Anesthesiology
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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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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.
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The mechanism of the protective actions of volatile anesthetics in ischemic myocardium has not been clearly elucidated. The role of myocardial adenosine triphosphate-regulated potassium (KATP) channels in isoflurane-induced enhancement of recovery of regional contractile function after multiple brief occlusions and reperfusion of the left anterior descending coronary artery (LAD) was studied in dogs anesthetized with barbiturates. ⋯ The results indicate that isoflurane prevents decreased systolic shortening caused by multiple episodes of ischemia and reperfusion. These actions result in improved recovery of contractile function of postischemic, reperfused myocardium and are mediated by isoflurane-induced activation of KATP channels.
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This study was designed to evaluate the effects of sevoflurane with and without nitrous oxide on human middle cerebral artery (MCA) flow velocity, cerebrovascular carbon dioxide reactivity, and autoregulation compared with the awake state using transcranial Doppler ultrasonography. ⋯ Sevoflurane (1.2 MAC) reduced Vmca compared with the awake condition, whereas the addition of nitrous oxide caused Vmca to increase toward the values obtained in the awake condition. The cerebrovascular carbon dioxide reactivity and autoregulation were well maintained during 1.2 MAC sevoflurane with and without 60% nitrous oxide.