Anesthesiology
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Pulse oximeter performance is degraded by motion artifacts and low perfusion. Manufacturers developed algorithms to improve instrument performance during these challenges. There have been no independent comparisons of these devices. ⋯ All oximeters detected hypoxemia during motion and low-perfusion conditions, but motion impaired performance at all ranges, with less accuracy at lower SaO2. Lower perfusion degraded performance in all but the Nihon Kohden instrument. We conclude that different types of pulse oximeters can be similarly effective in preserving sensitivity to clinically relevant hypoxia.
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Clinical and experimental data show that peripheral nerve blocks last longer in the presence of diabetic neuropathy. This may occur because diabetic nerve fibers are more sensitive to local anesthetics or because the local anesthetic concentration decreases more slowly in the diabetic nerve. The aim of this study was to investigate both hypotheses in a rodent model of neuropathy secondary to type 2 diabetes. ⋯ We demonstrate increased sensitivity of the diabetic neuropathic nerve toward local anesthetics, and prolonged residence time of local anesthetics in the diabetic neuropathic nerve. In this rodent model of neuropathy, both pharmacodynamic and pharmacokinetic mechanisms contribute to prolonged nerve block duration.
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The α2-adrenergic sedative/anesthetic agent dexmedetomidine exerts biphasic effects on isolated arteries, causing endothelium-dependent relaxations at concentrations at or below 30 nM, followed by contractions at higher concentrations. L-arginine is a common substrate of endothelial nitric oxide synthase and arginases. This study was designed to investigate the role of L-arginine in modulating the overall vascular response to dexmedetomidine. ⋯ These results suggest that when vascular nitric oxide homeostasis is impaired, the potentiation of the vasoconstrictor effect of dexmedetomidine by L-arginine depends on arginase activity and the production of urea and ornithine.