Anesthesiology
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Randomized Controlled Trial Multicenter Study Clinical Trial
Reduction of isoflurane minimal alveolar concentration by remifentanil.
Remifentanil is a new micro-specific opioid receptor agonist currently under investigation. The interaction between opioids and volatile anesthetics is complex. Defining this interaction provides a basis for more rational dosing schemes when such combinations are used for anesthesia and allows the anesthetic potency of remifentanil relative to other opioids to be determined. ⋯ The MAC reduction of isoflurane by remifentanil is similar to that produced by other opioids. Although remifentanil was given at extremely high concentrations in the absence of isoflurane, it did not provide adequate anesthesia. A 50% isoflurane MAC reduction is produced by 1.37 ng/ml remifentanil whole blood concentration compared to previously published plasma concentrations of fentanyl of 1.67 ng/ml or sufentanil of 0.14 ng/ml.
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Randomized Controlled Trial Clinical Trial
Effect of flumazenil on ventilatory drive during sedation with midazolam and alfentanil.
Patients who receive a combination of a benzodiazepine and an opioid for conscious sedation are at risk for developing respiratory depression. While flumazenil effectively antagonizes the respiratory depression associated with a benzodiazepine alone, its efficacy in the presence of both a benzodiazepine and an opioid has not been established. This study was designed to determine whether flumazenil can reverse benzodiazepine-induced depression of ventilatory drive in the presence of an opioid. ⋯ Flumazenil effectively reverses the benzodiazepine component of ventilatory depression during combined administration of a benzodiazepine and an opioid.
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Randomized Controlled Trial Clinical Trial
Dose-response characteristics of spinal bupivacaine in volunteers. Clinical implications for ambulatory anesthesia.
Small doses of bupivacaine may be a reasonable choice for spinal anesthesia for patients having ambulatory surgery. However, few dose-response data are available to guide the selection of reasonable doses of bupivacaine for different ambulatory procedures. ⋯ These dose-response data may guide the selection of reasonable doses of bupivacaine for various outpatient procedures, although individual responses vary.
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The mechanism by which volatile anesthetics act on neuronal tissue to produce reversible depression is unknown. Previous studies have identified a potassium current in invertebrate neurons that is activated by volatile anesthetics. The molecular components generating this current are characterized here in greater detail. ⋯ The results demonstrate a unique ability of halothane and isoflurane to activate a specific class of potassium channels. Because potassium channels are important regulators of neuronal excitability within the mammalian central nervous system, background channels such as the S channel may be responsible in part for mediating the action of volatile anesthetics.
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An in vitro model of epidural catheter contamination was used to determine if disconnected catheters can be safely reconnected. ⋯ There may be an area distal to the disconnected end of an epidural catheter where its interior remains sterile for at least 8 hr. Such an area exists only when the fluid in the catheter remains static. Furthermore, the exterior of the catheter can be adequately cleaned to prevent bacteria from entering the catheter when reconnected at that point.