Anesthesiology
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There are no clinical data regarding the ratios and concentrations in which morphine and bupivacaine should be combined, when given intrathecally, to improve analgesia while decreasing adverse effects. This study was undertaken to test the clinical efficacy of a constant infusion of 0.5 mg/ml morphine plus 4.75 mg/ml bupivacaine (morphine: bupivacaine approximately 1:10), given through open intrathecal catheters. ⋯ A constant intrathecal infusion with a morphine:bupivacaine ratio of approximately 1:10 and concentrations of morphine of 0.5 mg/ml and bupivacaine of 4.75 mg/ml may significantly improve the relief of refractory cancer pain with a certain risk of adverse effects (which should be balanced against pain by the patient) from the relatively high intrathecal bupivacaine doses and concentration.
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Opioids are thought to have equal analgesic effects when equivalent doses are used. However, sufentanil may achieve maximum effect while occupying fewer spinal opioid receptors (higher intrinsic efficacy). Therefore, sufentanil may be more effective than morphine when administered intraspinally in opioid-tolerant patients. ⋯ These results suggest that sufentanil can be used successfully in opioid-tolerant patients who do not experience adequate pain control in the early postoperative period despite a large dose of epidural morphine. Moreover, sufentanil should be considered an effective alternative therapy for postoperative pain control in chronic opioid users using high doses of oral opioids before surgical intervention.
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Recent experimental data indicate that anesthesia is often associated with significant changes in brain concentrations of dopamine (DA), an inhibitory neurotransmitter located in restricted, but functionally important, areas such as the striatum. Whether the presynaptic DA nerve endings represent potential targets for anesthetics remains unknown. Therefore, the current study was designed to investigate the effects of volatile anesthetics, thiopental, and ketamine on both spontaneous and depolarization-evoked DA release from striatal synaptosomes in the rat. ⋯ The authors conclude that: (1) volatile anesthetics, thiopental, and ketamine exert significant changes in both spontaneous and depolarization-evoked 3H-DA release in the rat striatum; (2) enflurane uniquely enhances NMDA-receptor mediated dopamine release; and (3) the results obtained from these receptor-mediated effects (AMPA and NMDA) may apply to postsynaptic, as well as presynaptic, glutamate receptors.
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Randomized Controlled Trial Clinical Trial
Epidural anesthesia impairs both central and peripheral thermoregulatory control during general anesthesia.
The authors tested the hypotheses that: (1) the vasoconstriction threshold during combined epidural/general anesthesia is less than that during general anesthesia alone; and (2) after vasoconstriction, core cooling rates during combined epidural/general anesthesia are greater than those during general anesthesia alone. Vasoconstriction thresholds and heat balance were evaluated under controlled circumstances in volunteers, whereas the clinical importance of intraoperative thermoregulatory vasoconstriction was evaluated in patients. ⋯ These data indicate that epidural anesthesia reduces the vasoconstriction threshold during general anesthesia. Furthermore, the markedly reduced rate of core cooling during general anesthesia alone illustrates the importance of leg vasoconstriction in maintaining core temperature.
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Randomized Controlled Trial Comparative Study Clinical Trial
Recovery characteristics of desflurane versus halothane for maintenance of anesthesia in pediatric ambulatory patients.
Desflurane is a new potent, inhaled anesthetic agent with low blood-gas solubility that should allow for the rapid induction of and emergence from anesthesia. However, its extreme pungency makes desflurane unacceptable for induction of anesthesia in children. This study was undertaken to determine the airway properties of desflurane administered by mask after anesthetic induction with halothane and nitrous oxide, and to compare the emergence and recovery properties of minimum alveolar concentration (MAC)-equivalent concentrations of desflurane or halothane in nitrous oxide in pediatric patients undergoing ambulatory surgery. ⋯ In children premedicated with intranasal midazolam, desflurane maintenance anesthesia allows for a faster recovery. However, depending on the institution's criteria for ambulatory surgical patient discharge, desflurane may or may not affect the overall hospitalization time.