Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2014
The Effect of Age on the Median Effective Dose (ED50) of Intrathecally Administered Plain Bupivacaine for Motor Block.
In this study, we sought to determine the median effective dose (ED50) for motor block of intrathecally administered plain bupivacaine in adults (20-80 years) and to assess the effect of age on ED50 required for motor block. ⋯ The ED50 for motor block of intrathecally administered plain bupivacaine decreased steeply with advancing age.
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Anesthesia and analgesia · Apr 2014
Dexamethasone produces dose-dependent inhibition of sugammadex reversal in in vitro innervated primary human muscle cells.
Corticosteroids are frequently used during anesthesia to provide substitution therapy in patients with adrenal insufficiency, as a first-line treatment of several life-threatening conditions, to prevent postoperative nausea and vomiting, and as a component of multimodal analgesia. For these last 2 indications, dexamethasone is most frequently used. Due to the structural resemblance between aminosteroid muscle relaxants and dexamethasone, concerns have been raised about possible corticosteroid inhibition in the reversal of neuromuscular block by sugammadex. We thus investigated the influence of dexamethasone on sugammadex reversal of rocuronium-induced neuromuscular block, which could be relevant in certain clinical situations. ⋯ This is the first report in which the effects of rocuronium and sugammadex interactions with dexamethasone have been studied in a highly accessible in vitro experimental model of functionally innervated human muscle cells. Sugammadex reverses rocuronium-induced neuromuscular block; however, concomitant addition of high dexamethasone concentrations diminishes the efficiency of sugammadex. Further studies are required to determine the clinical relevance of these interactions.
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Anesthesia and analgesia · Apr 2014
Differential suppression of intracranial self-stimulation, food-maintained operant responding, and open field activity by paw incision and spinal nerve ligation in rats.
Detection of ongoing spontaneous pain behaviors in laboratory animals remains a research challenge. Most preclinical pain studies measure elicited behavioral responses to an external noxious stimulus; however, ongoing spontaneous pain in humans and animals may be unrelated to hypersensitivity, and likely diminishes many behaviors, particularly motivated behaviors, that we hypothesize will decrease after induction of acute and chronic pain. ⋯ The acute effects of INC on decreasing lever pressing for VTA ICSS and FR (1-2 days after incision) correspond to the timeframe in which ongoing spontaneous pain is expected to occur after INC. Therefore, these decreases are likely mediated by ongoing spontaneous pain, which may be unrelated to mechanical hypersensitivity that persists for up to 4 days after INC. PWT is decreased similarly by SNL, yet operant behavior (lever pressing for VTA ICSS and FR) was not decreased by SNL. SNL, but not INC, decreased rearing behavior but not total distance traveled during OFA. This further indicates that the presence and the extent of hypersensitivity are not predictive of many behavioral changes in rats thought to be mediated by the presence of ongoing pain. Surprisingly, the behavioral effects of INC are not exacerbated in SNL rats. These data support the growing belief that acute pain models produce short-lived spontaneous pain behaviors that are often less pronounced or absent in neuropathic pain models, and highlight the need for assessment of both evoked and nonevoked pain behaviors in developing future therapies for acute and chronic pain.