Anesthesiology
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Randomized Controlled Trial Clinical Trial
Preemptive analgesia by intravenous low-dose ketamine and epidural morphine in gastrectomy: a randomized double-blind study.
Morphine and ketamine may prevent central sensitization during surgery and result in preemptive analgesia. The reliability of preemptive analgesia, however, is controversial. ⋯ The results suggest that for definitive preemptive analgesia, blockade of opioid and N-methyl-d-aspartate receptors is necessary for upper abdominal surgery such as gastrectomy; singly, either treatment provided significant, but not definitive, postsurgical pain relief. Epidural morphine may affect the spinal cord segmentally, whereas intravenous ketamine may block brain stem sensitization via the vagus nerve during upper abdominal surgery.
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Multiport epidural catheters are popular; however, the reliability of the air test has not been evaluated with this catheter design. The authors determined the effectiveness of aspirating for blood and the air test in detecting intravascular multiorifice epidural catheters. ⋯ The authors obtained false-negative results with both catheter aspiration and the air test. Fractionating the local anesthetic dose is important when using multiorifice epidural catheters.
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Neuronal excitability is in part determined by Ca2+ availability that is controlled by regulatory mechanisms of cytosolic Ca2+ ([Ca2+]cyt). Alteration of any of those mechanisms by volatile anesthetics (VAs) may lead to a change in presynaptic transmission and postsynaptic excitability. Using a human neuroblastoma cell line, the effects of halothane and isoflurane on cytosolic Ca2+ concentration ([Ca2+]cyt) in response to K+ and carbachol stimulation were investigated. ⋯ Volatile anesthetics acted on sites that differently affect the K+- and carbachol-evoked [Ca2+]cyt transients. These data suggest the involvement of an intracellular Ca2+ translocation from the caffeine-sensitive Ca2+ store to the inositol triphosphate-sensitive Ca2+ store that was altered by halothane and isoflurane.
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Systemically administered local anesthetics and other sodium channel blockers produce analgesia in patients with hypersensitivity disorders. To assess whether these agents have a role in the treatment of visceral pain, the present study examined the effects of intravenous lidocaine on neuronal and reflex responses to colorectal distension. ⋯ Intravenous lidocaine had dose-dependent, inhibitory effects on two spinal neuronal populations excited by colorectal distension and dose-dependently inhibited reflex responses to the same stimulus. This suggests there may be utility of sodium channel blockers in the treatment of pain of visceral origin.