Anesthesiology
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Comparative Study Clinical Trial
Suppression of spinal cord motoneuron excitability correlates with surgical immobility during isoflurane anesthesia.
Recent evidence suggests that the spinal cord is an important site of anesthetic action that produces surgical immobility. Inhalation anesthetics depress the Hoffmann's reflex (H reflex) and F wave, indicating spinal motoneuron suppression. The aim of this study was to assess the correlation between isoflurane-induced immobility and H- and F-wave suppression. ⋯ The degree of H- and F-wave amplitude and F-wave persistence suppression correlates with movement response, suggesting that isoflurane-suppressive action in the spinal cord plays a significant role in producing surgical immobility.
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Comparative Study
Effect of subarachnoid bupivacaine block on anesthetic requirements for thiopental in rats.
Subarachnoid bupivacaine blockade has been reported to reduce thiopental and midazolam hypnotic requirements in patients. The purpose of this study was to examine if local anesthetically induced lumbar intrathecal blockade would reduce thiopental requirements for blockade of motor responses to noxious and nonnoxious stimuli in rats. ⋯ This study demonstrates that lumbar intrathecally administered local anesthetic blockade decreases anesthetic requirements for thiopental for a spectrum of end points tested. This effect is due neither to altered pharmacokinetics nor to a direct action of the local anesthetic on the brain; rather, it is most likely due to decreased afferent input.
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Comparative Study
Pretreatment or resuscitation with a lipid infusion shifts the dose-response to bupivacaine-induced asystole in rats.
The authors sought to confirm a chance observation that intravenous lipid treatment increases the dose of bupivacaine required to produce asystole in rats. The authors also measured the partitioning of bupivacaine between the lipid and aqueous phases of a plasma-lipid emulsion mixture. ⋯ Lipid infusion shifts the dose-response to bupivacaine-induced asystole in rats. Partitioning of bupivacaine into the newly created lipid phase may partially explain this effect. These results suggest a potential application for lipid infusion in treating cardiotoxicity resulting from bupivacaine.
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Comparative Study
The effect of the reduction of colloid oncotic pressure, with and without reduction of osmolality, on post-traumatic cerebral edema.
It has been asserted that reduction of colloid oncotic pressure (COP) can aggravate traumatic brain edema. To explore this issue, the authors measured the effect of COP reduction, with and without a simultaneous decrease in osmolality, on the development of brain edema after fluid percussion injury (FPI). ⋯ These data, while confirming the important edematogenic effect of decreased osmolality, indicate that COP reduction per se can also aggravate brain edema after a mild to moderate mechanical head injury.