioral function and volatile anesthetic sensitivity in genetically modified mice. ⋯ TRESK alone is not critical for baseline central nervous system function but may contribute to the action of volatile anesthetics. The inhomogeneous change in anesthetic sensitivity corroborates findings in other K2P knockout mice and supports the theory that the mechanism of volatile anesthetic action involves multiple targets. Although it was not shown in this study, a compensatory effect by other K2P channels may also contribute to these observations.
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The concentration-response and time-response relationships of lipid emulsions used to reverse bupivacaine-induced asystole are poorly defined. ⋯ Lipid application in bupivacaine-induced asystole displays a concentration-dependent and time-response relationship in isolated rat hearts.
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The sites of action and cellular mechanisms by which spinal cord stimulation reduces neuropathic pain remain unclear. ⋯ These results suggest a potential cellular mechanism underlying spinal cord stimulation-induced pain relief. This in vivo model allows the neurophysiologic basis for spinal cord stimulation-induced analgesia to be studied.
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Temporary, antegrade amnesia is one of the core desirable endpoints of general anesthesia. Multiple lines of evidence support a role for the hippocampal θ rhythm, a synchronized rhythmic oscillation of field potentials at 4-12 Hz, in memory formation. Previous studies have revealed a disruption of the θ rhythm at surgical levels of anesthesia. We hypothesized that θ-rhythm modulation would also occur at subhypnotic but amnestic concentrations. Therefore, we examined the effect of three inhaled agents on properties of the θ rhythm considered critical for the formation of hippocampus-dependent memories. ⋯ At subhypnotic amnestic concentrations, θ-oscillation frequency was the parameter most consistently affected by these three anesthetics. These results are consistent with the hypothesis that modulation of the θ rhythm contributes to anesthetic-induced amnesia.
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Bedside assessments of cerebral oxygenation are sought to monitor cerebral injury in patients undergoing intensive care. Spatially resolved spectroscopy measures tissue oxygenation index (TOI, %) which reflects mixed cerebral arterial and venous oxygenations. We aimed to evaluate arterial and venous components of TOI (cerebral arterial to venous volume ratio [A:V ratio]) in the newborn lamb brain using cerebral arterial and venous blood samples, and to investigate the impact of acute hypoxemia on the A:V ratio and TOI. ⋯ TOI corresponds with cerebral oxygenation. The variable agreement of TOIsrs with TOIcox may reflect changes in cerebral A:V ratio due to arterial oxygenation-related vasoreactivity.