Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Antiemetic activity of propofol after sevoflurane and desflurane anesthesia for outpatient laparoscopic cholecystectomy.
Controversy exists regarding the effectiveness of propofol to prevent postoperative nausea and vomiting. This prospective, randomized, single-blinded study was designed to evaluate the antiemetic effectiveness of 0.5 mg/kg propofol when administered intravenously after sevoflurane- compared with desflurane-based anesthesia. ⋯ A subhypnotic intravenous dose of propofol (0.5 mg/kg) administered at the end of outpatient laparoscopic cholecystectomy procedures was more effective in preventing postoperative nausea and vomiting after a sevoflurane-based (compared with a desflurane-based) anesthetic.
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Remifentanil blood concentrations necessary for adequate intraoperative anesthesia have not been defined. The goal of this study was to determine the blood concentrations of remifentanil needed for anesthesia with 66% nitrous oxide during intraabdominal surgery. In addition, the pharmacokinetics of remifentanil and the effects of covariates on both the pharmacodynamics and the pharmacokinetics were determined. ⋯ The Cb50 differed according to patient gender. However, because surgery type was not specified for each man or woman, this may reflect a difference in surgical procedure.
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This study determined the induction profiles of immediate-early genes in the ovine brain after cardiopulmonary bypass (CPB) and hypothermic circulatory arrest (HCA), and the effects of the noncompetitive N-methyl-D-aspartate antagonist, aptiganel, on immediate-early gene expression, neuronal necrosis, and functional outcome. ⋯ The c-Jun and c-Fos proteins are expressed differentially in hippocampal neurons after CPB and HCA. Expression of c-Jun is associated with neuronal necrosis, whereas Fos protein expression is associated with survival. Aptiganel inhibits c-Jun expression, attenuates neuronal necrosis, and improves outcome.
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Desflurane, enflurane and isoflurane can be degraded to carbon monoxide (CO) by carbon dioxide absorbents, whereas sevoflurane and halothane form negligible amounts of CO. Carbon monoxide formation is greater with drier absorbent, and with barium hydroxide, than with soda lime. The mechanism, role of absorbent composition and water, and anesthetic structures determining CO formation are unknown. This investigation examined sequential steps in anesthetic degradation to CO. ⋯ A difluoromethoxy group is a structural requirement for haloether degradation to CO. Results are consistent with initial base-catalyzed difluoromethoxy proton abstraction (potassium > sodium hydroxide, thus greater CO formation with barium hydroxide lime vs. soda lime) forming a carbanion (reprotonated by water to regenerate the anesthetic, hence requirements for relatively dry absorbent), carbanion decomposition to a difluorocarbene, and subsequent difluorocarbene reaction to form CO.
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Potentiation by general anesthetics of gamma-aminobutyric acid (GABA)-mediated inhibitory transmission in the central nervous system is attributed to GABA(A) receptor-mediated postsynaptic effects. However, the role of presynaptic mechanisms in general anesthetic action is not well characterized, and evidence for anesthetic effects on GABA release is controversial. The effects of several intravenous general anesthetics on [3H]GABA release from rat cerebrocortical synaptosomes (isolated nerve terminals) were investigated. ⋯ Low concentrations of propofol, etomidate, pentobarbital, and alphaxalone facilitated [3H]GABA release from cortical nerve terminals. General anesthetics may facilitate inhibitory GABA-ergic synaptic transmission by a presynaptic mechanism in addition to their well-known postsynaptic actions.