Anesthesiology
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Comparative Study
Bayesian prediction bounds and comparisons of operating room times even for procedures with few or no historic data.
Lower prediction bounds (e.g., for fasting), upper prediction bounds (e.g., to schedule delays between sequential surgeons), comparisons of operating room (OR) times (e.g., when sequencing cases among ORs), and quantification of case uncertainty (e.g., for sequencing a surgeon's list of cases) can be done accurately for combinations of surgeon and scheduled procedure(s) by using historic OR times. The authors propose that when there are few or no historic data, the predictive distribution of the OR time of a future case be centered at the scheduled OR time, and its proportional uncertainty be based on that of other surgeons and procedures. When there are a moderate or large number of historic data, the historic data alone are used in the prediction. When there are a small number of historic data, a weighted combination is used. ⋯ The authors validated a practical way to calculate prediction bounds and compare the OR times of all cases, even those with few or no historic data for the surgeon and the scheduled procedure(s).
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Comparative Study
Memory enhancing effect of low-dose sevoflurane does not occur in basolateral amygdala-lesioned rats.
Certain anesthetics might enhance aversive memory at doses around 0.1 minimum alveolar concentration. This issue was investigated in a rat model of learning and memory. In addition, evidence for basolateral amygdala (BLA) involvement in mediating memory enhancement was sought. ⋯ Sevoflurane enhances aversive memory formation in the rat. The BLA likely contributes to this effect. The risk of aversive memory formation may be enhanced during exposure to low-dose sevoflurane.
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The sevoflurane degradation product compound A is nephrotoxic in rats. In contrast, patient exposure to compound A during sevoflurane anesthesia has no clinically significant renal effects. The mechanism for this difference is incompletely understood. One possibility is that the metabolism and toxicity of compound A in humans is prevented by sevoflurane. However, the effect of sevoflurane on compound A metabolism and nephrotoxicity is unknown. Thus, the purpose of this investigation was to determine the effect of sevoflurane on the metabolism and renal toxicity of compound A in rats. ⋯ Sevoflurane does not suppress compound A nephrotoxicity in rats in vivo. These results do not suggest that lack of nephrotoxicity in surgical patients exposed to compound A during sevoflurane anesthesia results from an inhibitory effect of sevoflurane on compound A metabolism and toxicity. Rather, these results are consistent with differences between rats and humans in compound A exposure and inherent susceptibility to compound A nephrotoxicity.
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The sympathomimetic drug ephedrine has been used intrathecally as the sole local anesthetic for labor and delivery. Because ephedrine may be a useful adjuvant to local anesthetics, the authors investigated the local anesthetic properties of ephedrine in a rat sciatic nerve block model and the underlying mechanism in cultured cells stably expressing Na channels. ⋯ Because ephedrine's properties are at least partly due to Na channel blockade, detailed histopathologic investigations are justified to determine the potential of ephedrine as an adjuvant to clinically used local anesthetics.