Anesthesiology
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Randomized Controlled Trial Multicenter Study Clinical Trial
Bispectral index monitoring allows faster emergence and improved recovery from propofol, alfentanil, and nitrous oxide anesthesia. BIS Utility Study Group.
The bispectral index (BIS), a parameter derived from the electroencephalograph (EEG), has been shown to correlate with increasing sedation and loss of consciousness. This study determined whether addition of BIS monitoring to standard anesthetic practice results in improvements in the conduct of anesthesia or in patient outcomes. ⋯ Titrating propofol with BIS monitoring during balanced anesthesia decreased propofol use and significantly improved recovery. Intraoperative course was not changed. These findings indicate that the use of BIS may be valuable in guiding the administration of propofol intraoperatively.
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Randomized Controlled Trial Clinical Trial
Dexmedetomidine does not alter the sweating threshold, but comparably and linearly decreases the vasoconstriction and shivering thresholds.
Clonidine decreases the vasoconstriction and shivering thresholds. It thus seems likely that the alpha2 agonist dexmedetomidine will also impair control of body temperature. Accordingly, the authors evaluated the dose-dependent effects of dexmedetomidine on the sweating, vasoconstriction, and shivering thresholds. They also measured the effects of dexmedetomidine on heart rate, blood pressures, and plasma catecholamine concentrations. ⋯ Dexmedetomidine markedly increased the range of temperatures not triggering thermoregulatory defenses. The drug is thus likely to promote hypothermia in a typical hospital environment; it is also likely to prove an effective treatment for shivering.
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Randomized Controlled Trial Comparative Study Clinical Trial
The comparative amnestic effects of midazolam, propofol, thiopental, and fentanyl at equisedative concentrations.
The authors evaluated the effects of midazolam, propofol, thiopental, and fentanyl on volunteer participants' memory for words and pictures at equisedative concentrations. ⋯ At equal sedation, propofol produces the same degree of memory impairment as midazolam. Thiopental has mild memory effects whereas fentanyl has none. Ondansetron alone has no sedative or amnesic effects.
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Randomized Controlled Trial Clinical Trial
Opioid-induced delay in gastric emptying: a peripheral mechanism in humans.
Opioids delay gastric emptying, which in turn may increase the risk of vomiting and pulmonary aspiration. Naloxone reverses this opiate action on gastric emptying, but it is not known whether this effect in humans is mediated by central or peripheral opiate antagonism. The importance of peripheral opioid receptor antagonism in modulating opioid-induced delay in gastric emptying was evaluated using methylnaltrexone, a quaternary derivative of the opiate antagonist naltrexone, which does not cross the blood-brain barrier. ⋯ The attenuation of morphine-induced delay in gastric emptying by methylnaltrexone suggests that the opioid effect is mediated outside the central nervous system. Methylnaltrexone may have the potential to decrease the side effects of opioid medications, which are mediated peripherally, while maintaining the central analgesia effect of the opioid.
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Randomized Controlled Trial Clinical Trial
Alfentanil blocks reflex pupillary dilation in response to noxious stimulation but does not diminish the light reflex.
Estimation of the mu-agonist opioid effect in anesthetized and paralyzed patients is often imprecise and can be obscured by concomitant administration of drugs that affect the sympathetic nervous system, such as beta-adrenergic blocking agents. As an alternative to hemodynamic measures of opioid effect, the authors tested the hypothesis that the pupillary light reflex or pupillary reflex dilation correlated with alfentanil concentrations during isoflurane anesthesia. ⋯ Dilation of the pupil in response to a noxious stimulus is a measure of opioid effect in isoflurane-anesthetized volunteers. In contrast, the pupillary light reflex is unaffected by alfentanil during isoflurane anesthesia. These data suggest that stimulus-induced pupillary dilation may be used to evaluate the analgesic component of a combined volatile and opioid anesthetic.