Anesthesiology
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Gabapentin reduces acute postoperative and chronic neuropathic pain, but its sites and mechanisms of action are unclear. Based on previous electrophysiologic studies, the authors tested whether gabapentin reduced γ-amino butyric acid (GABA) release in the locus coeruleus (LC), a major site of descending inhibition, rather than in the spinal cord. ⋯ These results suggest that peripheral nerve injury induces plasticity of GABAergic neurons differently in the LC and spinal dorsal horn and that gabapentin reduces presynaptic GABA release in the LC but not in the spinal dorsal horn. The current study supports the idea that gabapentin activates descending noradrenergic inhibition via disinhibition of LC neurons.
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Our previous and other studies have shown that hypotensive or hypothermic resuscitation have beneficial effects on uncontrolled hemorrhagic shock. Whether hypothermia can increase the beneficial effect of hypotensive resuscitation on hemorrhagic shock is not known. ⋯ Mild hypothermia before bleeding is controlled can increase the beneficial effect of hypotensive resuscitation on uncontrolled hemorrhagic shock. The mechanism underlying the benefits of short-term hypothermia may be related to the decrease in oxygen consumption and metabolism, and protection of mitochondrial and organ functions.
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Low mean arterial pressure (MAP) and deep hypnosis have been associated with complications and mortality. The normal response to high minimum alveolar concentration (MAC) fraction of anesthetics is hypotension and low Bispectral Index (BIS) scores. Low MAP and/or BIS at lower MAC fractions may represent anesthetic sensitivity. The authors sought to characterize the effect of the triple low state (low MAP and low BIS during a low MAC fraction) on duration of hospitalization and 30-day all-cause mortality. ⋯ The occurrence of low MAP during low MAC fraction was a strong and highly significant predictor for mortality. When these occurrences were combined with low BIS, mortality risk was even greater. The values defining the triple low state were well within the range that many anesthesiologists tolerate routinely.
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Opioids induce analgesia mainly by inhibiting synaptic transmission via G protein-coupled opioid receptors. In addition to analgesia, buprenorphine induces a pronounced antihyperalgesia and is an effective adjuvant to local anesthetics. These properties only partially apply to other opioids, and thus targets other than opioid receptors are likely to be employed. Here we asked if buprenorphine inhibits voltage-gated Na(+) channels. ⋯ Buprenorphine is a potent local anesthetic and blocks voltage-gated Na(+) channels via the local anesthetic binding site. This property is likely to be relevant when buprenorphine is used for pain treatment and for local anesthesia.