Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2003
The effect of sevoflurane and propofol on cerebral neurotransmitter concentrations during cerebral ischemia in rats.
Sevoflurane and propofol are neuroprotective possibly by attenuating central or peripheral catecholamines. We evaluated the effect of these anesthetics on circulating catecholamines and brain neurotransmitters during ischemia in rats. Forty male Sprague-Dawley rats were randomly assigned to one of the following treatment groups: fentanyl and N(2)O/O(2) (control), 2.0% sevoflurane, 0.8-1.2 mg x kg(-1) x min(-1) of propofol, and sham-operated rats with fentanyl and N(2)O/O(2). Ischemia (30 min) was produced by unilateral common carotid artery occlusion plus hemorrhagic hypotension to a mean arterial blood pressure of 32 +/- 2 mm Hg. Pericranial temperature, arterial blood gases, and pH value were maintained constant. Cerebral catecholamine and glutamate concentrations, sampled by microdialysis, and plasma catecholamine concentrations were analyzed using high-pressure liquid chromatography. During ischemia, circulating catecholamines were almost completely suppressed by propofol but only modestly decreased with sevoflurane. Sevoflurane and propofol suppressed brain norepinephrine concentration increases by 75% and 58%, respectively, compared with controls. Intra-ischemia cerebral glutamate concentration was decreased by 60% with both sevoflurane and propofol. These results question a role of circulating catecholamines as a common mechanism for cerebral protection during sevoflurane and propofol. A role of brain tissue catecholamines in mediating ischemic injury is consistent with our results. ⋯ During incomplete cerebral ischemia, the neuroprotective anesthetics sevoflurane and propofol suppressed cerebral increases in norepinephrine and glutamate concentrations. In contrast, propofol, but not sevoflurane, suppressed the ischemia-induced increase in circulating catecholamines to baseline levels. The results question a role for plasma catecholamines in cerebral ischemic injury.
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Anesthesia and analgesia · Oct 2003
Comment Letter Comparative StudyClinical manifestations of latex anaphylaxis during anesthesia differ from those not anesthesia/surgery-related.
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Anesthesia and analgesia · Oct 2003
Letter Case ReportsInterpleural migration of an interscalene catheter.
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Anesthesia and analgesia · Oct 2003
Can determining the minimum alveolar anesthetic concentration of volatile anesthetic be used as an objective tool to assess antinociception in animals?
We intended to evaluate the reliability of the minimum anesthetic alveolar concentration (MAC)-sparing effect as an objective measure of the antinociceptive properties of a drug. For this purpose, we tested different variables and analyzed the significance of the results obtained. In a first set of experiments, we studied rats under mechanical ventilation and sevoflurane anesthesia. Outcome variables such as gross purposeful movements consecutive to tail clamping, paw withdrawal consecutive to increasing pressure, and cardio-circulatory reactivity (MACBAR) after these stimuli were recorded. In a second set of experiment, sevoflurane-anesthetized rats under spontaneous breathing conditions were used. Thermal stimuli were compared with pressure. The MAC-sparing effect of several doses of sufentanil and clonidine was evaluated in both anesthetized and awake rodents. When considering the stimulus applied, larger concentrations of sevoflurane were required to suppress reactivity after tail clamp than after paw pressure or radiant heat (1.81 +/- 0.28 versus 1.45 +/- 0.22 and 1.53 +/- 0.26; P < 0.05). For the two first stimuli, no significant differences were noted between the concentrations that suppress motor or cardio-circulatory reactions. All doses of sufentanil tested significantly reduced (P < 0.05) the different MAC values except the smallest one (0.005 micro g x kg(-1) x min(-1)) that significantly increased MACBAR in ventilated animals and both MAC and MACBAR in spontaneously breathing rodents (P < 0.05). Clonidine, at its optimal dose (10 micro g/kg), significantly reduced both MAC and MACBAR to the same degree. In awake animals submitted to radiant heat or pressure challenge, none of the clonidine doses nor sufentanil doses (0.005 and 0.07) were active. In conclusion, the MAC-sparing effect provides several reliable and quantifiable variables that allow comparison between different analgesic substances. However, the observations made are not simply the result of antinociceptive effects of the tested drugs but rather that of complex interactions between these drugs and a halogenated vapor. ⋯ The MAC-sparing effect provides several variables that allow comparison between different analgesic substances. However, the observations made are not simply the result of the antinociceptive effects of the tested drugs but rather the result of complex interactions between these drugs and a halogenated vapor.
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Anesthesia and analgesia · Oct 2003
Comment Letter Comparative StudyComparing the ProSeal laryngeal mask airway with the laryngeal tube airway.