Anesthesiology
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The authors and others have demonstrated that supraspinal opiate receptors and spinal alpha2 adrenoceptors are involved in the analgesic mechanism for nitrous oxide (N2O). The authors hypothesize that activation of opiate receptors in the periaqueductal gray results in the activation of a descending noradrenergic pathway that releases norepinephrine onto alpha2 adrenoceptors in the dorsal horn of the spinal cord. ⋯ A descending noradrenergic pathway in the spinal cord links N2O-induced activation of opiate receptors in the periaqueductal gray, with activation of alpha2 adrenoceptors in the spinal cord. N2O-induced release of norepinephrine in the dorsal horn of the spinal cord is blocked by naltrexone, as is the analgesic response. Spinal norepinephrine is necessary for the analgesic response to the N2O.
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alpha2-Adrenergic agonists produce analgesia primarily by a spinal action and hypotension and bradycardia by actions at several sites. Clonidine is approved for epidural use in the treatment of neuropathic pain, but its wider application is limited by hemodynamic side effects. This study determined the antinociceptive and hemodynamic effects of a novel alpha2-adrenergic agonist, MPV-2426, in sheep. ⋯ MPV-2426 shares many characteristics of other alpha2-adrenergic agonists examined in sheep, but differs from clonidine and dexmedetomidine by lack of antinociception and minimal reduction in oxygen partial pressure after large intravenous and epidural injections. No hemodynamic depression was observed after intrathecal injection at antinociceptive doses. These results suggest this compound may be an effective spinal analgesic in humans with less hypotension than clonidine, although its relative potency to cause sedation was not tested in this study.
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Delayed elimination kinetics of steroidal neuromuscular blocking agents have been observed in patients with cirrhosis. Like other steroidal muscle relaxants, rapacuronium may, in part, be eliminated by the liver. To determine the influence of liver disease on its neuromuscular blocking effect, we studied the pharmacokinetics and pharmacodynamics of rapacuronium in patients with cirrhosis. ⋯ The neuromuscular blocking effect of a single bolus dose of rapacuronium in patients with cirrhosis is not different from that of patients with normal hepatic function. No decrease in plasma clearance of rapacuronium was observed in patients with cirrhosis.
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Allocation of the correct amount of operating room (OR) "block time" can provide surgeons with access to sufficient OR time to complete their elective cases while optimally matching staffing with the elective case workload (to maximize labor productivity). To evaluate how to predict accurately total hours of elective cases performed by a surgical group using data from surgical services information systems, the authors addressed the following questions: (1) How many previous 4-week periods of data should be used to minimize error in forecasting a surgical group's total hours of elective cases? (2) Using the number of 4-week periods from question #1, can we detect trends or correlations between successive periods that could be used to improve forecasting accuracy? (3) How can results from questions #1 and #2 be used to calculate an upper prediction bound (upper limit) for the total hours of elective cases that will be completed in a future period? Prediction bounds can be used to budget staffing accurately. ⋯ The average of the most recent 12 4-week periods can be used to predict surgical groups' future use of block time.
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Increasing evidence has suggested the possibility that the activation of N-methyl-D-aspartate (NMDA) receptors modulates spinal nociceptive transmission via a nitric oxide (NO)/cyclic guanosine 3',5'-monophosphate (cGMP) pathway. However, the existence and the role of an NO/cGMP pathway in the modulation of spinal nociceptive transmission has been unclear. The authors hypothesized that the activation of NMDA receptors stimulates an NO/cGMP pathway, and this pathway evokes glutamate release within the spinal cord, modulating spinal nociceptive transmission. ⋯ The results of this study support the hypothesis that the activation of NMDA receptors modulated pain-related behavior via an NO/cGMP/glutamate release cascade within the spinal cord.