Anesthesiology
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Randomized Controlled Trial Clinical Trial
Plasma concentration of fentanyl with xenon to block somatic and hemodynamic responses to surgical incision.
Although anesthesia with xenon has been supplemented with fentanyl, its requirement has not been established. This study was conducted to determine the plasma concentrations of fentanyl necessary to suppress somatic and hemodynamic responses to surgical incision in 50% patients in the presence of 0.7 minimum alveolar concentration (MAC) xenon. ⋯ Comparing these results with previously published results in the presence of 70% nitrous oxide, the fentanyl requirement in xenon anesthesia is smaller than that in the equianesthetic nitrous oxide anesthesia.
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Randomized Controlled Trial Clinical Trial
Investigation of effective anesthesia induction doses using a wide range of infusion rates with undiluted and diluted propofol.
The influence of infusion rate on the induction dose-response relation has not been investigated over a wide range of infusion rates. In this study, the authors defined the effect of different propofol infusion rates on the times and doses necessary to reach clinical induction of anesthesia. ⋯ Induction dose and time are dependent on infusion rate in a complex manner, and residual dose circulation was a factor in overdose and hemodynamic depression. Hypotension during induction was attenuated by diluted propofol.
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Occurrence of explicit memory (i.e., conscious recall) has been reported especially after surgical procedures in which anesthesia is considered to be "light." In addition, previous research has shown that implicit memory (e.g., improved memory test performance in absence of conscious recall) decreases with increasing hypnotic state. The current study investigated explicit and implicit memory during emergency cesarean sections with consistently light levels of hypnotic state. ⋯ This study shows that if words are presented at relatively light levels of anesthesia, patients are able to control their inclusion-exclusion decisions. This weak form of explicit memory can occur in the absence of conscious recall.
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Comparative Study
Contrasting synaptic actions of the inhalational general anesthetics isoflurane and xenon.
The mechanisms by which the inhalational general anesthetics isoflurane and xenon exert their effects are unknown. Moreover, there have been surprisingly few quantitative studies of the effects of these agents on central synapses, with virtually no information available regarding the actions of xenon. ⋯ For both isoflurane and xenon, the most important targets appear to be postsynaptic. The authors' results show that isoflurane and xenon have very different effects on GABAergic and glutamatergic synaptic transmission, and this may account for their differing pharmacologic profiles.
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Medical institutions are under increased economic pressure to schedule elective surgeries efficiently to contain the costs of surgical services. Surgical scheduling is complicated by variability inherent in the duration of surgical procedures. Modeling that variability, in turn, provides a mechanism to generate accurate time estimates. Accurate time estimates are important operationally to improve operating room utilization and strategically to identify surgeons, procedures, or patients whose duration of surgeries differ from what might be expected. ⋯ The authors recommend use of the log-normal model for predicting surgical procedure times for Current Procedural Terminology-anesthesia combinations. The results help to legitimize the use of log transforms to normalize surgical procedure times before hypothesis testing using linear statistical models or other parametric statistical tests to investigate factors affecting the duration of surgeries.